Thermal-Hydraulic Phenomena - March 15, 2001


                Official Transcript of Proceedings


Title:                    Advisory Committee on Reactor Safeguards
                               Thermal-Hydraulic Phenomena Subcommittee

Docket Number:  (not applicable)

Location:                 Rockville, Maryland

Date:                     Thursday, March 15, 2001

Work Order No.: NRC-112                               Pages 1-136

                   NEAL R. GROSS AND CO., INC.
                 Court Reporters and Transcribers
                  1323 Rhode Island Avenue, N.W.
                     Washington, D.C.  20005
                          (202) 234-4433                         UNITED STATES OF AMERICA
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                             AP1000 T/H ISSUES
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                               OPEN SESSION
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                              MARCH 15, 2001
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                            ROCKVILLE, MARYLAND
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                       The Subcommittee met at the Nuclear
           Regulatory Commission, Two White Flint North, Room
           T2B3, 11545 Rockville Pike, at 1:00 p.m., Dr. Graham
           B. Wallis, Chairman, presiding.
                 GRAHAM B. WALLIS, Chairman
                 THOMAS S. KRESS
                 WILLIAM J. SHACK
                                 I N D E X
                       AGENDA ITEM                         PAGE
           Introduction by Chairman Wallis. . . . . . . . . . 3
           Westinghouse Presentation:  Proposed Approach
             to Address AP1000 T/H Issues
             A.  AP1000 Pre-Certification Review Overview
             M. Corletti. . . . . . . . . . . . . . . . . . . 4
             B.  AP1000 Plant Description, Differences
             From AP600 Design, M. Corletti . . . . . . . . .12
             C.  AP1000 Passive Safety Systems Design
             and Analysis, T. Schultz . . . . . . . . . . . .29
             D.  Review of AP1000 PIRT and Scaling
             Approach (Closed), W. Brown. . . . . . . . . . .92
             E.  Approach to the Application of Analysis
             Codes to AP1000 (Closed), Include Discussion
             of Need for Uncertainty Assessments,
             J. Gresham . . . . . . . . . . . . . . . . . . 105
             F.  Concluding Remarks, M. Corletti. . . . . . 119
           NRR Staff Presentation:  Comments on
             Westinghouse Approach, Schedule Milestones,
             Potential Problem Areas (if any), J. Wilson. . 134
                                                    (1:00 p.m.)
                       CHAIRMAN WALLIS:  The meeting will now
           come to order.  This is a meeting of the ACRS
           Subcommittee on Thermal-Hydraulic Phenomena and I am
           Graham Wallis, the Chairman of the Subcommittee.
                       The other ACRS Members in attendance are
           Thomas Kress and William Shack, and we expect Mario
           Bonaca to be present within about an hour and we also
           may have a consultant, Dr. Novak Zuber present.
                       The purpose of this meeting is for the
           Subcommittee to review the Westinghouse Electric
           Company's proposed approach to address 
           thermal-hydraulic issues pertaining to its AP1000

           passive plant design.
                       The Subcommittee will gather information,
           analyze relevant issues and facts and formulate
           proposed positions and actions as appropriate for
           deliberation by the full Committee.  Paul Boehnert is
           the cognizant ACRS staff engineer for this meeting.
                       Portions of this meeting will be closed to
           the public to discuss Westinghouse Electric Company
           proprietary information.  I'd ask Westinghouse to let
           us know when the meeting should be closed.
                       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 March 1, 2001.
                       A transcript of the meeting is being kept. 
           And the open portions of the transcript will be made
           available as stated in the Federal Register notice.
                       It is requested that the 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.
                       I'd like to say that it's a pleasure to
           welcome Westinghouse back.  We haven't seen you in a
           while.  We've spent some time with your competitors in
           the last couple of years, but we're glad to have you
           here again and we look forward to your presentation.
                       MR. CORLETTI:  Good afternoon.  On behalf
           of Westinghouse, my name is Mike Corletti.  Thanks for
           the warm welcome.  
