Thermal-Hydraulic Phenomena - July 17, 2001


                Official Transcript of Proceedings


Title:                    Advisory Committee on Reactor Safeguards
                               Thermal Hydraulic Phenomena Subcommittee

Docket Number:  (not applicable)

Location:                 Corvallis, Oregon

Date:                     Tuesday, July 17, 2001

Work Order No.: NRC-325                               Pages 1-322

                   NEAL R. GROSS AND CO., INC.
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                          (202) 234-4433                         UNITED STATES OF AMERICA
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                           PTS RULE REEVALUATION
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                          TUESDAY, JULY 17, 2001
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                             CORVALLIS, OREGON
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                 The ACRS Thermal Hydraulic Phenomena
           Subcommittee met at Oregon State University,
           Richardson Hall, Room 313, Corvallis, Oregon, at 8:15 
           a.m., Dr. Graham B. Wallis, Chairman, presiding.
                 GRAHAM B. WALLIS, Chairman
                 THOMAS S. KRESS, Member
                 WILLIAM J. SHACK, Member
                 PAUL A. BOEHNERT, ACRS Engineer
                 VIRGIL SCHROCK, ACRS Consultant
                 DAVID BESSETTE, RES/SMSAB
                 JAMES T. HAN, RES/DSARE/SMSAB
                 ROY WOODS, NRC RES/DRAA/PRN3
                        Agenda Item                        Page
           Opening remarks and welcome from Dean. . . . . . . 4
           Overview of OSU Nuclear Reactor Research . . . . .35
           NRC Staff Report on Intentional Use of
                 OSU Work . . . . . . . . . . . . . . . . . 208
           Pressurized Thermal Shock Research . . . . . . . 211
           OSU PTS Test Facilities and Palisades
                 Operations . . . . . . . . . . . . . . . . 228
           Summary of Integral System Overcooling
                 Test Results . . . . . . . . . . . . . . . 249
           Numerical Simulation for APEX-CE MSLB and
                 SBLOCA Tests Using RELAP5/MOD 3.2.2
                 (Gamma Version). . . . . . . . . . . . . . 267
                                                    (8:15 a.m.)
                       CHAIRMAN WALLIS:  The meeting will now
           come to order.  This is a meeting of the ACRS
           Subcommittee on Thermal Hydraulic Phenomena.  I'm
           Graham Wallis, the Chairman of the Subcommittee.
                       ACRS Members in attendance are Dr. Thomas
           Kress, Mr. William Shack.  And also in attendance is
           ACRS Consultant Virgil Schrock.
                       The purpose of this meeting is to discuss
           the status of:
                       Item 1, the NRC Office of Nuclear
           Regulatory Research -- big topic -- experimental
           program being conducted at the Oregon State
           University, OSU, APEX-CE facility, pertaining to
           thermal hydraulic phenomena associated with
           pressurized thermal shock, PTS, in support of the NRC
           PTS Rule Reevaluation Program; and,
                       2, the RES Program underway at OSU to
           investigate phase separation phenomena in support of
           proposed model upgrades for the RES TRAC M and RELAP5
                       The Subcommittee will gather information,
           analyze relevant issues and facts, and formulate
           proposed positions and actions as appropriate for
           deliberation by the full Committee.
                       Mr. Paul Boehnert is the designated
           federal official for this meeting.
                       The rules for participation in today's
           meeting have been announced as part of the notice of
           this meeting previously published in the Federal
           Register on July 6, 2001.
                       A transcript of the meeting is being kept
           and will be made available as stated in the Federal
           Register notice.
                       It is requested that speakers first
           identify themselves and speak with sufficient clarity
           and volume so that they can be readily heard.
                       We have received no written comments or
           requests for time to make oral statements from members
           of the public regarding today's meeting.
                       Now I'm ready to start.  I wonder if
           Professor Adams is here.
                       MR. REYES:  Mr. Chairman?
                       CHAIRMAN WALLIS:  Yes.
                       MR. REYES:  If I might, this is Jose Reyes
           from Oregon State University.  Our department head,
           Andrew Klein is here.  He could give a talk about --
                       CHAIRMAN WALLIS:  Maybe he can, yes, give
           us a few words, and then I'll go ahead with the
           meeting.  Thank you very much.  Very appropriate.
                       MR. KLEIN:  My name is Andrew Klein.
                       THE REPORTER:  Could you go to the podium
           so we could record you?
                       MR. KLEIN:  Sure.  My name's Andy Klein. 
           I'm Department Head of Nuclear Engineering here at
           Oregon State University.  And we're very pleased to
           have this Committee, Subcommittee meeting here at
           Oregon State University to review some of the work
           that Drs. Reyes and Wu have done over the past few
           years.  It's been very important to the Department, to
           the College, and the University.
                       This is one of the key programs in the
           College of Engineering and certainly one of the key
           programs in the Department of Nuclear Engineering. 
           And we're very pleased that the NRC has supported the
           work here, and the DOE has supported work here over
           the years.  And we look forward to continuing to work.
                       If you have any questions, Teresa Culver,
           who is in the back there, will be able to help us out
           on logistics.  If you have any technical questions,
           I'll defer those to Dr. Reyes.  Thank you.
                       CHAIRMAN WALLIS:  Thank you very much.
                       Now we've gained some time.  Let's
           continue doing that.
                       Jack, are you ready for the opening
           remarks for RES?
                       MR. ROSENTHAL:  My name is Jack Rosenthal. 
           I'm the Branch Chief of the Safety Margins and Systems
           Analysis Branch in the Office of Research.  And I was
           just asked to make some opening remarks.
                       We see the APEX facility as very important
           at this point, that there's little else of places to
           do pressurized water reactor experiments.
                       And so we're using the OSU, both the
           experimental facility and their analytic ability, to
           work on issues such as pressurized thermal shock,
           after which we would do some work on bore and
           dilution, after which -- my sequence may not be right
           -- we have some plans for work on -- to answer some
           steam generators to the accident-related issues
           involving flow mixing that the ACRS has already
                       And then after that to work on AP1000 in
           some sort of yet-to-be-defined collaborative mode with
           the Department of Energy, similar to the arrangements
           that were made for AP600.  So that's a continuing
           long-term involvement.
                       In preparation for the meeting we were
           going over some of the work on two-phase flow
           separation.  And we intend to put those models into
           TRAC M within the next 12 months and probably sooner. 
           So the work is just very important to our overall
                       Later Nilesh, Dr. Chokshi, will be talking
           about an overview of the pressurized thermal shock
           effort.  And then the staff has just a slide or two as
           topics come up.
                       CHAIRMAN WALLIS:  Are there any other
           remarks from NRC?
                       (Comments off the record.)
                       CHAIRMAN WALLIS:  Yeah.  Would you like
           to?  Yes.  Thank you.
                       THE REPORTER:  When they speak from out
           there, we can't get them on the recording machine.
                       CHAIRMAN WALLIS:  Do you have a portable
           mic or something, or do they have to go up to...
                       (Comments off the record.)
                       MR. CHOKSHI:  Good morning.  My name is
           Nilesh Chokshi.  I'm Chief of the Materials
           Engineering Branch.  Your agent actually is Mike
           Mayfield, but I think he's at the Excelon meetings. 
           So in place of Mike, I think I'll give you a brief
           status and overview.
                       Let me start by thanking the Committee for
           having the meeting here.  Without this meeting I would
           never have come to this place and see the facility or
           understand a little bit -- improve my understanding of
           thermal hydraulics.
                       So I'm looking forward as much as anybody
           to this visit and seeing the facilities.  So it's
           going to be an interesting two days for me personally.
                       Since the focus of this meeting is the
           thermal hydraulics and research of the facility and
           discussion of projects, I'm going to limit myself to
           just a brief overview of where we are and discuss
           briefly the status of activities in two other areas of
           probabilistic fracture mechanics and PRA.
                       And a number of people are here from the
           staff, including Roy Woods.  So if you have some
           questions on PRA and so forth, he's here to answer. 
           But I'm going to take a very few minutes, and it won't
           take me half an hour, as shown on the Agenda.
                       We have been briefing ACRS Committees on
           the progress of this PTS Evaluation Project, so I
           think my remarks are -- basically it does not go into
           any background and introductory material, with a very
           brief introduction, so...
                       I'm going to take a few minutes to put in
           perspective this particular activity.  The current 10
           CFR 50.61 pressurized thermal shock rule was
           promulgated in 1983.
                       And between the '83-to-'86 timeframe work
           we conducted detailed studies called integrated
           pressurized thermal shock on the three -- three
           plants, I believe -- four plants, to develop
           methodology when somebody cannot meet the PTS
           screening criterion.
                       And as a result of this study, I think
           that Reg. 1.154 was published in 1987.  That's -- my
           recollection is 1987.
                       And then during the '89-l990, the Yankee
           Rowe application, attempts were made to use the Reg.,
           and subsequently it was discovered that there were a
           number of issues in applying that Reg. guide.
                       Since then a number of improvements in
           area of probabilistic fracture mechanics, some data as
           well as methodological.  So in April '99 we initiated
           this project.  And I think that's sort of a
                       And I think one of the features of this
           program -- some of the features are, one, this is the
           risk-informed application.  There has been extensive
           industry and public involvement.  We are working with
           a number of industry groups, as you know, Materials
           Lab Program, EPRI, and utilities, particularly in the
           PRA area to make sure that our models reflect the
           actual plant conditions.
                       And, as I mentioned earlier, we have been
           coming to ACRS frequently.
                       In the program the four plants that are
           being looked at, as you know, are Oconee, Calvert
           Cliffs, Palisades, and Beaver Valley.
                       With this, a little bit of introduction,
           I'm going to jump into the status of the program.
                       MR. KRESS:  You were using INEEL to do
           these four plants?
                       MR. CHOKSHI:  We started with INEEL, but
                       MR. ROSENTHAL:  Yeah.  I'll just put on my
           army voice.  We're doing the Palisades' calculations
                       The Oconee, Calvert, and Beaver Valley
           calculations are being done at ISL under Dave
           Bessette's supervision.  But I want you think of this
           as a joint staff and contractor effort, because there
           isn't a day of the week that we don't interact with
                       CHAIRMAN WALLIS:  What is "ISL," Jack? 
           What "ISL"?
                       MR. HAN:  Systems -- I can't remember.
                       (Simultaneous talking.)
                       MR. HAN:  Information System Laboratory.
                       MR. ROSENTHAL:  Information System
                       CHAIRMAN WALLIS:  It's a Scientec
                       MR. ROSENTHAL:  It's a Scientec derivative
           because there were conflicts of interest or potential
           conflicts of interest, so they spun off ISL.
                       CHAIRMAN WALLIS:  Where are they?
                       MR. ROSENTHAL:  Down the block from us.
                       They're in Rockville.
                       MR. BESSETTE:  Yeah, they're two blocks
           down Rockville Pike.
                       MR. CHOKSHI:  Okay.  I think the current
           status, we are making progress in all three areas of
           the major technical studies: the thermal hydraulics,
           fracture mechanics, and the PRA.
                       One of the significant activities
           underway, particularly in the fracture mechanics area,
           is to finalizing the FAVOR Code inputs.  The goal is
           to have all the uncertainty models and all the
           improvements by September.  And then we will be going
           into doing plant-specific analysis.
                       I won't say anything about thermal
           hydraulics.  I'll wait for the next two days, too, you
                       And in the progress on PRA, is -- I'll
           have more details, but you could have --
                       CHAIRMAN WALLIS:  But you say it's
           completed, so if we find anything that's not
           completed, then --
                       MR. CHOKSHI:  Well, that's why I sort of
           skipped over, because --
                       MR. CHOKSHI:  -- because I think it's
           probably premature for me to say it is completed until
           I hear.  But I guess what was planned has been
                       CHAIRMAN WALLIS:  "Completed" means
           they've submitted the last bill; is that what it
                       MR. BESSETTE:  The money ran out.
                       MR. SCHROCK:  Does this involve some new
           research, or is this massaging old data to find ways
           of improving its application?
                       MR. BESSETTE:  No, it's new.  This is
           David Bessette from Research.  It's new experimental
                       MR. SCHROCK:  Done where?
                       MR. BESSETTE:  Here, here.  It's done in
           the APEX --
                       MR. SCHROCK:  Oh, here?
                       MR. BESSETTE:  -- facility.
                       MR. SCHROCK:  Okay.
                       MR. BESSETTE:  And you'll hear -- this is
           one of the main topics, is to hear about the testing
           that was done at -- the next two days.
                       MR. SCHROCK:  I guess I was surprised at
           materials research.  I --
                       MR. BESSETTE:  Well, you're not going to
           hear anything about materials --
                       MR. SCHROCK:  Well, we'll hear what it is.
                       CHAIRMAN WALLIS:  Are we going to hear
           about this last one, the uncertainty in key variables
           in thermal hydraulics?
                       MR. BESSETTE:  Not too much in the next
           two days.  It's not --
                       CHAIRMAN WALLIS:  Is that part of the work
           here, is to look at uncertainty?
                       MR. BESSETTE:  Of course it feeds into
           uncertainty.  You know, the experimental results give,
           you know, us much more of a feeling about uncertainty. 
           And plus the analysis.
                       CHAIRMAN WALLIS:  So who's going to do
           that work, the formulation of uncertainty?
                       MR. BESSETTE:  Well, officially the
           uncertainty work is being done at the University of
           Maryland by the Almenas, and Mosleh, and Modarres.
                       CHAIRMAN WALLIS:  So they're using some of
           the results from here to assess uncertainty?
                       MR. BESSETTE:  That's right.
                       MR. KRESS:  Before we take that off,
                       MR. CHOKSHI:  Okay, sure.
                       MR. SHACK:  You're saying FAVOR, reeval-
           -- revision of the PFM Code FAVOR will be done in
                       MR. CHOKSHI:  We only -- we are in the
           process of implementing changes to the code.
                       MR. SHACK:  Okay.  Is that -- would that
           be a good time for you guys to come back to the
           Subcommittee, ACRS, and Materials Metallurgy
                       MR. CHOKSHI:  Oh, I think so, yeah.  Yeah,
           we'll be -- and talked about uncertainty modeling and
           different things, what improvement --
                       MR. SHACK:  Um-hum.  Yeah, because I know
           there's been some questions about that; they wanted to
           see that when it was completed.
                       Okay.  Thank you.
                       MR. CHOKSHI:  Yeah.  Right now we are at
           sort of documenting a number of things we are doing,
           so we should be ready by September.
                       MR. SHACK:  Okay.
                       MR. CHOKSHI:  In fact, just a last
           question regarding the uncertainties.  And as part of
           the PRA work, and as David mentioned, the University
           of Maryland is looking uncertainties modeling in all
           areas of the program.
                       MR. KRESS:  How are they dealing with
           epistemic uncertainties?
                       MR. CHOKSHI:  We are considering.  I mean,
           all right.  Now how is -- I think in each of the areas
           is somewhat of a different question.
                       For example, in the materials area, on the
           toughness and the flaw distribution, you know they
           each -- on the flaw distribution, for example, we have
           an expert -- expert elicitation as well as the ND
           examination of actual vessels, trying to get, you
           know, the different uncertainties.
                       On the toughness side there has been a
           joint effort with industry in developing epistemic and
           both aleatory uncertainties.  So --
                       MR. KRESS:  But specifically it's
           generally by expert opinion?
                       MR. CHOKSHI:  In part, not always.  You
           know, because on the flaw distribution, we have both
           the data simulations as well as expert opinion.  But
           epistemically more -- most part, I think I would say,
           an expert.
                       MR. SHACK:  Nilesh, just on the PRA, I
           thought you also had some additional work going on on
           sort of containment performance under --
                       MR. CHOKSHI:  Yes.  Yeah.  We --
                       MR. SHACK:  That's too new to make it, or
                       MR. CHOKSHI:  We are -- well, I think
           that's sort of butted into this second bullet, for
           acceptable risk figures of merit.  And I would say
           right now -- and, Roy, correct me -- that we are sort
           of still developing some concepts before -- and we had
           looked at some studies, actually, what, at Santa
                       MR. KRESS:  Is that Theophanus?
                       MR. BESSETTE:  Yes.  Well, we had a small
           effort with Theophanus where he looked at the effect
           of vessel failure on containment.
                       MR. SCHROCK:  That's an application of his
           rho M process?
                       MR. BOEHNERT:  Yes.  He wrote up some
           paper on it.  It's a -- I think it's at least out in
           draft form.
                       MR. CHOKSHI:  But I think we are still far
           from, you know, settling on that issue in any sense,
                       MR. SHACK:  I mean it will have
           substantial impact on your acceptance criteria,
                       MR. CHOKSHI:  And I think when we start
           doing some plant-specific analysis it will sort of
           start.  You know, how much we need to worry about that
           will come into focus, I think once we get some
           research and --
                       MR. KRESS:  But my impression of the rho
           M process is that it gives a bound that is such that
           you can rule out the particular issue or sequence
           because of the low probability.
                       In here you're supposed to be doing a best
           estimate.  I'm wondering how you are going to
           reconcile that sort of difference with the rho M
                       MR. CHOKSHI:  Let me ask David.
                       Did you hear Dr. Kress' question?  The
           calculation of what work is being done by Dr.
                       CHAIRMAN WALLIS:  Well, I think maybe we
           should move on to what's being done at OSU.
                       MR. KRESS:  Yeah, we'll hear more about
           this later.  Yes.
                       MR. BESSETTE:  Yeah.
                       CHAIRMAN WALLIS:  We'll get to you
           somewhere and ask you about Theophanus' work, but
           maybe we should --
                       MR. BESSETTE:  Yeah.  And we also did some
           inhouse work as well.
                       CHAIRMAN WALLIS:  Yeah.  We should spend
           time here on OSU work, --
                       MR. KRESS:  Yeah.
                       CHAIRMAN WALLIS:  -- because that's going
           to take a long time to go through, I think, anyway.
                       MR. KRESS:  Yeah.  Good thought.
                       MR. CHOKSHI:  Okay.  I think on the -- the
           next viewgraph is a little bit more details on what
           exactly is happening in the PRA area currently.
                       CHAIRMAN WALLIS:  Nothing exact ever
           happens in PRA.
                       MR. CHOKSHI:  I will just give you what I
           read.  We'll be complete -- I think by this, shown
           here on the last couple of bullets, that Oconee and
           Beaver Valley PRA models will be revised by September
           2001.  And we are working with utilities to make sure
           that all updates reflect the current plant operations.
                       And then the Palisades and Calvert Cliffs
           by mid-November.  And, you know, that that -- so by
           September then we'll start applying FAVOR to Oconee
           and start doing those calculations.
                       And I think, as it's shown here, that we
           are developing the PRA models for Oconee and Beaver
           Valley and basically updating Calvert Cliffs and
                       My next two viewgraphs are on the thermal
           hydraulics.  And I think I would say it's -- you know,
           you have the -- and I will just plan to skip that,
           because we were going to talk about this.  And let me
           talk about something I have more familiarity, so...
                       And the next major piece of the area is
           the probabilistic fracture mechanics Code.  And, as I
           mentioned, that there have been significant
           improvements in number of areas since the mid-'80s
           when we completed the IPTS program.
                       The flaw distribution was found to be one
           of the biggest area of uncertainties in the
           application of 1.- -- record 1.154.
                       Since then we have looked at a couple of
           pressure vessels through both nondestructive
           examination and destructive examination as well as, as
           I mentioned earlier, expert elicitation and simulation
           of -- through the codes like prodigal codes at --
           directing flaw distributions for the plate, weld, and
           heat-affected zone materials.  These are being right
           now programmed to the FAVOR Code.
                       At Pacific Northwest National Laboratory
           Steve Doctor and Fred Simonen have been doing most of
           the work.
                       The other area has been the crack
           initiation and arrest fracture toughness.  There has
           been also significant improvement in the modeling as
           well as the data.
                       And one of the key issues here has been of
           the uncertainty.  And we have been working with the
           University of Maryland to develop the epistemic as
           well as aleatory uncertainties.
                       Significant amount of new Smoglie data for
           the embrittlement correlations, and a new database as
           well as better correlations are being incorporated
           into the -- we also have a plant-specific material
                       The fluence maps.  And I think the
           beginning of this year we came and talked to the
           Committee about the Regulatory Guide.  And that
           methodology has been applied to now the four plants to
           make -- address the mix of the fluence.
                       There has been also the -- in the fracture
           mechanics itself improvements, things like better find
           element modeling, the treatment of residual stresses. 
           So all of this sort of has been incorporated into the
           PFM analysis.
                       Early in 1998 we did incorporate some of
           these improvements and did a test case, going back to
           one of the IPTS plants.  And at least based on that it
           looked like there could be some reduction, reduction
           of counterweightism in the screening criteria.
                       MR. KRESS:  In this context what do you
           mean by the "risk-informed model"?
                       MR. CHOKSHI:  I didn't hear that.
                       MR. KRESS:  Your first bullet, I was
           wondering in the context of this what do you mean by
           "risk-informed model"?
                       MR. CHOKSHI:  Well, because this -- all of
           this area has been integrated through the
           probabilistic risk assessment in making sure that the
           ultimate screening criteria and whatever we come up
           with has the, you know, the framework of Reg. Guide
           1.174 or similar, you know, risk.
                       CHAIRMAN WALLIS:  So you're revising a
           code using risk-informed methods?
                       MR. KRESS:  Yeah.  That's the part I
           didn't understand.
                       CHAIRMAN WALLIS:  Will you --
                       MR. CHOKSHI:  Well, I think that because
           of including the uncertainties in all the --
                       MR. KRESS:  That means best estimate with
           uncertainties, is what you're saying, right?
                       MR. CHOKSHI:  With uncertainties, right. 
           Yeah, that's right.  Exactly.
                       Because we're at the end of the -- when we
           make a run we'll have a distribution of the through-
           wall, correct.  And then it will have been to involve
           -- become involve with the initiating events and plant
           logic and --
                       CHAIRMAN WALLIS:  So it's not like sort of
           looking at some phenomena and saying, "Well, this
           phenomena is not important in its influence on the
           answer; therefore, we might as well as not use an
           equation.  We'll just assume a coefficient of 2," or
           whatever, "in order to get on with it," because it
           doesn't matter.  It's not that sort of level of
                       MR. CHOKSHI:  Right.  It's more, I think,
           a simulation, you know, Monte Carlo type --
                       CHAIRMAN WALLIS:  Because I haven't heard
           of people actually trying to look at the details of
           codes using risk information.  It would be interesting
           to do someday.
                       Where is it that your actual uncertainties
           in modeling have a big influence on the answer from
           the point of risk; that would be very interesting to
           do.  But I don't think that you folks are doing that
                       MR. KRESS:  That was the nature of my
           question.  I didn't understand it.
                       CHAIRMAN WALLIS:  Yeah.  That would be
           very interesting to do, though.  So now that you've
           opened the door, maybe we should ask you guys to do
           it.  Think about how to do it.
                       MR. CHOKSHI:  I think I already talked
           about my next viewgraph.  So let me just go to the --
           give you the overall schedule and -- where we are.  I
           think in the last three bullets, it sort of summarizes
           the --
                       CHAIRMAN WALLIS:  Are you talking about
           OSU here, or are you talking about much more general
                       MR. BOEHNERT:  No, just in general.
                       CHAIRMAN WALLIS:  You're talking about
           much more general stuff, aren't you?
                       MR. CHOKSHI:  In terms of the schedule?
                       CHAIRMAN WALLIS:  No.  When you say things
           like "good progress" thus far, that's a very general
           statement about --
                       MR. CHOKSHI:  Yeah.  That's some -- I'm
           talking about all three areas.
                       CHAIRMAN WALLIS:  That says nothing about
           OSU, does it?
                       MR. CHOKSHI:  No.
                       CHAIRMAN WALLIS:  Okay.
                       MR. CHOKSHI:  Because I think at the end
           of tomorrow you can judge.
                       Just to, I think, summarize.  We will have
           the fracture mechanics analysis of all four plants by
           end of this year, December 2001.  And then we will be
           putting through, you know, combining with the PRA.
                       And by February, next February, we should
           have that -- all of the plant-built specific analysis
                       And the idea is to have the
           technical-basis activity completed by July 2002.  And
           then we -- at that phase is the question of whether we
           go, move towards -- move forward with the rulemaking
           and probably some develop- -- about that time we will
           be sending a second paper to the Commissioners and
           seeking their advice based on what's the results we
                       CHAIRMAN WALLIS:  Well, you didn't say
           much about thermal hydraulics.  My understanding is
           that thermal hydraulics are presently in the
           calculations, but if OSU experiments give surprises,
           then you would have to revise the whole analysis?
                       MR. CHOKSHI:  Yeah.  Well, I --
                       CHAIRMAN WALLIS:  And that's a very key
           thing to know about, is the --
                       MR. CHOKSHI:  Well, I thought --
                       CHAIRMAN WALLIS:  -- is how much of this
           stuff that you say you're going to do all this on the
           schedule and you're going to achieve things by certain
           days.  How much of that depends on getting the right
           answer out of OSU?
                       MR. CHOKSHI:  Obviously a great deal, but
           -- but that's -- I thought since in these two days
           you're going to look at this in much more detail, --
                       CHAIRMAN WALLIS:  You know, I'm just
           trying to put the thermal hydraulics in perspective,
           but I didn't quite see how much -- it does play a
           pivotal role, doesn't it, in your --
                       MR. CHOKSHI:  Yeah.  From --
                       CHAIRMAN WALLIS:  -- development of
           whatever the rule is that you want to come out of
                       MR. CHOKSHI:  Right.  From my
           understanding, at least I -- I am not expecting, you
           know, that list as -- I don't know that there is
           anything right now which is going to adversely impact
           the schedule, but I -- I'll find out along with you if
           there is something.
                       MR. ROSENTHAL:  Let me just make the
           comment that it's very easy to put a Gant chart
           together.  And Gant charts are terrific for building
           office buildings where you pour the concrete and then
           erect the steel.
                       And here we're more in a design process,
           an iterative process.  And so we don't know quite what
           surprises will come to pass.
                       One of the early and crucial issues is
           because FAVOR is a 1D Code was the effect of thermal
           plumes.  And I think we have some answers for that
           that you'll be hearing about, because that was like a
           make/break issue.
                       A preliminary discussion from the
           University of Maryland says:  Well, you know maybe we
           can be very, very precise in our calculations, but we
           really don't know these temperatures to within 25 C.
                       And -- but that's not a fatal flaw,
           because we can pass that information on.  And it's
           sequence dependent with its associated probability to
           the fraction mechanics people.
                       And then the fracture -- and then having
           done the fraction mechanics calculations, we'll then
           see if we can live with those -- that lack of
           knowledge, that state of lack of knowledge, or if we
           have to loop through and attempt to refine methods.
                       So we're trucking down the announced
           schedule, but I think the fatal flaws haven't arisen
                       MR. CHOKSHI:  Yeah.  And I think to some
           extent the schedule has built some of the
           administrative process that -- you know, it's all
           recognized that we --
                       MR. KRESS:  The FAVOR Code uses the
           thermal hydraulics as an input.
                       MR. CHOKSHI:  That's correct.
                       MR. KRESS:  Is the plan to have a sample
           from that input in a Monte Carlo way, or is there some
           other way you're going to deal with these
                       MR. CHOKSHI:  Yeah.  You get the
           temperature, the pressure and temperature
           distributions and --
                       MR. KRESS:  Pressure, temperature, and
           heat transfer coefficient is, I think, --
                       MR. BESSETTE:  Yeah.  You know FAVOR takes
           FAVOR samples from things like flaw size and those
           kind of distributions.
                       MR. KRESS:  Um-hum.  Yeah.
                       MR. BESSETTE:  But it takes as a single
           value the thermal hydraulic input, but --
                       CHAIRMAN WALLIS:  There are no flaws in
           the thermal hydraulics.
                       MR. BESSETTE:  But, of course, you could
           input different --
                       MR. KRESS:  You could -- you could --
                       MR. BESSETTE:  -- you can change your
           input, of course, for the thermal hydraulics, so you
           can put in different temperatures.  So within your
           range of temperature uncertainty, you can vary that --
                       CHAIRMAN WALLIS:  Yeah.  You probably
           should do that, at least a little bit.
                       MR. BESSETTE:  But it just handles it at
           a different form of input.
                       MR. KRESS:  Well, the good thing about
           that is you know how -- pretty much how it affects the
           outcome, --
                       MR. CHOKSHI:  Right.  That's --
                       MR. KRESS:  -- so you can choose the
           bounding values, or something.
                       MR. CHOKSHI:  Right.
                       CHAIRMAN WALLIS:  I think that's part of
           the Maryland approach, is to see how uncertainty in
           one thing affects the outcome and develop some sort of
           influence coefficient, or something.  And...
                       MR. CHOKSHI:  That's the end of my
           presentation.  So just I wanted to give you an
                       CHAIRMAN WALLIS:  Thank you very much. 
           It's very helpful.
                       MR. CHOKSHI:  Thank you.
                       MR. KRESS:  Thank you.  It was.
                       CHAIRMAN WALLIS:  I note that Professor
           Ron Adams is here, and we'll give him a chance to say
           a few words a few minutes before we hear from
           Professor Reyes and get down to work.
                       MR. ADAMS:  Well, good morning, everyone. 
           Welcome to OSU.  I've got to tell you that the weather
           pattern today is unusual.  It's normally sunny this
           time in July, but you won't notice, as I can see.
                       I am pleased that you're here today.  And
           also this building that we're in is one of the special
           places at OSU because it houses the nation's best
           Forestry Program.  And with that I want to talk about
           what our plans are for engineering and how the work of
           Dr. Reyes and Dr. Wu are impacting what we're trying
           to accomplish.
                       OSU is building an engine for the
           knowledge economy.  And this is being driven by
           national needs as well as local needs here in Oregon.
                       One of the things that's happened in
           Oregon is that the technology sector is now the
           largest employer.  In fact, the employment in the
           technology sector in Oregon now exceeds the
           combination of all of the natural resource industries
                       Oregon State University has, in the last
           century, built great programs in natural resources, in
           forestry and agricultural and oceanography.  And now
           we're on a quest to build one of the best engineering
           schools in the U.S.
                       It's been done before.  We have
           benchmarked other schools, like North Carolina State
           University and the University of Cal San Diego.  And
           we're following some of the things that they have done
           to build excellence in their programs.
                       We have a plan.  It -- our plan is to
           achieve our goal by 2010.  And we're making progress
           towards that plan.  We have a tremendous amount of
           momentum right now, and I'll talk to you a little bit
           about that.
                       Part of our plan is to build our Research
           Program.  And one of the things that we've discovered
           is that we have a very strong competitive advantage in
           interdisciplinary research.  We have received a number
           of multimillion dollar grants this year because it's
           easy to work across departments here at OSU.
                       Now I know that from being inside here and
           I also know that from observations from colleagues
           from Stanford and other places, who have become
           familiar with what it's like here at OSU.
                       The Thermal Hydraulic Program that we have
           and you're reviewing today is one of those examples of
           a very strong program, a national asset.  And that's
           why you're here.
                       I want to talk about our momentum.  We
           have been growing tremendously in student enrollment
           for the past four years.  And today we're the twenty-
           third largest engineering program in the U.S.
                       Our Nuclear Engineering Program is also
           very strong and highly regarded, both for its
           undergraduate program as well as for the research
                       So that's our growth from a student-body
                       Since 1999 our research has grown 40
           percent.  This past year, 27 percent.  Inside of that
           27 percent are several multimillion dollar contracts,
           including today OSU will be a center for tsunami
           research.  That entails a partnership between Computer
           Science and Civil Engineering.
                       We're not just building the world's
           largest and most powerful tsunami simulator, we're
           going to put it on the internet.  That's an example of
           our ability to work across departments.
                       There are several other awards like that. 
           We landed $18 million in new grants and contracts this
                       Our plan calls for an investment of $180
           million in public and private funds.  So far we've
           raised over $50 million in private funds.  And the
           Legislature closed last Sunday -- a week ago Sunday at
           5:00 a.m., the State Legislature, and they
           appropriated $30 million to OSU.
                       That 30 million includes 10 million in
           operating expenses and 20 million to help us build a
           new engineering facility.
                       We also have a matching 20 million in
           private gifts for that building.  So we will be
           starting on that project soon.
                       The other thing that's happened here at
           OSU, since we've started our path to build this great
           engineering college, the faculty have gotten very
           excited and focused, and that's why we're getting the
                       We also have the backing of the leadership
           of private industry, as well as the public sector here
           in Oregon -- again, because this is important to
           Oregon's future and they see also the importance of it
           from a national standpoint.
                       So we have that leadership backing. 
           Oregon State is focused on results and a tremendous
           amount of momentum.
                       So today you're going to be reviewing one
           of our strongest research programs.  And again I hope
           you enjoy your stay here at Oregon State.  I also hope
           that when you depart from your hotel tomorrow morning
           you'll see the sun or when you leave here this evening
           you'll see the sun because, again, this is unusual for
                       Again we're pleased to have you here and
           thank you very much.
                       CHAIRMAN WALLIS:  Thank you very much.
                       Well, Jose, are you ready to tell us about
           the work that's going on here?
                       MR. REYES:  While that's warming up, I'll
           begin by saying welcome also.  And I appreciate Dean
           Adams' comments.  He's given you an overview of the
           college.  I'm going to give you a little bit of a more
           parochial view of our Research Program.  I want to
           talk about our thermal hydraulics in general, what
           types of research we're doing.
                       It works.
                        THERMAL HYDRAULICS RESEARCH
                       MR. REYES:  So I'll tell you a little bit
           our Advanced Thermal Hydraulic Research Laboratory and
           what our program mission is.  And this is kind of an
           umbrella laboratory that does a lot of
           interdisciplinary research, and includes the work that
           we're doing of course here and that we'll be
           discussing today and PTS and in base separation.
                       I'll mention who are researchers are and
           talk a little bit about each program, so this will be
           a fairly quick overview of the research that we're
                       Our goal from the beginning was to develop
           and maintain world-class research capabilities for
           assessing thermal hydraulic behavior in nuclear
           reactor systems and components.  And that was an
           overarching goal for our mission.
                       We have five primary areas of research
           that we have been focusing on:  Integral system
           research; separate effects/component research;
           fundamental phenomena research and model development;
           advanced instrumentation; and advanced thermal
           hydraulic computer analysis research.
                       So over the years we've developed in these
           different areas.  I think we've done quite well in
           developing that.
                       We consist of a team of professional staff
           augmented by graduate students and undergraduate
           students.  And during the academic year we have quite
           a few undergraduate students who work with us.  We've
           had at least 30 or 40 students, undergraduate
           students, work with us over the years on APEX-type
           design issues.
                       And today we have a couple of
           undergraduate students, Ian Davis and Chris Linrud,
           who have graduated and are moving on.  They just --
           for some reason they just keep graduating and leaving,
           I don't know.
                       And there are a couple of names I haven't
           listed there, Dan Wachs, who's helping us out today;
           and Ben Ralph, who is with us.
                       Integral System Research Programs.  We'll
           be talking about the PTS Program in detail, so I won't
           go over that at this point.
                       We do have some other test facilities that
           we're working with on the Integral System.  We have
           the Multi-Application Small Light Water Reactors. 
           This is a program we're doing for DOE jointly with
           Bechtel, Nexant, and INEEL.
                       We also have the AP1000 work which has
           just recently been funded by a DOE NERI Program.
                       The Multi-Application Small Light Water
           Reactor, which is funded by DOE, is going to be a
           one-third scale test facility.  This is a
           high-pressure facility.  It will be operating at about
           1500 PSI and at full temperature.
                       This is a very simple design.  The concept
           is basically a small -- I won't say portable -- but
           relatively small design.  We're talking about a
           40-foot tall containment section or a reactor section
           in a 60-foot reactor vessel or containment vessel.  So
           it's a vessel within a vessel.  A helical tube steam
           generator.  There's no cold legs, no hot legs, so
           nothing to break in terms of loops.
                       So we're going to be -- we've done the
           design jointly with Bechtel and with INEEL.  We're now
           in the process of constructing this facility.  So
           probably next time you come you'll see a high-pressure
           facility in the bay where we'll be taking you for a
           tour later today.  So that will be -- we're looking
           towards December having that facility operational.  So
           when we go do the tour we'll talk a little bit more
           about that.
                       So that's one of our Integral System
                       Of course, the AP1000 you're familiar
           with.  We are looking to do a testing of these new
           larger passive safety systems.  We hope to do some
           design basis accident test and probably beyond design
           basis accident test.  And this program is scheduled to
           begin sometime in September.
                       CHAIRMAN WALLIS:  Well, this will look
           very much like your AP600 work, won't it?
                       MR. REYES:  Correct.  Correct.
                       We will be modifying the facility
           extensively.  We will be -- this includes a brand new
           data acquisition system.  And a lot of the components
           will -- well, several of the components will change
           because of the scale.
                       In the Separate Effects area, today you'll
           be seeing the ATLATS facility, which has been used for
           the base separation work.  We'll also be looking at
           the APEX-CE transparent loop, which is what we've done
           -- we've used to do some of our visualization of the
           mixing in the Palisades geometry cold legs.
                       Fundamental phenomena.  We do quite a bit
           of different fundamental phenomena research.  Dr. Wu
           has certainly had a lot of capability in this area
           when he joined us.
                       Fractal enhancement of transport
           processes, bubble shearing-off rate, bubble-bubble
           coalescence rates, annular entrainment mechanisms, the
           natural frequency of attached bubbles, bubble
           condensation in subcooled liquid flows, fractal
           measurement of slug flow in vertical test loops.
                       So there's a lot of -- some of this
           research we'll be doing jointly with the Mechanical
           Engineering Department.
                       And the students have set up a whole bay
           full of displays for you.  So when we go over you'll
           be able to see that.
                       This one in particular, fractal
           enhancement of transport processes, again it was
           actually kind of a mix of a program:  Mechanical
           Engineering and Forestry.  So we had one of the
           engineers in the Forestry Department who was
           interested in the way leaves work.  And we worked with
           Mechanical Engineering.  We came up with a design.
                       We've gotten a provisional patent already
           on it, which was issued on the 5th of year 2000.  And
           then the final patent application was just submitted
           here 2001.  And we've gotten some interest from Intel
           and HP.  So we're kind of branching out.  And again
           it's an example of how we do some interdisciplinary
           research here at OSU.
                       MR. KRESS:  Is that just a process to
           maximize the surface area of transport?
                       MR. REYES:  Essentially -- that's correct. 
           Essentially it's an effective way of providing cooling
           by maximizing a surface area.
                       MR. KRESS:  Um-hum.
                       MR. REYES:  But we're looking primarily at
           an internal cooling process.  And so there's a whole
           range of products that can come from that.
                       We're doing fundamental phenomena
           research:  Two-fluid model improvements, interfacial
           area concentration modeling.  So we've done some --
           you'll see some work later on on the coalescence of
           breakage of droplets and bubbles in what we're doing
                       We're also looking for advanced
           instrumentation.  You'll see some impedance probe
           techniques.  We're looking at MRI applications.  We've
           done some work in the past.  That figure on the upper
           right-hand side of the screen there is an image of
           slug flow.  It's an MRI image of slug flow.  And so we
           find that we're able to get some good resolution of
           the images using MRI.
                       And this was with a one-and-a-half Tesla
           magnet.  We are looking at working with Argonne, Dan
           Wachs is here today, and hopefully using a 9 Tesla
           magnet to get much better imaging.  So we think we can
           get some good imaging of two-phase flows using MRI
           techniques.  It's completely nonintrusive.  And we get
           some good pictures.
                       Neutron and gamma radiography.  Dr. Wu
           will be talking, showing that a little bit later on
           with one of his students.
                       Imaging processing and some double-sensor
           conductivity probes.  So for void fraction
           measurement, bubble-size measurements, velocity
           measurements, we're using that technique here also.
                       We also are working hard to try to develop
           our computer abilities.  We have been using RELAP5
           Systems Analysis Codes.  We have been using the
           RELAP5-Gamma.  I guess it's mod 3. something, point
           something, Gamma, which is the NRC version, the latest
           NRC version.  And we've used that for the PTS work.
                       We also have the DOE version of RELAP5-3D,
           which we've been using for the multi-application small
           light water reactor work.  So we're getting familiar
           with both, both versions of the code.