                       Today, we're going to be talking about the
           precertification review of the AP1000 and I'd like to
           start with the purpose of today's meeting and the
                       Today's meeting is going to be an
           informational meeting.  It's really the first time
           we've been able to present this to the ACRS and we
           wanted to concentrate on the thermal-hydraulic -- the
           two major issues that this Subcommittee would be most
           interested in.  We're going to really outline what the
           objectives of the AP1000 precertification review are
           and review our proposed approach to resolution of the
           two key issues.
                       Those two key issues we'll talk a lot
           about later, but really they are whether our desire to
           use the AP600 test data in support of Design
           Certification for AP1000 and the applicability of the
           AP600 analysis codes.
                       Throughout the meeting we would be looking
           for feedback on our approach.  I understand you've
           just received our deliverables probably last week, so
           we have no expectations that you have reviewed it
           completely and thoroughly.
                       CHAIRMAN WALLIS:  We found all the
                       MR. CORLETTI:  If you found them all, that
           would be good, so we can correct them very quickly and
           resolve them.
                       But really, we'd like to get the feedback
           on our general approach to these two key issues and
           then talk about the expectations for our future
                       You see the agenda that's up there.  We're
           going to have myself speaking about the objectives of
           the review and some of the plant description overview. 
           We're going to have Terry Schultz talk about the
           AP1000 passive safety systems, the design that we've
           done in some of the analyses that are included in our
           plant description, an analysis report.  That's the
           first report that we've sent in.
                       Then we're going to have Bill Brown talk
           about our approach to scaling.  We've just recently
           last week sent in the PIRT and scaling assessment
           report and Bill is going to talk you through his
           approach to scaling and what the conclusions that
           we've drawn from that report.  And then Jim Gresham is
           going to speak to our plan for the use of the approved
           AP600 analysis codes and how we would plan to apply
           those.  He's going to be talking about a future report
           that we're still working on.
                       We went to the staff last year to talk
           about AP1000 and really introduce the staff to the
           AP1000 and what our major design objectives were. 
           Really, we're taking the AP600 design that went
           through very extensive design and analysis and
           starting with that, but trying to increase the
           capacity of selected systems to increase the power
           output.  To have a plant that would have an overnight
           capital cost in the range of $900 to $1000 per
                       CHAIRMAN WALLIS:  Now isn't the AP1000
           designed to compete in the U.S.?  What was the AP600
                       MR. CORLETTI:  The AP600 was also designed
           to compete in the U.S. and at the time that it began
           which was in 1988, the target economic goals were
           something on the order of $1500 a kilowatt.  AP600
           meets those goals, meets the original design, the
           goals that were set forth.
                       What's happened since 12 years passed, I
           think the deregulated market has come upon us and
           basically AP1000 is in response to that.
                       CHAIRMAN WALLIS:  So there wasn't some
           physical reason why it was smaller?  There wasn't some
           sort of design constraint?
                       MR. CORLETTI:  It was not a design
           constraint, but it really was a sampling of the
           industry and of the utilities and it was a size
           selected that they felt would be what they'd like to
                       CHAIRMAN WALLIS:  It seemed sort of a
           strange economic decision where most others are
           thousands --anyway, we should move on.
                       MR. CORLETTI:  So the realities of the
           AP600, we had invested quite a bit of money both in
           the design and licensing of AP600, some upwards of
           $400 million had been invested by Westinghouse and the
           industry as a whole.
                       We knew that going forward we would not be
           able to start with a clean sheet of paper, but we did
           want to -- but if we could design the AP600 with --
           the AP1000 within the space constraints of AP600, we
           would be able to have a plant design that would meet
           the economic targets that were necessary.  
                       When we say the space constraints, this is
           what we mean here.  Basically, the AP600 and AP1000
           side by side, the structural design, the --
                       CHAIRMAN WALLIS:  Looks like one of those
           things you have in high school or something, to spot
           the differences.
                       MR. CORLETTI:  There are a few.  
                       CHAIRMAN WALLIS:  There are a few --
                       MR. CORLETTI:  That's true and the
           structure -- you can lay them on top and they'd be
           exactly the same.
                       You'll see some of the differences, the
           much larger steam generators that we have there.  And
           that is -- besides that, it's probably tough to see.
                       But we also wanted to retain credibility
           of proven components.  We don't want to redesign all
           the components that -- our design approach is being
           still using proven components to the extent possible. 
           This gives us the advantage then that we can retain
           the cost basis of the AP600 which we have a very good
           handle on and by doing the changes, only those
           necessary to increase the power up of the plant --
                       CHAIRMAN WALLIS:  You say proven
           components, you mean components previously accepted by
           the NRC?  They haven't been built.
                       MR. CORLETTI:  We're going to get to that,
           but like the steam generators are based on the ANO
           steam generators that we just --
                       CHAIRMAN WALLIS:  Okay, some of them have
           been really proven.
                       MR. CORLETTI:  Yes, that's right.
                       CHAIRMAN WALLIS:  Thank you.
                       MR. CORLETTI:  I think you're going to
           find that most all of them been actually.
                       But also we set out to retain the AP600
           licensing basis.  What did that mean?  Well, AP600 met
           the regulatory requirements with large margins, large
           safety margins.  We knew it would be unacceptable to
           come in with a plant design that did not meet those
           large safety margins.
                       Except all the policy issues that we
           fought so long and hard with you and us and the staff
           and we came to resolution, we basically want to accept
           all those policy issues for AP1000.
                       So when we went to the staff, we explained
           that based on our -- the available resources that we
           saw that we thought we could pursue a Design
           Certification under certain conditions and basically
           we had -- those conditions were such that the staff
           thought it was a good idea that we review those first
           and get an agreement on those first before both the
           staff and us invest a large amount of resources in the
           whole Design Certification effort, that while we're
           improving the efficiency process, and basically, we're
           trying to leverage AP600 Design Certification.  The
           NRC, we just completed that review, not but two years
           ago it was at the time and we felt that staff had a
           good understanding of the design and why it was
           acceptable as did we and now is the best time to go
           forward with getting into some of these tough issues.
                       The issues that we are trying to -- we
           actually identified six issues.  ACRS also provided
           their insights and guidance.  I think the insights and
           guidance that you gave us are really not necessarily
           focused just on this Phase 2 review, but really for
           the Phase 2 and the Design Certification.
                       Two of the items that were identified, we
           did defer to Design Certification.  We will do them at
           that time, that being what percentage of the SAR we
           could retain from the AP600 for AP1000 and also the
           issues with regards to the AP600 PRA.  Those have
           totally been deferred to Design Cert.
                       The four issues that this phase will be
           dealing with, as I said, the sufficiency of the AP600
           test program to meet the requirements of 10 CFR Part
           52.  We had a very extensive, I think most of you were
           familiar with the AP600 test program.  We're going
           through a systematic review of that and in our report
           we've tried to show how we would plan -- how that test
           data, we believe is applicable to AP1000 and really
           what it means and I think that will be the subject of
           Bill's presentation.
                       The second item is the applicability of
           the NRC approved analysis codes, how we can use the
           approved codes for AP1000, what were the major issues
           that we had to resolve for AP600 and the way we
           resolved them, is that still applicable to the AP1000?
                       The two other issues are probably --
           they're not the subject of today's meeting, but in the
           third one is how we would use design acceptance
           criteria in lieu of detail design engineering in some
           of the selected areas such as piping, structural and
           seismic.  And the fourth issue was the applicability
           of the exemptions that were granted on AP600 and how
           we'd be able to use for AP1000.
                       Just to give you a status of the review,
           we submitted the Plant Description and Analysis
           Report.  In that report it gives a comparable
           description of the AP1000 design features and compares
           them to AP600.  We include a safety systems margins
           assessment which Terry is going to be talking about
           today.  Really, it's the first principles comparison
           of the key passive safety features.