                       We also have the GOTHIC Containment Code. 
           We're using that for the DOE work.
                       And then the CFD Code we're using
           currently is STAR-CD, and we've used that for the PTS
                       MR. SCHROCK:  What's the origin of that
           DOE RELAP5-5 to 3D Code?
                       MR. REYES:  This is from the Idaho
           National Lab.
                       MR. SCHROCK:  Idaho?
                       MR. REYES:  Right.  Right.
                       So just in summarizing as an overview,
           we'll be talking primarily at this meeting of two of
           our programs within our research umbrella in thermal
           hydraulics.  We will be talking about the phase
           separation of Tee work and the pressurized thermal
           shock work that we have done.
                       We do -- we've done a good job, I think,
           in developing our integral system capability, not just
           the physical machines, but the infrastructure that's
           required to operate these complex facilities.
                       We're doing a good job, I think, in the
           separate effects area.  We've built -- we're building
           model developers.  And I like that.  So I think Dr. Wu
           brings some good skills as far as model development to
           our program.
                       We are, because of the advancements in
           computers speed, we are able to run a RELAP5
           reasonably well here.  STAR-CD is a lot of work.  And
           we will see some presentations on that later.  But
           these Computational Fluid Dynamics Codes eat up a lot
           of computer time.
                       CHAIRMAN WALLIS:  What's the origin of
                       MR. REYES:  That's a good question.
                       MR. HAUGH:  It was built by Adapco.  It's
           their -- they've developed the code.  Their offices
           are in New York.
                       MR. REYES:  You need to say your name. 
           This is Brandon Haugh.
                       MR. HAUGH:  Oh, this is Brandon Haugh. 
           I'm a graduate student.
                       STAR-CD was developed by Adapco, which is
           a private company.  It's a commercially-available CFD
                       CHAIRMAN WALLIS:  It's like most of the
           other CFD Codes?
                       MR. HAUGH:  Yeah.  It's pretty -- pretty
           much the same, a little more graphical use interface,
           just modern software engineering techniques, but
           pretty much the same.
                       MR. REYES:  We continue developing in the
           area of instrumentation, so we've got fairly creative
           work going on.  And you'll see some new instruments. 
           Actually on the ATLATS you'll see a device that was
           developed by the students for measuring level, which
           is fairly unique.
                       And then we continue developing, doing our
           fundamental model research.  That's more in the area
           of the fundamentals of two-phase flow, coalescence,
           breakage of bubbles, and the transport equation.
                       So with that I think I'd like to turn it
           over then to start talking about the two different
           areas of research that we've been working on
           primarily, which is the phase separation Tees and then
           that will be followed by the pressurized thermal shock
           work.  And that's the presentation.
                       CHAIRMAN WALLIS:  Thank you very much.
                       Now we have a break scheduled for around
           10:00, so whenever it's natural for the speaker to
           break around that time then we'll have a break,
           because I noticed that the program just goes on for
           two hours.  But there's probably a natural break point
           in those two hours when we can have a break.
                       MR. WU:  My name is Qiao Wu, Assistant
           Professor of OSU.  Welcome.
                       My presentation today will be about phase
           separation in tees.  And currently the focus of our
           project is about the entrainment in a vertical branch
           of this on the horizontal main line.  And my
           presentation is divided into six parts.
                       The first part, the introduction on the
           modeling improvement and the future efforts, will be
           given by myself.
                       And the second part, test facility and
           test results, model evaluation, is going to be given
           by Mr. Kent Welter.
                       For the introduction part, before we go to
           the details, we would like to show you a cartoon to
           see what is the phase separation effect.
                       CHAIRMAN WALLIS:  Now this phase
           separation is very dependent on the flow conditions in
           the hot leg, is it not?
                       MR. WU:  Yes.
                       CHAIRMAN WALLIS:  And so this is -- so
           that rate is dependent?  It's very much tied in with
           the particular design of AP600, AP1000.
                       MR. WU:  Exactly.
                       CHAIRMAN WALLIS:  It might not be portable
           to a different situation.
                       MR. WU:  That's what we're going to
           evaluate.  And I'll show you why we're doing and --
                       CHAIRMAN WALLIS:  So one might have to be
           careful about putting it into NRC Code for some other
           situation and using it?
                       MR. WU:  We're going to show you how we
           develop a model in the general sense and see how we
           can apply it to this situation.
                       CHAIRMAN WALLIS:  Did you do separate
           effects tests, too, with other, other end conditions,
           and things like that?
                       MR. WU:  No, because we have some data
           from Schrock and Smoglie.  And we are going to use
           that as a general case with simplified or idealized
           unit condition, the outlet condition.  And for our
           purpose --
                       MR. SCHROCK:  I'm having difficulty
           hearing you.  Could you speak into the mic a little
                       CHAIRMAN WALLIS:  Is there a PA system
           here that --
                       MR. REYES:  No.
                       CHAIRMAN WALLIS:  There isn't.  So it
           doesn't help to speak in --
                       (Simultaneous talking.)
                       CHAIRMAN WALLIS:  It doesn't work.
                       MR. KRESS:  Just have to speak louder.
                       CHAIRMAN WALLIS:  It doesn't help to speak
           into the mic.  You just have to speak up then.
                       MR. WU:  We would like to use this
           facility to generate the data because we don't have
           such data available, and then to evaluate the existing
           models.  If we can find the efficiency of the models,
           then we try to improve it, because we don't know if
           it's practicable for this situation or not.
                       So the entrainment the process basically,
           so when the liquid level is below the off-take, you
           could still continue the work.  Under the process,
           it's similar like this, we show the experiment
                       CHAIRMAN WALLIS:  So the experiment
           doesn't look quite like the picture?
                       MR. WU:  No.  This picture is ideal.  That
                       CHAIRMAN WALLIS:  So you can develop a
           nice model for the picture, but the experiment is very
                       MR. WU:  Yeah.
                       CHAIRMAN WALLIS:  I think the waves depend
           upon what's happening at the end of that hot leg.
                       MR. WU:  That's correct.
                       CHAIRMAN WALLIS:  So it's -- you know, if
           you did it in a long pipe, it might be quite
                       MR. WU:  That's correct.  I show you the
           effect of the length.
                       MR. BESSETTE:  And I think our ultimate
           intent for us to be generalistic, I mean, so that we
           had different end-point conditions, you know, from a
           closed and to -- it's a symmetric condition, with
           different development lengths as well.
                       MR. SCHROCK:  I'm concerned about the sort
           of mixing together of so many different physical
           problems in what you've referred to as your database. 
           I know you have that report which has been sitting
           dormant for a couple of years now that summarizes the
                       I think the concept originally was:  Let's
           assemble what is known about this problem and lend
           some clarification to that.  I don't think that data
           report did that.  But I guess I'm looking forward to
           hearing what's being changed in relationship to that
           report that's going to guide you.
                       It seems to me you're pretty far down the
           line for it to be in that uncertain state.  And what
           you've just shown is, as Dr. Wallis has pointed out,
           indicating that there are many different
                       There are distinctly different physical
           processes that are important at different times and,
           to some degree, dependent upon the geometry.
                       If I look at the list of cited references
           in this database, it covers the waterfront.  And many
           of them have no relationship whatsoever to the problem
           that initiated this research program, which is the
           difficulty in calculating ADS flow in AP600.
                       So I think you need to focus a bit more in
           what you're telling us about why you're doing what you
           have and are doing and what --
                       MR. WU:  Yeah, the first --
                       MR. SCHROCK:  -- what you know about what
           has gone before you, because that's not very clear. 
                       MR. WU:  Yes.  The cartoons show you the
           process.  And you already pointed out the complexity. 
           So the introduction.  It's obvious, it's very
           significant.  It's a high-ranked phenomena in the
           OSU-CE meeting for the thermal hydraulics and u-sonics
           coupled code of development.
                       And also RELAP5 could not have predicted
           the core heat-up in the APEX of the NRC-25 series test
           which pinpointed the code deficiency for the vertical
           off-take entrainment process.
                       So for the database for entrainment model,
           if we build the database, we found that all these
           models were developed for breaks of relatively small
           sizes.  So there is a need for the new data for the
           larger breaks.  And it's scaled to prototype
                       And using these data to reevaluate the
           existing model, if we can, I think identifies a
           deficiency of the model, then we improve it or perhaps
           develop the new model.
                       MR. SCHROCK:  So this is, again, a little
           unclear to me.  What you're saying is there may be
           deficiencies in existing correlations that arise as a
           result of a lack of experimentation on an adequate
           range of geometries.
                       Now you're going to or are doing tests
           with larger ratios of the break diameter to the
           main-line diameter.  And now you're saying as a result
           of what you learned from those experiments, you'll
           reassess deficiencies in the previous experimental
           results or their correlations.
                       It's unclear to me how you can accomplish
           that unless you redo the experiments using the same
           diameter ratios.
                       MR. WU:  We treat your data and Smoglie's
           data as one of the targets that we're going to compare
           with.  And because you already -- already small breaks
           of data, or the data, we are not going to repeat it.
                       So the best look at the database, we don't
           have this larger break data.  So that's the
           motivation.  We say, "Well, we're going to do larger
           break data," and that --
                       MR. SCHROCK:  I think you missed the
           point.  The point is that you've said that you're
           going to reevaluate model deficiencies in the prior
           correlations or experimental results.
                       You're going to do this on the basis of
           data that are collected for larger ratios of diameters
           for the break line to the main line.
                       It's unclear to me how you will assess
           anything if it turns out that those correlations do
           not scale -- previous correlations do not scale to the
           range-of-diameter ratios that you're experimenting
           with, that you'll have anything to say about how good
           they are for the smaller diameter ratios.
                       I think that's what I heard you say you're
           going to do.
                       MR. BESSETTE:  I think they did put a lot
           of effort in to collecting and, you know, digitizing,
           and whatever, all the database in order to make sure
           that whatever they came up with encompassed or, let's
           say, was applicable to the range of conditions of, you
           know, the off-take diameter.
                       MR. WU:  I --
                       MR. BESSETTE:  But -- go ahead.
                       MR. WU:  Thank you.
                       The model deficiency, what I therefore
           hear is, say, when the model is being applied to the
           larger breaks and that obvious -- and these models
           were or correlations were geared with respect to the
           small-break data and we're already being evaluated
           thoroughly with the existing data.
                       And what I say are called the deficiencies
           is when we forcefully apply these models, correlations
           to the larger breaks, what effect and what other kinds
           of discrepancies we can get.
                       I hope I answered your question, sir.
                       MR. SCHROCK:  No, but go ahead.
                       MR. WU:  Okay.
                       MR. HAN:  Can I say something?  This is
           James Han from NRC.
                       Let me just add one quick comment.  I
           thought initially we conducted this research was
           because the existing database was not quite sufficient
           in the sense that it has a small-branch diameter over
           the main pipe diameter ratio.  And also the L over D
           is different.  So I saw that Professor Wu, do you want
           to show your review of --
                       MR. WU:  Yes.
                       MR. HAN:  -- of the existing database --
                       MR. WU:  I'm proceeding to there.
                       MR. HAN:  -- to start with?
                       MR. WU:  Um-hum.
                       For the database we collected, we wrote
           letters, emails to the researchers.  We collected 20
           sets of experiment facility on the data.  It ranged
           from 1980s to 1993.
                       All the data and the test facility and the
           analyses, preliminary analyses, are being ready in
           NRC's report and some first version was submitted --
           submitted to NRC for comments.
                       And some of the data were published in a
           product form.  We actually digitized, bought us --
           purchased -- purchased the software and digitized this
           data in an Excel format.  So it's convenient for
           further analysis.
                       When we look at the -- focus on the
           vertical branch on horizontal main line, the models
           were developed in two steps.  First is entrainment
           onset modeling.
                       The top figure shows when the liquid level
           below certain point, there's no liquid being drawn
           into the off-take.  That's called the entrainment
           onset condition.
                       And Smoglie, Schrock, and Maciaszek, all
           of them related that onset level to a Froude number
           based on the off-take gas velocity and the off-take
                       And the second step, if the level is above
           the onset entrainment level, then all of the liquid
           had been pulled into the off-take.  And Schrock's
           correlation, Yonomoto's correlation, and Smoglie's
           correlation basically correlate the branch quality to
           the real -- the real gas chamber height to the onset
                       CHAIRMAN WALLIS:  This must depend on the
           flow in the main tube.  And if you have a large liquid
           flow in the main tube, I would think you would carry
           that wave away.  There must be quite a dependence. 
           And then the gas flow in the main tube is going to --
           it has to go over that wave.  It's going to do a lot
           to its stability, or whatever.
                       MR. WU:  That's -- we found --
                       CHAIRMAN WALLIS:  So the flow rates in the
           main tube must have a big -- it can't just be the flow
           rate in the branch that matters.
                       MR. WU:  That's what we found in our
                       CHAIRMAN WALLIS:  Yeah.  That's what you
                       MR. WU:  Yeah.
                       CHAIRMAN WALLIS:  Yeah.
                       MR. SCHROCK:  Let me try to clarify for
           you a little better what my problem is.
                       In your database you have a number of
           references, notably the work by Lahey and his
           students, that deal with the bubbly flow in the main
           line.  And the question then of what is the phase
           separation as a result of the turning of the flow when
           it is a bubbly pattern upstream.
                       That's totally different physics from what
           you've shown a picture of here and totally different
           physics than the case of the quiescent stratified
           fluid, which is in the proximity of a take-off line
           that either sucks in the vapor phase when the break is
           submerged under the liquid or it may suck in the
           liquid when it's above.
                       And it's that latter case that you're
           addressing here that seemed to be a problem in the
           application of the existing correlations in RELAP5 for
           the ADS flow in AP600.  That's one isolated thing.
                       But in the broad range of things that are
           covered by all of these things that you have here,
           there are many different distinct two-phase flow
           problems that ought not be confused with the one that
           you're addressing here in these experiments.  So --
                       MR. WU:  The database --
                       MR. SCHROCK:  -- I'm really puzzled by why
           you want to do that.
                       MR. WU:  The database was built for all
           type of entrainment, like vapor pull-through, side
           branch.  And like at the beginning I pointed out
           currently our project phase is for the vertical or
           entrainment on the horizontal branch.
                       And the database itself is more generous
           and covered all type of branch with phase separation. 
           And we picked the data for the vertical branch on the
           horizontal for this analysis.  That's part of our
                       MR. SCHROCK:  Putting together numbers, a
           database, for a broad range of different physical
           problems is not a service unless you do something
           about telling the user of that compilation what
           physical problems each set of data addresses.
                       And there are different problems being
           addressed by this collection of prior works.
                       MR. BESSETTE:  Yeah.  I guess -- I can
           only say that we agree.
                       MR. SCHROCK:  But I hear the story coming
           out that we're going -- we're going to reassess
           deficiencies in all of this collection of things on
           the basis of, --
                       MR. BAJOREK:  It is --
                       MR. SCHROCK:  -- again, one isolated -- I
           mean you could say the criticism of all of these
           previous things is that they didn't cover the
           waterfront.  None of them were either funded at such
           a level that they could cover the waterfront, nor was
           it the intent either of the researchers or the
           sponsor.  So --
                       MR. BAJOREK:  This is Steve Bajorek.
                       I think there's two issues that are
                       First, there is a lot of data that was
           taken, all sorts of different flow regimes, all sorts
           of different physics.  Many of the conditions in
           geometries were nonprototypic of the AP600 or AP1000
                       MR. SCHROCK:  Yeah.
                       MR. BAJOREK:  What Dr. Wu's been doing at
           this point is trying to group all of the experimental
           data that has taken a look at off-take and Tees.
                       Now the next step has to be to segregate
                       MR. SCHROCK:  No, the --
                       MR. BOEHNERT:  Only a couple of those
           datasets were --
                       MR. SCHROCK:  -- the very first step
           should include critical comment about these results. 
           And that is lacking in this data report.  There's just
           no --
                       CHAIRMAN WALLIS:  Now you're saying that
           because you've read the report and you've seen it.
                       MR. SCHROCK:  I've said it because I've
           read the report.
                       CHAIRMAN WALLIS:  Well, I think that
           you're making very good points.  I think we will
           return to them as you make your presentation, because
           now we've sort of set the stage --
                       MR. SCHROCK:  Okay.
                       CHAIRMAN WALLIS:  -- for what we're
           looking for.
                       MR. SCHROCK:  I'll back off.
                       CHAIRMAN WALLIS:  And we'll see if we find
                       So I'd like you to continue the
           presentation, please.
                       MR. WU:  When we found the data for the
           vertical or off-take on the horizontal branch, it's
           several sets of data available, like Dr. Schrock
           pointed out, as Schrock, and Smoglie, and Anderson's
                       And when we compare, compare with the
           prototype condition, you'll see the prototype
           condition for the D over -- the branch size over the
           main pipe size is relatively large.  It's about .3. 
           However, all the test data is like .1, around there,
           and below .1.
                       And also the -- for the inlet condition,
           inlet length over the main pipe, it's very far from
           the inlet.  It's about over 20.
                       So for the real case, the inlet is very
           short.  So we think it's necessary for the -- from the
           horizontal pipe inlet to the branch location.
                       CHAIRMAN WALLIS:  You've got two inlets,
           one from the steam generator, one from the reactor
           vessel.  They're both short.
                       MR. WU:  No, from the offstream.  The
           inlet side.
                       CHAIRMAN WALLIS:  Well, it could be
           flowing both ways -- either way.
                       MR. WU:  Yes.  Yes.  But the other side is
           much longer, so we focused on the shorter side.
                       CHAIRMAN WALLIS:  So whenever you see a
           short L over D like that you say the inlet conditions
           to the big pipe must be very important?
                       MR. WU:  We would like to look into it.
                       And for the data sets, again, we covered
           all different branches of different orientations.  And
           we found only two sets of data were used for the
           horizontal entrainment to the vertical branch.  That
           is Smoglie's data and Schrock's data.
                       And all of them, except Smoglie's, data
           goes into a slug flow, but at a very low gas flow
           rate.  Smoglie's data is in the horizontal flow
           regime.  This flow regime map is a traditional flow
           regime map.
                       CHAIRMAN WALLIS:  So these are fluxes in
           the main pipe?  Is that what the jgs and jfs are here?
                       MR. WU:  Yes.
                       CHAIRMAN WALLIS:  They're based on the
           main pipe?
                       MR. WU:  Yes.  Yeah, that's superficial
           velocity.  That's a traditional flow regime map for
           horizontal pipe over two-inch size.
                       So the conclusion for this introduction
           was a correlation --
                       CHAIRMAN WALLIS:  Excuse me.  You didn't
           show AP600 on this plot?
                       MR. WU:  It's in the prototype because
           originally, when I prepared the transparency, I
           decided this is sensitive information, so I put a big
           spot there, about there so you can at least tell
           exactly what the number is.  It's .3 for the off-take
           size to the main pipe.
                       So the correlation is based primarily on
           this stratified flow data.  And branch size is
           relatively small compared to the prototype off-take. 
           And the inlet and the downstream conditions were
                       So for the objective of this project, the
           database construction and the design gave the facility
           for experiment, the investigation, conduct the test to
           generate the onset entrainment of the data and the
           entrainment to read the data.
                       And then using this data to evaluate the
           existing model correlation, see, for it's -- they are
           able to be applied for this situation.
                       And if they can, that's good news, and we
           don't need to go do further work.  If there is room
           for improvement, then we're going to do model or
           correlation improvement or development.
                       That's our logic of this project.
                       So for the second part and to the fifth
           part I'm going to hand to Kent Welter, and I'm going
           to come back to talk about the model improvement.
                       MR. WELTER:  Thank you, sir.
                       My name is Kent Welter.  I'm a Ph.D.
           candidate in the Department of Nuclear Engineering.
                       Before I go on to this, I'd like to take
           one minute and address Dr. Schrock's question since I
           am, I guess, the person who wrote the database that
           he's speaking about.
                       When we first constructed the database we
           had several things in mind.  And I've considered it as
           two parts.
                       The last half of the database which
           actually contains the experimental descriptions,
           facility descriptions, and data uncertainties, is a
           collection of phase separation experiments.  And those
           are very different.
                       Through them I've reviewed all the papers
           by Saba and Lahey and their models.  They consider,
           you know, a full set of Navier-Stokes equations.  It's
           different than what we are looking at here.
                       The phase separation is a larger set, so
           you can consider liquid entrainment as a subset of
           phase separation.
                       The first three chapters of the database
           is adding an analysis as applicable only to the AP600
           prototypic conditions.
                       The second half is a database that could
           be used more generally.  It could be used for
           different applications as a starting ground.
                       If I want to know about phase separations,
           there's no one place to go.  And that was the purpose
           of the second half of the database, which is why it
           includes a large collection of stuff.  The first half
           includes analysis only pertaining to the AP600 and
           liquid entrainment of vertical branch.
                       MR. SCHROCK:  Well, what is the status of
           that report?  The one that I've read --
                       MR. WELTER:  The one that you've read --
                       MR. SCHROCK:  -- has been said to be two
           years old and --
                       MR. WELTER:  Exactly.
                       MR. SCHROCK:  -- I don't know the extent
           to which you've --
                       MR. WELTER:  Revised that, --
                       MR. SCHROCK:  -- made a revision on it, --
                       MR. WELTER:  -- correct, sir.
                       MR. SCHROCK:  -- but it had serious flaws
           in it.
                       MR. WELTER:  It did, sir.
                       I wrote that report three years ago and
           about three months when I came into the program here. 
           And it was mostly a collection, a collection of
           basically leave-no-rock-unturned.  Okay.
                       I looked through everything, found
           everything, looked at it, reviewed it, and that's what
           I submitted.  And for the last two years, as I've
           increased my research, I've realized, well, that's not
           what I want to submit.  We've revised it.
                       The revision that we've now sent the NRC
           has condensed the experiments into the last section. 
           And we've added several chapters on the analysis.
                       MR. SCHROCK:  And so that exists?
                       MR. WELTER:  Yes.
                       MR. SCHROCK:  And when was it submitted to
                       MR. WELTER:  That was submitted to the NRC
           when we submitted our ACRS stuff several weeks ago.
                       MR. REYES:  That batch is still under
                       MR. WELTER:  And it's still under review
           actually.  So I am -- I am hoping that that will help
           clear up a lot of discrepancies that the first one
           saw.  And you are correct --
                       CHAIRMAN WALLIS:  This is under review by
           the NRC?
                       MR. WELTER:  No, not yet.
                       CHAIRMAN WALLIS:  Not yet.
                       MR. REYES:  It's being reviewed now.
                       MR. WELTER:  It's being reviewed now.
                       MR. SCHROCK:  Did NRC ever review the
           draft that you've had for two or three years?
                       MR. WELTER:  I received one comment back,
                       MR. SCHROCK:  I'm asking the NRC that.
                       MR. WELTER:  -- several comments back on
           it.  And then we revised it.  It's still in the
           original process.
                       MR. SCHROCK:  I didn't hear your answer,
                       MR. WELTER:  Oh, I'm sorry.
                       MR. BESSETTE:  The answer -- the answer is
           yes, but we most -- mostly we relied upon your review
           of it for --
                       CHAIRMAN WALLIS:  What you want to avoid
           is a situation we sometimes get where all this stuff
           goes through and the NRC thinks it's great and it's
           the basis of a rule.  Then it comes up to the ACRS and
           we don't like something about the whole basis of the
           analysis.  That's too late in the process to have much
                       MR. BESSETTE:  Well, in this case you saw
           the first draft.
                       MR. SCHROCK:  Well, it was never reviewed
           by the ACRS, as far as I know.  I saw it in February
           19- -- or 2001, which is very late in the game.  I
           don't know how...
                       MR. KRESS:  Well, we only get into the
           picture and if there are intentions to use it for
           basically decisionmaking or rulemaking.  And then we
           look at the basis for that, but I mean we wouldn't
           review a document like that just to review it.
                       CHAIRMAN WALLIS:  No.  No.  That is part
           of the problem, --
                       MR. KRESS:  Yeah.
                       CHAIRMAN WALLIS:  -- is that we don't see
           it until it becomes important.  By the time that
           happens it may be too late to do anything about it.
                       MR. KRESS:  Yeah.  Well, I --
                       MR. BESSETTE:  In this case you did -- you
           did see an early draft, or it was distributed at
           least.  The early draft was distributed.
                       CHAIRMAN WALLIS:  But it doesn't mean to
           say that we worked on it.  We work on it when it's
           part of our schedule to work on it.
                       MR. BESSETTE:  And -- and --
                       CHAIRMAN WALLIS:  We're not your
                       MR. BESSETTE:  No.  And we don't count on
           you as being the official reviewers.
                       CHAIRMAN WALLIS:  Well, again we should
           probably proceed with the presentation.
                       MR. WELTER:  Okay.  Thank you, sir.
                       CHAIRMAN WALLIS:  And maybe we'll be
           acting as reviewers today.
                       MR. WELTER:  Thanks.
                       I'd like to talk, take off where Dr. Wu
           left off, and speak about the scaling involved when we
           develop our separate effects test facility.
                       It includes considering the hot-leg flow
           condition using flow transition criterion developed by
           Zuber.  And if we determine the superficial gas
           velocity in the main line, we can get an appropriate
           HL over D, or a hot-leg liquid level to hot-leg
                       To preserve the geometry of the AP600, we
           also considered the main-line diameters of the hot leg
           and of the vessel and also of the inlet from the
           reactor vessel to the branch over the main-line
                       MR. SCHROCK:  So the problem that you're
           scaling is a quiescent stratified flow; is that
                       MR. WELTER:  For Zuber's flow condition,
           that's correct.
                       MR. SCHROCK:  Oh, I'm not talking about
           Zuber --
                       MR. WELTER:  I'm sorry.
                       MR. SCHROCK:  -- or anybody else.  I'm
           talking about the problem that you are presenting
           scaling analysis for.  You have to define your
           problem.  Your problem is stratified quiescent.
                       CHAIRMAN WALLIS:  By "quiescent," you mean
           it doesn't have big waves --
                       MR. SCHROCK:  It doesn't have waves on it.
                       MR. WELTER:  Sir, --
                       MR. SCHROCK:  And the picture you showed
           us a few moments ago with waves is a different
           problem.  So --
                       MR. WU:  No, that's not -- not what we --
                       MR. SCHROCK:  Not true?
                       MR. WU:  This flow regime is like a -- you
           can say, well, we preserve the flow regime phenomena
           by guaranteeing the Froude number on the left side is
           the same.  So whatever you -- your run, you say from
           a stratified to slug or stratified to annular, if you
           keep your Froude number the same as is this prototype
           condition, then you preserve the phenomena of flow
           regimes.  So we didn't say we keep that Froude number
           as under the transition line.  That's what you refer
           to the quiescent stratified flow.
                       CHAIRMAN WALLIS:  Now I'm trying to think
           here.  The liquid -- is the liquid actually flowing up
           into the steam generator?
                       MR. WELTER:  In through the steam
                       CHAIRMAN WALLIS:  Is this flow going out
           of the reactor up into the steam generator?
                       MR. WELTER:  To the lower plenum, but it
           does not make the loop.
                       CHAIRMAN WALLIS:  It doesn't make it?  So
           any liquid which comes in the pipe has to go out the
                       MR. WELTER:  Exactly.
                       CHAIRMAN WALLIS:  Nowhere else to go.  So
           this -- all the entrainment a hundred percent.
                       MR. WELTER:  In terms of injection flow,
           that's correct.  The correlations are developed on
           determining level in the hot leg and how that relates
           to the entrainment rate.
                       CHAIRMAN WALLIS:  So you've got down to
           the point where the level is so low that there's no
           entrainment going up into the steam generator?
                       MR. WELTER:  We've reached that point in
           experiments, yes.
                       MR. WU:  It's dry.
                       MR. WELTER:  It's dry.
                       CHAIRMAN WALLIS:  So that's just the exit
           condition?  You have to say something about the exit
           condition, which --
                       MR. WU:  Yes.
                       CHAIRMAN WALLIS:  All right.  And so this
           is one where there's no way in which liquid can get
           carried out at the end --
                       MR. WELTER:  That's on my next slide, --
                       CHAIRMAN WALLIS:  -- into the steam
           generator --
                       MR. WELTER:  -- which is the onset
           criterion we used.
                       One of the things that we also considered
           was the inlet flow condition.  And we used the void
           fraction from the vessel to properly scale the decay
                       CHAIRMAN WALLIS:  Now what does that mean? 
           I didn't quite understand alpha vessel.
                       MR. WELTER:  Alpha vessel.  You have
           decay, and there's of course boiling in the core.  And
           we wanted to make sure that we had the appropriate
           void fraction from the AP600 going into the hot leg so
           that we preserve the inlet condition from the reactor
                       CHAIRMAN WALLIS:  So you're going -- this
           is a bubbly flow sort of thing in the vessel that's
           going to be the same?
                       MR. WELTER:  A bubbly flow that, as the
           fluid is draining, will be going into the hot leg, or
           when you're -- sir?
                       CHAIRMAN WALLIS:  Okay.
                       MR. WELTER:  Yes.
                       MR. WU:  Basically if we run this test,
           the different void fraction in the vessel, then we'll
           get a different -- again from the vessel to the hot
           leg inlet, there is a phase of separation.  So if you
           don't guarantee the void fraction's the same, then you
           get a different level in the --
                       CHAIRMAN WALLIS:  So you have to maintain
           the vessel geometry?
                       MR. WELTER:  Correct.
                       CHAIRMAN WALLIS:  Correct.  Not just L
           over D hot leg.  You've got to have D vessel.
                       MR. WELTER:  We also maintain the diameter
           of the vessel --
                       CHAIRMAN WALLIS:  Yeah, okay.  Okay.
                       MR. WELTER:  -- on the right of their D
           vessel --
                       CHAIRMAN WALLIS:  Are there all kinds of
           internals in the vessel?  Are there internals in the
           vessel that --
                       MR. WELTER:  There are no reactor
           terminals on top of the vessel, no.
                       CHAIRMAN WALLIS:  But there are in
                       MR. WELTER:  There are in reality, that's
                       To preserve the onset criterion, which
           would make sure that we are at the correct flow rates
           at which entrainment begins, we use the onset of
           liquid entrainment developed by Zuber, Smoglie, and
           Schrock, where if we know the gas velocity in the
           branch, then that will give us the onset of liquid
           entrainment height, hb.  So it's a ratio of
           gravitational to inertial forces.  If the inertial
           force is greater than the gravitational force, onset
           will begin.
                       CHAIRMAN WALLIS:  Now hb is something you
           have to calculate?
                       MR. WELTER:  hb is onset of gas
           entrainment height.  So it's a gas chamber height. 
           It's the opposite of liquid level.
                       CHAIRMAN WALLIS:  It's not an independent
           variable?  It depends on all the other things you're
                       MR. WELTER:  That's correct.  It depends
           on -- in this sense right here, it depends on the gas
           velocity in the branch.
                       CHAIRMAN WALLIS:  Well, it depends on the
           amount of liquid.  Again, I get back to what -- how
           much --
                       MR. WELTER:  In the onset entrainment
           experiments there's no liquid injection flow.  So you
           can consider it as a small pool in the hot leg; that's
                       CHAIRMAN WALLIS:  So it's just -- there's
           no liquid flow, okay.  So you can control it simply by
           the --
                       MR. WELTER:  Yes.
                       CHAIRMAN WALLIS:  -- the void fraction in
           the vessel, I guess.  If you bubble through the vessel
           you raise the level of everything, including hb?
                       MR. WELTER:  That's correct.  Which gives
           the effect of the inlet.
                       From these scaling parameters we
           constructed an integral -- I mean a separate effects
           test facility.  I'd like to go through and explain the
           different components.
                       The critical complaints of the test
           section is a clear PVC with a horizontal hot leg, the
           vertical branch.  We have a stainless steel reactor
           vessel.  We have a steam generator connected to the
           downstream, which is appropriately scaled for the
           friction factor.
                       We have clear tigon tubing, and you'll see
           these in the tour also, for the steam generator tubes.
                       Injection flow is provided by a water pump
           from a large 5,000-gallon water tank.  Injection flow
           for the air is provided by an air compressor that goes
           through a 100-PSI air receiver.
                       We have 25 channels that record
           temperature, pressure, flow, and catch tank max, along
           with the mixture level and the hot-leg level.  And I'm
           going to introduce later how we determine the hot-leg
           level using instrumentation.
                       CHAIRMAN WALLIS:  Now where does the air
           go in this experiment?  It comes in through the bottom
           of the vessel?
                       MR. WELTER:  That's correct.
                       CHAIRMAN WALLIS:  And some of it goes out
           the water tank, I guess?
                       MR. WELTER:  The air goes -- I was just
           going to -- the next slide shows a cut-away of the
           reactor vessel, which talks a little bit more how the
           air comes in.
                       CHAIRMAN WALLIS:  Well, I'm ahead of you
           then, I guess.
                       MR. WELTER:  Yeah.  So if we take a closer
           look, this is a cut-away of the inside of the reactor
           vessel.  It's approximately a one-quarter length scale
           compared to the AP600.  It has air, water, and
           atmospheric temperature and pressure.
                       We use seven porous tubes in a shown
           configuration to simulate decay heat boiling.  Air
           flows through the bottom of this reactor vessel and
           through the porous tubes.
                       CHAIRMAN WALLIS:  Well, I guess I was
           looking at the previous figure.  The air has to decide
           whether it's going to go out through the catch tank
           and the drain line or to go out through the steam
                       MR. WELTER:  Exactly.
                       CHAIRMAN WALLIS:  I don't quite see where
           it goes when it gets out through the steam generator. 
           It's not clear to me there's any outlet from the steam
           generator for air.
                       MR. WELTER:  Everything goes through the
           catch tank.  So air coming from the steam generator --
                       CHAIRMAN WALLIS:  Everything has to go
           that way?
                       MR. WELTER:  -- is going to come this way.
                       CHAIRMAN WALLIS:  So nothing goes out
           through the steam generator?
                       MR. WELTER:  We have a return line, a
           one-inch return line to equalize the pressure on the
           reactor head.  And so --
                       CHAIRMAN WALLIS:  But all the air that
           comes through the reactor goes out the catch tank?
                       MR. WELTER:  Well, yes.
                       CHAIRMAN WALLIS:  That's not reality,
           though, is it?
                       MR. BESSETTE:  Well, yes.
                       CHAIRMAN WALLIS:  Well, it's a very
           limited reality, isn't it?
                       MR. BAJOREK:  Sort of.  Yeah, it's kind of
           real.  Where else can it go?  I mean there's only one
                       CHAIRMAN WALLIS:  The steam generator --
           there is no flow-through steam generator in the
                       MR. KRESS:  As long as you don't build up
           much back pressure in that tank.
                       MR. SCHROCK:  It goes the opposite way.
                       MR. KRESS:  It's like --
                       MR. WELTER:  There's flow through the
           steam generator, but it's backwards.
                       MR. BESSETTE:  Generally speaking, it can
           only go out the one place.
                       MR. BAJOREK:  It's going in the opposite
           direction here in the test.  In the AP600 and for the
           ADS-4 it was split through the intact loops, go
           through the steam generator, and you would have a gas
           velocity approaching the branch line from both sides.
                       CHAIRMAN WALLIS:  From both sides, right.
                       MR. WELTER:  From both sides.  Yeah, it's
           going the opposite way.
                       MR. SCHROCK:  See, this doesn't look like
           a clean-cut separate effects experiment.  I had
           thought that that was the objective for the OSU test,
           but --
                       MR. WELTER:  We varied the downstream --
           I'm sorry, sir.
                       MR. SCHROCK:  -- what you have is a system
           here which is not representative of any reactor system
           that I know of.  And so I don't know what the value of
           the results would be as a systems test.  But as a
           separate effects test, it misses the mark.
                       You have a variety of conditions entering
           the test section that result from system effects.  If
           you look at the KFK experiments, the Berkeley
           experiments, which I think are the main database for
           the phenomenon with a quiescent interface, what you
           see is that in those separate effects experiments
           pains were taken to smooth the flow, to ensure that
           there would be a smooth stratified flow.
                       What was sought was the conditions for the
           onset of entrainment and then the phase distribution
           following the onset of entrainment, those factors, for
           that specific condition at the onset of entrainment.
                       Your system has these system effects,
           which are atypical.  And I don't understand then how
           clarity is going to be brought to the problem if
           separate effects are addressed via some kind of
           randomly-put-together systems.
                       MR. BESSETTE:  Well, I think --
                       MR. SCHROCK:  It just doesn't follow.
                       MR. BESSETTE:  I think the system -- I
           mean, in fact, one of our objectives was to include
           some system effects because, as he's just pointed out,
           the system effects are -- see, you're correct that
           that Zuber -- the initial Zuber formulation was for
           smooth stratified flow, smooth stratified conditions
                       MR. SCHROCK:  David, we're talking about
           the distinction between separate effects and system
           effects, okay.
                       MR. BESSETTE:  Yes.  But --
                       MR. SCHROCK:  And the code has separate
           effects models in it.
                       MR. BESSETTE:  Yes.
                       MR. SCHROCK:  And what you set out to do
           is to improve on the code's separate effects models so
           it could calculate AP600 ADS flows better.  Isn't that
           where we started?
                       MR. BESSETTE:  That's -- yes.  But what we
           have seen at least is that the system effects are at
           least as important to the --
                       MR. SCHROCK:  Of course they are.
                       MR. BESSETTE:  -- or more important --
                       MR. SCHROCK:  If you have a wavy flow, as
           the previous --
                       MR. BESSETTE:  Yeah.
                       MR. SCHROCK:  -- cartoon showed us with
           animation here, it had a tremendous effect --
                       MR. BESSETTE:  Yeah.
                       MR. SCHROCK:  -- on the result that you
           get.  It would be naive to believe that it wouldn't. 
           But that's a different situation.
                       MR. BESSETTE:  But that's what we wanted
           to include.  We wanted to include the --
                       MR. SCHROCK:  Well, then do it in such a
           way that you have control over what the upstream phase
           distribution is.  And --
                       MR. BESSETTE:  But --
                       MR. SCHROCK:  Your code is going to have
           to know --
                       MR. BESSETTE:  That's correct.
                       MR. SCHROCK:  -- what the upstream phase
           distribution is --
                       MR. BESSETTE:  That's correct.
                       MR. SCHROCK:  -- in order to properly
           calculate what the branch flow rate.
                       MR. BESSETTE:  But what we have seen is
           that the code has to be able to calculate the flow
           regimes in the upper plenum in order to calculate the
           correct conditions in the hot leg.
                       So the code has -- the code has to be --
           you have to back up.  It's both in the experiments and
           in the code.  You see that you have to get the upper
           plenum conditions correct in order to get the right
           conditions in the hot leg.
                       So you have to feed the right flow from
           the upper plenum to the hot leg.  And we've seen that
           both in the code calculations and in the data.
                       CHAIRMAN WALLIS:  I think we'll have to
           accept this as not the totally separate effects test,
           not at all, but it seems to the --
                       MR. SCHROCK:  Well, I think --
                       CHAIRMAN WALLIS:  -- hybrid separate
           effects, system effects --
                       MR. SCHROCK:  -- it's a basic problem in
           the thinking of how you can improve what the codes are
                       The codes attempt to calculate, using
           correlations, for a wide range of different physical
           phenomena.  And unless you have adequate flow regime
           characterization, you can't begin to come up with a
           set of correlations that are going to correctly
           calculate --
                       CHAIRMAN WALLIS:  Well, the version --
                       MR. WELTER:  But that's correct.
                       MR. SCHROCK:  -- those flows.
                       MR. BESSETTE:  Yeah, I think we agree.  It
           seems to us that the conditions, the model for smooth
           stratified flow is quite -- quite transparent, let's
           say, and adequate, good.  There's nothing you could
           improve upon.  So --
                       MR. SCHROCK:  No, and I don't think that
           was your initial argument for starting this program.
                       It was that the choice of diameter ratios
           made in those earlier experiments, before there was
           any knowledge of what the AP600 geometry was going to
           look like, didn't envision that there would be need
           for data with such large -- large break diameters.
                       MR. BESSETTE:  Yes.  That was one of the
           motivations, yes.  Yes.
                       MR. SCHROCK:  Right.  All right.