                       And then we did safety analysis
           assessment.  We basically took the AP600 analysis
           codes and revised them all to reflect the AP1000 and
           ran those codes, really as a way to characterize the
           performance of the AP1000, not as the final Chapter 15
           safety analysis, but just to give everyone an
           understanding of the phenomena that we would be --
           that the AP1000 would exhibit compared to AP600.
                       CHAIRMAN WALLIS:  Now when you made the
           design choices, I noticed that you retained nearly the
           same -- some things are the same, right, and some
           things are different.
                       Some things are scaled up a little bit and
           some of the pipes are bigger --
                       MR. CORLETTI:  Right.
                       CHAIRMAN WALLIS:  But the reasons given in
           this blue document here are very simple sort of
           reasons.  It would seem you would have to actually run
           some codes to figure out if they're really the right
                       MR. CORLETTI:  And those codes are in the
           first report that we did.  We ran -- and Terry will be
           speaking of those in the colored -- it's the book that
           accompanied that.  
                       CHAIRMAN WALLIS:  It was something like
           -- I guess the accumulators are the same.
                       MR. CORLETTI:  Right.
                       CHAIRMAN WALLIS:  Those are some of the
           things that are the same.
                       And one would think that the optimum
           accumulator for a bigger reactor would be different.
                       MR. CORLETTI:  Terry's going to
           specifically --
                       CHAIRMAN WALLIS:  He's going to address
           that question?
                       MR. CORLETTI:  That's right and I think
           that takes us really to the next part which is the
           Plant Description and Analysis Report.
                       MR. BOEHNERT:  Mike, before you get off
           that last slide, when is the Analysis Report, the Code
           Applicability Report going to be available?
                       MR. CORLETTI:  We're working on that and
           our schedule is to submit that in April.
                       Our approach is really -- you can't decide
           on the code -- where the contents of the Code
           Applicability Report until you really resolve the test
           data that you used to validate those codes is still
           appropriate for AP1000.  That's been our approach and
           that's really the reason we've performed them in the
           order that we have.
                       The first slide is the comparison of some
           of the key selected parameters.
                       CHAIRMAN WALLIS:  The thing that strikes
           one the most, to me anyway, is the heat rating has
           been upgraded considerably?
                       MR. CORLETTI:  Yes, it has.  
                       CHAIRMAN WALLIS:  So you're going to have
           to convince someone that that's okay?
                       MR. CORLETTI:  Right.
                       CHAIRMAN WALLIS:  You're making quite a
           demand on cooling, both in normal operation and in --
                       MEMBER KRESS:  That was accomplished by
           increasing the enrichment.  
                       MR. CORLETTI:  Yes.  The focus of the --
           I'll get into the basis for the fuel, but it's -- we
           haven't brought our fuel people with us today  
           because it's really going to be part of the Design
           Certification and the review of the fuel design at
           that point.  This meeting is really the test and
           analysis, but I can give you a little basis of the
           fuel design and I don't want to go too deep into it,
           if that would be okay.
                       The reactor power is 3400 megawatts
           compared to the 1933 of the AP600, so as you said,
           we've increased the number of fuel assemblies from 145
           to 157.
                       MEMBER KRESS:  See, that's a change of --
                       MR. CORLETTI:  Twelve fuel assemblies.
                       MEMBER KRESS:  That's a change of what, 74
           percent in power?
                       MR. CORLETTI:  Yes.  We did it in two
           ways, increasing the number of fuel assemblies and in
           lengthening the fuel rods.
                       Our three loop course, our three loop
           plants typically have 157 fuel assemblies.  In fact,
           our 3XL which has the same fuel, 14-foot core, are
           operating Doel 4 Tihange 3 in Belgium, so really the
           fuel assembly design, the reactor vessel design is
           essentially the same as those units.
                       CHAIRMAN WALLIS:  So you bring it into
           line with something that already exists?
                       MR. CORLETTI:  Yes.  And the core power
           density has been increased over those units.  Those
           units are 3,000 megawatt units.  We've increased the
           core power density to be the same as our operating
           three loop plants that have 12 foot fuel.
                       MEMBER KRESS:  Does this give you any
           problem though of too much fluence on the reactor
                       MR. CORLETTI:  No, it really doesn't. 
           With the materials that are selected today, you can
           essentially radiate them --
                       MEMBER KRESS:  You can almost get away by
           selecting materials?
                       MR. CORLETTI:  Yes.  With good materials,
           you really can almost show infinite irradiation and
           you can still meet the 60 year design life.
                       MEMBER KRESS:  This is for 60 years?
                       MR. CORLETTI:  Yes.  This is 60 year
           design life.
                       CHAIRMAN WALLIS:  Infinite irradiation?
                       MR. CORLETTI:  Not exactly.
                       MR. CORLETTI:  Very long and essentially--
                       CHAIRMAN WALLIS:  The fluence did go up?
                       MR. CORLETTI:  Absolutely.
                       MEMBER KRESS:  But with the right
           materials you can stand it?
                       MR. CORLETTI:  Right, that's right.  The
           hot leg temperature, you'll notice, has increased from
           600 to 615, but again, it's still well within the
           operating range of most of our plants.
                       MEMBER KRESS:  Your RCS materials are all
           the same?
                       MR. CORLETTI:  Yes.  Again, the 17 by 17
           fuel assemblies.  The number of control rods has
           increased.  We've got 8 control rods, really filled up
           the available space.
                       MEMBER KRESS:  Now with the increased
           length of the fuel by two feet, does that mean you
           have to increase the length of the control rods also?
                       MR. CORLETTI:  Yes sir.
                       MEMBER KRESS:  By the same amount?
                       MR. CORLETTI:  By the same amount and then
           it's really the same as what we have in the South
           Texas Unit also which is also 14 foot.
                       MEMBER KRESS:  You already have
                       MR. CORLETTI:  Yes, we do, yes.
                       MEMBER KRESS:  Okay.
                       MR. CORLETTI:  Both in South Texas and in
           Doel and Tihange.
                       MEMBER KRESS:  Okay.
                       CHAIRMAN WALLIS:  Which are fairly old
                       MR. CORLETTI:  They've been around.  Yeah. 
           I don't thing -- South Texas is one of our newer old
                       CHAIRMAN WALLIS:  But the Belgium plant --
                       MR. CORLETTI:  I think they're the same
           vintage as the South Texas plants.
                       The reactor vessel did not change and
           basically it's the same -- the AP600 we started with
           a larger vessel to begin with.  We started with our
           three loop configuration vessels.
                       The steam generator, you'll see a big
           change in the surface area there.  We have some slides
           to show you the relative size of the two.  
                       MEMBER KRESS:  Did you put in more tubes
           or longer tubes?
                       MR. CORLETTI:  More tubes and we wanted to
           have a low pressure drop steam generator so that we
           could minimize the impact on the reactor coolant pump,
           so we have many tubes.
                       It's similar, I guess, it's not -- the
           last -- what happened when we started AP600, Delta 75
           was our replacement generators for our Model Fs.  So
           that was the generator we picked when we began AP600.
                       Since that time we've been supplying
           replacement steam generators and at the time we
           started AP1000, we were just finishing the design and
           we were actually finishing the construction of the ANO
           replacement steam generators which are about the same
           megawatt rating as this unit.
                       Now subsequent to that we have merged with
           Combustion Engineering and they have even more
           experience with large steam generators like this.  We
           really have had a collaborative effort on the Delta
           125.  They've been working, the two design teams have
           worked together to get the design of this --
                       MEMBER SHACK:  Do you use egg crates?
                       MR. CORLETTI:  No.
                       The reactor coolant pump is another that
           I'll talk some more about.  Reactor coolant pump flow
           rate was increased to accommodate the higher core
           power, the inertia is increased to accommodate longer
           flow coast down to meet the DNB requirements.
                       MEMBER KRESS:  You just make them bigger
           with a bigger motor on them?
                       MR. CORLETTI:  Well, you'll see it is a
           higher capacity.  It is a bigger motor.  Didn't get
           that much bigger.  The hydraulics are different and
           I'll show you a little sketch of that.