                       MR. BESSETTE:  But there was no -- we did
           not see any obvious problems with the stratified flow
           off-take modeling, other than the range -- the
           diameter ratio.
                       The other thing was that we did not
           believe that it adequately covered these conditions of
           stratified -- wavy flow and --
                       MR. SCHROCK:  Well, it doesn't.  And you
           need -- you need experiments for wavy flow, --
                       MR. BESSETTE:  Yeah.
                       MR. SCHROCK:  -- if that occurs in the
           real reactor systems.
                       MR. BESSETTE:  Yeah.  And that was, of
           course, one of the motivations.
                       CHAIRMAN WALLIS:  Well, I think we have to
           see the whole presentation and then maybe come back to
           these issues in a discussion later.
                       MR. WELTER:  Thank you, Mr. Chairman.
                       CHAIRMAN WALLIS:  But --
                       MR. SCHROCK:  I think the objective --
                       CHAIRMAN WALLIS:  -- these questions are
           going to emerge later --
                       MR. SCHROCK:  -- needs to be set out more
           clearly in the beginning, Mr. Chairman.
                       CHAIRMAN WALLIS:  But if we spend all the
           time on the prologue we'll never see the play, so I
           think we have to go on.
                       MR. SCHROCK:  All right.
                       MR. WELTER:  Thank you, sir.
                       The test facility, let's take a closer
           look at the test section geometry used.  This is the
           PVC test section.
                       Two test sections were constructed to
           enable three different inlet lengths for testing. 
           They were constructed by welding two PVC pipes
           together.  This enabled us to save a tremendous cost
           on test section.  Each one of these test sections is
           approximately $150 plus parts and labor, compared to
           casting acrylic which costs 4,000 to $7,000.
                       CHAIRMAN WALLIS:  You weld PVC?
                       MR. WELTER:  Weld PVC.  The investment was
           a $400 PVC welder.
                       CHAIRMAN WALLIS:  It doesn't electric use
           arcs, though, does it?
                       MR. WELTER:  Not usually, no.
                       MR. ROSENTHAL:  I'm sorry.  I know it's a
                       MR. WELTER:  Please.
                       MR. ROSENTHAL:  I'm just curious.  I'm
           used to gluing PVC together.  So what is a PVC welder?
                       MR. WELTER:  John.
                       MR. GROOME:  My name is John Groome.  It's
           basically used on a hot air gun.
                       THE REPORTER:  Would you come to a mic,
                       MR. GROOME:  Good morning.  My name is
           John Groome.
                       And on the question of welding PVC,
           basically you use a hot air gun.  And you have a
           filler rod.  And you actually melt PVC to do the
           welds.  So it's kind of like tape welding PVC, but you
           don't -- you don't actually melt the base material. 
           And you'll see some examples today of that when you
           look at the test sections.
                       CHAIRMAN WALLIS:  It's like mending many
           holes on the base of your skis.
                       MR. GROOME:  I couldn't tell you anything
           about skis, but --
                       MR. ROSENTHAL:  Says the man from New
                       MR. WELTER:  Thank you.
                       I'd like to take a moment to introduce the
           hot-leg measurement instrumentation.  It is a
           half-ring-type conductivity probe.  In this
           illustration there are two stainless steel semicircle
           wires placed within a PVC ring.
                       This PVC ring is then bolted between two
           flanges, the hot leg.  There are two of these, these
           types of instrumentation: one on the reactor side of
           the test section to give -- measure inlet hot-leg
           level, and one on the steam generator side to measure
           out-leg hot-leg level.
                       These wires are connected to signal
           conditioning.  We have a 100-kilohertz sine wave
           oscillator.  We use AC power to make sure there's no
           iron migration that you'd encounter with DC.
                       It goes through a current driver that's
           amplified, rectified, and then filtered.  And then we
           go ahead and measure the voltage.  And --
                       CHAIRMAN WALLIS:  This is just -- this is
           just conductivity, --
                       MR. WELTER:  A half-ring type --
                       CHAIRMAN WALLIS:  -- or is it impedance? 
           Is it --
                       MR. WELTER:  It's an impedance probe.
                       CHAIRMAN WALLIS:  It says "conductivity,"
           but -- so it measures actually --
                       MR. WELTER:  Impedance of the air and
           water, basically air.
                       CHAIRMAN WALLIS:  It measures capacitance,
           or does it measure...
                       MR. WELTER:  Resistance -- impedance.
                       MR. WU:  Impedance.
                       MR. WELTER:  Yes.
                       CHAIRMAN WALLIS:  So you could control the
           chemistry of the water pretty closely to measure
                       MR. WELTER:  We calibrate -- we calibrate
           the test section every test series --
                       CHAIRMAN WALLIS:  Every day, okay.
                       MR. WELTER:  -- to account for the
           impurities in the water.
                       CHAIRMAN WALLIS:  So is it mostly
           resistance, or is it mostly -- or it's a hybrid of
           some sort?
                       MR. WU:  Mostly --
                       CHAIRMAN WALLIS:  Mostly resistance?
                       MR. WU:  The AC current -- this is Qiao
                       The AC current put inside just want to
           avoid as the iron accumulated to one electrode, so
           cause kinds of drifting.  But we didn't raise to that
           high frequency.  Run just the probe, we -- in the
           capacitance mode.
                       MR. WELTER:  This -- this work was done by
           the Department of Oceanography to measure wave height
           in their wave pools.  And we've borrowed it, their
           circuit, and modified it for our case.
                       So before each test a calibration curve is
           run.  That's a picture of the calibration curve. 
           There's an output voltage on the bottom.  And we
           calibrate with the DP we have in the reactor vessel.
                       So I flood and then drain the reactor
           vessel and get output versus height in the hot leg.
                       And I run this before each test series.
                       CHAIRMAN WALLIS:  So during the test
           you've got this continuous output from this probe and
           it shows waves and things?
                       MR. WELTER:  At a one-second scan rate.
                       CHAIRMAN WALLIS:  A one-second scan rate,
           so it doesn't show waves?
                       MR. WELTER:  There is some oscillation
                       MR. SCHROCK:  The calibration curve is
           done with static conditions?
                       MR. WELTER:  That's correct.  No gas flow,
           just water draining and filling.
                       MR. SCHROCK:  Oh, the water is moving?
                       MR. WELTER:  That's correct.
                       Okay.  So I went and I described the test
           facility.  The --
                       CHAIRMAN WALLIS:  Excuse me.  Where --
                       MR. WELTER:  I'm sorry.  Yes.
                       CHAIRMAN WALLIS:  Where is the probe in
           the circuit?
                       MR. WELTER:  There are two -- yes, there
           are two probes.  One is on the reactor side.  I'll
           back up a bit.
                       CHAIRMAN WALLIS:  Are they both ends of
           the test section?
                       MR. WELTER:  Yes.
                       CHAIRMAN WALLIS:  Okay.
                       MR. WELTER:  That's correct.
                       Can you back up about three slides on the
           test facility?
                       (Comments off the record.)
                       MR. WELTER:  This is break time; is that
           what you wanted?
                       CHAIRMAN WALLIS:  No, you're going to
           finish before break time.
                       MR. WELTER:  Okay.  This is --
                       CHAIRMAN WALLIS:  No, wait a minute. 
           You're going to finish this topic.
                       MR. WELTER:  Yeah, okay.  That will be
           pretty fast.
                       Here are both of the impedance probes. 
           One is on the inlet side and the other one is on the
           outlet side.  That's correct.
                       CHAIRMAN WALLIS:  So are you finished
           describing the facility?
                       MR. WELTER:  That's correct.  I'll be
           moving on to the tests, results.
                       CHAIRMAN WALLIS:  Do you want to take a
           break now?
                       MR. WELTER:  Great.
                       CHAIRMAN WALLIS:  Does that allow us time
           to finish the rest of the --
                       MR. WELTER:  Yes, I believe so, enough
           time, yes.
                       CHAIRMAN WALLIS:  You're going to do
           sections 3 and 4 this morning, or you're going to do
           all of this.  Okay.  Let us take a break for 15
                       (Recess taken from 9:54 a.m. to 10:10
                       CHAIRMAN WALLIS:  Go ahead.
                       MR. WELTER:  Okay.  Thank you.
                       Just before the break I finished speaking
           about the test facility and instrumentation.  I'd like
           to go on and describe the two groups of tests that we
           ran, one for the onset of entrainment, determining
           that; and then one for determining the rate of
           entrainment through the AF 4 line, or the off-take.
                       The first will be the onset of
           entrainment.  I'd like to describe the test procedure
           that we went through to achieve the onset of
                       At first, from this figure, the hot leg is
           flooded.  Then gas is throttled to a specified flow
           rate at constant value.  And when that happens, from
           this animation, entrainment will begin, and you will
           lose primary inventory and the level in the hot leg
           will drop.
                       CHAIRMAN WALLIS:  Well, it's not
           entrainment to start with.  It's just flowing out,
           because it has to go somewhere.
                       MR. WELTER:  There's no liquid injection.
                       CHAIRMAN WALLIS:  Yeah, but there's gas.
                       MR. WELTER:  Which is pulling the liquid
           with it.
                       CHAIRMAN WALLIS:  It displaces the liquid.
                       MR. WELTER:  There's pulling the liquid up
           through the vertical branch.
                       CHAIRMAN WALLIS:  Well, in the first
           picture it was all full of liquid, so...
                       MR. WELTER:  It was flooded initially.  So
           initially -- so we get the same -- the accurate -- we
           start at the same spot every time, a flooded hot leg.
                       After a certain amount of time liquid
           entrainment will stop, and basically there will be
           only gas flowing through the ADS-4 line and you will
           receive a constant level in the hot leg.  This is the
           point at which onset of entrainment begins.
                       And we go ahead and run a test series for
           different gas flow rates to get the liquid level for
           each gas flow rate.
                       CHAIRMAN WALLIS:  Now in reality there
           might be some boiling in the steam generator because
           this secondary is a heat source and things.  There's
           all kinds of scenarios where things happen in the
           steam generator.
                       MR. WELTER:  That's correct.
                       CHAIRMAN WALLIS:  Here it's just a deadend
           for you.
                       MR. WELTER:  That's correct.
                       And in this figure, it's not shown, there
           is actually an air line connected to the bottom of the
           porous tubes.
                       The test scope of the onset of entrainment
           includes determining the effect of the inlet length. 
           We want to know what the effect of the inlet length 
           in regards to the effect of the reactor vessel and the
           void fraction that we scaled.
                       Also the effect of the steam generator. 
           We have a valve on the three-inch cold-leg return that
           can be opened and closed so that we can simulate.  A
           close would simulate a filled loop seal in the cold
                       CHAIRMAN WALLIS:  There's a challenge here
           of oscillations imposed between the cold leg and the
           react- --
                       MR. WELTER:  The oscillations occur in the
           entrainment rate tests with a steady injection flow. 
           No oscillations occur for the onset of entrainment
           with zero injection flow.
                       CHAIRMAN WALLIS:  Nothing's happening?
                       MR. WELTER:  Nothing's happening.
                       MR. SCHROCK:  Is --
                       MR. WELTER:  Sir?
                       MR. SCHROCK:  Is the condition with a
           voided steam generator and dome but a flooded hot leg
           a condition that's calculated for AP600?
                       MR. WELTER:  It's part of the -- sir. 
           Sir, go ahead.
                       MR. BESSETTE:  It's -- of course, the
           situation when ADS-4 opens is that the generator is
           voided and the hot leg is full.
                       MR. SCHROCK:  What's the condition of the
           steam dome -- or of the vessel?
                       MR. BESSETTE:  The vessel is -- when ADS-4
           opens the vessel is filled to about the top of the hot
                       MR. WELTER:  May I go on?
                       Okay.  Thank you.
                       We also are curious to the effect not only
           of the steam generator and its influence, mainly the
           lower plenum, but also the effect of gas flow
           direction.  Meaning that if we open the three-inch
           cold-line return, how much -- what is the effect of
           gas flowing through both the cold leg and the hot leg
           so that you get gas from both directions up through
           the branch, not just a flow from a single direction.
                       Flow through.  The cold leg is -- is
           smaller than the hot leg, of course, because it has to
           travel all the way through the cold leg into the other
           side of the steam generator.  So the majority of flow
           is still from the hot leg.
                       Brandon, can you have the next one for me? 
                       Some test results.  This is a plot that we
           have used the same convention that Zuber used to
           classify his onset data.  It is a flow regime map with
           the Froude number in the main line based upon the
           superficial gas velocity in the main line.
                       I've plotted against hl, which is the
           liquid level in the hot leg over the main line
           diameter.  The regions you see here are in the bottom
           left are stratified, plug, and slug, and annular, and
                       Our onset data for this case, which we're
           trying to determine the effect of the inlet condition,
           falls within the stratified flow regime.
                       The different test series and the
           different dots are for different L over Ds, from 2.71
           up to 4.75.  We can see that there is not a
           significant impact due to hot-leg inlet length on the
           onset of entrainment level.  So this is a case where
           we have taken into effect the inlet conditions.
                       Effects of the steam generator.  We are
           interested in knowing what happens when we basically
           put a static pressure boundary on the exit.  So we
           have col- -- the previous onset data, there was no
           three-inch cold-line return.
                       In this case we opened the three-inch cold
           line, cold-line return.  And the new -- the data for
           with the steam generator has brought the onset level
           to a slug transition line.  So --
                       CHAIRMAN WALLIS:  So you're saying that
           the onset of entrainment is the same as the onset of
           slug flow?
                       MR. WU:  Yeah.
                       CHAIRMAN WALLIS:  So it's nothing to do
           with droplet entrainment.  It's the formation of the
           big wave and --
                       MR. WU:  I think physically later you will
           see it's the same argument.  And the surprise --
           that's not a surprise.  But the surprise is you don't
           need to -- so this coefficient that you get is exact
           in the line for the larger breaks.
                       CHAIRMAN WALLIS:  So what is the steam
           generator doing to make the data different when it's
                       MR. WU:  It's --
                       MR. WELTER:  Flow direction.  This is the
           effect of the steam generator.  One of the things is
           that there is flow coming from the cold leg.  So
           basically you're not just flowing past, you're flowing
           from both.
                       CHAIRMAN WALLIS:  Flowing air?
                       MR. WELTER:  Air, that's correct, sir. 
           There's no injection.
                       MR. SHACK:  It would be more accurate to
           say loop seal or no loop seal, right?
                       MR. WELTER:  Exactly.  One, one is where
           the loop seal is filled and the other is where the
           loop seal is blown out.
                       CHAIRMAN WALLIS:  I don't understand how
           the air gets around the other side in your experiment.
                       MR. WELTER:  The cold leg is above the hot
           leg, and so air flowing from the reactor vessel can go
           either to the cold leg or the hot leg since the --
                       CHAIRMAN WALLIS:  In your experiment? 
           Your experiment has a cold leg down the bottom of the
                       MR. WELTER:  Oh, I'm sorry.  The cold leg
           in the AP600 is above the hot leg.  In the
           illustration I have connected it just back to the
           reactor vessel.
                       CHAIRMAN WALLIS:  The illustration, oh, is
           wrong then?
                       MR. WELTER:  That's correct, sir.
                       CHAIRMAN WALLIS:  Oh, it's probably
                       MR. WELTER:  Okay.  Thank you.
                       CHAIRMAN WALLIS:  Okay.  So now really the
           cold leg is attached to the proper place?
                       MR. WELTER:  The cold leg is attached
           above the hot leg.
                       CHAIRMAN WALLIS:  But it's drawn below the
           hot leg in the diagram.
                       MR. WELTER:  Another figure.  That's
                       CHAIRMAN WALLIS:  Gee whiz.
                       MR. WELTER:  That is misleading.  I
           apologize for that.
                       CHAIRMAN WALLIS:  Okay.
                       MR. SCHROCK:  So is the wavy condition
           from one set of these data and not the other, is that
           the distinction?
                       CHAIRMAN WALLIS:  No, it's coming from
           both directions.  What's the J in the Froude number?
                       MR. WELTER:  The J we used is the inlet.
                       CHAIRMAN WALLIS:  The inlet.
                       MR. WELTER:  That's correct.
                       MR. WU:  Now the J is totally calculated
           from the branch of the take, and we consider it's only
           coming from one side for this, for regime transition.
                       MR. WELTER:  It's only coming from one
           side, okay.
                       CHAIRMAN WALLIS:  So this Wallis
           transition is sort of --
                       MR. WU:  For the one side.
                       CHAIRMAN WALLIS:  -- entirely fortuitous
           because this fellow Wallis, --
                       CHAIRMAN WALLIS:  -- whenever it was, over
           30 years ago, didn't have the prescience to realize
           that you were going to connect a cold leg at the other
           end of the pipe.
                       MR. WU:  Yeah, but that's the surprise
           here, you see.  That can use a --
                       CHAIRMAN WALLIS:  This is invocation of a
           correlation which doesn't really apply to the
                       MR. WELTER:  That's correct.
                       CHAIRMAN WALLIS:  So, well, --
                       MR. WELTER:  An interesting fact.
                       CHAIRMAN WALLIS:  The impression, though,
           that you get some authority by quoting this fellow,
           but I'm not sure --
                       CHAIRMAN WALLIS:  I'm not sure that's
                       MR. WU:  No.  It's...
                       MR. SCHROCK:  I'm still trying to
           understand what you're saying about the two sets of
           data.  I don't understand.  Is it --
                       MR. WELTER:  The first set of data --
                       MR. SCHROCK:  Is it that there are waves
           on the surface in one case and not the other case, or
                       MR. WELTER:  What does the flow regime
           look like when I look at my experiments; is that
                       MR. WU:  Quiet.
                       MR. WELTER:  Quiet.  They're both calm. 
           So the effect you're seeing is the flow direction.
                       MR. SCHROCK:  The flow direction?
                       MR. WELTER:  Right.  Through this case
           with a steam generator, your gray dots are for a
           blinded outlet, which means that we have placed a
           blind, a physical blind, where the steam generator is,
           so it just smacks into a wall.  For that case it is
                       For the case where we have a steam
           generator attached, the blind is removed, it's also
           calm, but the level --
                       MR. SCHROCK:  Do you -- do you --
                       MR. WELTER:  Yes.
                       MR. SCHROCK:  -- see it or are you
           imagining this?
                       MR. WELTER:  No.  We have a clear PVC
           pipe, and we've recorded the flow regime.
                       CHAIRMAN WALLIS:  So the difference isn't
           only that you've got some flow in the cold leg, it's
           that you removed some sort of a plug at the end of the
                       MR. WELTER:  Exactly.
                       CHAIRMAN WALLIS:  An open-ended pipe
           instead of a closed pipe.
                       MR. WELTER:  Exactly, yes.
                       CHAIRMAN WALLIS:  So I guess what you're
           showing us is what we've been saying all along, the
           end conditions make a difference.
                       MR. WELTER:  Exactly, yes.
                       MR. BAJOREK:  Do you have an idea of what
           the flow split is, how much of the gas is coming from
                       MR. WELTER:  We are currently --
                       MR. BAJOREK:  -- the vapor side versus the
           steam generator side?
                       MR. WELTER:  In terms of actual figure,
           no.  We are going to install a meter on that side to
           meter that.  In terms of just considering friction,
           there's at least a hundred times more length to go
           through on the cold-leg side.  So we, of course,
           expect a lot less flow.
                       CHAIRMAN WALLIS:  The difference in flow,
           it's an h over D of a half is a factor of about three,
           log paper.  It's a big difference.
                       MR. WELTER:  Yes.  This is a log on the
           horizontal axis; that's correct.
                       MR. SCHROCK:  That's why I have a hard
           time believing that it's a flat interface in both
                       MR. WU:  It's no entrainment.  There's no
           liquid that has been pulled out of the branch, so it's
           calm.  The key part is to --
                       MR. SCHROCK:  The data for the onset of
                       MR. WU:  -- see which level is higher when
           it's become too quiet.  So for the waves of the steam
           generator case, it's a -- the higher level, then it
           becomes quiet.  And without the pressure boundary
           there, your plant flooded.  Then it's a lower level
           and the level becomes quiet.  So that means when
           you're bring flooded, there is a kind of wave bouncing
           back from that pressure boundary, and that will
           entrain more liquid out.  Then that causes the
           entrainment --
                       MR. SCHROCK:  So the open circles, --
                       MR. WU:  -- onset a level lower --
                       MR. SCHROCK:  It's -- the open circles,
           it's picking up liquid off the tops of waves; is that
                       MR. WU:  That's -- that's right.  And at
           the end there's no more liquid being pulled out.  The
           liquid level becomes quiet.
                       CHAIRMAN WALLIS:  So you have a plug at
           the end of the pipe so waves can reflect from it,
                       MR. WELTER:  Exactly.
                       MR. WU:  That due course of the
                       CHAIRMAN WALLIS:  Because one thing that
           happened in this, where you quote here, which had a
           wave-absorbing thing at the end of the pipe, so it
           wasn't a reflection.
                       MR. WU:  It's because -- if you open the
           return line, it becomes quieter.
                       CHAIRMAN WALLIS:  So now I'm a bit happy
           of it, because there is something -- you know, we took
           care to have no waves reflected from the end of the
           pipe in these experiments that you quote here.  Okay.
                       MR. WELTER:  Thank you, sir.
                       So that was a test series that was ran to
           determine the effect of a steam generator blinded or
           open --
                       CHAIRMAN WALLIS:  Wait a minute.
                       MR. WELTER:  Yes, sir.
                       CHAIRMAN WALLIS:  My colleague's asking me
           how do you know hl.  Is hl something you measure
           before you turn on the --
                       MR. WELTER:  Hl is the hot-leg level at
           which entrainment stops.
                       CHAIRMAN WALLIS:  And this is as
           determined by your probe?
                       MR. WELTER:  It's determined by the
           impedance probe.
                       CHAIRMAN WALLIS:  Whatever the probe is
           measuring.  And it's an average of --
                       MR. WELTER:  It's an average over time. 
           And we determine if it's constant, if it approaches
           some moving average.
                       MR. BAJOREK:  Is it based on both the
           vessel side and the steam generator side conductivity
                       MR. WELTER:  For the onset of entrainment,
           there is -- the same.  For the onset of entrainment,
           the levels are the same.
                       When you encounter the entrainment rate
           levels we'll show that that's different when we do the
           entrainment rate tests.
                       We ran a test series to better understand
           the effect of downstream condition.  We also installed
           a one-inch return line to the top of the reactor
           vessel to give us a little bit of refinement to the
           effect of the downstream condition.
                       What we have seen here is with the steam
           generator installed no return line, which means both
           the three-inch and the one-inch line are closed, which
           gives the effect of the lower plenum of the steam
           generator on the onset level.
                       Then we have the three-inch line open. 
           And then we have the one-inch line open.  And of
           course the three-inch closed.
                       CHAIRMAN WALLIS:  I just have to ask you
           something else, too.
                       MR. WELTER:  Yes, please.
                       CHAIRMAN WALLIS:  Once you get this
           entrainment, it goes up into the ADS line.
                       MR. WELTER:  Yes.
                       CHAIRMAN WALLIS:  And I assume that you
           have enough flow rate to carry it up that line, --
                       MR. WELTER:  Yes, yes.
                       CHAIRMAN WALLIS:  -- because if the line
           is too big, it's not going to go over the line; you
           have a different condition where you actually entrain
           it, but it runs back down into the pipe again.
                       MR. WU:  Yes, we guarantee its annular
           flow.  It's over 14 --
                       CHAIRMAN WALLIS:  So you have enough flow
                       MR. WU:  The minimum is a 14-meter per
           second JG.
                       CHAIRMAN WALLIS:  So it doesn't actually
           go up like a jet in the middle.  It actually splatters
           onto the wall, or something?
                       MR. WELTER:  That's correct.
                       I assume you're referring to the
           illustration of the jet in the middle.  Okay.
                       CHAIRMAN WALLIS:  Most of the flow is
           coming from the vessel so that entrainment is probably
           carried to the left as it goes around the corner into
           the branch pipe, or something.
                       MR. WELTER:  Yes, that's correct.
                       CHAIRMAN WALLIS:  It doesn't go off the
                       MR. WELTER:  Yes.
                       Okay.  This shows the case with the effect
           of the downstream condition flow, which means
           basically I am changing the amount of flow that comes
           in from one side.
                       So with the return line closed there, of
           course, is only flow from one direction from the
           reactor vessel to the hot leg through the ADS-4 line. 
           And then I open up the cold leg, and so I get a varied
           amount of flow rates from the other direction.
                       MR. KRESS:  Does the gas flow spiral as it
           goes up the tube?
                       MR. WELTER:  Spiral?
                       CHAIRMAN WALLIS:  Spiral.
                       MR. KRESS:  Spin.
                       MR. WELTER:  Spin.
                       MR. WU:  We can't tell.
                       MR. WELTER:  I can't tell exactly.  I wish
           I could measure that.
                       MR. SCHROCK:  What is the return line
           that's referred to here?
                       MR. WELTER:  Which one, the one-inch or
           the three-inch, sir?  Both of --
                       MR. SCHROCK:  Gosh, I don't know.  I'm
           asking you --
                       MR. WELTER:  Okay.  The return -- the
           three-inch --
                       MR. SCHROCK:  -- to tell me what is the
           return line.
                       MR. WELTER:  Okay.  The return -- the
           three-inch -- okay.  The three-inch return line goes
           from the outlet of the steam generator.  And it's
           basically a model of the cold leg, which returns to
           the top of the vessel head.
                       MR. SCHROCK:  And can you relate it to a
           picture you've shown us of the system?
                       MR. WELTER:  I can relate it.
                       MR. WU:  System 1.
                       MR. WELTER:  The system 1.
                       Brandon, can you go back about 12 slides?
                       This is not an elevation view, so this
           doesn't dip this far down.  The cold leg, the
           three-inch return line comes off the exit of the steam
           generator.  It comes back around.  We have a valve
           there.  It comes back into the top of the reactor
                       CHAIRMAN WALLIS:  Now why should there be
           any circulation in that loop at all?
                       MR. WELTER:  Circulation?
                       CHAIRMAN WALLIS:  There's no pump in that
           loop.  Why would anything flow around that loop?
                       MR. WELTER:  If there's flow from decay
           heat boiling, there's vapor flow from here.  Air is
           being supplied through the porous tubes up through
           here.  The flow can choose.
                       CHAIRMAN WALLIS:  Oh, it could go the
           other way around?
                       MR. WELTER:  Right, exactly.
                       CHAIRMAN WALLIS:  Okay.  Okay.
                       MR. WELTER:  It can choose which way,
           depending on the friction.  Exactly.
                       CHAIRMAN WALLIS:  It's on its way to the
           break, okay.
                       MR. WELTER:  Exactly.  We're trying to
           determine basically how much goes the other way.  So
           we're either cutting it off, opening it, or opening a
           small one-inch return line that isn't shown here,
           which is basically the same as a three-inch.
                       CHAIRMAN WALLIS:  Okay.  Okay.
                       MR. SHACK:  The one-inch return line has
           the same geometry?
                       MR. WELTER:  As the three-inch return
                       MR. SHACK:  Yeah.
                       MR. WELTER:  In terms of geometry?  No.
                       MR. SHACK:  No.
                       MR. WELTER:  It's smaller and just goes
           straight across.
                       MR. SHACK:  Okay.
                       MR. WELTER:  Yeah.
                       MR. KRESS:  If you have a valve in the
           line, why did you need a one-inch line?
                       MR. WELTER:  Because --
                       MR. KRESS:  Couldn't you simulate a
           one-inch --
                       MR. WELTER:  -- we didn't -- we don't --
           it's a gate valve, as you'll see.  And so --
                       MR. KRESS:  Oh, you can't set it very --
                       MR. WELTER:  No.
                       MR. KRESS:  Okay.
                       MR. WELTER:  You can't set it, but open,
                       MR. KRESS:  Okay.
                       MR. WELTER:  So this shows the effect of
           the gas flow direction.  All of the data is still well
           behaved, and so there is little effect of the gas flow
           direction, meaning there is not very much flow going
           through the cold leg or going through the return
           lines.  Most of the flow is still from the reactor
           vessel into the hot leg through the ADS-4 line.
                       CHAIRMAN WALLIS:  I notice there's a lot
           of data scattered.  It doesn't seem to be consistent. 
           If you make the return line size bigger, that's sort
           of a consistent trend.
                       So these are some sort of data points, but
           presumably if you repeated the experiment you wouldn't
           get quite the same point?
                       MR. WELTER:  Are you asking about the
           repeatability of our experiment?
                       CHAIRMAN WALLIS:  Well, it just seems that
           if you look inside the trends, when you have no return
           line, one-inch, three-inch, there's no sort of obvious
           trend.  And so --
                       MR. WELTER:  Sure.  There is an effects --
                       CHAIRMAN WALLIS:  -- I conclude this is
           just scatter that you're showing.
                       MR. WELTER:  There is no significant
                       MR. WU:  Yes, he said that.
                       MR. WELTER:  Yeah, there's a scatter.
                       MR. WU:  He already shows that the --
                       MR. WELTER:  The dots are above.
                       MR. WU:  -- symbol, circle is above --
                       CHAIRMAN WALLIS:  They're sort of above,
                       MR. WU:  Yeah.  We choose this plot to
           represent our experiment data, as we want to leave the
           correlation comparison later, because this was
           originally initially using this -- you noticed that
                       When we calculate the Froude number, we
           use the gas, all the gas for -- to one side to
           calculate it there.  So basically you see that
           shifting I think is because of the flow direction.
                       CHAIRMAN WALLIS:  So this Froude number is
           based on the total gas flow?
                       MR. WELTER:  From the injection, exactly.
                       MR. WU:  Yes.
                       MR. WELTER:  From the meter.
                       CHAIRMAN WALLIS:  It's the only thing you
           know.  You don't know how much is going each way.  So
                       MR. WU:  That's right.  So that means when
           that pipe is getting bigger, like you said, maybe it's
           going to shift up because one side of the gas flow
           rate is not that much.
                       So if we can't -- right now we installed
           -- we are going to install a flow meter.  Maybe we can
           bring that down, we hope.  But this is not the final
           correlation or model we are going to use for this
           entrainment answer --
                       CHAIRMAN WALLIS:  So I guess I have to --
                       MR. WU:  -- test --
                       CHAIRMAN WALLIS:  -- ask:  What's the
           purpose of showing this picture?
                       MR. WU:  Just to see the effect of gas.
                       CHAIRMAN WALLIS:  Just to show that having
           a return line doesn't make much difference?
                       MR. WELTER:  Exactly.
                       CHAIRMAN WALLIS:  But, you see, in the
           code you'd have to actually calculate the flows in the
           return line and use some kind of a correlation.  I'm
           not quite sure how that captures what's shown here.
                       MR. WU:  Originally we -- in this figure
           we expected a scatter, and -- like you already said. 
           And we -- my intention was to say, well, this is for
           regime map -- for regime transition criteria; it
           shouldn't work for this case, and -- but right now
           it's very -- grouped like that give you maybe false
                       You'll say, "Well, this is -- this is
           correlation can't work for that."  I apologize for
                       CHAIRMAN WALLIS:  Is that the correlation
           that's in the code?
                       MR. WU:  The correlation of that is for
           our transition.
                       CHAIRMAN WALLIS:  Is that what's in RELAP?
                       MR. WU:  It's not the one we are going to
           use.  We are going to use the one --
                       CHAIRMAN WALLIS:  You're going to use
           something else?
                       MR. WU:  -- in the code or improve it,
           trying to compare with other correlations like
           Maciaszek's correlation.
                       MR. SCHROCK:  You have a horizontal solid
           line.  Is that part of the slug transition?  What's
           the meaning of that?
                       MR. WELTER:  That's the difference between
           annular, dispersed, and a plug and slug flow regime.
                       CHAIRMAN WALLIS:  That's a Dittus-Boelter
           transition criteria?
                       MR. WU:  Yeah.
                       MR. WELTER:  Yeah, okay.
                       So I summarized the test results on the
           onset of entrainment.  And the second group of tests
           was to discuss -- or take a look at was the steady
           state entrainments.  And the major difference here is
           that we have a steady injection flow.
                       CHAIRMAN WALLIS:  Are you getting onset of
           entrainment by extrapolating back from finite amounts,
           or something?  How do you know onset?  How do you know
                       MR. WELTER:  You mean when does it stop,
           when does it start?
                       CHAIRMAN WALLIS:  When does it start,
           yeah.  Sometimes --
                       MR. WELTER:  We take a look at the data
           and we take a look at the liquid level.  If it
           approaches a moving average, then we assume that no
           liquid is being pulled out and the level does not
           drop.  That is the level at which onset begins.
                       CHAIRMAN WALLIS:  Do you extrapolate it
           then back from when it is dropping?  Measuring zero is
           not very easy.
                       MR. WELTER:  There is still a level in the
           hot leg, but there is a level at which entrainment
           does not drop the level any farther.  Basically --
                       CHAIRMAN WALLIS:  So it has come to an
           equilibrium level?
                       MR. WELTER:  It -- yes, it comes to a
           constant level --
                       CHAIRMAN WALLIS:  So you're extrapolating
           to equilibrium?
                       MR. WELTER:  It just stops.
                       CHAIRMAN WALLIS:  Okay.  So you do --
                       MR. WELTER:  That's correct, yes.
                       CHAIRMAN WALLIS:  -- have an extrapolation
           of the thing going on.
                       MR. WELTER:  Okay.  Yes.  I was confused. 
           I'm sorry.  Thank you.
                       MR. SCHROCK:  The onset as reported in the
           previous literature is dependent to some extent on the
           method of observation.
                       MR. WELTER:  That's correct.
                       MR. SCHROCK:  In the KFK experiments, for
           example, they used an acoustical method for measuring
           the onset.  We looked at it visually.
                       And in both cases there were circumstances
           in which you would get intermittent lifting of the
           liquid at a certain level.  And then at a slightly
           higher level you get continuous flow of the liquid.
                       And so you have to make a decision what is
           it that you're using as the basis in your correlation,
           because you need that hb or hl, as you've designated
           it, in your correlation for the flow in the break line
           after the onset of entrainment as a function of the
           level in the stratified zone.
                       So I'm simply mentioning that, because I
           don't hear any significance attached to the method of
           observing the level for the onset.
                       CHAIRMAN WALLIS:  He's measuring the --
                       MR. SCHROCK:  Are you --
                       CHAIRMAN WALLIS:  -- the opposite.  He's
           measuring the stopping of entrainment.
                       MR. SCHROCK:  Are you giving the value for
           continuous entrainment, the value for intermittent
           entrainment, a value that's seen visually, or a value
           that's detected by some instrument, such as the KFK
           experiments using an acoustical detection in the
           branch line?
                       MR. WU:  For the entrainment onset level,
           like Dr. Wallis' point, we measured when it stops so
           that level is quiet --
                       MR. SCHROCK:  When it stops?
                       MR. WU:  Yeah.
                       CHAIRMAN WALLIS:  So -- could you draw on
           the thing here --
                       MR. SCHROCK:  So you're not giving the
           onset; you're giving the cessation?
                       CHAIRMAN WALLIS:  Draw us what you
           actually -- what you actually measure.
                       MR. KRESS:  They're actually using those
           probes on each end, I think they said.
                       CHAIRMAN WALLIS:  You measure hl versus
           time, or something?
                       MR. WU:  Yeah.
                       MR. WELTER:  Okay.  So I'll draw -- I
           think you were wondering what the data looks like,
           draw a picture of what --
                       CHAIRMAN WALLIS:  Yeah.  How -- what
           actually -- when do you say it stops and that sort of
                       MR. WELTER:  Okay.
                       CHAIRMAN WALLIS:  Could you use a thing
           that shows up, not the plain red one.
                       MR. WELTER:  Yeah.
                       Okay.  So this is the time during the
                       CHAIRMAN WALLIS:  Right.
                       MR. WELTER:  And this would be with the
           calibration curve then, the level in the hot leg, hl.
                       CHAIRMAN WALLIS:  Right.  That's hl.
                       MR. WELTER:  That's correct.
                       You would see -- at the beginning of the
           test you would see a full hot leg right there.  And as
           you throttle the gas flow, you would, of course, see
           a sharp drop in the level in the hot leg.  And after
           a period of time --
                       CHAIRMAN WALLIS:  You leave the gas flow
           constant now?
                       MR. WELTER:  Leaving the gas flow as
           constant.  There's no injection rate.  After a period
           of time this level will go like that, the level in the
           hot leg.
                       CHAIRMAN WALLIS:  Okay.  So --
                       MR. WELTER:  This is the level --
                       CHAIRMAN WALLIS:  It's its last gasp.  In
           fact, it's the level at which the last little piece of
           wave comes off.
                       MR. WELTER:  Exactly.  And so we take a
           look, and we say that this level right here, we take
           an average of time and we compare it, of course, the
           time's average between this one, average there, a
           moving average.  And we compare what does this
           approach to, what does that value approach to.  That's
           where onset stops.  And we have then said that's when
           onset begins.
                       MR. WU:  So for --
                       MR. SCHROCK:  Well, how do you know
           there's not a hysteresis involved in the phenomenon?
                       MR. KRESS:  You would expect some.
                       MR. WU:  We tried to bring the liquid
           level up.  But once you overbring it, it's going to
           put it out.  Because of our branch size, we guarantee
           the branch's velocity is overly, a full regime
           transition for the annular flow.  So anything being
           put to that branch exit is going to pull out.  So it
           mustn't pull out.
                       So if you go for -- we go -- we went from
           the bottom up, bring liquid there, and to come back to
           -- if we overshoot it, it will bring up to the
           stopping point.  That's the same result.
                       MR. BAJOREK:  But can you tell, when you
           bring that level up, whether you're getting
           entrainment and then it drops back down to the level? 
           You could have been getting entrainment at a lower
           level and you won't see it until you've entrained a
           whole bunch of it --
                       MR. WU:  Well, --
                       MR. BAJOREK:  -- and drop back down.  So
                       MR. WU:  No, no.  There's no drop back,
           back down significant.  We bring it up to the -- when
           the entrainment occurs, you -- you obviously, when you
           say "entrainment," that's already overshooting the
           level, right?
                       Then you bring down a little bit, and
           actually it's the same condition as what we -- we are
           talking about.
                       You have a minimum in the gas count
           constant, and then the entrainment stops.  Here is you
           just overshoot a little bit, and it just finally stop. 
           For our case it is from the top to the stop.  It's --
                       MR. BAJOREK:  But it's a question of
           whether there's a hysteresis if you get entrainment at
           a lower case in g- --
                       MR. WU:  We didn't find that.  For our
           test we didn't show that.  We didn't find that.
                       CHAIRMAN WALLIS:  I'm uncertain about the
           time now because you're describing a test and you've
           had about four or five different correlations and
           analyses to go through.  And if we ask as many
           questions about each one of those you're going to be
           here until about three o'clock before we get lunch.
                       But we may -- you know, it may be
           worthwhile asking those questions.  We just don't have
           the time.
                       MR. SPEAKER:  You have to do what you can
           to keep us going.
                       MR. WELTER:  Okay.  Thank you, sir.
                       I didn't describe those, okay.
                       For the steady state entrainment test,
           this is for constant liquid injection and a constant
           gas flow rate.  We will go ahead and the reactor
           vessel will start basically dry.  And I will throttle
           the flow rate of the liquid to fill the reactor
           vessel, at the same time throttling the air at a
           specified flow rate.
                       And this will go ahead and will raise --
           the two-phase mixture will raise.  At a certain point
           the hot-leg level will start to entrain.
                       And we will then take this data for a
           period of time, approximately four to six minutes. 
           And this is the time the h, the level at which there's
           steady state entrainment.
                       And in this case, since flow cannot go
           around the steam generator, the injection is equal to
           the entrainment rate.  We're trying to determine what
           the hot-leg level is for those flow conditions.
                       The test scope, the matrix that we did is
           the effect of the steam generator, close it, open it
           -- the blind.  I'm sorry.  And the effect of the gas
           flow direction on that entrainment rate.
                       CHAIRMAN WALLIS:  Now when you do a
           theory, are you going to use different theory in the
           different places in the flow regimes in the different
           -- in the next figure?
                       MR. WELTER:  Theory?
                       CHAIRMAN WALLIS:  You've got plug, slug,
           stratified, wavy.  I'm just following ahead.
                       MR. WELTER:  Oh, yes.
                       CHAIRMAN WALLIS:  Are you going to use
           different theories in the different parts of the
                       MR. WELTER:  Oh, okay.  I'll go ahead
                       CHAIRMAN WALLIS:  Are you going to use
           different theories in those different flow regimes?
                       MR. WELTER:  I'm sorry.  Could you clarify
           "theory," what you mean by "theory"?
                       CHAIRMAN WALLIS:  On the right you've got
           four flow regimes.
                       MR. WELTER:  This is classic flow regime
                       CHAIRMAN WALLIS:  Are you going to use the
           same theory for all points?
                       MR. WELTER:  In terms of the model
           development, sir?
                       MR. WU:  This one, in this case you have
           liquid flow.  For the previous one you don't have
           liquid flow.
                       CHAIRMAN WALLIS:  Yeah, but I'm just
           saying you're going to develop a theory for liquid --
                       MR. WELTER:  All of them, he wants to know
                       CHAIRMAN WALLIS:  Is it the same theory,
           or different?
                       MR. WU:  For this flow regime map we use
           -- if you -- you don't have a JF you cannot do it,
           right?  That's for this stratified, okay.  So without
           the liquid flow in the main pipe you cannot use this
           for a regime map.
                       The one Zuber proposed for that one is a
           -- said that VF equal to zero.  We'd use your
           transition criteria.  We said we have equal to zero. 
                       MR. WELTER:  Okay.  I think it would be
           more explained when he talks about the model
           improvement, when he talks about the actual model
                       The test matrix includes gas flow rates of
           up to 300 standard cubic foot per minute.  We can --
           our compressor is capable of at least three times
           that, but with corresponding pressures we, since it is
           PVC, rate at 20 PSI, we maintain low, so we maintain
           integrity of our test section.
                       Similar with that, our liquid flow will go
           up to 60.  Our pump is capable of 600.  We maintain it
           low so the test section does not break or leak.
                       These are the data points we ran.  We
           wanted to get a good full spectrum as possible.  And
           when we look at a classic flow regime map, this is
           different in the fact that this is not the flow
           regimes that we see in our test section because we do
           not have a developed flow.  We have a short inlet. 
           But if it were, this is where the data would fall.
                       This is an illustration or a visualization
           from the separate effects.  We would like to see
           what's happening, and so I have a clear PVC test
                       This is a visualization data that we
           recorded.  I have another animation.  And it
           illustrates the oscillatory phenomenon that you see
           when the three-inch return line is closed or the loop
           seal is filled.
                       CHAIRMAN WALLIS:  Are you going to show us
           movies?  I guess you are.
                       MR. WELTER:  I'm going to show you a
           movie.  So that is the oscillatory nature and that is
           approximately real time.
                       CHAIRMAN WALLIS:  I would think that no
           theory is going to predict that.
                       MR. WELTER:  That -- okay.  It comes to a
           point that previous studies, of course, what liquid
           level are you going to use for h.  There are two
           levels.  And since we have two probes that measure a
           hot-leg level, we have two distinct different levels.
                       CHAIRMAN WALLIS:  And this stuff about
           potential flow out to a sink or something isn't going
           to be relevant to that picture, is it?
                       MR. SCHROCK:  Let's see.  This is what I
           was trying to point out earlier.  What you're showing
           here illustrates that the phenomenon that you're
           studying has nothing to do with the physics of the
           flow of the gas creating a low-pressure zone that
           lifts liquid off of a smooth interface and entrains it
           into that branch flow.
                       CHAIRMAN WALLIS:  It doesn't matter,
                       MR. SCHROCK:  These --
                       CHAIRMAN WALLIS:  The theory's going to
           work anyway.
                       MR. SCHROCK:  Huh?  I mean --
                       MR. WELTER:  This is -- I'm sorry.
                       MR. SCHROCK:  -- how you could imagine
           you'd fit this into the format of the correlation --
                       CHAIRMAN WALLIS:  Well, it may well --
                       MR. SCHROCK:  -- that represents the onset
           of entrainment as a function --
                       MR. WU:  No.  We hope --
                       MR. SCHROCK:  -- of a liquid level.  There
           is no definable liquid level in this thing.
                       CHAIRMAN WALLIS:  There is whatever's
                       MR. WU:  There's an average in the --
                       MR. SCHROCK:  No.  There is not --
                       CHAIRMAN WALLIS:  It's whatever's measured
           by the probe.
                       MR. SCHROCK:  -- even a definable average. 
           Try to define it.  See how far you get.
                       MR. WU:  So that means we may need to do
           some more modeling or --
                       CHAIRMAN WALLIS:  No, no, no, no.  You
           finished the program, we heard.  I think we've got to
           go on, --
                       MR. WELTER:  Thank you, sir.
                       CHAIRMAN WALLIS:  -- but obviously there's
           some skepticism.
                       MR. WELTER:  Thank you, sir.
                       So we are concerned with, of course, the
           real case.  There are two levels.  How to determine,
           when we're using a model, which level to use, average
           the reactor side, the steam generator side.
                       And part of our test scope I wanted to
           illustrate what we just spoke about which is the step
           phenomenon, and that is these data points.  The square
           dots are for the test series with a closed return --
           I mean -- I'm sorry.  This is mislabeled.
                       (Presenters Mr. Welter and Mr. Wu confer
           off record.)
                       MR. WELTER:  So with the closed line there
           is not a large difference in the levels when we open
           the steam gen- --
                       (Presenters Mr. Welter and Mr. Wu confer
           off record.)
                       MR. WU:  So the upper circle is the --
           within the same -- oh, yeah, it's over it.
                       MR. WELTER:  It's opposite, yes.  I'm
           sorry.  The graph is incorrect.  These data points
           should be switched in terms of the squares are with
           the three-inch line open.  And the circles are with
           the three-inch line closed.
                       So when the three-inch line is closed,
           then the oscillatory behavior is seen.  And you can
           tell that by the difference in level.  One level is
           the react- -- this is the steam generator side,
           hot-leg level.  This is the reactor hot-leg level.
                       And when the case -- when the three-inch
           line is open it's a much more calm surface and the
           levels are much more similar.
                       MR. SCHROCK:  What is the meaning of "step
                       MR. WELTER:  "Step phenomenon" is meaning
           -- I'm sorry -- that there is a step in your level. 
           You're basically seeing a lower level in the inlet to
           your test section and a higher level on your steam
           generator side, so the level is stepping.
                       MR. SCHROCK:  Well, the thing that you
           refer to as steady is shown, in three different views,
           something that's very unsteady and you imagine some
           average condition about it.  But can --
                       MR. WELTER:  We have taken a time average
           of that condition; that's correct.
                       MR. SCHROCK:  Yeah.  But for step
           phenomenon, what do you imagine, that you have a level
           that suddenly changes as the liquid progresses?
                       MR. WELTER:  I'm sorry.  I was not clear.
                       MR. SCHROCK:  I want you to explain to me
           what the term "step phenomenon" means.
                       MR. WELTER:  The term "step phenomenon"
           means to me, in the way that we have described it, is
           that there is a difference in levels between the
           reactor side and hot leg, if we look at an average.
                       CHAIRMAN WALLIS:  It seems to me what's
           happening is that you have a plug of liquid in the
           steam generator and then the -- everything's clear for
           the --
                       MR. WELTER:  Exactly.
                       CHAIRMAN WALLIS:  -- hole, so the gas goes
           out, the plug runs back.  As soon as it comes back to
           the hole, it blocks the hole, the pressure goes up, --
                       MR. WELTER:  Right.
                       CHAIRMAN WALLIS:  -- and it gets shot back
           up into the steam generator.  You're generating
           oscillation of a slug of water.
                       MR. WELTER:  And the plug does not reach
           the inlet side.
                       CHAIRMAN WALLIS:  Right.  This is very
           system dependent.  So what you're studying is
           entrainment.  When you have an oscillating plug going
           into a steam generator, it's completely different from
           Professor Schrock's experiment --
                       MR. WELTER:  That's correct.
                       CHAIRMAN WALLIS:  -- and Lahey's, and so
           on.  It's a different thing altogether, but it may
           apply to AP600.
                       MR. WELTER:  Yes.  Thanks.
                       So this is also the --
                       MR. SCHROCK:  It may not, too.
                       MR. WELTER:  This is also the effect of
           the steam generator, again similar to the onset, with
           a blind compared to with the steam generator.  You see
           with no steam generator there is going to be a higher
           liquid level, similar to what we discussed with the
           onset of entrainment tests.
                       So the steam generator is also important
           when we're considering entrainment rate phenomena at
           steady-state conditions.
                       CHAIRMAN WALLIS:  How is this going to get
           fit into a code, the fact that the steam generator is
                       MR. BAJOREK:  At this point we've got to
           be very careful on what and how we would apply this
           model.  The problem in RELAP is that the horizontal
           stratified model was grossly underpredicted in the
           total entrainment.
                       I think what we see in the movies here is
           something that's more flow-regime dependent rather
           than something that's giving us entrainment off of a
           horizontal stratified.  The flow regime is sitting
           there quiescent.
                       I think that at this point we should be
           taking the correlations, Maciaszek, Schrock,
           potentially the new one, and looking at the
           sensitivity of entrainment that we might be getting,
           but I don't know if we're far enough along that we
           would say that this is a great model and we should
           drop this in and replace what we've got there.
                       I think what we are seeing based on their
           work so far is that they are seeing higher rates of
           entrainment than the previous model that had been in
                       And that puts it more in line with the
           no-reserve tests, some of the other -- I guess there
           was another one of the tests that was showing much
           higher entrainment than what they've been getting out
           of the existing correlation.
                       We're going to need something like that
           for AP1000, where the gas velocities coming out of the
           core are going to be substantially higher and we're
           going to expect more entrainment.
                       So I think it's headed in the direction of
           increasing the -- being able to predict higher
           entrainment.  But I wouldn't say that this is a model
           that we can say is completely adequate for all
                       CHAIRMAN WALLIS:  I'm not sure yet that
           the model represents the physics.  I'm sort of with
           Virgil.  Perhaps we need to get to the model.
                       MR. SCHROCK:  Well, I think this is the
           problem always with the codes, is that -- I said this
           in our private discussions -- you make comparisons of
           the code predictions against integral system
           performance.  And you get an impression that the
           reason that the code doesn't predict the experimental
           data well is one of hundreds of correlations that are
           embedded in that code isn't right for that situation.
                       Now what you've just said focuses very
           clearly on what the difficulty in their thinking is.
                       It's not that the correlations were
           entrainment from a stratified region are the problem;
           it's that the code is telling you you have a
           stratified region when, indeed, it's not stratified. 
           And, therefore, you're getting something altogether
                       The problem is in the characterization of
           the flow regimes, which is excessively simplistic in
           the codes and leads to all kinds of difficulties and
           confusions in interpreting these comparisons of
           integral test performance and code prediction.
                       And you're never going to improve that
           following the course that this is taking.  You're
           dealing here with different phenomena than the
           references taken from the literature addressed.
                       MR. KRESS:  It does -- it does --
                       MR. SCHROCK:  You have to address the
           phenomena that are occurring in that system.
                       MR. KRESS:  It does point you to where you
           need to work on your code, because basically the
           RELAP-type formulation won't predict this oscillatory
           behavior because of the way it's set up.  And that's
           what you need.
                       You'll need something that predicts when
           you get this behavior, and then perhaps your results,
           or whatever correlation you put out of them, could be
           used if the code could predict that behavior.
                       MR. SCHROCK:  Right.
                       MR. KRESS:  But you need to work on that
           part of the RELAP.
                       MR. BESSETTE:  Yeah.  I think we agree --
           I think -- you know, see, what we have in RELAP right
           now is -- simply invokes the off-take model when the
           code says you have stratified conditions at that node.
                       So if we have -- so you have to invoke the
           model at the right time.  So if we have, you know, one
           particular model for slug flow, one for wavy, one for
           stratified, of course, as a starting condition, the
           code has to get flow regime right, you know, --
                       MR. SCHROCK:  Right.
                       MR. BESSETTE:  -- in order to invoke the
           model at the right time.
                       MR. SCHROCK:  That's precisely my point.
                       MR. SHACK:  The physics are different in
           each one of those regimes in what it does.  And right
           now it just gravitates from regime to regime and makes
           it very simplistic.
                       CHAIRMAN WALLIS:  I'm just wondering where
           you're going to go with this presentation.  I see
           you've got what looks like three models that we sort
           of agree don't apply.
                       Are you going to just simply say here are
           three lousy models that don't apply and go on to the
           one that works that you developed, or are you going to
           spend a lot of time going through something which
           doesn't apply?
                       MR. WU:  No.  We want to say the two
           models we compare are the two asymptotical condition. 
           And then we want to say bridge them together.
                       CHAIRMAN WALLIS:  Well, we don't need to
           worry about Schrock's sink flows and things like that,
           do we, because it doesn't apply?
                       MR. WU:  Well, --
                       CHAIRMAN WALLIS:  Are you going to drag us
           through --
                       MR. WU:  The case is for this project, we
           are trying to extend for small breaks.  And Schrock's
           correlation obvious for small breaks should work for
           that.  And then we want -- we don't want to abandon
           these --
                       CHAIRMAN WALLIS:  For very small breaks.
                       MR. WU:  Yes.  So we say, well, we cannot
           develop a model say just for the larger break.  We
           have to consider some model that already worked in the
           past.  So we want -- so we figure out from the
           theoretical reasoning we found it is Maciaszek's and
           Schrock's work.  It's actually two asymptotic
           conditions.  And then we try to bridge them together.
                       So if you have a small break, it works. 
           Basically it is approaching to Schrock's work.  And
           then larger break approaches to Maciaszek's work. 
           That's what our intention.  We didn't try to abandon
           what is the previous work.
                       MR. WELTER:  Thanks, sir.
                       I think that's my last slide in the test
           results section, determining the importance of the gas
           flow downstream, the gas flow direction.
                       In the onset tests we saw that there was
           a little bit of scattering compared to the entrainment
           rate tests.  When I open or close a three-inch return
           line, there is a large difference in the liquid level
           in the hot leg.
                       CHAIRMAN WALLIS:  Well, how are you going
           to use these data?  Do you know the flow rate in the
           return line?
                       MR. WELTER:  In terms of where -- we're
           installing a metered flow line.
                       CHAIRMAN WALLIS:  Oh, you don't know it
                       MR. WELTER:  That's correct, sir.
                       CHAIRMAN WALLIS:  So we're simply
           observing there's a difference, but --
                       MR. WELTER:  That's correct.
                       CHAIRMAN WALLIS:  So the data aren't
           usable yet until you've done some more measurement --
                       MR. WELTER:  That's correct, sir.
                       CHAIRMAN WALLIS:  -- to know what's really
           going on?
                       MR. WELTER:  That's correct, sir.
                       This is showing just the effect.
                       CHAIRMAN WALLIS:  But it's an effect which
                       MR. WELTER:  It's important.
                       CHAIRMAN WALLIS:  -- can't be reflected in
           a theory because you don't know the flow rate split.
                       MR. WU:  Not yet.
                       MR. WELTER:  Not yet.
                       CHAIRMAN WALLIS:  You don't know the flow
           rate split going in the two directions?
                       MR. WELTER:  Yes, that's correct.
                       MR. WU:  We know one is closed --
                       CHAIRMAN WALLIS:  So you can't have
           finished -- you can't have finished the work.
                       MR. WU:  The closed case, we know.  That's
           -- that presented the real case of the loop seal case. 
           That's the major, and --
                       CHAIRMAN WALLIS:  It's a major effect,
                       MR. WELTER:  In this presentation we
           haven't presented an entrainment rate model.  We've
           presented an onset model.  The entrainment rate model
           is continuing work at this point.
                       CHAIRMAN WALLIS:  Well, you've explored
           some things which influenced the entrainment.
                       MR. WELTER:  That's correct.
                       And so this shows the effect of the return
           line or the flow direction.
                       Noticeably, with the three-inch line open
           there is no oscillatory behavior.  So when the loop
           seal is filled and the three-inch line is closed, the
           oscillatory behavior occurs.  When it's open, it's
           much more calm.
                       I'd like to take a few minutes because,
           like Dr. Wu said, the new model proposed is asymptotic
           conditions of Schrock and Maciaszek's work, so take a
           moment to look at those models.
                       That's Schrock and Smoglie using a
           potential flow formulation.  The stream lines go to a
           sink.  The break is modeled as a sink.  The stream
           lines intersect the interface, so there's in effects
           of the interface, gas leak or interface on the
           potential.  And hb is far from the break, or the other
           way to say that is the break size is very small, can
           be considered a point sink.
                       For noise equate --
                       CHAIRMAN WALLIS:  There's a flat ceiling,
           too, isn't there?  There's no curvature to the pipe
           and all that.
                       MR. WELTER:  That's correct.  Exactly how
           strong it gets.
                       Hb again is considered as the gas chamber
           height at which entrainment begins.
                       CHAIRMAN WALLIS:  What does he do with his
           interface then?  He's got another sink reflecting an
           interface, or something?  How does he --
                       MR. WELTER:  In the model?  Without
           improvement?  I'm sorry, sir?
                       CHAIRMAN WALLIS:  The stream lines come
           out of the interface like that?
                       MR. WELTER:  The stream lines --
                       CHAIRMAN WALLIS:  Magically come out of
           the interface?
                       MR. WELTER:  That's correct.  It's a sink.
                       MR. SCHROCK:  I don't know why you've put
           my name on there, but --
                       MR. WELTER:  Smoglie.  I'm sorry, go
                       MR. SCHROCK:  -- apart from the fact that
           it's misspelled.
                       MR. SCHROCK:  The history here is that the
           program at KFK involved extensive experimentation
           under the direction of Dr. Reimann -- Reimann and
           Kahn, Reimann and some other people.
                       Smoglie was a student who did a
           theoretical thesis employing potential flow to make a
           prediction of the value of hb for a stratified
           upstream condition.
                       I don't recall her having stream lines
           intersecting the interface, but it's been more than 10
           years since I last looked at that.  Maybe she did, but
           I kind of doubt that.
                       But, in any case, it's not something that
           I suggested or that any of my co-workers suggested.
                       MR. WU:  We put Smoglie --
                       MR. SCHROCK:  Also in your reporting of
           the KFK data you refer to that as Smoglie data.  She
           had no data.  I mean she -- in the sense that she did
           experimentation, she was not an experimentalist.  She
           was a theoretician -- is a theoretician I presume now.
                       MR. WU:  Thank you.  We should represent
           it as KFK data later.
                       And for this Smoglie, they arrived at
           that.  That's true.  The interface, the stream line
           goes to the interface.  I mean there is no interface
                       For your name put there is because your
           correlation.  It's almost identical with that, except
           that the gas density --
                       MR. SCHROCK:  Well, that's kind of a loose
           description.  I mean --
                       MR. WU:  So the two correlation basically
           the same, --
                       MR. SCHROCK:  Yeah.
                       MR. WU:  -- to the fifth power, so we
           didn't see this derivation is yours.  We should have
           cleared it up before.  And yours is based on the
           Froude number.  And the Froude number is based on the
           branch velocity.
                       CHAIRMAN WALLIS:  One of the units here,
           W is a flow rate?
                       MR. WU:  Mass flow rate.
                       CHAIRMAN WALLIS:  Mass flow rate.  I don't
           understand how the units of the final correlation work
           out.  It doesn't even make sense to me, but -- three
           in -- oh, well, maybe it does.  Okay.  Maybe it does.
                       MR. WELTER:  So Bernoulli's equation can
           be written along the Z axis from the interface to the
           point sink.  You take the derivative in terms of that
           with respect to the distance away, then you can
           develop a criterion based on the pressure gradient at
           the interface.  If --
                       CHAIRMAN WALLIS:  We're beginning to pick
           up the interface.
                       MR. WELTER:  That's correct.
                       So at some condition if this pressure
           gradient is greater than or equal to the gravity
           potential, then entrainment begins.  So it's an onset
           entrainment criterion.
                       CHAIRMAN WALLIS:  So something happens.
                       MR. WELTER:  Exactly.  Something happens.
                       CHAIRMAN WALLIS:  Is there any
           confirmation that this works?
                       MR. WELTER:  Oh, yeah.  The next slide
           will show data and how well this correlation -- yes.
                       Hb is then -- you can get that from this
           correlation.  And hb is a function of the gas mass
           flow rate to the one-fifth power or squared to the
           two-fifths power.
                       CHAIRMAN WALLIS:  So the Smoglie data,
           compared with theory, spans about two orders of
                       MR. WELTER:  Yes, that's correct.  But
           this -- the KFK data --
                       CHAIRMAN WALLIS:  Worst case.
                       MR. WELTER:  Yeah.  The KFK data has large
           uncertainties in the determination.  There are several
           -- you see several gas flow rates for the same liquid
                       This graph is a W3g squared, which is
           what's in the brackets.  So this is raised to the
           one-fifth power.
                       CHAIRMAN WALLIS:  So this is theory versus
           experiment; is that what it is you're saying?
                       MR. WELTER:  That's correct.  So it shows
           the degree of collapsing of the data, how well the --
           so the exact -- the exact data would lie directly on
           this line.  Left side versus right side.
                       This is the correlation by Smoglie, and it
           shows -- the red is ATLATS data for large -- or for
           small data.  I'm sorry.  And for Smoglie and Schrock
                       CHAIRMAN WALLIS:  The only thing that
           works well is the Schrock data.
                       MR. WELTER:  Yes.  That is right there. 
           It's beautiful.  It has --
                       CHAIRMAN WALLIS:  You deny --
                       MR. SCHROCK:  Absolutely amazing.
                       CHAIRMAN WALLIS:  -- having created this
                       CHAIRMAN WALLIS:  I thought you were
           denying having created anything.
                       MR. SCHROCK:  No, no.  I created a lot of
                       CHAIRMAN WALLIS:  Oh, you created it, but
           you didn't have any theory.
                       MR. SCHROCK:  Smoglie had the theory only.
                       MR. WELTER:  But it has difficulty
           predicting where D over D is small.
                       CHAIRMAN WALLIS:  Yeah.
                       MR. WELTER:  The large breaks, that is.
                       Next we'll take a look at Maciaszek, who
           used a formulation by Wallis.  Considering -- Wallis
           considered a branch or just basically a tube on top of
           a large pool with gas flowing over it so gas flows
           from all directions into an entrains liquid into the
           branch.  It considers an interface condition with a
           two-bump sort of phenomenon, wave phenomenon, where
           the wave crest height is determined and defined as
                       And you can write a simple continuative
           equation here, where velocity of the inlet or velocity
           from all sides in a virtual cylinder here, so it's rho
           v pi times number, which is diameter of the sphere --
           of the cylinder.
                       And the cylinder is from hb minus delta,
           so it's the cylinder right here (indicating).  And
           that's show in this here.  And that is --
                       MR. SCHROCK:  Is this --
                       MR. WELTER:  Yes.
                       MR. SCHROCK:  -- a cylindrical off-take,
           or what --
                       MR. WELTER:  Yes, this is a cylindrical
           off-take.  So this is a cylindrical cylinder that the
           gas is flowing into.
                       MR. SCHROCK:  And so it's in cylindrical
           geometry in that sense, and so these bumps represent
           a ring of --
                       MR. WELTER:  A ring, that's correct.
                       MR. SCHROCK:  Um-hum.  Why does it do
                       CHAIRMAN WALLIS:  I have no recollection
           whatsoever of any of this.
                       MR. SCHROCK:  Why would the liquid deform
           in that way?  It implies that the -- that there's a
           ring of low pressure lifting it into that format.
                       CHAIRMAN WALLIS:  I guess there has to be
           a stagnation point in the middle, must be the
                       MR. WELTER:  That's correct.  Velocity at
           this point is zero.  There's a maximum velocity at the
           wave crest.  Work done by Dr. Wu in the model
           improvement section I think delves a little bit deeper
           into that question.
                       CHAIRMAN WALLIS:  This leads to a theory
                       MR. WELTER:  Yeah.
                       CHAIRMAN WALLIS:  -- which compared on the
           next figure.
                       MR. WELTER:  Yes.  So this leads to a
           theory which is surrounded in this box here.  The
           difference being it has a different
           experimentally-determined coefficient.  And it uses
           the break size diameter d and it's different as to the
           one-third power inside of the one-fifth.
                       Here is how well the correlation -- it
           brings our data down well, but it's skewed, the
           Schrock and Smoglie data you can see, slightly skewed
           compared --
                       CHAIRMAN WALLIS:  Now why are you calling
           it W2 over d5?
                       MR. WELTER:  Okay.
                       MR. SCHROCK:  That's this divided by h.
                       MR. WELTER:  It's divided by d5 for
           nondimensional.  So the Maciaszek correlation, the
           horizontal axis is hb over d.
                       MR. SCHROCK:  What's on the axis of that?
                       MR. WELTER:  I'm sorry.  What?
                       MR. SCHROCK:  What is being plotted on the
                       MR. WELTER:  Okay.  Yeah, the Maciaszek
           correlation.  So this is experiment -- this is
           experimental and this is your theoretical.  So this is
           Maciaszek's correlation.  It's the other --
                       MR. SCHROCK:  No.  What -- what quantity
                       MR. WELTER:  Hb is on --
                       MR. SCHROCK:  -- is on -- is on the
           abscissa?  It's unlabeled.
                       MR. WELTER:  Okay.  Yes.  Hb over small d
           to, in this case, the third power.
                       MR. SCHROCK:  We should never have to
           imagine that, you know.
                       CHAIRMAN WALLIS:  Oh, is that what it is?
                       MR. SCHROCK:  Even undergraduate students
           know that.
                       CHAIRMAN WALLIS:  I didn't think that.  I
           thought it was theory versus experiment.  I guess in
           a sense it is, but --
                       MR. WELTER:  It is.
                       CHAIRMAN WALLIS:  -- it's essentially flow
           rate versus height, is what you're plotting.  Flow
           rate squared versus height.
                       MR. WELTER:  That's correct.  Can I go on?
                       Okay.  To summarize, the model --
                       MR. SCHROCK:  I'd just --
                       MR. WELTER:  Yes, sir.  Please.
                       MR. SCHROCK:  -- finally like to tell you
           that I saw this at close range many, many times and
           never did I see a ring of liquid pulled up, never. 
           Always a symmetric --
                       MR. WELTER:  Like this.  Right here, yeah.
                       MR. SCHROCK:  Right, yeah.  Single little
           thing coming up and drops coming off the top of it.
                       CHAIRMAN WALLIS:  This happened so often
           in two-phase flow.
                       MR. WU:  Yeah.  Maybe -- maybe --
                       CHAIRMAN WALLIS:  The theory is based on
           the physics which is utterly different from reality
           and yet the correlation works.
                       MR. WU:  Maybe the instability taken one
           point then break the other symmetric.
                       MR. WELTER:  To summarize the evaluation
           of the entrainment onset models, Smoglie's data is a
           large scattering with large uncertainties.  The
           Smoglie model is effective.  As we saw, it predicts
           that da- -- Schrock's data, and it's very effective
           for small break sizes or when the interface level is
           far from the break.
                       Maciaszek's model, which takes into
           account the break size, is valid for large breaks and
           -- which we saw why it pulled the ATLATS data down to
           that line, or when the liquid interface level is close
           to the break.
                       MR. SCHROCK:  I guess you haven't shown us
           any data yet that would tell me that you ought to plot
           those on the same piece of graph paper.  The data that
           you have is for conditions upstream that are not
           stratified for the most part, so far as I can tell.
                       MR. WELTER:  Onset data -- the onset data
           is a calm surface.  The entrainment rate is the
           oscillatory.  Am I confusing that?
                       MR. SCHROCK:  I just heard a lot of
           discussion about the fact that you don't even measure
           the onset of entrainment.  What you measure is the
           cessation --
                       MR. WELTER:  Cessation of entrainment.
                       MR. SCHROCK:  -- of entrainment.
                       Cessation of entrainment in relationship
           to what kind of phase distribution you had upstream
           was left quite unclear.  But you've not shown us any
           evidence of the fact that you have cleancut
           measurements of the onset of entrainment from
           stratified upstream conditions.  I've not seen that. 
           If you have it, show it to us.
                       MR. WELTER:  Okay.  Sir.
                       CHAIRMAN WALLIS:  Well, presumably the
           bubbling in the reactor vessel sets up some sort of
           wave motion in the pipe.
                       MR. SCHROCK:  Well, I'm not arguing that
           all these complications don't exist out there in the
           reactor systems.  But what I'm saying is you're not
           going to improve your computer code by this kind of
           pursuit of what is wrong with what the code is
           currently doing.
                       What's wrong with what the code is
           currently doing is, predominantly, it has no idea what
           the upstream flow regime is.
                       CHAIRMAN WALLIS:  Okay.  We're getting
           close to the break, Jose, are we?  We're supposed to
           go to 11:15 and then we're supposed to do a tour.
                       What would you like us to do?
                       MR. REYES:  It would be valuable at this
           point possibly to take a break and go look at the test
                       CHAIRMAN WALLIS:  We're going to come back
           and see this in the afternoon.
                       Then I think the interesting will be what
           you have done to get better agreement with data.  As
           I understand, you have a better model, but it seems to
           be based on these somewhat iffy past models rather
           than a new model that really reflects what's actually
           happening; is that the case?
                       MR. REYES:  I don't believe we've gotten
           to that point yet in the --
                       CHAIRMAN WALLIS:  Can we discuss that
           after lunch when we feel happier?
                       MR. REYES:  Quite likely.
                       CHAIRMAN WALLIS:  Is that good?  Okay.
                       Thank you very much.  Very interesting
                       So we're going to take a break now.  We
           don't have a recorder at the inspection of the test
           facility.  We don't --
                       MR. BOEHNERT:  No.
                       CHAIRMAN WALLIS:  So we're no longer in
           session.  And when are we going to come back?  When do
           we reassemble here?
                       MR. REYES:  We would go to lunch from the
           demonstration and then --
                       CHAIRMAN WALLIS:  And then we'll return to
           where we were here.
                       MR. REYES:  At 1:30, I believe.
                       CHAIRMAN WALLIS:  Shall we have a short
           lunch; can we try and get back early?  How soon can we
           be back?
                       MR. REYES:  I think a short lunch would be
                       CHAIRMAN WALLIS:  Can we have a quick tour
           and get back at 1:00?
                       MR. REYES:  Let's do that.
                       CHAIRMAN WALLIS:  Let's meet here at one
           o'clock.  We'll meet here again at one o'clock.
                       (Tour and luncheon recess taken from 11:15
           a.m. to 12:58 p.m.)
                       CHAIRMAN WALLIS:  And we'll continue with
           the presentations by OSU.
                       MR. WELTER:  I hope you enjoyed a good
           lunch at West Cafeteria.  I know I'm ready to fall
           asleep now, but I don't get to do that.
                       We left off, I finished summarizing the
           onset of entrainment model evaluation.  I wanted to
           then step into and discuss entrainment rate models
           that we're evaluating also, the first one being the
           Schrock correlation.  It's based on a curve fit of
           entrainment rate data based on your actual gas chamber
           level, h, and then divided by your onset gas chamber
           level, hb.  That determined the quality or the rate to
           your branch.
                       CHAIRMAN WALLIS:  X is a mass flow rate? 
           There's nothing here about third properties at all?
                       MR. WELTER:  It's predicting the quality,
           which gives you a --
                       CHAIRMAN WALLIS:  It's called a mass
                       MR. WELTER:  Exactly.  It gives you the
           fraction of liquid.
                       CHAIRMAN WALLIS:  There's nothing about
           densities or anything when -- if they were both water,
           that wouldn't make any difference.
                       MR. WELTER:  Hb.
                       CHAIRMAN WALLIS:  It's remarkedly
                       MR. WELTER:  Smoglie also developed a
           correlation based on the dimensionless h over hb.
                       CHAIRMAN WALLIS:  She has densities,
           though, so...
                       MR. WELTER:  And there is a rho f and rho
           g in this model.  It's based on the right-hand term. 
           One minus that term is based on a vapor pull-through
           through a down branch.
                       And then she went and said that for upward
           is one minus the down, and then she modified the
           experimental coefficient 2 over hb to match the data.
                       Yonomoto developed the correlation model
           for determining x3.  It has A and B, which are
           experimentally-determined constants based on the void
           fraction in your main line.
                       CHAIRMAN WALLIS:  In the main line.  It
           says on branch void fraction.
                       MR. WELTER:  Oh, I'm sorry.  Branch.
                       CHAIRMAN WALLIS:  Do you mean the main
           line --
                       MR. WELTER:  Thank you.  Branch void
                       CHAIRMAN WALLIS:  So it's kind of funny
           because x3 is a submeasure of the void fraction, isn't
           it, indirectly.
                       MR. WELTER:  Quality, yes.  You can relate
           quality in void fraction.
                       CHAIRMAN WALLIS:  So it depends on itself
                       MR. WELTER:  Yes.
                       CHAIRMAN WALLIS:  -- in a sense.  You have
           to know the void fraction to predict the quality.  You
           might be in a little bit of trouble.
                       MR. WELTER:  They ran a -- we ran
           experiments to determine the void fraction in relation
           to that.
                       The correlation is based on determining a
           sphere of influence and within that sphere of
           influence all of the liquid in the hot leg will then
           be sucked up the branch.
                       CHAIRMAN WALLIS:  If you plot these three
           curves as versus h over hb, you're doing that
                       MR. WELTER:  Yeah.
                       CHAIRMAN WALLIS:  They're actually -- on
           the same piece of paper?
                       MR. WELTER:  That's correct.  Smoglie is
           not plotted on this one.  H average, when we consider,
           when we look at our data, we have oscillatory
           behavior.  So we have to have some way of placing that
           on this graph.  We use h average, which is the average
           between the reactor side and the steam generator side,
           liquid levels in the hot leg.
                       CHAIRMAN WALLIS:  What shall I conclude
           from this figure?
                       MR. WELTER:  You can conclude from this
           figure that the data -- that we ran ATLATS predicts
           significantly higher entrainment rates than the
           correlation.  Higher h, yeah.
                       CHAIRMAN WALLIS:  It's lower, isn't it? 
           X3 is lower?
                       MR. WELTER:  Oh, I'm sorry.
                       MR. WU:  Yeah, lower rate -- well, higher,
           higher rate.
                       MR. WELTER:  Well, the quality is lower,
           so there's more liquid going in for the same -- for
           the same level -- I'm sorry -- for the same level, if
           you have the same level here, our data is a quality --
                       CHAIRMAN WALLIS:  Oh, quality, okay.
                       MR. WELTER:  -- less than .2.
                       CHAIRMAN WALLIS:  Quality means --
                       MR. WELTER:  And then theirs would be all
           the way over here --
                       CHAIRMAN WALLIS:  Okay.  Sorry, that's
           right.  That's right.
                       MR. WELTER:  -- up to 9, so there would be
           entrainment rate, --
                       CHAIRMAN WALLIS:  That's right.
                       MR. WELTER:  -- higher entrainment rate.
                       CHAIRMAN WALLIS:  X is a measure of vapor
           fraction, not liquid fraction.
                       MR. WELTER:  That's correct, sir.
                       CHAIRMAN WALLIS:  Yeah.  That's right.
                       MR. WELTER:  I need to go back here.  I
           pressed the wrong button.  Okay.  So the different
           graphs, Yonomoto is the higher one.  Schrock's
           correlation is the one in the center.
                       CHAIRMAN WALLIS:  H ab over h break?  Why
           -- what's the --
                       MR. WELTER:  Hb is the inception.  H over
           hb.  This is the real hb that we find in our
           experiments.  So this is the hb from our new model.
                       CHAIRMAN WALLIS:  So there the
           correlations never go beyond 1 for h over hb, but
           yours does?
                       MR. WELTER:  Exactly.
                       CHAIRMAN WALLIS:  Is that some physical --
                       MR. WELTER:  Yes, there's a significance
           in that, --
                       CHAIRMAN WALLIS:  -- peculiarity?
                       MR. WELTER:  -- in that our level in the
           hot leg is below the onset level.
                       CHAIRMAN WALLIS:  You get more entrainment
           below the level which gives you the onset?
                       MR. WELTER:  Yes.
                       CHAIRMAN WALLIS:  It doesn't make sense.
                       MR. WELTER:  Exactly.
                       CHAIRMAN WALLIS:  When you're actually
           entraining you have a lower level than at the onset?
                       MR. WELTER:  Yup.  That's what we see in
           our data.
                       CHAIRMAN WALLIS:  It seems to be
                       MR. WELTER:  Yeah.  Because what happens
           -- well, a physical meaning, when the oscillatory
           behavior is set up, the level in the inlet side is
           actually being -- I'd like to draw it.  Can I draw
           that?  A better illustration.
                       If you look at the mixture level in the
           reactor vessel, during steady-state entrainment it's
           actually higher than the hot leg.  So what's happening
           is it's pushing down the level on the inlet.  Then the
           oscillatory behavior begins there.
                       CHAIRMAN WALLIS:  So how does --
                       MR. WELTER:  So this level is actually
           being pushed --
                       CHAIRMAN WALLIS:  So how does the gas get
           out of the -- squeezes through out of the hole --
                       MR. WELTER:  It squeezes through there and
           it pushes this level down lower below the onset. 
           That's what our data is saying.
                       CHAIRMAN WALLIS:  Okay.  That's a huge
           difference.  I mean if you've got this factor of two
           and a half.  It's --
                       MR. WELTER:  Yes.
                       CHAIRMAN WALLIS:  There's very high data
           points there.
                       MR. WELTER:  Yes.
                       MR. SCHROCK:  I didn't understand what h
           average means.
                       MR. WELTER:  H average is the average --
           because we have the oscillatory behavior, we have this
           step.  There's two levels between -- we have these two
           different levels.  Average is the average between
           these two different levels over time.  So if this was
           h2, this is h1, h average.  H1 plus h2.
                       MR. SCHROCK:  That presumes pretty
           detailed knowledge of the shape of that interface in
           a horizontal pipe.  That's a complicated thing to come
           by.  How did you get that number?
                       MR. WELTER:  Sir, h average?
                       MR. SCHROCK:  Yeah.
                       MR. WELTER:  Oh, the measurement.  We
           measure the liquid level here.  We have a ring probe
           that can measure this liquid level, and we have a ring
           probe that can measure this liquid level.
                       MR. SCHROCK:  You mean at -- at --
                       MR. WELTER:  The inlet and the outlet.  We
           have a measurement --
                       MR. SCHROCK:  Certain axial locations,
           both of which are away from --
                       MR. WU:  About 2D.
                       MR. WELTER:  Oh, okay.
                       MR. WU:  But 2D downstream and upstream.
                       MR. SCHROCK:  But why would you think
           there would be a correlation of what's happening for
           two-phase flow going into the vertical off-take pipe
           that depends on the average of those two.  It depends
           on the local conditions where it comes off.
                       MR. WELTER:  We're not necessarily
           presuming that there is a relation between those.  We
           want to evaluate the model with our data.  And this is
           the only way to determine some sort of an h, is to use
           what we consider an average --
                       CHAIRMAN WALLIS:  What happens if you --
                       MR. WELTER:  What happens if.
                       MR. SCHROCK:  Well, I don't see how it
           relates to the correlation that we proposed or to our
           experimental data.  Our experimental data --
                       MR. WELTER:  That's true.
                       MR. SCHROCK:  -- were for a level h which
           is seen visually at -- at the axis of the take-off
           pipe, --
                       MR. WELTER:  Correct.
                       MR. SCHROCK:  -- not upstream, downstream.
                       MR. WU:  So when you --
                       MR. SCHROCK:  So how can you plot your
           data against --
                       MR. WELTER:  Your level is right here; am
           I correct?
                       MR. SCHROCK:  -- our correlation, on the
           one hand, or how can you compare your data with our
           data when the --
                       DR. WU:  My question --
                       MR. SCHROCK:  -- data-reporting scheme is
           totally different?
                       MR. WU:  My question is when entrainment
           occurs, you see the liquid level jumping under there. 
           How can you observe by research just a crack in it to
           determine the right under the off-take is a liquid
           level.  Your visualization window is both downstream
           and upstream.  And there are small windows there, two
                       MR. SCHROCK:  Yes, you're right.  That's
           true.  That's true.