                       CHAIRMAN WALLIS:  It's interesting you
           have a table of these parameters, whereas the other
           parameters that are really the key, the passive like
           the CMTs and all of that, you really ought to compare
           those.  I don't see a table of that comparison.
                       MR. CORLETTI:  That will be in Terry's on
           the passive -- I was just trying to set the stage for
           the main reactor coolant system.
                       CHAIRMAN WALLIS:  The message I get from
           this is that you've been there before with other
           reactors and there's nothing unique about AP1000.
                       MR. CORLETTI:  I can move on then.
                       MEMBER KRESS:  With the exception of that
           last one on there --
                       MR. CORLETTI:  Which one is that, sir?
                       MEMBER KRESS:  Containment height.
                       MR. CORLETTI:  Containment height.  We
           have increased the containment height.  I don't
           believe it's taller than the AP600, but I don't
           believe it's taller than -- I don't have a good
           comparison with operating plants.
                       MEMBER KRESS:  I mind the aspect ratio, it
           seems like it's unusual compared to containments I'm
           used to, the lift diameter.
                       CHAIRMAN WALLIS:  It's nowhere near in
           proportion to the power, is it?  It's gone up a little
           bit, 10 percent.
                       MR. CORLETTI:  We've done a couple of
           things.  We've increased the design pressure.  We've
           made the wall thicker.  And we've increased the
                       CHAIRMAN WALLIS:  But the height is 10
           percent, the volume is 10 percent bigger and the
           diameter is the same.
                       MR. CORLETTI:  I think it's about 20
           percent actually.  I have -- Terry has a slide that
           gives the percentage of change.
                       It's 12 percent.
                       MEMBER KRESS:  So you got about that much
           more surface area to take out 74 percent more heat?
                       MR. CORLETTI:  The mass and energy aren't
           -- yeah, I think Terry has -- Terry is going to get
           there, yeah.
                       MEMBER SHACK:  You really kicked up the
           design pressures.
                       MR. CORLETTI:  We increased the design
                       MEMBER KRESS:  Which makes a substantial
           difference in terms of heat transfer.
                       MR. CORLETTI:  Again, I think we've
           covered most of this.  When we did this upright, we
           basically started with a proven fuel design, again
           fuel core that we've had experienced with before. 
           Core power density has been increased. 
                       We then went about -- the reactor vessel
           was similar to Doel 4 and Tihange 3.  Basically, we
           fixed the elevation of the hot leg and cold leg
           pipings and we let the bottom of the vessel drop to
           accommodate the longer fuel.
                       I think the steam generator, we talked
           about that.  Reactor coolant pump, I have a slide on
                       Again, you'll see, this is a comparison. 
           We've added three fuel assemblies on the periphery. 
           That's the main difference.  Again, that looks -- that
           is basically the same as our three loop operating
                       This shows a comparison of the overall
           length and as you were saying not only does the vessel
           get longer, but the integrated head package, to be
           able to pull the control rods out gets longer also.
                       And this shows the relative dimensions of
           the steam generator.  
                       One of the items -- I know the steam
           generator is a lot bigger, the mass energy is larger,
           but the flow restricter is the same diameter, so
           really the rate of the discharge from a steam line
           break, for instance, is the same.
                       The reactor coolant pump, AP600 was based
           on a proven motor design at the time that we began. 
           But due to the higher power density of AP1000 we
           required really a longer flow coastdown, which means
           we had to increase the inertia.  We also had to
           increase the pump head and flow to get sufficient flow
           through the core, to accommodate the core power.
                       MEMBER SHACK:  People used depleted
           uranium before for that?
                       MR. CORLETTI:  As part of AP600, we did
           for the AP600 pump.  And we ran a test, we built one
           of the flywheels to demonstrate that we could.  I'm
           not sure, no one uses them -- the Navy doesn't use
           them in these kind of pumps and we typically use shaft
           steel pumps, so that was a new feature of AP600.