                       MR. WU:  So it's not right under -- well,
           right under the off-take you cannot get it, that
                       MR. SCHROCK:  Yeah.
                       MR. WU:  So we tried the different ways. 
           We use the --
                       MR. SCHROCK:  But, on the other hand,
           never was there a situation such as is depicted here.
                       MR. WU:  You don't have the jump.
                       MR. SCHROCK:  No.
                       MR. WU:  You don't have the different --
           difference.  That's a difference of our data -- of
           your -- under your data.  Your levels, both the inside
           and the outside, is the same -- are the same.  So --
                       MR. SCHROCK:  But you're comparing apples
           and oranges, is what it amounts to.
                       MR. WELTER:  Okay.  The purpose of this
           slide, I think, is not to necessarily show that the
           correlation does not predict our data, but shows the
           inappropriate application.  The correlation is fine
           for predicting the data of your case.
                       MR. KRESS:  How do you determine the
           quality?  Is that the ratio or the average flows --
                       MR. WELTER:  Yes.
                       MR. KRESS:  -- averaged over the --
                       MR. WELTER:  That's correct.
                       MR. KRESS:  -- time period?
                       MR. WELTER:  That's correct, sir.
                       MR. KRESS:  Okay.
                       MR. WELTER:  That it would be liquid mass
           flow rate over the total.
                       MR. KRESS:  Yeah.  You know, --
                       MR. WELTER:  And that's injection.  So
           basically our flow meter is what we inject from the
           water pump, what we inject from the air compressor; 
           we use that.
                       MR. KRESS:  So that's a -- um-hum.
                       That thing varies with time, but it would
           -- as an average it averages out.
                       MR. WELTER:  The quality for the steady
           state is quite, quite steady, because we have a steady
           injection flow, steady air flow, and they're both
           pretty steady over time.
                       MR. KRESS:  Yeah, but there's capicitants
           in the system that would mess that up.
                       MR. WELTER:  Okay.  We do take an average.
                       MR. KRESS:  Yeah.
                       MR. WELTER:  Yeah, a time average.
                       CHAIRMAN WALLIS:  Well, the Schrock theory
           looks pretty lousy compared with the Schrock data,
           too.  I mean it doesn't predict the trends.  And have
           you had a --
                       MR. SCHROCK:  Well, I don't understand
           that.  I mean our data didn't look like that against
           our correlation, but --
                       MR. KRESS:  Because you just fitted it to
           your correlation, hum?  I mean you code-fitted it,
                       MR. SCHROCK:  That's what they're saying
           it did, but I --
                       CHAIRMAN WALLIS:  It doesn't look like a
           code fit at all, especially in low x3s.
                       MR. SCHROCK:  It doesn't ring any bells
           for me.
                       CHAIRMAN WALLIS:  Anyway, we should
           probably move on.  This just shows that nothing works
           very well so far.
                       MR. WU:  That's right.
                       And also we tried to use the different
           levels.  The front level and back level, it doesn't
                       MR. WELTER:  At this point I'd like to
           turn the model development and conclusion, Section 5
           and 6 of your presentation, over to Dr. Wu.
                       Thank you very much.
                       MR. WU:  As you may have noticed, the
           entrainment rate test has a lot of irregularities in
           the slug and oscillation.  But the entrainment onset
           data is grouping very well.  At least our data, the
           Maciaszek correlation predicted our data reasonably
                       And also Schrock and Smoglie's
           correlations also was predicted their small branch of
           data very well.
                       So we think we have the hope here to do
           some more research modeling to bridge these two models
           and to try to find the physics behind it.
                       What we did here is we followed
           Maciaszek's approach.  Basically what his approach is,
           which is the wavy ring, the diameter, you go to the
           off-take diameter.  And we think the liquid level goes
           far away from the break.  The wavy ring is getting
           bigger and bigger, so we try to use importation flows
           theory to find that ring change.
                       So what we did is we used a mirrored
           distributed sink using potential flow to find the
           velocity distribution, allowing this X line.
                       Like Dr. Schrock pointed out, if we can
           find that somewhere the velocity goes to maximum, that
           means the pressure there is minimum, then we say,
           well, the bumps are supposed to -- the wave will crest
           -- is supposed to be at that location.  So that's our
                       So we write -- we wrote this velocity
           distribution using potential for theory.  And we tried
           to -- well, we kind of get the analytical solution. 
           So we went to a numerical solution to check it.
                       The upper corner of the figure is the
           velocity at the -- the velocity on the interface
           versus over the velocity in the average velocity in
           the branch.  And this is so a distribution, allowing
           the interface, go away from this interface.
                       We found the crest can never move into
           this break.  That means when they -- this varies. 
           This -- that should be -- all you can say is a liquid
           very approach to the break, then that mandates you go
           to the D.  But when the level go away from the break,
           then maximum point is drifting away.
                       So we're trying to find the maximum point,
           velocity maximum point.  That's the dotted i on the
           right side of the figure.  And you say, well, that's
           when -- that's the limiting case is you go to wall. 
           That means the diameter of that wave crest, you go to
           the diameter.
                       And the way it's drift away, the
           asymptotic condition matches the point sink, mirror
           point sink, sink condition.  That's one point -- the
           square root of 2 of hb.
                       So that's -- basically you say, well, the
           wave crest diameter is equal to the -- A is
           proportional, directly proportional to the gas chamber
                       So if we put this number into the
           correlation originally Maciaszek developed, we found
           that the number is this term.  When the hb over d,
           that means the -- a gas chamber height versus the
           break side is getting very big, then this correlation
           approaches to what the Smoglie and Schrock's
           correlation, as it goes to the fifth power.
                       And when this hb over d approach to zero,
           that means the level approach to the break, this term
           goes away.  Then you get the one here.  That means the
           correlation approach to Maciaszek's correlation
           gathers the one-third power and the diameter of the
                       So we thought that this is a nice approach
           to this bridge this small-break correlation and
           large-break correlation.  And both of them proved
                       And then we -- we just have one adjustable
           coefficient, similar like what they did.  With this
           coefficient, .5, and the theoretical value of this
           coefficient is .4.  So we were very, very satisfied. 
           It brings them together and both are satisfied.
                       However, when we look at this we still
           have a scattering.  Again, make -- Kent, Mr. Welter
           pointed out, KFK data has a lot of scattering. 
           Schrock's data and our data has risen in the group
           very well.
                       So if we take out these blue squares, I
           think this correlation is -- and we did the
           sensitivity analysis.  The standard deviation of this,
           only Schrock's data and our data, it's like 30 percent
           off.  By the way, Smoglie's data then, the error is
           standard.  It goes to like 15 percent.
                       Well, this approach, like Dr. Wallis
           pointed out, is for the flat -- flat top without the
           confinement of a side confinement.  And our approach
           didn't consider the side confinement.
                       So basically our approach, you say, well,
           the infinite place, the liquid velocity is -- the gas
           velocity is supposed to be zero.  Then for our case
           gas is confined in the main pipe.  And the infinite
           place is so that the gas velocities are supposed to
           not be zero.  So we modified that.
                       Then we got a new correlation, is the
           same.  But it has two adjustable parameters.  I don't
           like it because if you get an x for parameter, you can
           fit everything.  So -- but, nevertheless, what is
           necessary what's is a collapse of -- it's like a 20
           percent standard dev- -- very well the data.
                       So as a summary of entrainment on the --
           before we go further, I still want to go back to visit
           this flow regime transition.
                       And the red line, solid line is the symbol
           of Wallis' slug flow transition.  And we use a --
           since we don't know the -- which flow direction come,
           we say, well, all the gas flow in the branch coming
           from one side of.
                       So it's all this in this plot, our data
           follows this very well for all regime transition.
                       And also Schrock's data -- one group of
           Schrock's data also follow this line very well.  And
           the way I checked it, it's the -- the diameter is the
           -- the break diameter is about 17 --
                       CHAIRMAN WALLIS:  So I'm trying to figure
           this out.  Which of these is this slug transition?
                       MR. WU:  The red and solid line.
                       CHAIRMAN WALLIS:  That one that goes
           through your data?
                       MR. WU:  Yeah.  And then I have a 20, 20
           percent.  And then a bracket dashed line is the
           Smoglie and Schrock correlation.
                       CHAIRMAN WALLIS:  They seem to be just two
           different families that are completely unrelated --
                       MR. WU:  You see here you have some...
                       CHAIRMAN WALLIS:  -- on this plot.
                       MR. WU:  Yeah.  This plot doesn't have the
           diameter effect inside.  Well, I show this plot as the
           -- one purpose is to say, well, if we treated this as
           a small break and this as a large break, I think
           anything should be between these two.
                       So if you run a sensitivity calculation in
           your code, you can treat this as two asymptotic
           conditions, like we just discussed for the
           theoretical.  So anything else should happen between
           these two.
                       CHAIRMAN WALLIS:  So the mechanism of a
           small break is this sort of potential flow sucking out
           from the surface.  And the mechanism for the big break
           is sort of similar, but it's really a civility of the
           big-wave criteria.
                       MR. WU:  Interface, because we -- we based
           on the interface wave a gross, that delta gross, so
           it's -- it --
                       CHAIRMAN WALLIS:  The momentum of the gas
           and the -- it's a Froude number in both cases.
                       MR. WU:  Yes.
                       CHAIRMAN WALLIS:  But it's a different --
                       MR. WU:  Yes, sir.
                       MR. SCHROCK:  Now the coordinates on this
           graph seem to be the same as in an earlier slide where
           you showed the Berkeley data.
                       MR. WU:  That's right, yeah.
                       MR. SCHROCK:  And somehow magically now
           it's separated into two groups, which seems strange. 
           I don't understand how you managed that.
                       MR. WU:  No.
                       MR. SCHROCK:  Coordinates are unchanged,
           but now the data seem to plot as two distinct groups.
                       MR. WU:  No.  It changed -- this to the
           Froude number in the main pipe based on the velocity
           in the main pipe, the superficial velocity in the main
           pipe, and the Froude number.
                       In the previous one, your model and --
                       MR. SCHROCK:  Well, you don't put numbers
           on your pages, but I go back to one that's got a big
           -- three test results, onset of entrainment, -- that's
           quite a ways back -- has exactly the same coordinates
           as this one.
                       MR. WU:  Yeah, that's right.  We used the
           two group of --
                       MR. SCHROCK:  FR1, the square root of rho
           g1 over delta rho.  It's the same thing, but --
                       MR. WU:  Yeah, this figure.  Is that what
                       MR. SCHROCK:  That's the one.
                       MR. WU:  Yeah, that's the same -- same
           coordinates.  Using this Froude number is based on the
           superficial velocity in the main line, not based on
           the velocity in the branch.
                       MR. SCHROCK:  Well, look, you've got to
           define your terms and use notation to convey what you
           mean.  You can't expect we're going to understand
           different interpretations for the same notation.
                       MR. WU:  Well, this is a different
           approach.  The one we go through -- went there the
           model development, that one, is following you and
                       This one is just to show you the finding
           we found, to say, well, it's basically -- the
           horizontal 9 has a Froude transition for the larger
           break.  It matches what our argument is, an
           entrainment happens, so for the larger break is like
           an interface, a wave,, instability on the interface. 
           And for the small-break case, maybe a potential for
           the large going up.
                       So it's -- eventually I want to say this
           is the two-boundary condition.  One is to emphasize
           what I say, for small break and the larger break, it's
           a true asymptotic condition.  And the real data should
           lie between these two.  That's from --
                       MR. SCHROCK:  Let me try one more time.
                       MR. WU:  -- a larger point of view to
           argue my point.
                       MR. SCHROCK:  Let me try one more time.
                       In engineering communications we have
           certain principles that have to be followed.  And one
           of them is that you define your terms clearly.  You
           set down the notation and define what the notation
           means physically.
                       MR. WU:  Um-hum.
                       MR. SCHROCK:  And then you don't use the
           notation redundantly.  And I think what I've heard you
           explain is that FR1 on one graph is different than FR1
           on the other graph.
                       MR. WU:  No, no.  We use only one FR1
           here.  We didn't use any other FR.
                       MR. WELTER:  Sir, this is Ken Welter.
                       These are -- this is for the onset of
           entrainment.  The graph we showed you previously was
           for entrainment rate, so those are different datasets. 
           This is for the onset of entrainment, this graph.  The
           graph that we were previously discussing is for
           entrainment rate.  So they're different datasets, but
           it is the same FR1.
                       MR. SCHROCK:  This -- this one is onset of
                       MR. WU:  Yes.
                       MR. SCHROCK:  The one that began this
           discussion is number 5, model improvement. 
           Entrainment onset criterion.
                       MR. WU:  Yes.
                       CHAIRMAN WALLIS:  That's where it's the
           same FR1.
                       MR. WELTER:  Could you go to the last
           slide that we were at?
                       CHAIRMAN WALLIS:  I think we're mixed up
                       MR. WELTER:  One more.
                       MR. SCHROCK:  Well, I'm -- I'm trying to
           resolve in my mind what you've done that produced the
           result that --
                       MR. WELTER:  Okay.  That was wrong --
                       MR. SCHROCK:  -- that our Berkeley data --
                       MR. WELTER:  Is that right?
                       MR. SCHROCK:  -- separated into two clear
           and distinct groups, which I never saw in our data.
                       CHAIRMAN WALLIS:  Where are the two
                       MR. SCHROCK:  Well, it's the --
                       MR. KRESS:  On this curve you've got --
                       MR. SCHROCK:  It's the sort of ghosty
                       CHAIRMAN WALLIS:  "...ghosty"?
                       MR. SCHROCK:  Yeah.  Light colored gray
           dots.  There's a set of them on each of those lines.
                       MR. KRESS:  Down here and also down here.
                       CHAIRMAN WALLIS:  Oh, those are Schrock's
           up there?
                       MR. SHACK:  Yeah.
                       CHAIRMAN WALLIS:  Well, I think that's a
                       MR. KRESS:  There must be some mistake.
                       MR. SCHROCK:  Well, is there a mistake?
                       MR. WU:  No.
                       CHAIRMAN WALLIS:  I'm really puzzled by
           these ghostly data.  The Schrock data lie exactly on
           both curves, so that's pretty well.  That's really
                       MR. WU:  You mean these lines?
                       MR. SCHROCK:  Well, they always lie on
           whatever curve you choose.
                       CHAIRMAN WALLIS:  Something is very
                       MR. WU:  Well, this -- this is a different
                       MR. KRESS:  It's a quantum effect.
                       MR. WU:  This is based on the main line
           superficial velocity.  It's not based on the branch
           line super- -- I just tried to present this from a
           different perspective, from the flow regime transition
           perspective.  It's different from what we just
           discussed about the entrainment from the vertical.
                       CHAIRMAN WALLIS:  Oh, I see what you mean.
                       MR. WU:  Yeah.
                       CHAIRMAN WALLIS:  It's these strange gray
           things, though.  And Smoglie doesn't have any data. 
           So those are the Schrock data, those square things, or
           those are the Reimann data?
                       MR. SCHROCK:  No.  Those are -- those are
           KFK data, Reimann and Kahn.
                       MR. WU:  Square KFK data.
                       CHAIRMAN WALLIS:  So the mystery is why
           there's some Schrock data on the Wallis line.  That's
           the thing which is the mystery.
                       MR. KRESS:  There you go.
                       CHAIRMAN WALLIS:  And why this?
                       MR. SCHROCK:  We never would have expected
                       MR. WU:  Well, sometimes it has to agree
           with you again.
                       CHAIRMAN WALLIS:  On the wrong line.
                       MR. WU:  And this is -- we weighted -- we
           just -- what we did is your branch gas flow rate we
           are showing as coming from one side.  And this data is
           a relatively larger break, and it's coming from --
           that's -- we didn't do anything.
                       It's the same abiscus for the previous
           sets of data, but we just changed the perspective.  We
           changed the velocity for -- from the branch to the
           main line.
                       What I would like to say this figure is,
           again, I want to say is one-fifth and one-third all
           here is for the flow regime transition.  It's
           represented to boundary condition.  I think the --
           anything should happen between these two, and that was
           what we did to bridge these two together.
                       So as a short summary of this model
           improvement for entrainment, the onset criteria, for
           Smoglie and Schrock's correlation, it's based on --
           well, Smoglie did -- single-point sink, no interface
           effect, and the effect was far from a break or small
           break case.
                       For the Maciaszek, based on Wallis'
           interface instability argument, he uses a wave crest
           interface instability kind of option and chooses a
           crest, wave crest, as the basing and as the break
           diameter.  And it is effective for the larger break or
           the liquid level is very close to the break.
                       For the new model we proposed, wave crest,
           this basing is a function of the onset height.  And
           you -- and valid for both and it can be reduced to
           Maciaszek's situation and Smoglie and Schrock's
           correlation's case.
                       So that's what -- it was a challenge to us
           because we cannot come up with something without
           considering the previous contribution.
                       So I think we have the physical
           interpretation here, and it's -- the data is -- not
           much irregularity there because -- so we think this is
           a good model.
                       For the further improvement, improvement
           data, based on what we say is the velocity in the --
           gas velocity in the pipe is different from the open
           kind of case of flat pipe.  So we made a further
                       However, that made the correlation more
           complicated.  And we have two adjustable coefficients.
                       And for slug flow transition, I don't know
           if we can use it a whole lot.  We need to go do a
           further analysis.  Until we know which side, how much
           gas is coming from which side, then we can revisit
           that kind of argument.
                       But for previous KFK data and the Smoglie
           data, they -- I show them as coming from one side, but
           the aperture is -- the break is so small, so basically
           the gas flow velocity in the main line doesn't
           contribute too much.
                       So we -- it is suggested one of the
           logical, we just jump -- tried to jump out of the loop
           seal, is there any other simpler option for us to
           take.  That's it.
                       For the model improvement of entrainment
           rate, again we -- we have -- we follow the similar
           approach, argument of h over hb, the actual gas
           chamber height versus the entrainment onset.
                       The rationale, as I say, any excess of
           this kinetic energy of a gas or that contribute to the
           pressure difference from the interface to the break,
           overtakes the gravity.  That excess of kinetic energy
           is going to the liquid kinetic energy.
                       And when this liquid velocity and mass
           velocity is equal to zero, left aside, this equal to
           zero, that gives us the entrainment onset condition. 
           Using this argument, we derived -- the equation
           quality in the branch is equal to this function.  It's
           a function of density ratio.  And the function for the
           h over hb, plus there's another one, is the diameter
           effect of the break.
                       MR. SCHROCK:  Is that derivation available
           to us?
                       MR. WU:  Yes.  Yes.  It's simply, just put
           that k in front of this group, the right-hand group. 
           Then we can straightforward again.
                       CHAIRMAN WALLIS:  Then you must use some
           kind of a one-dimensional theory, or something,
           because --
                       MR. WU:  Yeah.  The --
                       CHAIRMAN WALLIS:  Or does the k take
           account of two dimensionality, or...?
                       MR. WU:  No.  The only thing coming from
           this part, that's the -- say were the -- we are shown
           the -- a liquid of void fraction in the branch is a
           function of h over h -- 1 minus of h over hb.
                       CHAIRMAN WALLIS:  But these Vf3s, Vg1s,
           these are averages across the whole area.  It's a
           one-dimensional --
                       MR. WU:  Yeah, that's right.
                       CHAIRMAN WALLIS:  -- approach.
                       MR. WU:  That's right.
                       What --
                       MR. SCHROCK:  What I asked is, is the
           derivation available to us?  Can you tell us, are we
           going to have that derivation?  Is it in a report that
           we're going to get?
                       MR. WU:  I can do it right now here, if
           you --
                       MR. SCHROCK:  Hmm?
                       MR. WU:  I can do it right on the
           blackboard, if you prefer.
                       CHAIRMAN WALLIS:  Now is this compared
           with data somewhere?
                       MR. WU:  No.
                       CHAIRMAN WALLIS:  The new --
                       MR. WU:  It cannot solve that jump.  So
           what we compare with Smoglie -- Schrock's correlation,
           for the D -- this -- this 9 can be treated as you have
           fixed the gas flow rate.  And as you change the liquid
           flow rate to change the quality.
                       In such a case the hb is a constant
           because that's based on the gas flow rate.  And you
           see the diameter ratio is when this is about
           one-hundredths of the hb should be, that's very close
           to Smoglie's situation.
                       The KFK correlation actually exactly is 
           shaped like this.  Unfortunately, we didn't put on
           that figure because it has the densi- -- has several. 
           I don't know.  Previous, last year we put on a figure.
                       This year we -- I can't -- in a final one,
           I will show you how this -- and also for Schrock's
           data, it's about 17 to 30.  So this is a tenth of it. 
           So it's -- the correlation goes through it.
                       When that break is getting bigger, then
           it's going up like this.  It's more like our data
                       CHAIRMAN WALLIS:  You said there was
           Smoglie correlation down the bottom there that we
           can't see?
                       MR. WU:  Smoglie, no, we didn't put it
                       CHAIRMAN WALLIS:  You said he was close to
           the bottom curve?
                       MR. WU:  Yeah, that's right.
                       CHAIRMAN WALLIS:  The .01h?
                       MR. WU:  Yeah.  It's the --
                       CHAIRMAN WALLIS:  Smoglie is down there?
                       MR. WU:  They have a data only in this --
           in this shortened mix, very high quality data.  And
           their correlation, all of the way we extrapolate it to
           zero quality.  That was in Schrock's report, too, to
           mention to the KFK.
                       And this correlation doesn't express one
           thing -- let me -- okay.  In our data we have a jump
           like this.  What this give us the trouble is for one
           h liquid level you have two qualities.  That means
           using there's -- like you said, before you mentioned,
           maybe it's related to liquid flow rate or gas flow
           rate explicit and beside the hb.
                       And otherwise, only use the information of
           h, we can't gather this bump like that.  And that's
           what we are working on, trying to see averages.
                       You will see later a behavior, see if we
           can -- and amazingly we -- we found these -- out of
           the turbulence here you will see -- in this region is
           actually -- I will say the ration occurs (phonetic). 
           And the way it's flattened out is like a high gas,
           very -- no liquid flow rate.  The oscillation
                       So the bump itself, it's coming from that. 
           It was initiation behavior.  And we try harder to get
           an average parameter to represent it.  And we are
           still working on.
                       CHAIRMAN WALLIS:  Are you sure there's a
           curve.  Earlier where h over hb was bigger than one.
                       MR. WU:  Yes.
                       CHAIRMAN WALLIS:  And here it's less than
           one.  Are these different data or something?
                       MR. WU:  No, no, no.  Then we use the
           average h -- h in that previous --
                       CHAIRMAN WALLIS:  In the other one.  No,
           this is the h on the --
                       MR. WU:  We are trying to say this is the
           high side.
                       CHAIRMAN WALLIS:  So this is the h on the
           reactor side here?
                       MR. WU:  Or 4 times vessel size.
                       CHAIRMAN WALLIS:  Vessel size.
                       MR. WU:  Oh, no, the steam generator size. 
           That's the higher part, because it was originally --
           when you see -- when you saw the experiment at lunch
           time, there was initiation actually occurs downstream
           of the branch.
                       CHAIRMAN WALLIS:  So if you're going to
           use this in a system-solving computer model, you'd
           have to somehow predict h over hb, then you'd predict
           h -- x3 from that; is that what you'd do?  And the
           problem with yours --
                       MR. WU:  This is the traditional approach.
                       CHAIRMAN WALLIS:  The problem with your
           curve is you don't know which one to pick.  And the
           fact that it's going to curve up again, you get three
           xs for the same h or hb.
                       MR. WU:  Yes.  So that's got to be related
           to the gas velocity or liquid velocity.  That's what
           we are -- we are trying.  Right now we only use this
           simply -- simple representative.  If you don't
           consider the other, then you've got this -- you cannot
           find this bump, and you can't -- and that means use h
           over hb and x as a correlation, you miss something
                       CHAIRMAN WALLIS:  Well, my comment in all
           of this is what I saw in the experiment.  It seems to
           me you need a dynamic analysis, so the rate of
           build-up of liquid in the plug which goes to the steam
           generator, when it comes back, you sweep some out the
           pipe, how long it takes to sweep that out depends upon
           sort of the length of the pipe to the -- to the
           air-water separator, or something.
                       All these things are very system
           dependent, aren't they?  So you really need a system
           model in order to predict the entrainment.
                       MR. ROSENTHAL:  Yeah.  And why don't we
           let him finish the presentation, and then Steve can
           make some comments about our intent, how we can
           ultimately use this and track that.
                       MR. BAJOREK:  One question on that last
           figure.  The bump there, --
                       MR. WU:  Yes.
                       MR. BAJOREK:  -- does that include the --
           both the -- with the block steam generator and without
           the steam generator?  Is that all the data together?
                       MR. WU:  Yes.  Waves of -- but waves of
           the steam generator with a returning line, it's
           calmer, but it still have a bump.
                       MR. BAJOREK:  Would you still get that
           bump --
                       MR. WU:  Even Schrock's data has a small
           bump there.  If we go back.  Please, go back.  Go
           back.  I think go more, just go ahead.  Go.  Go.  Go. 
                       You see this, you called it ghostly.  It
           has some...
                       CHAIRMAN WALLIS:  This is the one where
           the Schrock correlation has no relationship to his
           data, or not much.
                       MR. SCHROCK:  I haven't gotten it figured
           out yet.
                       MR. WU:  It's actually published in the
           left --
                       MR. BAJOREK:  Well, you see the hump even
           more when you plot it in what you call h2, in the
           other one.  That is when you don't use the average the
           hump is even more.
                       MR. WU:  That's in your --
                       MR. BAJOREK:  Yeah.
                       MR. WU:  -- actually we tried to see which
           side we're going to use.  When we use h2 we brought it
           down.  But in this one we didn't know it.
                       In your handouts actually have a lot --
           has a lot -- another figure.  It's -- I use a steam
           generator side of the gas chamber, and it can bring it
           to about below one.
                       Well, we can go back.
                       MR. SCHROCK:  Well, my recollection of our
           data is that they did not look like this against our
           correlation.  I'll have to dig that out and refer to
           it to understand what's wrong here.
                       MR. WU:  Shall I proceed?
                       As a summary, we built our database that
           actually covers all the branch separation cases.  And
           we picked out the material related to the vertical
           branch entrainment.  And we found the data is -- the
           correlation works for small breaks, but it doesn't
           work for the larger break.
                       We build our percentages relatively
           complicated in that like Dr. Schrock and Dr. Wallis
           pointed out.  And it's amazing, we run a test of
           entrainment now, said the test, the correlation
           actually two ends meet -- it's -- there's not much
           irregularity there for entrainment onset case.
                       And in that length we varied the form to
           .7 to 4.7.  It doesn't have much impact within the
           test range.  And also the downstream structure or
           steam generator, with a steam -- with a steam
           generator and without a steam generator.  That means
           we're being flooded.
                       It does have the effect because of the
           wave bouncing back and so of course the entrainment
           and that lower.  But the gas flow rate direction from
           the downstream in this case has negligible effect, but
           we cannot quantify it.  We didn't put a flow meter
           there.  And that's what we are doing right now after
                       And for the steady-state entrainment case,
           a downstream structure or steam generator affects the
           entrainment rate.  And the gas flow from downstream
           changes so the entrainment rate is substantial.  And
           also we need to quantify how much a gas flow from the
           downstream side and get a better data.
                       And for the model evaluation, the model of
           Smoglie and Schrock, this is used in RELAP5, is
           effective for relatively small breaks that was
           evaluated from their experiment data.
                       Maciaszek's model works well for larger
           breaks.  That's what our case.
                       And for the entrainment rate model, model
           of Schrock that is used in RELAP5, it seems it does
           not collapse our test data.  Like Dr. Schrock pointed
           out, what hb is going to use, we don't know what hb is
           going to use because in the new phenomenon you have
           two levels there.  And we use either one of them and
           we use the average of them, still can work.
                       So we think there is room to do some more
           work if we want to predict this phenomena using our
           system code.
                       In the model improvement for the
           entrainment onset model, we did a potential flow
           analysis.  We found Maciaszek and Schrock, Smoglie's
           correlation can be interrelated if we consider a
           wave-crest size as a function of the liquid level
           height.  And it's two asymptotic condition anything
           have, and it should be covered within this -- within
           this range.  So it's one --
                       MR. SCHROCK:  I'd like to make a comment
           about one of your conclusions.  And that is that the
           correlation form that evolved earlier is okay for
           small breaks but not for larger breaks.
                       I think that that conclusion is misguided. 
           And I say that because having seen the experiment in
           operation now I'm convinced that you're dealing with
           a completely different phenomenon that had been
           addressed in our work and in the work at KFK, totally
           different phenomena involved.
                       I do believe that if we tested with a
           larger diameter break on our apparatus that we would
           get consistent results with those already taken in
           that apparatus.
                       So I would not conclude from the
           combination of what you've learned from what we did,
           what was done at KFK, and what you've done in these
           experiments, that it is the diameter, the larger
           diameter of the break line that causes disagreement
           with the correlation.
                       The fact is if -- if you had the kind of
           surging, pulsating slugs of liquid moving back and
           forth in the test section with the smaller diameter
           breaks, you would not expect the results to agree with
           the correlation that we've developed for the
           stratified flow case.
                       MR. WU:  So, well, the oscillatory effect
           only happened --
                       MR. SCHROCK:  So your conclusion I think
           is wrong and for the reasons that I just stated.
                       MR. WU:  The oscillation for the
           entrainment onset, you don't see oscillation.  When
           you went to see the experiment for the onset, it's a
           little bit wavy interface.  There's no oscillatory for
           onset correlation.  There's some -- no such a
           complication or irregularity.
                       Only for the entrainment rate tests we
           observed this step phenomena.  So you try to mix these
           two together to justify our conclusions, I don't agree
           with that.
                       MR. SCHROCK:  Well, maybe you can make
           that apparatus produce a smooth stratified interface. 
           What you showed us did not include that kind of
           interface, did not.
                       MR. WU:  No.  It -- for the entrainment
           onset we don't have --
                       MR. SCHROCK:  Yeah.
                       CHAIRMAN WALLIS:  Even for onset it was
           not smooth.
                       MR. SCHROCK:  No.
                       MR. WU:  And it's a little bit wavy, but
           you don't see the jump like that.  One side is
           substantially higher than the other side.  And we
           measure, we use our probe with the measure to --
                       MR. SCHROCK:  The onset that you
           demonstrated was distinctly pulsating.  It was not a
           more or less continuous two-phase flow into the break
           line.  It was a highly-pulsating flow.
                       MR. WU:  No.
                       MR. SCHROCK:  That's what I saw.
                       MR. WU:  Onset, there is nothing happened. 
           What we called the onset is the pulsating, everything
           stops.  There's nothing being drawn into the branch. 
           If you see the pulsing, that's still being entraining. 
           That's in the process.  It's not stopping.
                       So if that's the case, then we -- it's not
           our entrainment onset and measurement yet.  Only when
           it stops, that's what our value of entrainment onset.
                       When you say something's been drawn into
           the branch, the entrainment is still there.  That's
           not our entrainment onset condition.
                       So when you say, well, say later and
           there's some pausing and being pulled out, that's not
           the entrainment onset condition yet.
                       MR. KRESS:  Well, you do have -- as you
           approach the condition of no entrainment, you do have
           wavy surfaces.
                       MR. WU:  Yes, that's right.
                       MR. KRESS:  And what he's saying is even
           then your entrainment is possibly not the same
           mechanism as his was.  So when you stop that, --
                       MR. WU:  Yeah.
                       MR. KRESS:  -- you're stopping something
           different than what his is stopping.
                       MR. WU:  If you have like 10 meters --
           five meters of gas blowing over a surface you don't
           expect that surface is calm.  There is a capillary
           wave which is being developed there.  So that one, if
           you say that's the case, that we cannot make it a --
                       CHAIRMAN WALLIS:  Well, I think the waves
           are coming from the reactor vessel.
                       MR. WU:  Yes.
                       CHAIRMAN WALLIS:  And you have this
           bubbling and frothing, and there's sort of a big plume
                       MR. KRESS:  That's right.
                       CHAIRMAN WALLIS:  -- of stiff arising
           which is stirring up the surface.  And that goes into
           the pipe, which is much bigger than these capillary
                       MR. SCHROCK:  You said you've simulated
           AP600, but in fact -- you say it's scaled to AP600 -- 
           but in fact I think these big disturbance waves that
           are entering that horizontal pipe from the vessel
           depend significantly on the geometry of that entry.
                       You've joined two cylindrical surfaces
           with sharp edges.  That doesn't exist in the reactor.
                       MR. WU:  I agree.
                       CHAIRMAN WALLIS:  Now when you're
           correlating your rate of entrainment, are you doing it
           with this one-inch bypass, and so on?  You're not
           doing it with the closed end, because you get
           different answers.
                       MR. WU:  We did close it.  We opened it,
           opened --
                       CHAIRMAN WALLIS:  But your correlation is
           for the open end with the bypass?
                       MR. WU:  Yes.  We did open.  We did close
           it.  And we did it with one-inch --
                       CHAIRMAN WALLIS:  Yeah, but your
           correlation that you're offering --
                       MR. SHACK:  No, but it's for the steam
           generator.  Sometimes you have the loop seal and
           sometimes you don't, right, but don't include the
           blind data.
                       MR. WU:  Oh, we close the -- with the
           steam generator there, we close the three-inch and the
           one-inch.  That's what these -- that's with the
           loop-seal case.
                       CHAIRMAN WALLIS:  Yeah, but that's not
           what's being correlated.  The data for entrainment do
           not include the one where you shut off the --
                       MR. WU:  Can you go back?  Go back to the
                       CHAIRMAN WALLIS:  You can't, because
           they're two different groups.  I mean you can't
           correlate the same thing --
                       MR. WU:  No.  That one is blind flooded as
           dif- -- if we blind flood it, it's then coming from a
           different group.  For the other case with the steam
           generator, we have three case.  One is a three-inch
           and line open, one is one-inch line, and all of the
           line being closed.  That's all the line closed --
                       CHAIRMAN WALLIS:  But these data here are
           for the three-inch line open, or the one-inch line
           open, or something?
                       MR. WU:  Go back.
                       Both -- all of them group with --
           together.  There's no effect --
                       MR. SHACK:  Well, the peak -- the peak
           there is for the closed-return line, right?
                       MR. WU:  No.  You are talking about an
           entrainment onset or entrainment rate?
                       CHAIRMAN WALLIS:  Apparently this is a
           phenomenon even with an open line.
                       MR. WU:  So this case is --
                       MR. SHACK:  But for -- are we talking
           about entrainment rate, because --
                       CHAIRMAN WALLIS:  Yeah, this is
           entrainment rate here.  Yeah.
                       MR. WU:  Are we talking about the
           entrainment rate.  If it's entrainment rate, this bump
           will come --
                       MR. SHACK:  When I look at the one with
           the data on it, I mean I see that huge peak with the
                       MR. WU:  That's for the --
                       MR. SHACK:  Isn't that really with the
           closed line?
                       MR. WU:  Yeah, that's for the closed line. 
                       MR. SHACK:  So he gets two -- he does get
           distinctly different results with the line --
                       CHAIRMAN WALLIS:  Well, the steam -- he
           even has this awkward one with the open line.
                       MR. WU:  I got a little bit like that, but
           what I -- when I did the conclusion I was the first to
           mention the entrainment onset correlation first.
                       CHAIRMAN WALLIS:  So when we saw the
           experiment this thing was chugging like a steam
           engine, the thing there.
                       MR. WU:  Yeah.
                       CHAIRMAN WALLIS:  That was with the closed
           -- something was closed?
                       MR. WU:  Closed the returning --
                       CHAIRMAN WALLIS:  But it's not -- it's not
           ended.  There's not a plug.  You actually can go into
           the steam generator and come back again?
                       MR. WU:  That's right.  That's right.
                       CHAIRMAN WALLIS:  So it simply means you
           close the valves in the three-inch and one-inch line.
                       MR. WU:  That's right.
                       CHAIRMAN WALLIS:  It's not as if you --
                       MR. WU:  No, see -- okay.
                       CHAIRMAN WALLIS:  -- block the end.
                       MR. WU:  No.  No.
                       CHAIRMAN WALLIS:  So there's a big
           difference between having those valves closed and
           having them open.
                       MR. WU:  That's right.
                       But that doesn't affect the entrainment
           onset data.
                       CHAIRMAN WALLIS:  No.  No, no.  We're
           talking about rate.
                       MR. WU:  Yeah.  That was my conclusion
           when --
                       CHAIRMAN WALLIS:  We should probably go
                       MR. WU:  Yeah.  For the entrainment com-
           -- go to the previous page, please.
                       So for the entrainment onset model, again
           the model of Smoglie and Schrock uses the RELAP.  That
           is used in -- RELAP5 is effective relatively for small
           breaks.  And Maciaszek models works well for the
           larger break.
                       And for the entrainment, we already
           covered that.
                       And the model improvement, we see the
           entrainment onset model.  What we did is we bridge
           these two together.  And we try -- we figured out a
           way to sink that wave crest.  The maximum pressure
           point, it's a ring type.  And that is a function of
           the liquid level.  And the --
                       CHAIRMAN WALLIS:  I think you should --
           excuse me.  You should do an experiment where you
           don't put the air in through the bottom of the reactor
           and bubble it up, but you put it in through the head. 
           You have the same flow rate, but you wouldn't be
           bubbling it through the surface and disturbing the
           surface.  You'd get a very different answer probably,
           or a different answer.
                       MR. WU:  You mean...
                       CHAIRMAN WALLIS:  Depending on how you put
           the air in.
                       MR. SHACK:  Just do a genuine gas flow.
                       CHAIRMAN WALLIS:  I mean the gas flow's
           more like -- it's just more like what Schrock did.
                       MR. SCHROCK:  Yeah.
                       MR. SHACK:  A separate effects test.
                       MR. WU:  Yeah, we can run that.  That --
           yeah, we were -- originally we run this to simulate
           the prototypic.  Yeah, we can run that.  We put up a
           -- bring on that --
                       CHAIRMAN WALLIS:  And you'd probably get
           a different group of data.
                       MR. REYES:  Jose Reyes of Oregon State. 
           Just a brief comment.
                       I think one thing that is happening with
           this data and what we've seen in the APEX test this
           morning during the 25 uncovery series is that this
           data matches our test.
                       And so we're seeing the same kind of
           dynamic behavior that's giving us this over -- an
           increase entrainment rate in their facility as we see
           in ours.
                       CHAIRMAN WALLIS:  What you're -- he's
           correlating something which is very much like AP600 in
           terms of end condition.
                       MR. REYES:  That's right.  That's right.
                       CHAIRMAN WALLIS:  Right.  It really
           doesn't apply to a separate-effects type of thing.
                       MR. REYES:  That's right.  It basically is
           -- geometry is -- it's a realistic geometry to try to
           predict what's going on in a very specific case, the
                       MR. SCHROCK:  Well, it's superficially
           realistic, but I mentioned the differences in the
           entrance into the horizontal pipe.  Sharp edges versus
           a well-rounded entrance.  It makes a lot of
           difference.  And I don't think you want to sweep that
           under the rug.
                       MR. REYES:  No, no.  I think you're right.
                       There are some geometry differences
           between our facility and even in the air warp
           facility.  We have upper internal structures, for
           example.  So I know that changes some of the
           entrainment rate behavior.
                       MR. KRESS:  Yeah.  The real question is
           for this kind of phenomena of entrainment, have you
           used the right scaling parameters with respect to
                       MR. REYES:  Right.  And --
                       MR. KRESS:  You may have scaled the wrong
           things, because you weren't thinking of this
                       MR. REYES:  Yeah.  What we measure -- so,
           for example, we do see a hydraulic jump in our -- in
           our hot leg, just like they see, because we do measure
           level on both sides.  So we're seeing familiar
                       Now the question is let's look maybe more
           closely at that to determine:  Is that what we'd
           expect to see for the AP600.
                       CHAIRMAN WALLIS:  Well, in your results
           for your APEX facility, you did see oscillations in
           that --
                       MR. REYES:  Absolutely.
                       CHAIRMAN WALLIS:  -- that relief line.
                       MR. REYES:  There was a chugging behavior.
                       CHAIRMAN WALLIS:  ABS-4 relief line.
                       MR. REYES:  In fact, we put a transparent
           line in a portion of that.
                       CHAIRMAN WALLIS:  And isn't that -- isn't
           that because of the slugs, and the pulses of liquid,
           and all that stuff?
                       MR. REYES:  Right.  You see -- you see --
           you don't see a stratified smooth interface.  You see
           a very wavy energetic interface.
                       MR. SCHROCK:  Well, given that, it seems
           unlikely that an analysis based on the cartoon in page
           number 5 model improvement should succeed, that that
           would be very surprising and yet --
                       MR. REYES:  Yeah.  I think what we're
           seeing --
                       MR. SCHROCK:  -- you're saying essentially
           that fortuitously it does succeed.
                       MR. REYES:  Yeah.  Yeah.  I think what
           we're seeing is that we're hitting a limit like a
           slug.  In essence, he's looking at a transition limit. 
           And I think that might be what's allowing us to
           collapse the data at that higher point, which was a
           surprise, I think, even when Dr. Wu looked at --
                       MR. SCHROCK:  I want to ask, once again,
           to have a copy of the derivation.  Don't take the time
           to put it up there, but I'd like to see that, please.
                       MR. WU:  In consideration for future
           effort, it's the test of liquid gas flows through the
           main line is more general case or more general or --
                       A test for the smaller main line for
           probably a noninnerflow case, because we are running
           only the intermittent flow case.  A test of ward down
           -- downward break, branch and break, and also will
           have an effect of gas flow from the downstream and the
           effect of gas flow through the main line.  And so we
           just think about the possibilities.  It's not to say
           we are going to do it.
                       And one more phenomenon we would like to
           point out is the pool entrainment.  In our case when
           the mixture level is way below the hot leg in that,
           it's about, say, six inches below the hot leg in that. 
           Under the entrainment, pool entrainment, pool droplet,
           and since this hot leg is the ADS-4 line is very close
           to the inlet, some droplets go in through this ADS
           line and have been transported to the upper plenum.
                       So we think the pool entrainment there is
           one of the mechanisms, those with our inventory.  And
           we have one still.  Right now it's trying to use the
           existing model to predict this flow rate we measured.
                       And APEX was also run the data in last
           year and also found the entrainment down continues so
           when the mixture level is below the hot leg.
                       That concludes my presentation.  Thank
                       CHAIRMAN WALLIS:  You have no theory to go
           with this?  This is just an observation?
                       MR. WU:  We have some models selected from
           publication and we are trying to simplify it, because
           it's --
                       CHAIRMAN WALLIS:  It looks like a very low
           flow rate, what, .01 kilogram a second.  Is that --
           that's about a pint a minute, or something.
                       MR. WU:  Yeah.  Yeah, that's right.  But
           as it now running it goes...  It's a mechanism.
                       MR. KRESS:  Is that --
                       MR. WU:  Those -- those are water
                       MR. KRESS:  Is that kind of entrainment
           very important for the nuclears' side?
                       MR. WU:  I think so.  I think so because
           that carry the droplets is not vapor going -- going
           through the break.  So you actually know the water
           inventory faster than you just depressurize the vapor. 
           So that actually should be considered, I think.
                       MR. KRESS:  Yeah, that looks like it's
           such a low rate of liquid being lost that it wouldn't
                       MR. WU:  That's a per second --
                       MR. KRESS:  -- wouldn't -- it wouldn't
           impact the rate at which you lose inventory by
           vaporization.  It seems like it's very, very
           negligible compared to the vaporization rate in terms
           of mass.  So it may not be important for accident
           sequences, it seems to me like.
                       MR. WU:  We need to calculate the numbers
           to this 1,000, like a kilogram per thousand.  You're
                       MR. BAJOREK:  I think the gas flow right
           there may also be low.
                       MR. WU:  Um-hum.
                       MR. BAJOREK:  We've run into this type of
           a problem before at Westinghouse at hot-leg
           switchover, where you have a period where you may not
           be putting as much liquid into the vessel as you
           normally would and you have a period of time where
           boil-off and potential entrainment could drop that
           level.  It's only two or three feet down to the top of
           the core.  I think the gas velocities are also fairly
           low there.  If that goes up the liquid entrainment --
                       MR. WU:  Yeah.
                       MR. BAJOREK:  -- would also go up quite a
                       MR. KRESS:  In the business of how
           suppression pools extract aerosols from steam rising
           up through it, one of the problems is how much liquid
           carryover you get, because it carries over part of it. 
           And there's some data in that field.  And a lot of it
           has to do with the bubble size that goes up through
           and --
                       MR. WU:  That's right.
                       MR. KRESS:  -- it's the --
                       MR. WU:  A burst.
                       MR. KRESS:  -- it's the film -- it's the
           film that breaks, that kicks up -- kicks up the stuff.
                       MR. WU:  That's right.  The burst.
                       MR. KRESS:  And there's basically two
           populations of droplet sizes that's seen.  But you
           might want to look into that field --
                       MR. WU:  Thank you, sir.
                       MR. KRESS:  -- to see.
                       MR. WU:  Thank you.
                       And also I think if we want to do a
           thorough investigation, maybe we need to add the
           internal, because droplets, or some of them are
           deposited down in the re-entrainment, and so we need
           to see.
                       Thank you, sir.
                       CHAIRMAN WALLIS:  Thank you.
                       Are we ready to move onto pressurized
           thermal shock?  Any more questions or points about
           this program?
                       MR. ROSENTHAL:  Yeah.  I thought that the
           staff ought to make a summary statement about how we
           intend to use the work and --
                       MR. BAJOREK:  Sure.  I guess first this
           program initiated a couple of years ago.  It was in
           response to, I think, largely an ACRS concern and also
           a co-development concern that the entrainment model,
           the face separation models in RELAP and other codes
           were deficient.
                       It was a problem in AP600 that was
           resolved primarily because there was so much other
           water in the system for the conditions, the power
           level of AP600, you wouldn't suspect entraining so
           much to challenge the top of the core.
                       It remains an important problem.  With a
           high uncertainty in AP600 it will become more of a
           concern and problem in the AP1000 when the gas
           velocities go up.
                       Our long-term intent is to use this data
           and similar data to develop better models for TRAC and
           RELAP.  Clearly we're not there yet.
                       In looking at the data, what we saw in the
           lab, there's still a lot of problems in our
           understanding of what are the true physics of
           entrainment and what's going on in this system right
                       It's not solely entrainment off of a very
           steady interface that is dominating the physics, but
           it's clearly related to system effects, dynamic
           oscillations in the hot leg.
                       They may be affected by geometry and
           scaling of the facility itself.  The split between
           what goes down the hot leg from the vessel versus the
           steam or air that goes through the rest of it and the
           size of these waves relative to the size in the pipe.
                       It's not clear that we've really addressed
           that total scaling issue at this point.
                       Our long-term intent, however, is to
           continue to use this data, to look at the data, to try
           to develop better models out of it; potentially to
           refine the facility; and to deal with and better
           understand the system effects before we get a model
           that's going to be put into TRAC and/or RELAP.
                       As Dr. Wu mentioned, the long-term goal
           does go beyond AP600.  We've talked about that and the
                       Your limiting small break usually is
           determined from a small branch line at the bottom of
           the cold leg.  That type of an orientation.
                       If we're ever going to be successful with
           code consolidation and improving the codes, we're also
           going to have to understand the side-oriented branch. 
           Practically that's important in several plants. 
           There's not a whole lot of those that have side
           orientations, but there's a lot of experimental tests
           primarily in the ROSA facility that would be
           absolutely vital for co-development.
                       That unless we can get the side branch
           correct we'll be forever dealing with the
           compensating-error issue.  So we need to be able to
           get the top branch, the side branch, and the bottom
           branch right in the long-run.
                       MR. SCHROCK:  Well, we have data for the
           side branch.  But I think that, again, you'll find
           that if the upstream conditions in the actual system
           looked more like in the OSU mock-ups of the system,
           that the data would not be applicable.
                       I certainly wouldn't want to argue those
           data for anything that looks like this sort of
           churning, pulsating flow in that horizontal pipe.
                       CHAIRMAN WALLIS:  Okay.  Do you want a
                       MR. ROSENTHAL:  I think it would be fair
           to the presenters, et cetera, if we could take a short
           break, if you wouldn't mind.  I mean it's your
                       CHAIRMAN WALLIS:  Well, we just got back
           from lunch.  So I was thinking of having a break at
           about the time that was originally anticipated, --
                       MR. ROSENTHAL:  It's your meeting.
                       CHAIRMAN WALLIS:  -- halfway through,
           otherwise -- see, we're a little bit -- we are late. 
           I mean you can get up and walk around, whatever.  We
           don't have to sit here all the time.
                       MR. ROSENTHAL:  I will.
                       CHAIRMAN WALLIS:  Okay.  I think that
           Jose's been dying to get up there.
                       MR. REYES:  Okay.  Now I'll get into the
           pressurized thermal shock research.  This presentation
           is to give you a -- I've actually combined three of
           the presentations to save a little time.
                       That includes the research objectives, a
           little bit of the prior work that's been done on PTS,
           and then a discussion of what test matrix was
                       So I'll to jump straight into some of the
           -- does this go backwards.
                       So we'll talk about overview; give you a
           little bit about our research program, what's been
           done; and then I'll mention what tests have been
           performed and what calculations have been performed,
           and just a brief summary.  So this is by way of an
           introduction to what you'll be seeing in more detail. 
           So each of these areas will be discussed in detail by
           the different presenters.
                       CHAIRMAN WALLIS:  And a lot of this stuff
           we won't see 'til tomorrow, right?
                       MR. REYES:  Correct.  Correct.
                       Now on the overview there are 10 slides on
           what's been done in the past.  And I think this is an
           optional area, and I'll leave it to the discretion of
           the Chairman.  We --
                       CHAIRMAN WALLIS:  Does it matter?  Does it
           matter to the present?
                       MR. REYES:  I think we can jump 'til -- we
           can jump to slide 12, and we'll gain some time. 
           Basically -- what it does is discuss what's been done
           in the past.
                       And then beginning on slide 12 there it
           discusses the results of my review of the previous
           work.  Does that sound fair?
                       CHAIRMAN WALLIS:  Okay.  That's fine. 
           Let's do that.  Let's do that.
                       MR. REYES:  That'll advance us --
                       CHAIRMAN WALLIS:  I think that we were
           most interested in what you have done.
                       MR. REYES:  Okay.
                       CHAIRMAN WALLIS:  And then at the end we
           might see what everybody's done and tells us about the
           conclusions we should be drawing.
                       MR. REYES:  Right.  So let's -- we'll jump
           to page number 12, please.  And so basically what I've
           done is I've gone through and looked at what's been
           done in the past.  And of course I already had some
           familiarity.  And this would be the results of my
           review of the previous research.
                       So I looked at integral system research
           that had been done previously.  Well, the integral
           system work really was related to calculation.  So
           what we had were calculations performed by TRAC and
           RELAP for the Oconee and the H. B. Robinson and the
           Calvert Cliffs plants.  So all we had were
           calculations.  There was no integral system test data
           available specifically for the PTS scenarios of
                       So as a result of the review of the prior
           work there was a need to benchmark the system analysis
           codes to determine their ability to predict loop
           stagnations, train the system pressure and downcomer
           temperatures.  So we'd like to have some benchmark
           data for those codes.
                       We'd like to be able to integrate the
           separate effects test results with the integral system
           behavior.  What we had were two sets of experiments. 
           We had -- well, actually all we had were the
           separate-effects experiments.  We didn't have integral
           system tests.
                       And I think what you'll see is that they
           do link together and that some of the separate LOCA
           behavior affects loop stagnation, which is an integral
           behavior.  And so we'll be talking about that later
           on.  So that was one of the motivations for the
                       Also there was an effort to examine the
           effect of core heat, heat transfer on downcomer fluid
           temperatures.  The pre-separate-effects tests were --
           essentially modeled the cold leg, loop seal,
           downcomer, the lower plenum, and then they had a stand
           pipe.  So there was no core sitting behind the barrel
           wall to heat up the core barrel wall.
                       So heat transferred from the core barrel
           to the fluid is going to be examined also in this
           study.  So that was another thing that we noticed that
           was missing from past research.
                       In the area of separate-effects testing we
           need to obtain some fluid mixing data for low-flow
           HPSI operation in a side injection cold-leg geometry. 
           So we didn't find in the existing literature any
           low-flow HPSI for a Palisades-type geometry.  So we
           actually have done some flow visualization testing,
           and we'll demonstrate some of that for you tomorrow.
                       We also saw the need to develop a
           criterion for the onset of loop seal cooling.  In
           these plants you actually have a -- as John will show
           in a little bit -- you have a reactor cool pump with
           a lip on it that prevents the -- that keeps a layer of
           cold fluid on the bottom of the cold leg essentially.
                       And when that spills over it has a
           particularly important effect in cooling the loop seal
           and it affects the loop behavior.  So we need a
           criterion for that.
                       Also we want to assess some of the advance
           CFD Code capabilities.  We've seen a tremendous
           increase in speed.  Back in '85 when we were trying to
           run SOLA-PTS and some of the other CFD Codes, it was
           painstakingly slow.
                       And the nodalization, we were able to get
           maybe 4,000 nodes in the downcomer, and it was taking
           10 hours to run maybe 10 seconds of transient.  So it
           was -- and of course at the time we needed to perform
           amounts of 200 transients for 7,200 seconds apiece. 
           And you do the math and you figure, well, not in my
           lifetime, I don't think.
                       So -- but what we've seen now is the CFD
           Codes have been -- are much more robust now.  They are
           -- the computational speeds are much better.  And
           you'll be seeing some fairly-heavily meshed systems
           later on in the presentations.
                       Okay.  So now we set up this research
           program here at OSU.  We want to perform some integral
           system and some separate-effects tests to address the
           earlier research limitations.  We've got -- we've had
           a very good cooperation in place.  It's worked very
           well.  From the NRC Research, Dave Bessette, Gene
           Rhee, Sarah Colpo, Chris Boyd.  Those folks have been
           very supportive of what we're doing.
                       They have allowed us to -- it's allowed us
           to be able to work with Oak Ridge and with Consumers
           Energy -- I was misspelling it.  Oak Ridge of course
           is had interest in where we put our thermocouples to
           measure our temperatures.  And they have been helpful
           in providing input in that area.
                       Consumers Energy, the Palisades Plant,
           they've been very helpful in providing plant data. 
           And they've also done some other work in having us
           have discussions with their operators so we know how
           operators realisticly respond to main stream line
           breaks and small break LOCAs.  And we'll talk about
           that a little bit more later.
                       So this is by way of the structure of our
           research plan.  And it might be hard to read on there,
           so I'm just going to talk about the big, the overall
                       We essentially started off with a review
           of what had been done.  Did a scaling analysis to see
           whether or not our APEX facility could be modified to
           give us behaviors or to produce a geometrically
           similar system to the Palisades Plant.  That was the
           plant selected.
                       We found that it was geometrically
           similar, remarkably so, that the CE 2-by-4 design is
           very, very similar to the AP600 design.
                       So in scaling that cross-section flow
           airs, the volumes, we're essentially using a constant
           factor all the way around the loop, so it was very
                       We did some facility modifications, and
           then we were able to perform our testing.  We've had
           two types of tests, as I mentioned before, integral
           system tests, and then we also did some
           separate-effects test.
                       In the area of thermal hydraulic analysis
           we're using RELAP5, the NRC version, the Gamma
           version.  And we're using REMIX and STAR-CD to do more
           detailed LOCA separate-effects types of analyses.
                       So what we plan to present to you is the
           summary of all this work in each of these areas and
           try to provide you with some result in each of these
           areas that will be helpful to the overall PTS
                       So I mentioned the scaling analysis.  I
           won't get into a lot of details.  We established that
           the degree of geometric similarity between Palisades
           and APEX was -- the plants are similar geometrically.
                       We developed a detailed scaling basis for
           looking at the -- for assimilating the onset of loop
           stagnation.  So our flows, and our injection flows,
           and our cold-leg flows under natural circulation
           conditions are maxed so that we're able to get the
           onset of loop stagnation under the same conditions.
                       The onset of thermal stratification, the
           cold legs.  This has been interesting.  We've learned
           a lot from our tests here.  Both the flow
           visualization and the APEX-CE test.  We'll talk more
           about that.
                       We have also did some scaling in the area
           of thermal fluid mixing.  And that also required doing
           some separate-effects tests in APEX.  We did some
           very, very simple benchmark tests on those.
                       Now we developed scaling bases for
           comparing the main steam line break and a small break
           LOCA in our facility to Palisades.  And we also
           identified which of the PTS PIRT phenomena would be
           adequately simulated in APEX-CE.
                       Facility modifications.  The APEX design
           was modeled, of course, after the AP600.  What we've
           done is we've added loop seals to this design to
           simulate a Palisades plant.  We've changed the
           configuration of the cold legs to simulate the
           Palisades Plant.
                       We've eliminated all the -- in essence,
           all the passive safety systems of the AP600.  And
           we've changed the logic.  We've isolated all the logic
           of the AP600 to come up with a design that was similar
           to Palisades.
                       We've also added four safety injection
           lines on the cold legs in prototypic geometry,
           including the check valves on those lines, to simulate
           the inactive emergency core cooling system.
                       The types of integral system tests that we
           performed, we -- in all the tests we measured
           downcomer fluid temperatures and of course the
           corresponding system pressures.  And we did a series
           of small break LOCAs and what are called excess steam
           demands on main steam line breaks, a stuck-open
           atmospheric dump valve test.
                       And in these tests we've tried to identify
           the conditions that lead to primary loop stagnation. 
           And we've nailed those down pretty well, I think.
                       This is our test matrix just for the
           integral system test.  We start off very simply with
           just a natural circulation flow benchmark test, making
           sure that all of our loop resistances were similar to
           the Palisades.
                       We did a stepped inventory reduction test
           which was reminiscent of the semiscale tests done back
           in the, I guess it was, late '70s, early '80s.  We
           were able to duplicate that work.  Again we're trying
           to characterize single-phase and two-phase natural
           circulation in our loop.  And I'll show you those
           results later on.
                       And then, of course, we did the small
           break LOCA tests.  We had a -- it's actually -- we did
           a 1.4-inch hot-leg break from full power conditions. 
           And actually number 8 was a two-inch hot-leg break
           from full power conditions.  So that test -- that's an
           old test nomenclature.  So that was actually a
           two-inch break that was performed, number 8.
                       We did the stuck-open pressurizer 4 from
           full power; 10 was revised also.  We did stuck-open
           pressurizer power with a combination stuck-open
           automatic atmospheric dump valve.  So some of these
           have changed, and I guess we didn't catch it on this
           slide.  Sorry.
                       We did do two main steam line breaks, one
           from full power and one from hot and zero power.  And
           then test number 13 we still need to perform.  That's
           one where we have an opportunity to do something a
           little bit different there.
                       We're looking at HPSI injection in a
           partly-voided downcomer.  Now you've got level in a
           downcomer.  And we're essentially pouring cold water
           into it.  So it's a little bit different than what's
           been done in the past.  And we do need to get a little
           bit of guidance on the best way to perform that test. 
           But that's all that's left from our original integral
           system test matrix.
                       And we also performed some
           separate-effects test in APEX, APEX-CE.  And these
           were steady-state HPSI tests.  And these were similar
           to what was done at Creare in their half-scale
           facility.  And we also simulated those in our
           transparent loop.  We wanted to see the thermal
           stratification in the cold legs.
                       We wanted to study the plume development
           interaction in the downcomer.  And we wanted to look
           at plume heat transfer downcomer walls.  And so this
           was an APEX-CE, so we were at full pressure.  We were
           injecting -- essentially it is a constant HPSI flow
                       And these were done with no core power, so
           it was very similar to what was done at Creare.  And
           we'll show some of the differences that we've seen
           from our data and what was done at Creare in the past.
                       Our test matrix, Tests 3, 4, 5, and 6, 3
           was essentially a parametric study.  And that was
           safety injection under natural circulation fluid
           mixing conditions.  So we've looked at 16 different
           conditions there.
                       And 4, 5, and 6 were just like the Creare
           half-scale type test.  We did it with one HPSI
           injection and then with four at two different flow
           rates.  And the big difference there is we do see some
           of the effect of the core barrel stored energy
           release, and it plays a significant role.
                       And then in the flow bridge relation
           series, we're still continuing to do some of those. 
           We're looking at onset of rear wall spillover and how
           to go about modeling that.
                       In terms of analyses, we're doing two
           types, of course.  We're doing integral system
           analyses and we're doing separate-effects analyses. 
           We're using RELAP5, the NRC, the Gamma version to do
           the integral system analyses.
                       We've performed actually five analyses
           there.  One was a steady-state natural circulation. 
           The other one was Test Number 2, which was a reduced
                       Then we've done two main steam line break
           analyses and one small break LOCA analyses.  So Dr.
           Lafi will be presenting that later this afternoon.
                       In the area of separate-effects analysis,
           we used STAR-CD to do some analyses there.  And this
           was kind of a very good experience for our students.
                       What we did, we said, here we have some
           folks with some good basic engineering background.  We
           hand them the code and say, "You have a year to learn
           this code," and to try to get -- to benchmark it
           against existing data to see if it works.  "I want you
           to report back to me all your difficulties, all your
           experiences, and how difficult it was to learn this
           type of code to get to a point where you feel
           proficient and able to use it to come up with
           predictions for a new geometry."
                       So they've got some feedback and some
           lessons learned there.
                       And we also used the REMIX Code for
           predicting some of our separate-effects test.  That's
           one that had been used in the past in the previous
           effort.  It's a regional control volume type of
           analysis technique that's used and had been used in
           the past to predict the downcomer temperatures and
           actually the -- all the way through the downcomer and
           out the exit of the downcomer.  And we've got some
           calculations to show you there.
                       This mentions the tests that had been
           performed or analyzed using RELAP.  Again, we have
           four there.  And there was an additional one which was
           basically our benchmark -- a benchmark case.  And that
           has the right nomenclature there with the two-inch
           hot-leg group.
                       So you'll be seeing -- you'll be seeing
           some of those calculations later today.
                       For the STAR-CD calculations, we did
           benchmark the code against the Creare half-scale test,
           MAY 105.  You'll see that result.
                       And then we have also looked at
           OSU-CE-0003 as one of the parametric studies that
           included flow in the cold leg, a natural circulation
           flow rate.
                       For the REMIX calculations we'll be
           showing three of those today.  OSU-CE Number 4, 5, and
           6.  And those are similar to what had been done in
           Creare, except now we are doing an integral loop with
           some of the heat transfer from the core barrel going
           to the plenum.  And we see that it does make a -- it
           does impact the results quite a bit.
                       Okay.  So this is an outline of what
           you'll be seeing.  Okay.  I wanted to show you the
           overall structure.  We had integral system testing. 
           We had separate-effects testing.  And then we had
           modeling approaches or analysis approaches for each of
           those areas.  RELAP for the integral system, STAR-CD
           and REMIX for the separate-effects test.
                       So we performed those analyses, and you'll
           see those today.  We were able to modify the facility,
           and we think it scales quite well.  We've got eight
           integral systems tests that have been completed.  We
           have one test, number 13, lucky number 13, which
           remains to be performed.
                       We have four separate-effects tests which
           have been performed, and it includes one parametric
           study which has actually 16 separate conditions.  And
           then we're right now continuing to do a series of flow
           visualization tests in our transparent loop.
                       And that's that.  Any questions on what
           you're about to see?
                       So that's an overview of our research plan
           and what's been done.  I think the next thing on the
           Agenda is to start describing working through this. 
           So the facility, I think, description is next.
                       CHAIRMAN WALLIS:  Now we're due to have a
           break after you stop talking; is that still
                       MR. REYES:  I'm sorry?
                       CHAIRMAN WALLIS:  We're due to have a
           break after you stop your series of presentations.  Is
           that still appropriate?
                       MR. REYES:  Sure, that will be fine. 
           We'll take a short break.  So I have stopped talking.
                       What I've done is I've combined those
           three presentations into one.  So I've talked about
           test matrix, what was performed.
                       CHAIRMAN WALLIS:  Yes.  Right.
                       MR. REYES:  I talked about our research
           plan.  And what I skipped a bit of was the prior work
           and the PTS research that's been done.  But I did
           summarize the results of that or the areas that we
           felt we could contribute.
                       CHAIRMAN WALLIS:  Are you going to give --
           are you going to give John Groome's presentation?
                       MR. REYES:  So now John Groome is ready to
                       CHAIRMAN WALLIS:  Okay.
                       MR. GROOME:  Would you like me to present?
                       CHAIRMAN WALLIS:  Sure.
                       MR. GROOME:  Okay.
                       CHAIRMAN WALLIS:  And then what do you
           have to do after that, before --
                       MR. REYES:  Well, then it's a separate
           presentation -- oh, I see.  The break's after my
           second, okay.  Yeah, the second presentation.
                       CHAIRMAN WALLIS:  Your second
           presentation.  We'll see how long John Groome talks. 
           We may --
                       MR. GROOME:  I'll try to go real fast.
                       MR. GROOME:  Good afternoon.  My name's
           John Groome.  I'm the Director of Facility Operations
           on the APEX Test Facility.
                       I've outlined what we're going to talk
           about.  And I'm just going to go fairly fast.  And if
           you have any questions you can certainly slow me down
           to ask.
                       I'm going to talk about the APEX-CE Test
           Facility, some of the modifications that we performed
           to the facility, a basic description of the facility. 
           I'll also show some slides of the flow visualization
                       I'll talk briefly about the NRC meeting at
           Palisades.  We traveled with NRC to Palisades, and we
           actually observed the operators perform main steam
           line breaks and small break LOCAs at their simulator.
                       And we learned -- what we tried to do --
           the AP600 philosophy was hands off, the plant logic
           takes care of the plant during an accident scenario.
                       Palisades is more like a traditional plant
           where the operators actually interface with the plant
           during the accident.  And so we tried to incorporate
           some of those operator actions into our tests.
                       And I'll talk briefly about some
                       CHAIRMAN WALLIS:  Are we only doing this
           work for CE plant?
                       MR. GROOME:  Well, the facility that we've
           -- the APEX facility was modeled after the Palisades
           CE plant.
                       CHAIRMAN WALLIS:  All right.  But the
           conclusions are going to be applied to pressurized
           thermal shock in some other plants, or what's the NRC
           going to do?
                       MR. BESSETTE:  Yes.  Well, the reason we
           -- you know, the scaling was done to compare APEX to
           CE plants because the APEX configuration falls very
           close to the CE configuration.  The other plants we're
           doing analysis on were Oconee and the Westinghouse 3
           Loop Plant, Beaver Valley.
                       So -- but in terms of, you know, looking
           at -- some of these phenomena, of course, should be
           generic, like the interruption of loop flow, you know,
           flow stagnation.
                       CHAIRMAN WALLIS:  Well, the method of
           injecting ECC is different.
                       MR. BESSETTE:  The method -- the method of
           -- you know, the injection is similar.
                       CHAIRMAN WALLIS:  It's different in
           different plants.
                       MR. BESSETTE:  Yeah.
                       CHAIRMAN WALLIS:  A side injection is
           rather unusual.
                       MR. BESSETTE:  Yeah.  You know, the plants
           will have any -- all configurations, from top to side
           to bottom.
                       CHAIRMAN WALLIS:  I thought some CE plants
           have top injection, don't they?
                       MR. BESSETTE:  Possibly.
                       CHAIRMAN WALLIS:  I think so, yeah.
                       MR. BESSETTE:  But basically you can find
           every configuration.
                       Now the other aspect is the general
           question of code assessment is part of the objective. 
           So we look at different kinds of secondary side and
           primary side transients with steam line break and
           small break LOCA.
                       So, you know, we picked, let's say, the
           most PTS-significant types of transients to run as
           integral to the experiments.
                       Again I think, say, for a steam line
           break, phenomena are similar.  Small hot-leg breaks,
           again the phenomena are going to be similar.
                       CHAIRMAN WALLIS:  But you're going to
           rewrite some PDS rules, aren't you, for all plants? 
           Isn't that in the offing?
                       MR. BESSETTE:  Yes.  Yeah, because the PTS
           rule applies to all the plants generically.
                       CHAIRMAN WALLIS:  So you're going to have
           to show some sort of generic applicability of this
                       MR. BESSETTE:  Yes, -- well, you know, the
                       MR. KRESS:  These methodologies, though,
           would show up in a Reg.  Yeah, they would show up in
           a rule, wouldn't they?
                       MR. BESSETTE:  So I think, you know, the
           -- what we do is we say, well, the phenomena are going
           to be -- the dominant phenomena are going to be the
           same for different plant designs.  We're doing some --
           we're also incorporating -- let's say part of the
           objective here is to assess RELAP.  We've got the same
           down on phenomena, so presumably the assessment is
           going to be valid for those different plants.
                       Like I say, when we did the scaling eval-
           -- when, you know, Jose did his scaling evaluation, he
           did it looking at the geometric similartude of APEX
           with respect to CE plants.
                       Was that an answer?
                       CHAIRMAN WALLIS:  But RELAP doesn't model
           this stratification, does it?
                       MR. BESSETTE:  Some of these phenomena,
           you know, of course RELAP can't do.
                       CHAIRMAN WALLIS:  That's right.  So how
           can you test RELAP on phenomena you can't model?
                       MR. BESSETTE:  Well, if we can show that
           the downcomer temperatures -- if it turns out that
           downcomer temperatures calculated by RELAP are similar
           to the experiments, then we can argue that -- if
           that's so, then we can argue that the phenomena it
           can't calculate it don't seem to be that significant.
                       If there are differences, I think we have
           to supplement the RELAP analysis with the CFD and/or
                       CHAIRMAN WALLIS:  Okay.
                       MR. GROOME:  The APEX-CE Test Facility is
           geometrically similar to the Palisades Plant.  It
           includes a reactor vessel with a 48-rod
           electrically-heated bundle.  We have to two hot legs,
           four cold legs with reactor cold pumps, and we added
           high-pressure safety injection nozzles on a side
           orientation, similar to Palisades.
                       One pressurizer.  Two inverted U-Tube
           steam generators, a feed-water pump.  And we have a
           programmable logic controller that we actually use to
           model the Palisades Plant logic.
                       This is a brief summary of the
           instrumentation.  We have thermocouples.  We added
           approximately 50 thermocouples to the downcomer to
           measure the plume temperature distribution for the PTS
                       We have pressure and differential pressure
           detectors.  Some of our differential pressure
           detectors are actually used to measure level and pipes
           in various tanks.
                       Primarily for our liquid flow we use
           magnetic flow meters.  We use vortex flow meters for
           measuring of steam flow.  Some of our tanks have load
           cells to actually get a mass.
                       And we installed Coriolis flow meters,
           mass flow meters, on our four injection lines that we
           added to the plant.
                       Testing capabilities in the CE
           configuration include hot-leg breaks, cold-leg breaks,
           main steam line breaks, stuck-open pressurizer safety
           relief valves, and stuck-open steam line atmospheric
           dump valves.
                       OSU modified the APEX to simulate the
           Palisades' 2-by-4 PWR.  Again we added four cold-leg
           high-pressure injection lines.  We actually modified
           our cold legs to include a loop seal.
                       We looked at the Palisades Plant, and I'll
           show you a slide here in a minute, and we added a weir
           wall in our cold leg to simulate the Palisades'
           primary-cooled pump housing lip.
                       And what that does is it prevents the cold
           leg from completely draining.  And we added again
           approximately 50 additional thermocouples and 12
           loop-seal thermocouples to our loop and four mass flow
           meters to the injection nozzles.
                       This is an elevation view of the
           Palisades' loop.  And you can see the -- I'll just
           point.  This is the primary cooler pump lip here we're
           talking about.  The cold-leg nozzle would actually
           inject -- would actually come off the screen here
           perpendicular that prevents the cold leg from
           completely draining.
                       CHAIRMAN WALLIS:  So there's no loop seal
           in this --
                       MR. GROOME:  Well, I'll show you a side
           view.  So this is an artist's rendition of the APEX-CE
                       One of the things that's different, this
           is a planned view here showing the similarities
           between the two plants.  Here's an elevation view.
                       One of the things that's different is our
           reactor coolant pumps were made specifically for the
           APEX, the AP600 configuration, and they mounted
           vertically to the bottom of the steam generators.
                       Typically on a PWR they're mounted
           vertically upright on the top of the loop seal.  What
           we did is we dropped the pump vertically at the bottom
           of the loop seal.  And then there at the flange right
           on the discharge on the vertical section or the
           horizontal section of the cold leg, we added a weir
           wall in the cold-leg pipe to simulate that lip of the
           Palisades' primary coolant pump.
                       We also built a flow visualization loop to
           help us understand the mixing in the cold leg.  Again
           it was constructed of clear PVC pipe.  The test loop
           includes a single cold-leg piping geometry
           representing APEX-CE, a high-pressure safety injection
           nozzle on the side with a check valve, a weir wall in
           the cold leg, and we have a 50-gallon salt water
           mixing tank that we use to simulate the difference
           between the hot and cold streams.
                       Our high-pressure injection pump is
           capable up to 20 gallons per minute and our cold leg
           flow pump is capable of 500 gallons per minute. 
           Typically we ran the flow visualization tests at much
           reduced flows.
                       CHAIRMAN WALLIS:  This salt water mixing
           is only for a separate-effects test?
                       MR. GROOME:  Correct.  It was just for
                       And here is a side view of the test loop. 
           The green dye is actually in the salt water when we
           inject it.  This is actually a post-test.  You can see
           the weir wall right there.  Right there's the weir
           wall in our clear test section.
                       If we had a pump here that simulated the
           APEX-CE, the pump would actually be installed down
           here.  But we just took a -- we have a test pump there
           in the facility, and we just took a flow off of the
           pump that's mounted on the floor there to simulate
           natural circulation flow rates.  And we could vary
           that parametrically up and down.
                       CHAIRMAN WALLIS:  Are you going to show us
           this, or are you --
                       MR. GROOME:  Well, you kind of saw it if
           you --
                       CHAIRMAN WALLIS:  Yeah, it was there.
                       MR. GROOME:  -- when you were there, but
           we didn't actually put on a demonstration.  But we can
           do that for you.
                       MR. SCHROCK:  Now what does the weir wall
                       MR. GROOME:  The weir wall simulates the
           loop, the lip seal.
                       Can you make me go back there, Brandon, to
           where that picture was?  One more maybe.  Two more. 
           There you go.  There's the mouse.
                       So this is the lip here that I'm talking
           about that exists in the primary coolant pump casing. 
           And right here projecting perpendicular from the
           screen is the cold leg nozzle.
                       And so what it does is it prevents you
           from draining, completely draining this cold leg if
           you were to open up a drain valve.  In other words, in
           order to spill over into the loop seal you have to get
           by this lip.
                       And since our pumps are at the bottom of
           the loop seal we added this lip here on the horizontal
           section of our cold-leg pipe to simulate this lip of
           the Palisades' primary coolant pump housing.
                       MR. SCHROCK:  In what way does it simulate
           it?  It's got the same height restriction or --
                       MR. GROOME:  The same -- it's the same
           elevation.  It doesn't simulate necessarily the
           roundness of the geometry.  It's just a vertical plate
           that's welded on the inside of the pipe.
                       And again this is a top-down elevation of
           the flow visualization loop showing the side injection
           nozzle there.
                       We also traveled to Palisades to -- we
           found out where Kalamazoo is.  If everybody ever wants
           to know where Kalamazoo is, it's in Michigan.  And --
                       CHAIRMAN WALLIS:  It's a Covert operation.
                       MR. GROOME:  Yeah, it's in Covert.  The
           plant's actually in Covert, but you fly into Kalamazoo
           to get to Covert, which we had to look at a map for
           quite a while to figure out where that was at.
                       But we actually talked with the Palisades'
           operators trying to understand the logic that they do
           for their accident scenarios and when they train on
           the simulators.
                       We actually observed, I think, about four
           tests, two main steam line breaks and two small break
           LOCAs.  And based on discussions with the Palisades'
           operators and our observation and understanding of the
           scaling limitations of the facility, we developed a
           set of test procedures for the APEX-CE tests that we
           performed as part of our NRC work.
                       And I'm just going to briefly just kind of
           -- Dr. Reyes wanted me to talk a little bit about just
           to give you kind of a feel for what Palisades'
           operators would do during tests.
                       We looked at some of their emergency
           operating procedures, their standard post-trip
           actions:  Loss of coolant, accident recovery
           procedure, an excess steam demand, their functional
           recovery procedures, and some of their EOP supplements
           when we were developing our test procedures.
                       And this is just a general outline for
           Palisades for a small break LOCA, their general
           sequence of events that you would see.
                       They normally would manually scram the
           reactor whenever their second charging pump was
           started.  They have three charging pumps that can vary
           the flow from anywhere from 30 to 150 gallons per
                       They manually tripped two reactor coolant
           pumps at 1300 PSI, one on each loop.  And they tripped
           a second pair of reactor coolant pumps whenever they
           approach less than 25 degrees subcooling margin.  And
           typically that will happen about five minutes.
                       Depending on the scenario that they're
           running, typically will happen about five minutes
           after tripping the first reactor coolant pumps.
                       And the operator determines this by
           looking at T hot and temperature to core and
           pressurize the pressure.  And they actually have a
           screen, and I don't have a viewgraph, but they
           actually part -- I do have a little bit of a viewgraph
           showing the operator trends as they depressurize.
                       And typically the reactor coolant pumps
           are not restarted during a small break LOCA, even if
           subcooling is regained.  And that's because -- well,
           this assumes -- for a steam break inside a
           containment, they lose cooling water to the reactor
           coolant pumps.
                       And so whenever they're isolated they have
           about five minutes to regain cooling to the reactor
           coolant pumps, otherwise they have to go to a warm-up
           procedure that takes them about 30 to 40 minutes to
           warm up before they can open up the cooling water back
           to the reactor coolant pump.  So they just go ahead
           and lose the second pair, and they don't immediately
           worry about restarting the reactor coolant pumps.
                       Monitor.  They monitor the pressurizer and
           reactor pull, reactor pressure level.  The small break
           LOCA does not adequately remove decay heat, so they
           use the steam generators to remove decay heat via the
           turbine bypass valve or atmospheric dump valves.  The
           turbine bypass valves are limited to five percent. 
           And then they manually control aux feed water to
           maintain the steam generator level.
                       There's no automatic steam generator
           isolation.  And when the T hot approaches about 550
           degrees Fahrenheit, they secure the main feed pumps. 
           And note this is approximately after the test T hot or
           after the small break LOCA, the temperatures are
           approximately 530 degrees Fahrenheit immediately
           following the reactor trip.
                       The turbine bypass valve is -- the set
           point is 900 psia, which is approximately Psat for
           532.  So the turbine bypass valve will open up and
           start to dump steam also.
                       The main steam line break.  They get their
           signal either on a containment pressure greater than
           four PSI inside a containment.  They will isolate the
           main feed pumps and main steam.  Auxiliary feed water
           and atmospheric steam pump valves are available.
                       They manually trip the reactor or allow it
           to trip on a set point, but they will get a
           power-to-flow set point scram.
                       They'll determine the affected steam
           generator and isolate on excess steam demand or tube 
           rupture.  So they have a procedure where they try to
           determine if it's a U-tube rupture or a main steam
           line break.  They'll isolate the aux feed water.
                       And for our tests we were not
           conservative, and we assumed that it took them about
           10 minutes to isolate aux feed water to the affected
           steam generator.
                       And they'll also isolate the atmospheric
           dump valve, turbine bypass valve, and the safety
           isolation valves.  And they'll allow the affected
           steam generator to blowdown.
                       They'll stabilize the plant.  They'll cut
           back on the charging pumps when the pressurizer level
           is gained to 40 percent if it's a main steam line
           break in the containment; and 20-percent pressurizer
           level if the break is outside the containment.
                       They'll maintain the normal steam
           generator -- the normal steam generator level on the
           intact steam generator by using aux feed water.
                       When the steam generator pressure is less
           than 800 PSI, they'll close the main steam isolation
                       The reactor coolant pumps are on unless
           the excess steam demand is inside the containment. 
           And again what happens there is that the containment
           is isolated and they lose coolant water to the reactor
           coolant pumps.  And the reactor would most likely trip
           on their power-to-flow set-point.
                       Palisades has a set of pressure and
           temperature limit curves that are available to the
           operator on a CRT screen.  These curves are basically
           designed to help them avoid a PTS event.
                       This is a look at the pressure and
           temperature curves from one of their emergency
           operating supplements.  There's three curves on the
           bottom there.  You could perhaps read a little bit
           better from your notes.
                       The bottom curve is the saturation curve. 
           The curve right above it here is the 25-degree
           subcooling curve.  So if they got down to this curve
           here they would secure the sector of reactor coolant
           pumps during a small break LOCA.
                       And this third curve that's right above it
           that actually crosses over the 25-degree subcooling
           curve is their minimum-pressure temperature for
           reactor coolant pump operation.  And this is just an
           abbreviated screen.  This actually goes -- there's
           another page that actually goes all the way out to 50
           degrees Fahrenheit.
                       The upper limits of these curves, there's
           a 200-degree subcooling curve.  And there's this VLTOP
           curve which is their variable limit for temporary
           overpressure protection.  I like to refer to this as
           the brittle fraction prevention curve here, so that
           when they're shut down this is the set-point that
           would actually open up their primary power-operating
           relief valves to avoid exceeding the pressure for the
           temperature that they're at.
                       Normally this curve is not -- the VLTOP
           curve, when they're operating, is not in play.  They
           use a 200-degree subcoolant curve until it comes down.
                       And the operator -- I'll show you a screen
           here.  This is from the actual main steam line break
           simulation.  And this is just -- there's a wide
           variety of information on this CRT when you're
           actually looking at it.  And we just pulled one image
           off.  But this is their pressure and temperature limit
                       Number 2 here and 3 are the hot and
           cold-leg temperatures.  So what they're doing, as the
           main steam line break is progressing, the operator is
           trying to control pressure and temperature to maintain
           the plant within the two limits, the subcooling curve
           here and saturation curve, and their 200-degree
           subcoolant curve here on the top or the VLTOP curve.
                       The APEX plant operating procedures and
           the plant actions were generally realistic with the
           following very important exceptions.  We did not allow
           -- for our test procedure we did not allow throttling
           of the high-pressure safety injection.  So we just
           started our high-pressure injection safety, and we
           modeled the full flow during the whole entire test.
                       Isolation of the feed water flow to the
           broken steam generator was assumed to take 10 minutes.
                       And no effort was made to keep the plant
           within the pressure and temperature band, scaled, as
           required by Palisades' emergency operating procedures. 
           So we essentially just let the plant behave as it
           would with no operator actions once we started the
                       The APEX-CE Test Facility includes all the 
           key components needed to simulate the Palisades'
           thermal hydraulic overcooling behavior.
                       The transparent loop provides
           visualization of the fluid-mixing behavior in the
           APEX-CE cold legs.
                       The NRC meeting at Palisades in March and
           the emergency operating procedures provided valuable
           insight into operator actions during the main steam
           line breaks and small break LOCAs.
                       The Palisades' emergency operating
           procedures are designed to avoid a PTS event.  The
           APEX-CE test procedures were based on Palisades'
           emergency operating procedures, discussion with plant
           operators, and actual observation of plant
                       The APEX-CE operator actions were
           generally realistic with a few very important
           exceptions designed to produce PTS test conditions
           needed to benchmark codes.
                       And I believe that's my presentation.  Are
           there any questions?
                       CHAIRMAN WALLIS:  Not at this time
                       MR. GROOME:  Thank you.
                       CHAIRMAN WALLIS:  Thank you very much.
                       So you train your operators to simulate
           Palisades or something, or do you put it in the
           computer ahead of time, or...?
                       MR. GROOME:  Actually we did both.  For
           the most part, for repeatability we programmed it in
           our programmable logic controller.
                       But actually during the performance of
           this test we had an equipment failure where we lost
           our main feed pump.  And so we had to use our pump
           that we use for high-pressure safety injection for our
           main feed pump.  We have that capability.  And so we
           actually performed operator actions because of that
           equipment failure at this plant.
                       MR. KRESS:  The operators, their actions
           are intended to keep you away from pressurized thermal
           shock --
                       MR. GROOME:  Correct.
                       MR. KRESS:  -- or at least minimize it. 
           But your test, you're trying to see what happens here
           in a pressurized thermal shock.
                       MR. GROOME:  Exactly right.
                       MR. KRESS:  So you don't really want to do
           everything they do.
                       MR. GROOME:  Exactly.  That's what we did.
                       MR. KRESS:  Yeah.
                       MR. GROOME:  We looked at the actions that
           they performed during the test, because it was quite
           a bit different than the AP600.  You know AP600,
           basically the operator's dead.  Plant logic takes care
           of itself.  There's no operator actions at all.
                       Palisades, there's operator actions that
           affect the outcome of the test.  So what we did was we
           -- to understand that, we traveled to Palisades, read
           and reviewed their emergency operating procedures,
           talked to their operators, and incorporated some of
           those operator actions into the test procedures.
                       For example, you know, we assumed that it
           took a minimum of 10 minutes to isolate aux feed want
                       MR. KRESS:  Um-hum.
                       MR. GROOME:  But we didn't try to --
           unlike Palisades' operators, they'll actually try to
           control temperature and pressure to keep the plant
           within the two bounds of the P and T curves.  We did
           not do that.  We let the test just progress after that
                       MR. WOODS:  Could I -- I'm Roy Woods.  I'm
           in Research, NRC.  I just wanted to point out that
           what these gentlemen are talking about, we take the
           PRA contractors and the HRA contractors, and we've
           gone to each of the plants that we are analyzing.
                       And one of the main things we do when we
           go to these plants is go through some simulator
           exercises so our HRA people and our PRA people can see
           what the important human actions are and see how the
           training the plant operators get corresponds to the --
           whether or not they'll actually do those actions, and
                       So you gentlemen went on the trip because
           you were analyzing Palisades.  And we also have
           already gone to two other plants for the same kind of
                       So the fact that they saw these human
           actions and then chose not to simulate them, you know
           that's okay.  I mean they were looking for one purpose
           and we were looking for a different purpose.
                       MR. KRESS:  Yeah, that's what I get.
                       MR. REYES:  Any other questions?
                       MR. REYES:  Let's proceed.  What I'd like
           to do is just start off with our integral system tests
           and just give you the -- we'll start off with kind of
           the big picture.
                       For PTS we're interested in the system
           pressure and the downcomer temperatures, so we'll talk
           a little bit about that.
                       In the presentations that will follow
           we'll talk more about the details of how we got to
           those temperatures and what's happening specifically
           in the downcomer.  So let's start with just an
                       So we'll look at downcomer fluid
           temperatures, at some of the temperature and pressure
           extremes for all the integral system tests that were
           performed.  And I'll just give you some conclusions
           based on the big picture.
                       So you'll be seeing several presentations
           looking at the specifics of the downcomer fluid
           temperature under different conditions.  So that will
           -- that's to follow.
                       But in general the fluid temperatures were
           relatively uniform around the downcomer at about eight
           cold-leg diameters down into the downcomer.  So we saw
           good mixing for all the integral system tests at 8D.
                       And for the most of the tests at 4D, four
           cold-leg diameters down, we saw good mixing.  So
           that's just perhaps a rule of thumb that you can keep
           in the back of your mind.
                       MR. SHACK:  Where does that put me
           relative to the beltline?
                       MR. REYES:  The beltline for this
           particular plant, their beltline wells were right
           about five cold-leg diameters down.  Their centerline,
           beltline -- well,...
                       Several of the tests that did experience
           axial thermal stratification in the downcomer.
                       So we saw a cold temperature on the bottom
           stratified all the way up to the top.  But radially
           they were all relatively uniform.
                       Here's the six integral system tests that
           we performed.  And this is just kind of trying to pick
           the extremes.  The minimum downcomer temperature for
           that particular test and then in the column next to it
           what the minimum pressure was.
                       And again in terms of scaling, you might
           want to think of it this way:  360 psig would
           correspond to about 1200 psig in the Palisades Plant
           on a pressure-scaling basis.  Okay.
                       So what we saw was an minimum downcomer
           temperature for the smallest break, the 1.4-inch small
           break LOCA, which was off of the hot leg, the minimum
           downcomer temperature is about 255 degrees Fahrenheit. 
           We initially were at 420 degrees.  It came down.
                       And the minimum pressure -- temperature --
           the pressure at that minimum temperature was about
           131.  You can look at all the numbers there.
                       In terms of the case which produced the
           most -- the highest pressure at the lowest
           temperature, we're looking at the main steam line
           break at hot zero power.
                       And I think that's consistent with what we
           saw in the previous analyses that were done almost 20
           years ago -- about 10 years ago.
                       So the minimum downcomer temperature is
           about 230 degrees Fahrenheit and about -- we
           repressurized essentially on that test, okay.
                       And what I'll do now is I'll show you the
           plots of each of those scenarios, the pressures and
           temperatures, so we can do a little bit of a
                       CHAIRMAN WALLIS:  What's the last column
                       MR. REYES:  Oh, thanks --
                       CHAIRMAN WALLIS:  You actually observed
           stagnation for part of the time, or something?
                       MR. REYES:  That's right, yeah.  So if the
           cold leg experienced stagnation anytime during the
           transient, we identify which cold leg's that.
                       CHAIRMAN WALLIS:  But they're not all at
           the same time then?
                       MR. REYES:  Right.  And we did see some
           asymmetric loop stagnation, and that was very
           interesting phenomenon.  We can explain that.  There
           will be a whole separate presentation just on loop
           stagnation mechanisms.  We've isolated those,
           identified what causes loop stagnation for this
                       MR. SHACK:  What are we really talking
           about when we say the "main steam line break" here?
                       MR. REYES:  Right.  In this test we were
           doing, it was the equivalent of a one-square-foot main
           steam line break.
                       MR. SHACK:  Oh, one square foot.
                       MR. REYES:  And the assumptions that were
           involved in that, we had -- we assumed a
           one-square-foot break on the main steam line.  It was
           assumed to be inside containment.  And so we used the
           operator or the -- the operator actions that would
           correspond with a break inside containment.  So that
           requires isolating containment.
                       And when you isolate the containment what
           happens is you lose your component cooling water to
           the reactor coolant pumps.  You lose your ceiling, so
           you basically trip your pumps.  And so we followed
           that logic there.
                       So we performed two of these cases, one at
           hot zero power which essentially assumed that the
           plant had been scrammed about -- for a period of about
           100 hours.  And then full power, which assumes that an
           immediate scram going to a decay curve.
                       For the hot zero power case we essentially
           picked the -- we picked the power at 100 -- scaled
           power at 100 hours.  And essentially that power varies
           very, very slowly at that point.  And so for our test
           we just used a constant low power.
                       For the full-power case we went to a decay
                       So we can see the two different scenarios
           there.  For the full-power case, we're looking at
           pressure.  That's in the solid black line there.  The
           red-dash line is the case for the hot zero power.
                       We see that because we're initially at a
           lower power.  We get -- so we wind up at a lower
           pressure.  What brings the pressure back up in this
           scenario -- okay, the main steam break force drives
           the pressure down in the primary side -- what brings
           it back up is just the action of the high-pressure
           injection system.
                       Unlike Palisades in their scenarios where
           they would throttle and just keep bringing pressure
           down, we just let the system run and, given enough
           time, the plant would repressurize.  So this would be
           -- this is a good benchmark case for RELAP Code, to
           try to see if it could match these curves.  So again
           it's more severe than what you would see in the real
                       Now this is for the same test, same pair
           of tests, what we saw for the downcomer temperatures. 
           And this is at the eight-diameter location, 8 cold-leg
           diameter down into the downcomer.
                       And we see that the full power case,
           because we still have core decay heat being generated
           at a fairly substantial rate -- actually not only did
           it repressurize, but it also reheated.
                       For the hot zero power case we stayed
           fairly low in temperature.
                       We also did some of the small break LOCA
           tests.  And so here's the three scenarios that we did. 
           We did a 1.4-inch hot-leg break, a simulation of a
           1.4-inch hot-leg break.
                       Then we did a large break, a two-point --
           a two-inch small break LOCA.
                       And then we also did a stuck-open safety
           relief valve on the pressurizer, which was the
           smallest of the breaks.  And so we can see -- an
           interesting phenomena for the 1.4 inch.  That's the
           solid line that has kind of this jagged behavior.  In
           that case the HPSI pumps are capable, can actually
           keep up with the break flow.
                       And so we see kind of a pressurizing and
           then we fill up the pressurizer volume.  And then we
           would sweep all the liquid out again and repressurize. 
           And so we saw kind of a isolated behavior for that
                       So if your pumps are able to keep up with
           the break-flow rate, you see kind of a
           repressurization in this kind of a jagged behavior.
                       When we went to a larger break, a two-inch
           break, we see the pressure basically just come down
           and it just keeps coming down.
                       MR. SCHROCK:  How do you simulate the SRV
           of the actual plant?  What valve do you have and how
           do you go about qualifying it as a simulation of the
           actual plant valve?
                       MR. REYES:  Right.  Yeah, that's a good
           point.  All we do is we have a flow nozzle which is
           sized to the diameter, a scaled diameter.  And that's
           -- it's well characterized, so we know the loss
           coefficient for that flow nozzle.  So all we can do is
           characterize that.  It's not -- it doesn't represent
           the geometry of the valve throat in the real plant. 
           So that's a good point.
                       MR. SCHROCK:  So you assume that critical
           flow behaves in the same manner as loss coefficients
           for incompressible flow?
                       MR. REYES:  Come again?  You said the
           critical flow?
                       MR. SCHROCK:  Yeah.  It's critical flow
           through the SRV.
                       MR. REYES:  Right, that's correct.
                       MR. SCHROCK:  And that's unrelated to a
           loss coefficient ordinarily.  So --
                       MR. REYES:  Right, right.
                       MR. SCHROCK:  -- when you say you have the
           same loss coefficient, what's the significance of
                       MR. REYES:  In terms of loss -- what we do
           is we characterize the flow nozzle for a range of
           conditions.  So we look at critical-flow conditions,
           but we also look at essentially a subcritical flow.
                       For critical flow, of course we do have a
           -- what this allows us to do at least with a code like
           RELAP is specify what the conditions are at the valve. 
           So we're not giving it a complicated structure at the
           valve to analyze, in essence.
                       So we don't -- to make the long answer
           short, we don't simulate the geometry of the actual
           SRV for Palisades.  But we have -- but we know what
           our geometry is, and we can characterize it.
                       MR. SCHROCK:  But the scaled leak flow is
           somehow demonstrated to be related to the, or the same
           as in the plant for their actual valve?
                       MR. REYES:  The data that we have for
           their valve, they give a -- for a given pressure
           condition in their plant, they give a given steam-flow
           rate, and so we scaled to that.
                       So -- but they only give us that top
           limit, so we know that their maximum -- we're given
           pressure in their plant and what the flow should be
           for that plant, but it's only one value.
                       And then it does behave quite well as a --
           it's very close actually to a perfect gas behavior.
                       For the same three tests the small break
           LOCA is looking at the downcomer temperatures.  Again
           this is somewhere down below the beltline weld.
                       CHAIRMAN WALLIS:  Are you going to show us
           the 4D ones, too?
                       MR. REYES:  The -- oh.
                       CHAIRMAN WALLIS:  Well, you said 8D.  I
           mean this --
                       MR. REYES:  Right.  Right, yeah.
                       CHAIRMAN WALLIS:  You measured the various
           Ds presumably.
                       MR. REYES:  Well, we'll have several
           presentations looking just at the downcomer fluid
           temperatures.  So I picked one in particular just to
           -- as a characteristic like --
                       CHAIRMAN WALLIS:  So we're going to
           revisit that?
                       MR. REYES:  Oh, absolutely.  Absolutely. 
           We'll spend quite a bit of time in the downcomer.
                       The downcomer temperatures for the small
           break LOCA, again looking at which would be -- gave us
           the lowest temperatures.  A two-inch break of course
           because you're depressurizing gave us the lowest
           condition there, followed by the 1.4 inch, and then
           the smaller -- the small -- so we're just following a
           saturation curve there.
                       We did do one combination test, and this
           was kind of interesting.  It was a stuck-open
           pressurizer and the safety relief valve followed
           immediately by a stuck-open or single stuck-open
           atmospheric dump valve on the main steam line.  Okay.
                       So we basically have a break on both sides
           of the plant.  And this is what we saw.  Again initial
           immediate depressurization, and then it gradually
           tapers off, and then it just flattens off at a fairly
           low pressure.
                       In terms of temperature we see somewhat of
           an exponential-type decay which would go with a
           primary side depressurization.  And then a relatively
           linear plot after that or trend after that.
                       The SRV is fairly small compared to the
           other breaks.  They have a fairly small valve size
           that they use for that.
                       MR. SCHROCK:  These are test data and yet
           you get rather sharp changes in the slope of the
           pressure curve.  Not in this graph but in a previous
                       MR. REYES:  In the previous?
                       MR. SCHROCK:  Yeah.
                       MR. REYES:  Right.
                       CHAIRMAN WALLIS:  Presumably something
           happened to that point.
                       MR. REYES:  Right.
                       CHAIRMAN WALLIS:  TMI is low, though. 
           Something happened.  The valve opened or closed, or
           someone did something.  A very sharp change in
                       MR. REYES:  Right.  Yeah.  This test I
           don't recall if we fed the steam generators at some
           point in the test.
                       MR. SCHROCK:  So you've got about three,
           four, five, six of those.
                       MR. REYES:  So we have the -- we have a
           sequence of events for each one of these tests.  We
           have a lot of details we can provide you.  But I want
           to give you kind of the big picture, the big picture
           being that --
                       CHAIRMAN WALLIS:  And you're going to show
           us that RELAP predicted exactly?
                       MR. REYES:  Yeah.  We won't go there yet.
                       And this is one that we did not use to --
           we have not benchmarked our RELAP against this one. 
           This is a prechallenging test.
                       Okay.  So what we saw overall was that the
           fluid temperature's relatively uniform around the
           entire downcomer at about the 8D location, and for
           most tests at the 4D location we saw that.  So we're
           seeing good mixing up in those regions.
                       So plumes appeared to be relatively well
           mixed by the 4D axial location.
                       Test Number 11 resulted in the lowest
           downcomer temperatures while at repressurized
           conditions.  And that was the main steam line break,
           one-square-foot main steam line break at hot zero
                       So that kind of gives you -- of the
           scenarios we performed, that gives you a feel for
           which one was, in essence, in terms of PTS probably
           the most limiting.
                       That doesn't mean that there are other
           pressures that could be of importance, though.  We
           looked at one that repressurized.  Others kind of
           tapered off to a lower pressure.  But in terms of PTS
           I'm not sure what, what the limit is --
                       CHAIRMAN WALLIS:  So these were mixed four
           diameters.  And four cold-leg diameters below the cold
           leg everything is mixed out?
                       MR. REYES:  Right.  So we look at the
           temperatures all --
                       CHAIRMAN WALLIS:  So pretty rapidly.
                       MR. REYES:  -- the way around the
                       CHAIRMAN WALLIS:  It's a pretty
           rapidly-spreading plume, is it not?
                       MR. SCHROCK:  These are diameters of the
                       MR. REYES:  Cold-leg diameters.  Cold-leg.
                       MR. SCHROCK:  Cold-leg diameters.
                       CHAIRMAN WALLIS:  You're never going to
           get eight diameters down.
                       MR. SCHROCK:  My gosh.
                       MR. REYES:  Yeah, yeah.  So -- and when we
           talk about the plume, the characteristics of the
           plume, you will see that the injection flow rates are
           very low in this design.  And so they're fairly --
           they tend to be weak plumes that break up relatively
                       MR. SHACK:  Oh, yeah.  Is that -- I mean
           is that related to the wimpiness of the high-pressure
           injection system?
                       MR. REYES:  Correct.  Yeah.  And then
           we'll look at some other conditions where you're able
           to preserve the plume a little bit further.
                       MR. SHACK:  A very low flow rate out of
           these safety injection systems, right, relative to
           other systems?
                       MR. BESSETTE:  Especially a CE plant.
                       MR. BAJOREK:  Especially a CE.
                       MR. SCHROCK:  So how does that work out? 
           The circumferential spacing of the cold legs is how
           many Ds?
                       MR. REYES:  The circumferential spacing of
           each -- what are their angles on our plant, John?  Are
           we on 90s?
                       MR. GROOME:  I believe we're 90, but I'm
           not -- I'd have to look to answer the question
                       MR. REYES:  Yeah.
                       CHAIRMAN WALLIS:  It would be good if you
           showed -- maybe you will -- show an unwrapped annulus
           and --
                       MR. REYES:  Right.  Right.  And that --
                       CHAIRMAN WALLIS:  -- an unwrapped
           downcomer with all the pipes and --
                       MR. REYES:  Absolutely.  Right, that'll
           show the configuration.
                       And we'll see that we've used -- well,
           we've used STAR-CD and we've used REMIX to try to
           benchmark those codes to see how well they predict our
           behavior with the hope that maybe they could be
           extended to other, other plant designs and conditions.
                       With that do we have any other questions?
                       MR. SCHROCK:  Well, you've got uniformed
           fluid temperature, but what about the metal
                       MR. REYES:  Right.  We do -- we have a
           region of the vessel which is measuring metal
           temperatures.  And it's an outside wall temperature. 
           And it's mostly in the vicinity of the upper
           downcomer.  And we do see a distribution of
           temperatures there.
                       Now our vessel wall, of course, is very
           thin.  We're a half-inch-thick wall compared to
           Palisades, which has a half-inch of -- or quarter-inch
           of stainless steel with about six-inch of
           carbon-steel-based metal.  So it's a significant
           difference in our wall behavior.
                       So we focused primarily on the fluid,
           fluid temperatures.
                       MR. WACHS:  To answer your question about
           the separation, the peak diameter is that -- it's I
           guess --
                       MR. ROSENTHAL:  You need to speak into the
           mic here.  Identify yourself, too, please.
                       MR. WACHS:  I'm Dan Wachs.  And to answer
           the question about the separation of the cold legs, I
           believe it's about eight diameters between each one. 
           You have about a 25-inch radius.  I guess that's going
           to be 16.  if you just pi times the diameter, divide
           by three-and-a-quarter inches.
                       CHAIRMAN WALLIS:  They're closer together
           than you think, I think.
                       MR. SCHROCK:  Well, what he's saying is
           they're far apart in comparison to what the data show
           produces complete circumferential mixing.  Surprising.
                       CHAIRMAN WALLIS:  It seems very rapid
           mixing to me.
                       MR. SCHROCK:  Yeah, right.  That was why
           I asked.  It seemed very rapid.
                       MR. REYES:  Now we'll look at some cases
           where, in fact, part of it is because the flow rates
           are so low in this plant.  Even on these low-flow
           rates there are some cases where we'll see that loop
           flow, natural circulation loop flow, acts to preserve
           the plume.  And so we'll talk about that a little bit
           later.  That's kind of an interesting effect.
                       CHAIRMAN WALLIS:  So you're keeping all
           that exciting stuff for tomorrow, are you?
                       MR. REYES:  Yes.  That way I'll be sure
           you come back.
                       CHAIRMAN WALLIS:  I have a question.  Is
           this a good time to take a break?
                       MR. REYES:  Sure, I think this is perfect.
                       CHAIRMAN WALLIS:  Then let's do it.  We'll
           take a 15-minute break, and we'll start again at 3:25.
                       (Recess taken from 3:08 p.m. to 3:25 p.m.)
                       MR. LAFI:  Shall I start?
                       CHAIRMAN WALLIS:  Yes, please.
                       MR. LAFI:  My name is Abd Lafi, and I'm an
           Assistant Professor at the Nuclear Engineering
           Department at OSU.
                       My presentation will be focused on
           numerical simulation for APEX-CE main steam line break
           and the small break LOCA tests using RELAP5, Model
           3.2.2, Gamma version.
                       The outline of my research will include
           objectives, input modifications, APEX-CE model
           nodalization, RELAP5 calculation matrix, RELAP5 run
           strategy, and then mention and discuss some
           comparisons between the tests that I analyzed.
                       These tests will include a one-foot-square
           main steam line break from hot zero power.  This is
                       And then the second test is
           one-foot-square main steam line break from full power. 
           This is OSU-CE-12.  And then two-inch hot-leg break,
                       I will end up with some conclusion after
           each of these tests.
                       The objectives of all of these analyses is
           to assess the ability of RELAP5, Model 3.2.2, to
           predict transient overcooling behavior.  Actually, in
           particular, I will focus on the onset of loop
           stagnation during the integral tests under
           considerations; and then I will discuss some finding
           about the general behavior or general trend of
           downcomer fluid temperatures and system pressures.
                       We use our version of the input -- and the
           reason I say "our version," is because the original
           input deck was developed up by our new -- this input
           deck was adopted by Science Tech to analyze some of
           the NRC tests that was conducted at OSU.
                       Now this was input related to the original
           APEX with the new APEX-CE geometry that's required and
           necessitated a lot of changing.
                       Also after I explain the modification
           briefly to the whole input deck, I adapted also some
           modification, according to the operating condition and
           the geometrical configuration of each test.
                       So the first modification was to isolate
           its own APEX, AP600 passive safety system and DVI
           lines.  There were ADS systems, there were CMTs,
           accumulator, IWST, PRHR.  All of these components were
                       And I isolated these components in
           addition to all the input related to these components.
                       Also elimination of all APEX AP600 safety
           system actuation logic.  As you recall, with the APEX
           Test Facility, there was, for example, ADS, which were
           actuated based on the CMT level and sometimes CMT
           level plus time, as the case with ADS-4.  So there
           will be no LOCA CMT, no ADS, too.  So all of these
           logics were eliminated.  This is just one example of
           these logics that we no longer use it.
                       Also with the new configuration we added
           the new seals, and a lot of piping associated with it,
           and also some heat structures, some tables, some --
           also, for example, the loop seal and the changing of
           dropping the pumps down.
                       It was originally connected directly to
           the steam generator on one side and the other side
           directly to the cold leg.  In this configuration we
           dropped it by almost 18.75 inch.
                       So this needed some changes in the pumps. 
           Also the other side was connected to the loop seal.
                       In addition to this we added the
           high-pressure safety injection head curve.  And the
           nodalization diagram that I used.  This shows just the
           primary.  The secondary is not shown in this diagram. 
           As you see, there are loop seals and there are four
           injection systems.
                       RELAP5 calculation matrix, as I mentioned
           in the introduction, we analyzed almost five tests. 
           But I want to present, since the topic was just focus
           on main steam line break and the small break LOCA, I
           will discuss three tests which is two actually for the
           main steam line break and the second one for this hot
           -- of the top of hot leg number one, a break which is
           called APEX-CE-08.
                       I have the result, and I can also offer a
           conclusion of my finding in the other two tests.
                       I adapted the same strategy that was
           adapted by Science Tech.  Actually this strategy
           includes running RELAP, a steady-state case.  And the
           purpose of this run is just to establish the initial
           condition for each test.
                       In these kind of runs, I introduced some
           control volumes and control runs and some
           time-dependent volumes.  The purpose of this is just
           to bring the facility fast to the initial condition of
           each test.  These additions will be dropped later.
                       Then I run usually each test for 1200
           seconds until I see just some stable initial condition
           that fits or close to the real test.  Then I stop. 
           This is 1200.  From experience I found that sufficient
           to reach stable initial condition.
                       Sometimes you reach it within 400, 500. 
           It's just because I introduce what I mentioned just
           before, introduced some time-dependent volume that
           accelerate the calculation.
                       I run another -- after actually the
           steady-state test, I initialize and I zero the time
           just out in the steady-state case to make the 1200
           second is just zero.  So the initial point or the time
           equal to zero will be the initial condition at the
           1200 second.
                       Another -- I didn't mention this, but I
           run another one which is called null transient.  I
           just run the transient for short time, just to see
           whether whatever I adapted in the control of the
           steady state, the time different in that I added, does
           not affect the transient case.  So to see whether the
           transient case will hold.  And that's why we call it
           null transient.
                       The real transient comes after, which is
           called restart run, sometimes runs, not run, because
           sometimes -- actually all the time I monitor the kill
           the condition.  If I see some abnormal condition, I
           stop RELAP, look to the problem, fixing it, and then
           I run restart run to continue.
                       The first test is called RELAP5
           calculation for all OSU-CE-011.  And some brief
           description of this test.  It was simulated,
           one-foot-square main steam line break conducted at a
           constant power.
                       Steam generator number one, the
           power-operated relief valve was open to simulate the
           main steam line break.  And then upon the initiation
           of the break, the reactor coolant pumps were tripped
           and the power brought from 100 kilowatt to the 54.8
                       The pressurized heaters were allowed to
           cycle on and off based on the pressure of the
           collapsed liquid -- pressurizer liquid level.  In this
           test we turned it off when -- the test turned it off
           when the pressurizer liquid level reached 16.  And
           then it turned on when the pressurizer collapsed
           liquid level reached 26-inch.
                       The auxiliary feed water was maintained
           for the broken steam line for 10 minutes, and it was
           isolated from the intact steam generator.
                       This is a brief description of the test. 
           And the sequence of events will be discussed along
           with the RELAP sequence of events when I come to the
                       The steady state.  As I said, each test I
           run steady-state analysis to initialize the input deck
           to start with the correct initial condition that match
           the real test.
                       The code was run for 1200 second,
           time-dependent for volumes and some controls that were
           added, as I said.
                       I run it for 1200 second and the results,
           the calculated versus much of initial condition, as
           you see it, is almost similar exactly.  The power 100
           kilowatt.  Pressurizer pressure 370 for both.  The
           hot-leg temperature almost the same.  The cold-leg
           temperature.  The steam generator 1 and 2, 272 psig,
           which is the case with the calculation.
                       Pressurizer level, steam generator water
           level, and the steam generator feed water temperature,
           the steam generator feed water mass flow rate, all of
           these almost even.  The cold-leg natural circulation
           flow is almost comparable.  There is an -- I put 15.3. 
           As I recall the test, it was 15.29.
                       So this is the transient case comparison
           between the pressurizer pressure.  The red line is the
           test.  The dotted line is the RELAP calculation.  It
           shows the comparison.  The general trend is
           acceptable, except faster depressurization with the
           RELAP calculation.  I would connect this, the impact
           of this on other calculated parameters.
                       The general trend of the broken steam
           generator was almost an accurate agreement.  This is
           the pressurizer level.  And the high pressure
           injection system is almost for the first part.
                       (Comments off the record re pointer.)
                       MR. LAFI:  This chart comprises all the
           four high-pressure injection system flow rate RELAP
           calculation.  As you see before this point is almost
           comparable except with this, because here the
           high-pressure injection system comes into play when
           the pressure reach 360 psig.
                       That's why I initiated almost at 160
           seconds at the beginning, but when it reach the 360 it
           initiated when it drop below 360.  When it reached
           360, the high-pressure injection system flow rate will
           be zero.
                       So the reason for this discrepancy is due
           to the pressure prediction with RELAP reach the 360
           later, different from the real test.  But the general
           behavior is acceptable.
                       CHAIRMAN WALLIS:  I would think the
           integral under the curves has to be the same because
           this is -- maybe not.
                       MR. LAFI:  What?  What is it?
                       CHAIRMAN WALLIS:  No, it's not.  No, it's
           not.  Okay, that's all right.  Forget that question.
                       MR. SHACK:  The pressure's not the same.
                       CHAIRMAN WALLIS:  No.
                       MR. LAFI:  Shall I continue?
                       CHAIRMAN WALLIS:  So we conclude that the
           comparison is pretty good?  Is that what you conclude?
                       MR. LAFI:  I think so, yeah.  The
           comparison between -- this is -- because the
           high-pressure injection system is pressure system
           dependent.  Okay
                       There is impact in this area on the end of
           the temperature, for example, but for the most part
           it's acceptable.
                       The break flow rate, the general one, is
           -- looks acceptable.  The maximum flow rate comes
           immediately after you initiate the break.  And then in
           the test it seems to reach a cutoff area, which is
           corresponding to almost 120 cubic feet per minute,
           while in the test and the RELAP prediction it's almost
           150.  This cutoff, it sounds, the test they used
           vortex flow meter.  And this is -- reach zero and
                       I don't know whether the RELAP adapted
           some cutoff in this area or not, but it sounds similar
           behavior.  It reaches a certain point and then at a
           drop zero.  I will make sure about whether there is
           anything adapted.
                       MR. SCHROCK:  Well, the difference is
           quite large at certain times.
                       MR. LAFI:  The difference in the --
                       MR. SCHROCK:  And one has to wonder, is
           there an error in the stagnation state that's causing
                       MR. LAFI:  Actually I will mention the
           stagnation first, but it sounds to me the opposite. 
           The stagnation is affected by whatever discrepancy I
           saw earlier.
                       So if -- because here, if you look to
           this, -- by the way, the stagnation or the onset of
           stagnation happened in the main steam line break -- in
           this test happened in cold leg 2 and 4.
                       The stagnation didn't occur in cold leg 1
           and 3, which are both in the same side of the plant. 
           And the reason for this, I tried to find some cause in
           the calculation.  I plot the hot leg number 1 against
           the steam generator number 1, the cold side of the
           steam generator against the hot leg, which is the hot
           leg side of the steam generator.
                       If you look to the hot leg, the steam
           generator number 1, the test data, the red color, all
           the time it's below this hot leg number 1.  That means
           still there is natural flow from the primary to the
           secondary.  In other words, still the steam generator
           is acting as a sink to the primary.
                       This is the same situation, even little
           bit different.  If you look to the hot-leg temperature
           prediction for RELAP, this one, this scale, against
           the steam generator RELAP, number 1 RELAP calculation,
           all the time also -- even the difference is not as
           significant as in the real test -- all the time you
           see the hot-leg temperature is higher than the steam
           generator temperature.
                       This is -- it makes sense that I can
           conclude that because of not having the stagnation in
           cold leg 1 and 3 -- by the way, this is just a plot
           for hot leg 1 against steam generator 1, just to
           represent the behavior of cold leg 1 and cold leg 3
           corresponding to the steam generator number 1.
                       This make me convinced that the reason for
           this not having a stagnation, still I have a flow from
           the primary to the secondary.  If I go to the hot leg
           number 2 against the steam generator number 2, just to
           find a reason why we had stagnation in cold leg 2 and
           4, if you look to this, whether RELAP or whether the
           test, you see the steam generator 2, the first part
           here is almost -- at almost 100 or 200 second you see
           the hot-leg temperature is higher than the steam
           generator temperature.
                       After that you will see the steam
           generator, whether the test or the steam generator in
           the RELAP calculation, you see is higher than the
           temperature of the hot leg number 2.
                       This make me feel that now at this moment
           the steam generator is acting as a heat source to the
           primary.  That's why it develop some potential to
           reverse the flow.  That's why we conclude that the
           stagnation is due to this situation.
                       And if you go to the plot of the flow rate
           for the cold leg number 2, you see the stagnation
           happened almost at 500 second or so.  It's actually
           subjective.  For the test maybe you can consider it at
           this point, while for RELAP you can consider it later.
                       But the general behavior and the
           stagnation occurred really in the RELAP calculation. 
           So RELAP predicted the stagnation like what happened
           in the real test.
                       This is cold leg number 2.  I said
           stagnation happened 2 and 4 -- and also on 4.  This is
           the test against the experimental data.
                       CHAIRMAN WALLIS:  The stagnation means no
           flow rate; is that right?
                       MR. LAFI:  Yes.  The stagnation --
                       CHAIRMAN WALLIS:  So the red is never
           really zero unless there's an error in the plot.  It
           jiggles around as a negative and it crosses -- I guess
           it crosses very, very briefly there.  Does that --
                       MR. LAFI:  Yeah.  We --
                       CHAIRMAN WALLIS:  Is that stagnation 4
           long enough to really make any difference?
                       MR. LAFI:  I consider -- I don't know.  I
           consulted the experimental team.  They think that the
           stagnation or when the flow meter read like negative
           value, that means is it reverse or...
                       MR. REYES:  The flow meters that we have
           now installed, the electronics do allow us to
           calculate or measure reverse flow.
                       CHAIRMAN WALLIS:  Yes.
                       MR. REYES:  -- reverse flow.  Whenever it
           says --
                       CHAIRMAN WALLIS:  You're worried about
           stagnation because it leads to the maximum or the
           minimum temperature of the cold fluid going into the
           vessel; is that --
                       MR. REYES:  That was the -- the original
           assumption was that --
                       CHAIRMAN WALLIS:  That was the idea.
                       MR. REYES:  -- was that if you stagnate
           the cold legs you get stronger plumes in the
                       We're going to show tomorrow a little bit
           of -- that's not always true.
                       CHAIRMAN WALLIS:  So there's nothing
           really magic about stagnation.  It's not necessarily
           the worst case.
                       MR. REYES:  Correct, not for this plant.
                       CHAIRMAN WALLIS:  It looks as though
           there's quite a difference here.  That in the test the
           flow is getting very low.  This RELAP is giving these
           other bursts of flow in the two directions.
                       MR. LAFI:  Yeah.  It's isolated.  But if
           you compare it to this, for example, --
                       MR. REYES:  Excuse --
                       MR. LAFI:  You can't compare the previous
           one to this one.  I say there is no stagnation in cold
           leg 1 or cold leg 3.  This is true; there is no
           stagnation.  While in this...
                       MR. SCHROCK:  That spike is the test data.
                       MR. ROSENTHAL:  What's the accuracy in
           your flow meter?  Are we just looking -- should we be
           painting this with a paint brush, with a...  You're
           talking about being off by two, three gpm.
                       MR. LAFI:  Yeah, but I think if you take
           the average -- this is my thinking -- that RELAP
           calculation isolated actually from positive to
                       CHAIRMAN WALLIS:  Well, should we care
           about it?
                       MR. LAFI:  At least the stagnation
           occurred, but at different time.  Even if you consider
           the stagnation here, but I think -- but this will
           contradict the temperature against -- the hot-leg
           temperature and steam generator temperature will plot.
                       So that's why I thought the mechanism
           behind the stagnation is whenever the steam generator
           -- actually not exactly, because even in the test the
           stagnation occurred not at exactly when this steam
           generator exceeded the hot-leg temperature, that there
           is some time in order to develop some potential to
           reverse the flow.
                       That's why actually almost when the
           temperature in RELAP, the temperature difference
           between the steam generator and the hot leg reach
           almost 80 degree, then the stagnation occurred.  This
           is what I saw even in the test, almost there is a
           60-degree difference then the stagnation occurred.
                       MR. ROSENTHAL:  Can you flip back to slide
           20; would you mind, 20, if you -- that's good.  So you
           see if you go out about 1800 seconds you will see that
           steam generator 2 RELAP versus --
                       MR. LAFI:  This is --
                       MR. ROSENTHAL:  That's good.
                       MR. LAFI:  This one?
                       MR. ROSENTHAL:  Yes, please.
                       -- about 1800 seconds --
                       MR. LAFI:  Yes.
                       MR. ROSENTHAL:  -- is a difference of like
           100F.  So that's --
                       MR. LAFI:  The difference --
                       MR. ROSENTHAL:  Okay.  Now -- I'm sorry.
                       MR. LAFI:  You say that --
                       MR. ROSENTHAL:  No, between the blue --
                       MR. LAFI:  Yes.
                       MR. ROSENTHAL:  -- and the top --
                       MR. LAFI:  And the top.
                       MR. ROSENTHAL:  -- is about 100F.
                       MR. LAFI:  Yeah.  This is the difference
           between the RELAP -- that's why there is discrepancy
           between the RELAP prediction of the steam generator
           temperature in both calculation and the test.
                       But there is in both, the test and the
           RELAP prediction, the case occurred when the steam
           generator temperature exceeded the hot-leg
                       There is difference between RELAP
           prediction for the steam generator temperature and the
           test.  But this does not mean that there is a case
           when the -- this difference, whatever happened, for
           example, in real test, when the temperature difference
           exceeds 60 or 63 degree or almost -- I think 63 degree
           the stagnation in the test occurred.
                       A RELAP calculation, and this is almost
           here, when at 500 something, between 420 and -- almost
           80 degree between the steam generator and the hot leg. 
           So this is where I saw stagnation, or at least I
           considered the stagnation.
                       But if you talk about the discrepancy
           between the RELAP prediction for the steam generator
           temperature, I say there is a discrepancy.
                       Again I'm talking about -- I'm looking for
           the cause of stagnation.
                       And if you look to this, also the steam
           generator -- RELAP prediction for the steam generator,
           not as good as the test, but all the time during the
           test the steam generator temperature did not exceed
           the hot-leg temperature.  That's why we couldn't get
           stagnation in both the test and the calculation.
                       CHAIRMAN WALLIS:  So we can go on now?
                       MR. LAFI:  Yeah.  This is just the
           stagnation, and this is another stagnation in cold leg
           1 and cold leg number 3.  And actually this is
           supported by the fact that the steam generator during
           the stagnation was full.  And this is the plot of the
           liquid volume fraction --
                       CHAIRMAN WALLIS:  It's always liquid. 
           It's full of liquid; is that right?
                       MR. LAFI:  Full of liquid, yes.
                       CHAIRMAN WALLIS:  Or is it full of vapor? 
           Which is which?
                       MR. LAFI:  No.  This is liquid volume
                       CHAIRMAN WALLIS:  Liquid?
                       MR. LAFI:  Yes.
                       CHAIRMAN WALLIS:  Okay.
                       MR. LAFI:  In RELAP they call it voidf.
                       The portion regarding the downcomer
           temperature prediction by RELAP.  I saw within 2,000
           second RELAP prediction for the downcomer temperature
           is in good agreement with the test.
                       And also I didn't notice this is the case
           at 8 diameter in the downcomer and the same position
           in RELAP.  I plot different spot at 1.3 diameter; 2
           diameter; 3, 4, 5 diameter; 'til 8 diameter.  And I
           saw the temperature profile.  There is no significant
           -- or actually there is no stagnation -- no
                       This is the cold leg number 1, and the
           same case with cold leg number 2.
                       As conclusions, the trend of the
           pressurizer pressure is similar for the OSU-11 test
           and RELAP5 prediction, although the depressurization
           RELAP5 calculation was faster.  This is what was
           indicated in the first figure that I showed you.
                       RELAP5 successfully predicted the general
           trend of the broken steam generator, starting with the
           maximum flow rate, gradually decreasing to the cutoff
           area, similar to what we notice in the test.
                       The steam generator pressure, the broken
           one, was almost in a very good agreement.  The flow
           rate through the cold legs, the main steam line break,
           the high-pressure injection system, and the downcomer
           temperature almost in good agreement.
                       RELAP successfully predicted the
           stagnation.  Noted the same exact point.  If we have,
           for example, the pressurizer pressure here for exactly
           and the injection system, which we say is
           system-pressure dependent, then we will have
           everything exact, but this is the problem with the
           RELAP prediction.
                       CHAIRMAN WALLIS:  How big is the cold --
           is the injection nozzle?
                       MR. LAFI:  The injection nozzle?  The
           high-pressure injection nozzle?
                       MR. REYES:  I think it's about 1.3 inches.
                       CHAIRMAN WALLIS:  How big?
                       MR. REYES:  About 1.3.
                       CHAIRMAN WALLIS:  It's this size hole?
                       MR. LAFI:  Yeah, it is.
                       CHAIRMAN WALLIS:  It's dribbling in at .1
           gpm.  It's hardly got any velocity at all.  This is 
           scaled from a real plant?
                       MR. REYES:  So the maximum flow rate, it
           goes from about 1.1 gallons per minute per cold leg to
                       CHAIRMAN WALLIS:  What?
                       MR. REYES:  The maximum is 1.1.
                       MR. BESSETTE:  It comes in at a low
           velocity in the plant.  It's about a -- something like
           a foot a second in the plant.
                       CHAIRMAN WALLIS:  The figure we have here
           is -- yeah.  It's one foot a second in the plant?
                       MR. BESSETTE:  Something like that, yeah.
                       CHAIRMAN WALLIS:  I thought it came in
           gangbusters, hundreds of feet a second.  It came
           really in.  I mean it's got several hundred PSI
           driving it, isn't it, or is this not?
                       MR. BESSETTE:  You see, it comes in at a
           fairly large -- it comes in -- in the plant it comes
           in at about a seven-inch pipe.
                       CHAIRMAN WALLIS:  Well, this must be a
           very different plant from the kind we used to -- we
           did -- you know, Creare did experiments with cold-leg
           injection and stuff trying to simulate fast.  I think
           we had a fairly small scale, but the water still came
           pouring in through that injection nozzle at a pretty
           high velocity.
                       MR. BESSETTE:  It will.  In the B&W Plant
           it comes in at about 20 feet a second or so.
                       MR. REYES:  Right.
                       CHAIRMAN WALLIS:  So it's a completely
           different beast?
                       MR. REYES:  Right.
                       CHAIRMAN WALLIS:  Okay.  All right.
                       MR. LAFI:  The hot leg number 2 and the
           steam generator number 2 temperature histories
           indicate that the steam generator became a heat source
           at almost 180 second into the test in both the test
           and calculation.
                       Loop flow continued for another 320 until
           we reached the thermal potential, enough to reverse
           the flow.  So the difference at that time it was in
           the RELAP calculation 80 degrees between the hot leg
           and the steam generator.  And then the primary loop
           stagnation occurred.
                       Hot leg number 1, steam generator number
           1 histories indicate that all the time hot leg number
           1 exceed the temperature of steam generator number 1. 
           And this varies in -- there was no stagnation.
                       It can be concluded that the action of
           steam generator number 2 as a heat source was the
           cause of stagnation in cold leg 2 and 4, given that
           the steam generator was full as indicated by liquid
           volume fraction, the one that I showed you.
                       By comparing the steam flow rate out of
           the break we can find the following:  That the maximum
           is almost -- happened exactly at the time when you --
           when we initiated the break.
                       The flow experienced some sharp drop at
           120 cubic foot a minute for the test, while for the
           calculation it was 150.
                       There was similar gradual decrease in
           between.  Further assessment for the parameters
           controlling the break flow in RELAP5 is being
           conducted because there are some parameters that
           affect the flow out of the break.
                       CHAIRMAN WALLIS:  This is just a steam
           flow, is it?  It's not a two-phase flow?
                       MR. LAFI:  This is the steam flow.
                       CHAIRMAN WALLIS:  So you would expect to
           be able to predict it quite well?
                       MR. LAFI:  Actually I am trying to play
           with the -- because here there is some parameters --
           this is what I expect for --
                       CHAIRMAN WALLIS:  I'm sorry to -- when you
           say "cfm," that means that's some condition?  I mean
           it's not a mass -- usually it's a mass flow rate that
           you want.
                       MR. LAFI:  This is part of --
                       CHAIRMAN WALLIS:  Because I don't know
           what the condition is and we're valuating the cfm at. 
           I guess you can do cfm.  Was it standard cubic feet
           per minute, or something, or is it...  What is it,
           velocity times area; without --
                       MR. LAFI:  This is volume --
                       CHAIRMAN WALLIS:  -- any reference to
                       MR. LAFI:  -- actually cubic foot per
           minute, right?
                       CHAIRMAN WALLIS:  So it's volumetric load.
                       MR. LAFI:  Is it 120, it was.
                       MR. SHACK:  But is it reduced to a
           standard condition, or is it just v times a?
                       CHAIRMAN WALLIS:  Velocity times area?  It
           must be.
                       (Comments off the record.)
                       MR. LAFI:  Converted to mass flow rate?
                       MR. REYES:  The flow meter rate, I
           believe, is the standard.
                       CHAIRMAN WALLIS:  It's just velocity times
                       MR. REYES:  The vortex.  That's it.
                       MR. LAFI:  Is the vortex flow meter --
                       MR. REYES:  So the vortex flow meter is
                       CHAIRMAN WALLIS:  It's kind of strange,
           because I mean if you were dropping the pressure and
           you can get sort of the same velocity, but a lot less
           mass flow rate -- no.  Maybe you can -- that's going
           to be all clear when we read the report?
                       MR. LAFI:  That test is 12, which is
           similar to 11.
                       CHAIRMAN WALLIS:  I think the ACRS has a
           preference for never using cfm or gallons per minute
           as a unit-to-flow rate, because different gallons and
           different pressures and temperatures.  If you use
           mass, then it's clearer what you -- what's going on.
                       MR. SHACK:  Sometimes gallons are nice,
                       CHAIRMAN WALLIS:  Well, gallons of cold
           injection are quite different from gallons of hot
           ejection in terms of mass flow.
                       MR. SCHROCK:  In your detailed comparisons
           you have some poor results for hot leg -- or for steam
           generator number 2 temperature.  And then you have
           some poor results for the collapsed liquid level
           beyond 2,000 seconds.  But those poor predictions
           don't seem to be reflected in your summary
                       MR. LAFI:  Actually the poor prediction
           for the pressurized level actually -- in the first
           portion it was good comparison, while in the -- almost
           1, 3, 16-inch in the test, that was -- after it
           reached the 26-inch the pressurizer heater turned on
           for --
                       MR. SCHROCK:  It what?
                       MR. LAFI:  In the real test, when the
           pressurizer level reached 26 amps, the heater -- the
           pressurizer heater turned on.
                       For RELAP this 26-inch -- and I can show
                       MR. SCHROCK:  I don't understand what the
           heater on or off has to do with the level.
                       MR. LAFI:  So you're asking me about the
           poor prediction of RELAP for the pressurizer level?
                       MR. SCHROCK:  Yeah.  I just looked at your
           comparisons of test data against predictions, and I
           see it made poor predictions of collapsed liquid level
           beyond about actually 1500 seconds.  And it made poor
           predictions of the steam generator number 2
                       But, as I listened to your summary
           descriptions, it seemed as though those rather poor
           predictions are not reflected in your summary.
                       MR. LAFI:  I -- my --
                       MR. SCHROCK:  Are they regarded as
           insignificant, or what's the -- what should be --
                       MR. LAFI:  Actually --
                       MR. SCHROCK:  -- interpreted from that?
                       MR. LAFI:  -- I expect, my conclusion that
           the general run of RELAP predictions and, of course,
           all acceptable agreement with the first.
                       Consequently, I don't expect from RELAP to
           match exactly what happened in the test.
                       MR. SCHROCK:  Well, the difference in
           pressurizer level of 70 and less than 50 is a
           significant amount of water.
                       MR. LAFI:  Yeah.
                       MR. SCHROCK:  And so I would think that
           would have some -- if I didn't know anything else
           about the test, I'd suspect that there's something in
           the calculation that needs to be made better in order
           to get reliable predictions from that code.
                       CHAIRMAN WALLIS:  Well, that's the problem
           with all of these comparisons.  We don't have a
           criterion for saying what's good enough, and what you
           have to do, and how you're actually measuring the
           goodness of RELAP with all these various wiggles, and
           squiggles, and lines, and curves, and things.  I mean
                       MR. SCHROCK:  Yeah.  But I keep --
                       CHAIRMAN WALLIS:  -- that's the always the
                       MR. SCHROCK:  -- noticing these things and
           I mention them when I notice them.
                       CHAIRMAN WALLIS:  Yeah.  Well, I think you
           really ought to -- really the NRC should start off
           with some kind of an intellectual roadmap which says
           how do we make these comparisons, what are we looking
           for, and --
                       MR. BESSETTE:  The thing about pressurizer
           level, and it may -- it may be due to this difference
           in the HPI flow between the -- see, pressurizer level
           in this case is an effect of something else.  So this
                       CHAIRMAN WALLIS:  The extra water has to
           go somewhere.
                       MR. BESSETTE:  Yeah.
                       CHAIRMAN WALLIS:  So that's a good, simple
                       MR. BESSETTE:  So it looks like it goes
           back to this difference in the HPI calculations.
                       CHAIRMAN WALLIS:  Because this is the only
           -- pressurizer is the only place which can accommodate
           extra water.
                       MR. BESSETTE:  Yeah, right.
                       CHAIRMAN WALLIS:  The rest of it's solid.
                       MR. ROSENTHAL:  And let me point out that
           50 percent versus 70 percent of the pressurizer volume
           is a much -- it looks like a lot, but the pressurizer
           is, what, 10 percent or something of the total system
           volume, so it really isn't that big of a deviation.
                       MR. BESSETTE:  So I mean it's got to
           relate back to a difference in --
                       CHAIRMAN WALLIS:  I think we have
           something similar with the next one, too.  We have a
           similar difference with the pressurizer level and come
           back to that.
                       MR. BESSETTE:  It can only be due to a
           difference in the RELAP calculation of the injection
           or the system temperature.
                       CHAIRMAN WALLIS:  As long as RELAP is
           conserving mass.
                       CHAIRMAN WALLIS:  Maybe it's conserving
           gallons of something.  We're in trouble.
                       MR. BESSETTE:  There you go.  Conserving.
                       CHAIRMAN WALLIS:  Okay.  We should go on,
           I think.
                       MR. LAFI:  The next test is CE-12, which
           is similar to one-foot-square main steam line break
           initiated from 610 kilowatt from full power.
                       Steam generator number 2 power-operated 
           relief valve was open to simulate the break.  And then
           upon initiation the break, the same thing, the reactor
           coolant pumps were tripped.  The power and state of
           test 11, it was kept constant at low pressure -- lower
           power.  Here it converted or switched to a decay mode. 
           And this decay was included in the input.
                       The pressurizer heater were tripped upon
           the collapsed liquid level of the pressurizer, were
           turned off -- switched between on and off.  Again 16
           under 26.
                       The auxiliary feed water was maintained
           for the broken steam generator, which is the case of
           11, for 10 minutes.  And it was isolated from the
           intact one.  And this is the sequence of events of the
           real test.  And again the RELAP Code was run for
           steady -- was run for steady-state for 1200 second. 
           And we established the initial condition, which was
           almost similar to the initial condition of the real
                       The mass, the auxiliary -- the feed water
           mass flow rate is higher in this case.  And this is
           almost -- the pressure is different.  In the previous
           test it was 272, this one 232.  Almost -- the other
           parameter is close to each other, so this make me
           satisfied that I will start my transient case.
                       So the comparison, also the behavior of
           the pressurizer pressure not exactly but similar to
           what I saw before, the depressurization rate and RELAP
           prediction is faster, especially in this area.
                       And the steam generator pressure of the
           broken one, RELAP prediction just in good agreement
           trend-wise with the test.
                       This is the pressurizer level.
                       CHAIRMAN WALLIS:  So you got the same
           problem as with the previous one?
                       MR. LAFI:  The same thing.
                       CHAIRMAN WALLIS:  Except the HPI
           prediction is okay.  Look at that one after this.  It
           looks as if you're predicting the injection rate
           right.  Where is the water coming from or going to?
           Maybe it's a question of getting the temperature
                       MR. LAFI:  Can I -- could I just one...
                       CHAIRMAN WALLIS:  You're not -- you're not
           losing water, are you, from this?
                       MR. LAFI:  Actually I'm not losing water
           in this test.
                       MR. ROSENTHAL:  Well, then something's
                       CHAIRMAN WALLIS:  Something's hotter. 
           This is the steam -- the water is more -- expanded
           more somewhere.
                       MR. ROSENTHAL:  Someplace.
                       CHAIRMAN WALLIS:  Yes.  Okay.
                       Well, maybe we should move along.  But I'm
           not sure we learned -- what did we learn from that?
                       MR. LAFI:  This is --
                       CHAIRMAN WALLIS:  What are you testing,
           that RELAP conserves mass, or something?
                       MR. LAFI:  The high-pressure injection
           system RELAP predicted well, compared to the test
                       CHAIRMAN WALLIS:  Presumably, unless
           there's one of these traces which is invisible.  I
           mean there are eight traces, and I can't see eight. 
           I assume they're all on top of each other.
                       MR. LAFI:  Yes.  This is the RELAP
           prediction, the solid line.  This one.  You cannot
           recognize, but this is RELAP.
                       The stagnation occurred in this test in
           cold leg 1 and 3.  In the previous test it occurred in
           2 and 4.  Now 2 and 4, no stagnation.  This is 4, no
                       And 1 and 3, you will see some kind of a
           stagnation and resumption of the flow in both test and
           RELAP prediction.  So RELAP in this situation, this
           case, it predicted what we saw in the test,
           stagnation, and then followed by resumption of the
                       And when I tried to look for the reason,
           it sounds the same reason, the same mechanism, when
           the steam generator becomes a heat source, you would
           have stagnation.  When it goes back to the normal
           situation, the flow will be resumed or will resume.
                       This is similar to what I saw in cold leg
           3, stagnation and resumption of the flow in both tests
           and a RELAP prediction, although at different times. 
           And this is the reason again.  This is supported by
           the plot of hot leg number 1 against steam generator
           number 1.
                       You will see that the steam generator
           number 1 for the test.  And this is the hot leg number
           1 -- what is it -- for the test.  This one.
                       So when the steam generator higher in
           temperature than the hot leg, then you will have the
           stagnation.  Whenever you have the hot leg exceed the
           steam generator temperature, then the flow will
           resume.  This has happened in this point and this
           point with RELAP prediction.
                       So at this point the hot leg temperature,
           also predicted by RELAP, exceeded the steam generator
           temperature.  That's why the flow was resumed.
                       And these spots is corresponding to the
           time of occurrence of stagnation and resumption that
           I showed you.
                       Even, again, the steam generator
           temperature is not exact between RELAP prediction and
           test, but all the time this condition hold.  You have
           heat sink, steam generator as a heat sink.  You would
           have stagnation.  When it comes back it will go to the
           normal flow.
                       For steam, for not having stagnation in
           hot leg number 2 and number 4, this is the reason that
           hot leg temperature all the time exceed the steam
           generator temperature.
                       Again, again, the temperature of the steam
           generator not as exact -- as exact or similar to the
                       This is supported also by being in the
           steam generator at that time.  When the stagnation
           occurred it was full.  There is no voiding.
                       The temperature profile for the downcomer. 
           This is at eight diameter.  And it match the test to
           this portion exactly, while after that it match the
           trend of the temperature profile.
                       This has happened also with the cold leg,
           because here at RELAP the downcomer was divided into
           sectors, so each -- when I say cold leg 2 downcomer it
           is corresponding to the sector that is in the cold leg
           number 2 side.  So this is the temperature profile in
           the downcomer corresponding to the cold leg number 2.
                       And again I tried all of the cold legs,
           and it seems the cold -- the downcomer temperature is
           well mixed and there is no stratification.
                       I plot some data at 4 and at 6 and at 8. 
           There was no stratification.  But when I plot the
           downcomer temperature, even it does not show, there is
           some almost 20-degree or maybe 30- --
                       CHAIRMAN WALLIS:  It seems to me the
           conclusions from this experiment are much like the
           conclusions you drew from the previous experiment.
                       MR. LAFI:  Exactly.
                       CHAIRMAN WALLIS:  So maybe we don't need
                       MR. LAFI:  Except -- except the
           resumption, and actually --
                       CHAIRMAN WALLIS:  So maybe we don't need
           to read through all the conclusions.
                       MR. LAFI:  Okay.
                       CHAIRMAN WALLIS:  Is there something new
           in the conclusions?
                       MR. LAFI:  I think there's no significant
                       CHAIRMAN WALLIS:  It's very similar to the
           last conclusion.
                       MR. LAFI:  The only -- what?  The only
           difference is I think the resumption of the normal
           flow.  This is what happened in this test.
                       Now the last test is the OSU-CE-08, which
           is a break.  That is located at the top of the hot leg
           number 1, which is two-inch break.
                       Again this test, not all the reactor
           coolant pumps were tripped at the same time.  Two of
           them, called pump 1 and 4, were tripped.  And then the
           second and fifth were tripped based on subcooling.
                       The pressurizer heater also allowed to
           cycle on and off based on the pressurizer low level.
                       The sequence of events for this test will
           be explained in the comparison.
                       A steady-state test was run like before
           for 1200 seconds.
                       CHAIRMAN WALLIS:  You've got flow rate
           stagnating all of the cold legs --
                       MR. LAFI:  Yes.  Yes.
                       CHAIRMAN WALLIS:  -- at the same time?
                       MR. LAFI:  No.  At different times.
                       CHAIRMAN WALLIS:  But they -- you don't
           have it stopping.  Does it -- so I guess that, in your
           sequence of events, cold leg 1 stops.  There seems to
           be a long period when there's no flow in any of the
           cold legs, right?  You take away that thing, will you? 
           That thing between 1841 and --
                       MR. LAFI:  This is not RELAP prediction,
           by the way.
                       CHAIRMAN WALLIS:  It seems to me between
           4723 and 5326, we have no flow in any of the cold
           legs, because none of them are restarted yet; is that
                       MR. LAFI:  For the real test, tell --
                       CHAIRMAN WALLIS:  They all stagnated at
           the same -- they're still all stagnated -- at 4723
           they are all stagnated?
                       MR. LAFI:  From 1841 until 4,723.
                       CHAIRMAN WALLIS:  They are all stagnated?
                       MR. LAFI:  Yes.
                       CHAIRMAN WALLIS:  So there's -- what's
           cooling the core, just the HPSI dribbling in?  The
           HPSI's over, too, isn't it then?
                       MR. LAFI:  Let's see, HPSI at that time --
                       CHAIRMAN WALLIS:  It's finished.
                       MR. LAFI:  -- if it is injecting.
                       CHAIRMAN WALLIS:  So there's nothing
           happening.  It's just sitting there.  Where's the heat
           going?  It's going out the break?  It's just boiling
           it?  Is the pot boiling it out the break and there's
           no circulation through anywhere?
                       MR. BESSETTE:  That's right.  The break is
           big enough to take out the decay heat.
                       CHAIRMAN WALLIS:  Okay.
                       MR. BESSETTE:  And the HPSI is on the
           whole time.
                       CHAIRMAN WALLIS:  HPSI's on the whole
                       MR. BESSETTE:  Yeah.  Or starting at 40
           seconds earlier.
                       CHAIRMAN WALLIS:  So you don't want to
           close the break and repressurize.
                       MR. LAFI:  HPSI all the time except if it
           reach above the 360 psig there's no HPSI.
                       MR. BESSETTE:  If you did close the break,
           at some point those generators would become active
                       MR. SCHROCK:  Well, why have they got all
           these ADS things?
                       MR. LAFI:  They're calculated versus
           measured initial condition, as shown in this table. 
           The pressurizer pressure behavior trend was predicted
           by RELAP but, as you see, there is some -- at the
           first portion it was acceptable.
                       Here it reach a certain plateau for both
           of them, the test, and the RELAP prediction.  And then
           it goes -- it decrease in both tests and RELAP
                       CHAIRMAN WALLIS:  Well, now the pressure
           in the system is determined by the heat generation
           rate and the flowing out the break, isn't it?  And the
           pressure it takes to drive that flow right out the
           break to carry out the heat essentially.
                       MR. LAFI:  So that's --
                       CHAIRMAN WALLIS:  You've have a certain
           amount of heat making a certain amount of steam and it
           has to go out the break, so the pressure is big enough
           to get that right out the break.  I'm saying that it
           looks simple enough.  You ought to be able to predict
           the pressure pretty well.
                       MR. LAFI:  Actually even this -- this will
           reflect, this discrepancy between RELAP prediction and
           the test will reflect on the flow rate of the break. 
           You will see big difference --
                       CHAIRMAN WALLIS:  Yeah, that's right.  You
           ought to be able to predict that pretty well, or is it
                       MR. LAFI:  No, it's not very well.
                       CHAIRMAN WALLIS:  Is it because you can't
           predict the liquid carry over out the break just like
           what we talked about this morning, or what is it
           that's difficult about the break flow?  It's a
           two-phase flow out the break?  It's a two-phase flow.
                       MR. LAFI:  It should be two-phase.
                       CHAIRMAN WALLIS:  So the difficulty is
           because you can't predict the two-phase flow very well
           out the break, but you have these deviations here?
                       MR. LAFI:  Actually what I know, that
           maybe the critical flow model at the break, this led
           to this problem because, as I understand, Henry
           Foskey's particular model is adapted by this version
           of RELAP.  This is -- so I am thinking to look for
           that parameter that control, for example, the
           discharged coefficient or...
                       I will show you the break flow later.
                       This is actually the feed water flow. 
           This is just -- I used whatever the test used.  And
           this is the feed water mass flow rate RELAP and the
           test.  And the injection, since the pressure is
           different, the injection now funnels because, as I
           said, the HPSI is system-pressure dependent.
                       So if you look to the top here is the test
           results, while the lower is the RELAP prediction.
                       CHAIRMAN WALLIS:  So those four RELAP5 are
           all in that one bottom curve, are they?
                       MR. LAFI:  Actually four for RELAP.  This
           is --
                       CHAIRMAN WALLIS:  The fuzzy curve is the
           four tests, right?  That bottom curve is -- all the
           RELAP5 are on top of each other; is that right?
                       MR. LAFI:  Yes.  The level one is four
           RELAP prediction while the top is four HPSI.  The test
                       CHAIRMAN WALLIS:  This is presumably
           because you have the pressure system pressure wrong?
                       MR. LAFI:  Exactly, different.
                       CHAIRMAN WALLIS:  Right.
                       MR. LAFI:  So it behaves -- if you look,
           the pressure goes like this and down, it's different
           from the test.  That's why this is a discrepancy.
                       CHAIRMAN WALLIS:  They don't cross at the
           same point, but they...
                       MR. LAFI:  As I told you, the break flow
           is not predicted except at the beginning, but the
           behavior reached maximum, then go down and then
                       MR. SCHROCK:  What is the test measurement
           of break flow?
                       MR. BESSETTE:  But how is the break flow
                       MR. REYES:  The break flow --
                       MR. BESSETTE:  It goes --
                       MR. REYES:  -- on --
                       (Simultaneous discussion held among others
           in the room off the record.)
                       MR. REYES:  We are using a separator
           system.  This is all --
                       MR. BESSETTE:  So he runs it through the
           separator, and he measures the -- you measure the
           liquid flow --
                       MR. REYES:  The closed end and cfms.
                       MR. BESSETTE:  And the vapor flow.
                       MR. REYES:  Correct.
                       MR. SCHROCK:  And you get these kinds of
                       CHAIRMAN WALLIS:  I don't know which is
           the test and which is the RELAP.
                       MR. SCHROCK:  The liquid coming out of the
                       MR. KRESS:  Well, I can tell you which. 
           This is the test and this is the RELAP.
                       MR. LAFI:  The problem is the test --
                       CHAIRMAN WALLIS:  So we have a question
           now.  We say that RELAP is predicting more flow out
           the break, about twice as much as in the test, so I
           gather from this curve.  When I go back to page 58 --
                       MR. LAFI:  Yeah.  It's overpredicted --
                       CHAIRMAN WALLIS:  Overpredicted the break.
                       MR. LAFI:  Yes.
                       CHAIRMAN WALLIS:  We go back to page 58. 
           RELAP is holding the pressure up higher.
                       Do you think if it's predicting more flow
           out the break it would depressurize faster?  It
           doesn't seem right.
                       MR. BESSETTE:  It seems peculiar.
                       MR. SHACK:  Yeah, something's wrong. 
                       CHAIRMAN WALLIS:  Something seems strange. 
           I don't know if it's wrong.  It's just strange.  I
           mean --
                       MR. LAFI:  What's this conflict?
                       MR. BESSETTE:  Could you flip back to the
           pressure comparison?
                       CHAIRMAN WALLIS:  This --
                       MR. BESSETTE:  Page 58.
                       CHAIRMAN WALLIS:  RELAP holds the pressure
                       MR. LAFI:  RELAP within 1,000 seconds --
                       CHAIRMAN WALLIS:  In the early part.
                       MR. (SPEAKER):  Oh, in the early part.
                       CHAIRMAN WALLIS:  The early part up to
           about 5,000, RELAP is predicting a higher pressure
           than reality.  And yet RELAP's also predicting a
           higher break-flow rate, which is consistent with
           having a higher pressure.
                       But if you look at -- you'd expect the
           higher flow out the break to depressurize faster. 
           That's why it doesn't seem to make sense.
                       MR. HAN:  How about HPI in comparison?
                       CHAIRMAN WALLIS:  HPI is being predicted
           pretty well.
                       MR. LAFI:  Yeah.  It follows this one. 
           Look, it follows this --
                       CHAIRMAN WALLIS:  I guess this is the
           first time we're able to see something we can latch
           onto which we can get cause and effect and try to
           figure it out.  I'm not sure we really need to pursue
           it, but it does look a bit odd.
                       So it's something for you to think about
           this.  Can we leave it at that.
                       MR. SCHROCK:  I have a question about your
           initial conditions.  The RELAP prediction of initial
           conditions seems to me to be impressively good with
           one exception, and that is the steam generator number
           1 and 2 water level, seems to be off by quite a bit,
           not just in this particular experiment but in the
           others, too.
                       Is there an explanation for that?
                       MR. LAFI:  Actually I noticed this.  Even
           if I start with the same volume of the steam generator
           level, like the test, it leads me to higher volume. 
           And I couldn't find out what's the reason, but this is
           what happened in many cases.
                       For example, if I see the initial steam
           generator 15 and I set it as 15, it run --
                       CHAIRMAN WALLIS:  To 27.
                       MR. LAFI:  -- for a few seconds and then
           it goes to 25, or something.
                       CHAIRMAN WALLIS:  And you can't even blame
           Bill Gates for that.
                       MR. LAFI:  No.
                       MR. LAFI:  As I said, the stagnation
           occurred in all cold legs, similar to the test but at
           different times.
                       And even I can't conclude, because it
           sounds to me subjective whether I consider the
           stagnation in the -- for example, in the test, it is
           clear for RELAP.  I don't know what I --
                       CHAIRMAN WALLIS:  You have to stand by the
           mic or you -- we lose the transcription.
                       MR. LAFI:  It sounds to me subjective to
           determine which is as far as that.  I will -- but I
           thought without the test, I will choose some point,
           but this is what happened.  RELAP predict the
           stagnation, but at different time.
                       Not predicting the stagnation at its exact
           time is due to other discrepancy in other factors.
                       CHAIRMAN WALLIS:  I guess what really
           matters here is what difference does it make to your
           assessment of pressurized thermal shock if you have
           these kinds of differences.  And I have no idea.
                       How accurately do you need to know this
           sort of -- is it stagnated, or is it close to
           stagnation, and all that, in --
                       MR. LAFI:  Actually --
                       CHAIRMAN WALLIS:  -- order to assess
           pressurized thermal shock?
                       MR. LAFI:  It seems the stagnation -- I
           found no stratification in the cold -- in the
           downcomer temperature after stagnation.  And this is
           what we noticed in the test.  Also the temperature in
           the downcomer is uniform during the entire test.
                       CHAIRMAN WALLIS:  Everywhere?
                       MR. LAFI:  Huh?
                       CHAIRMAN WALLIS:  It doesn't stratify
           vertically, or anything; it's uniform everywhere?
                       MR. REYES:  There are some tests where we
           see vertical stratification.  And as far as the timing
           of when stagnation occurs, in this plant we -- because
           of the low injection flow rates, we see a relatively
           good mixing under stagnant conditions.
                       In other plants stagnations are important
           because if you have high injection flow rates under
           stagnant conditions you may see more penetrating
           plumes.  So the timing becomes an issue.
                       Tomorrow I'll be presenting.  We'll look
           at this scenario again and go --
                       CHAIRMAN WALLIS:  See, I have no criterion
           for deciding is this good, or bad, or indifferent, or
           what shall I conclude, or --
                       MR. REYES:  Right.
                       CHAIRMAN WALLIS:  -- why should I worry,
           or should I.
                       MR. REYES:  Tomorrow what we'll do is
           we'll look at loop stagnation mechanisms.  That'll be
           the first talk.  And we'll come back to this, what was
           causing stagnation in this particular test.  And we'll
           relate that to some of the separate-effects tests and
           what we were seeing there.
                       MR. LAFI:  This is cold leg 4.  And
           actually what I discovered through a RELAP calculation
           that the mechanism of stagnation in this test is
           different from the mechanism of stagnation in your
           tests, as I will show it to you.  This is -- again
           stagnation occurred but different time.
                       This is cold leg 3.  And if you notice
           this, the hot leg temperature number 1 against steam
           generator number 1 temperature is almost higher, the
           hot leg temperature higher than the steam generator
           temperature, except it reach a point when they are the
                       And at this point, when I discovered the
           steam generator voided, empty.  And that's why I
           conclude that the mechanism of the stagnation
           according to RELAP calculation for this test is the
           voided of the steam generator.  This is supported by
           this figure.
                       CHAIRMAN WALLIS:  Now this -- wait a
           minute.  This is TF 143 is a thermocouple in the hot
                       MR. LAFI:  Yes.  143, yeah, in the hot
                       CHAIRMAN WALLIS:  And it has these
           enormous dives that go off the picture and the one
           picture before that.  Is that real, or is that a
           glitch in the instrumentation?  Why do those things go
           down to the bottom of the graph there?
                       MR. LAFI:  This one, this figure or --
                       CHAIRMAN WALLIS:  Yeah.  There's -- the
           color I can't describe.
                       (Comments off the record.)
                       CHAIRMAN WALLIS:  Whatever you call that.
                       MR. LAFI:  TF 143?
                       MR. SHACK:  Teal.
                       CHAIRMAN WALLIS:  Teal.  Teal, or
                       CHAIRMAN WALLIS:  Yeah, Teal.
                       Why does it go down to -- is that a real
           thing, or is that a...
                       MR. LAFI:  With the temperature profile?
                       CHAIRMAN WALLIS:  The temperature plunges. 
           It comes back.
                       MR. SHACK:  The measured thermocouple
                       MR. SCHROCK:  Right there.
                       MR. LAFI:  This one?
                       MR. SHACK:  Yeah.
                       CHAIRMAN WALLIS:  And it's in a hot leg. 
           Why does it do that?  Does it suddenly sees a slug of
           cold liquid?
                       MR. LAFI:  Is this the --
                       MR. REYES:  I don't -- I don't believe
           that's --
                       CHAIRMAN WALLIS:  If you see something you
           don't like, you don't believe it?
                       MR. REYES:  No, no.  There are -- there
           were two thermocouples that we were looking at
           earlier.  One was giving us spikes in the high
           direction.  And, of course, we want to look at both of
           those, but --
                       CHAIRMAN WALLIS:  So --
                       MR. REYES:  So the --
                       CHAIRMAN WALLIS:  Give them a break and
           let them have low ones, too.
                       MR. REYES:  That's right.  We think there
           might be some noise problem with --
                       CHAIRMAN WALLIS:  It's a noise problem. 
           It's not a real thing?
                       MR. SHACK:  Just put a bigger averaging in
           the circuit.
                       MR. SCHROCK:  Somebody put a little ice
           water in there.
                       MR. LAFI:  This condition, again, occurred
           with hot leg number 2 and steam generator number 2. 
           And this is when the stagnation occurred when you have
           the hot leg temperature as equal to the steam
           generator temperature, which is corresponding now to
           the voided of the steam generator.
                       This is steam generator number -- what is
           it?  The -- this one 225, which is the steam generator
           number 2, this one.  And this one's steam generator
           number 1.
                       So this is the time when the stagnation
           occurred.  I didn't, and I doubt RELAP can predict
           what is happening in the other location.  But this is
           what I connected the stagnation cause because of the
           voidage of the steam generator going from volume
           fraction 1 to zero.
                       And the downcomer temperature profile is
           acceptable, except RELAP overpredicted the downcomer
                       And this is the cold leg to downcomer,
           which is the sector corresponding to the area when the
           cold leg number 2 connected to the downcomer.
                       As the conclusion, RELAP predicted general
           behavior of the system depressurization, the
           high-pressure injection system, feed water, and the
           break-flow rates.  Just in general for the break-flow
           rate.  We see -- we saw some significant difference.
                       By comparing the break flow rate one can
           notice that the maximum break-flow rate at the
           beginning of the test was 12 ga- --
                       CHAIRMAN WALLIS:  So this is a two-phase
           flow, not the break?
                       MR. LAFI:  Out of the break, I suppose.
                       CHAIRMAN WALLIS:  It's a two-phase flow?
                       MR. LAFI:  I suppose two-phase flow.
                       CHAIRMAN WALLIS:  What's a gallon of
           two-phase?  I don't understand the break flow of
           gallons per minute.
                       MR. REYES:  You're looking at the liquid
           flow as the --
                       MR. LAFI:  This is the RELAP prediction
                       MR. REYES:  Liquid?
                       MR. LAFI:  Yes.
                       CHAIRMAN WALLIS:  The beginning of the
           test it's all liq- --
                       MR. LAFI:  Because the mass flow rate
           for...  However, RELAP5 overpredicted.
                       CHAIRMAN WALLIS:  This break flow in the
           two-phase is still measured in gallons per minute?
                       MR. REYES:  Basically what we have is a
           separator with a loop seal.  And the magnetic flow
           meter on that loop seal measures in gallons per
                       CHAIRMAN WALLIS:  So you're measuring the
           -- okay.
                       MR. REYES:  So I think what he's comparing
           there then is just that flow meter liquid --
                       MR. LAFI:  Comparing not after leaving the
                       CHAIRMAN WALLIS:  So it's the liquid flow.
                       MR. LAFI:  After separating the liquid
           from the two-phase.
                       CHAIRMAN WALLIS:  So this is the liquid
           flow out the break?
                       MR. LAFI:  Yes.
                       CHAIRMAN WALLIS:  Then the steam flow
           isn't counted?
                       MR. LAFI:  No.  This is what -- the data
           I think -- after I think the separation, right?  Yeah,
           it depends.
                       MR. REYES:  So in RELAP were you comparing
           just the liquid?
                       MR. LAFI:  The mass -- the mass flow rate
           for the liquid RELAP.  That's why I compared this to
                       CHAIRMAN WALLIS:  So the steam isn't
           counted in some way?
                       MR. LAFI:  There is control volume.  It
           occurred in RELAP to calculate the mass flow rate for
           the vapor, for the steam.
                       CHAIRMAN WALLIS:  So you have a phase
                       MR. REYES:  Right.
                       CHAIRMAN WALLIS:  You measure the water
           and steam flow rates?
                       MR. REYES:  Separately.
                       CHAIRMAN WALLIS:  And you measure them
           both in gallons per minute?
                       MR. REYES:  No.  They're -- the magnetic
           flow meter is in gallons per minute.  The vortex flow
           meter is in the standard cubic feet per minute.
                       CHAIRMAN WALLIS:  Standard cubic feet per
           minute?  Standard cubic feet per minute?
                       MR. GROOME:  Well, most flow experts do
           not measure mass.  Only Coriolis measured mass.  So
           the raw data is in volumes.  If you want mass, there's
                       CHAIRMAN WALLIS:  It drives me up the
           wall.  And graduate students get always very confused
           by all flow meters because they have these stupid
           measurements, like standard cubic feet per minute
           which no one understands.  People are always
                       MR. REYES:  I agree.
                       CHAIRMAN WALLIS:  Okay.  Sorry.
                       MR. LAFI:  RELAP5 predicted flow
           stagnation in all cold legs at different times, as was
           the case during the test.
                       The stagnation cause in this test is not
           similar to that of the main steam line break tests. 
           It is believed that the cause of stagnation here is
           the voiding of the steam generator tubes.
                       RELAP5 prediction for the downcomer
           temperature profile is in good agreement with the
           test.  RELAP5 is one-dimensional cold.  Therefore,
           studying the stratification that occurred during the
           test in the cold legs and the loop seals was not
                       I think this is the end of my
                       CHAIRMAN WALLIS:  Thank you.
                       That's the end of the day's presentations,
                       MR. REYES:  That's correct.
                       CHAIRMAN WALLIS:  So we're finished ahead
           of time.  And we're going to go and look at the
           experiment now?
                       MR. REYES:  We can do that for a short
                       CHAIRMAN WALLIS:  Yes.  I think that would
           be very appropriate, while it's cold and we can get in
                       MR. REYES:  That'd be fine.
                       CHAIRMAN WALLIS:  Then we're going to see
           it tomorrow when it's hot and running?
                       MR. REYES:  Hot and running.
                       John has guaranteed it.
                       MR. GROOME:  Well, I don't know.  We're
           going to be in gallons per minute.
                       (Laughter and comments off the record.)
                       (Whereupon, the meeting was adjourned at
           3:05 p.m. on July 17, 2001, to resume on Wednesday,
           July 18, 2001 at 8:15 a.m. in Corvallis, Oregon.)

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