                       CHAIRMAN WALLIS:  Just to make sure, if it
           flies apart, it's unstoppable?
                       MR. CORLETTI:  Right, that was part of 
           -- that was a lot of what the review on AP600 was, was
           the flywheel integrity.
                       One of the things we did to minimize the
           impact on the pump motor size is we have added a
           variable speed controller that allows the pump to
           operate at low speed during cold conditions in the
           reactor coolant.  So as you're heating up the reactor
           coolant system, they typically heat up the loops on
           pump heat, until the system has come up to operating
           temperature, then we basically disengage the variable
           controller and it's really locked out.  So it's really
           only operating at shutdown condition.
                       Another difference is the hydraulics. 
           It's really -- hydraulics, different hydraulics.  It's
           one that we've designed and actually built for the
           Saruga plant that we're working on.  We built a test
                       Here, you see some of the operating
           conditions.  The pump flow, the head has been
           increased and the inertia has been increased from
           5,000 to roughly 15,000.
                       MEMBER KRESS:  Your test model, is it a
           full-size prototype?
                       MR. CORLETTI:  Of the hydraulics, yes.
                       MEMBER KRESS:  Of the hydraulics.
                       MR. CORLETTI:  And you see, we've
           increased the motor rating.  It still is significantly
                       CHAIRMAN WALLIS:  The megawatts is 6000?
                       MR. CORLETTI:  6000 horsepower.  Our AP600
           pumps were roughly 6 megawatts for the four of them.
                       CHAIRMAN WALLIS:  So this is maybe 11 or
           12 or something?
                       MR. CORLETTI:  Yeah, that's right, 12
                       CHAIRMAN WALLIS:  Energy efficiency.
                       MR. CORLETTI:  Yes.  The thing with these
           hydraulics are slightly more efficient than the AP600,
           but yes.
                       As you see, the interesting thing, the
           overall size is not increased that much which is
           important to us because we had to make sure we could
           take the pump out for pump replacement which was one
           of the key limiting design criterias that we placed on
           EMD, our pump designers as we have been doing this is
           make sure you can replace, pull the pump out.
                       CHAIRMAN WALLIS:  Presumably things are a
           big tighter, things are bigger in the same containment
           and it's tighter.
                       MR. CORLETTI:  Yes, it is.  Things are
                       We did in the Safety Analysis Report, we
           performed a loss of flow analysis.  The same way we
           did AP600 really.
                       MEMBER KRESS:  Is that a pump coastdown?
                       MR. CORLETTI:  Basically, you lose all
           four pumps simultaneously.
                       MEMBER KRESS:  Yes, but they coast down?
                       MR. CORLETTI:  And they coast down, that's
                       And the next slide here really shows the
           analysis results for that.  And you'll see with the
           higher efficiency AP1000, at the time of minimum DNB,
           it's a significantly higher flow than we had for
           AP600.  You need that to meet the DNB requirements for
           the higher power core.
                       This is presented in the first report, the
           Plant Description and Analysis Report.
                       My final slide is one that really just
           shows the increase in the pressurizer.  Again, we did
           not increase the diameter.  We did increase the volume
           by raising the height, so it can fit in the same
           pressurizer compartment.  We didn't want to change the
           structures around the pressurizer.  It's larger to
           accommodate pressure transients associated with the
           higher power.
                       CHAIRMAN WALLIS:  What's the major
           criterion for pressurizer design?
                       MR. CORLETTI:  It's really for loss of
           load, you want to prevent --
                       CHAIRMAN WALLIS:  In-surges?
                       MR. CORLETTI:  Yeah, in-surges and
           minimize pressure -- basically, you want to limit
           design -- the pressure to 110 percent of design
           pressure -- and you don't want to over-pressure above
           110 percent of design pressure.  So it works in
           combination with the safety valves to really accept
           the pressure transients.  There's many different ones,
           but that tends to be the limiting one.
                       With that I'm going to move to the passive
           safety systems and Terry is going to talk about that.
                       MEMBER KRESS:  Now that volume is changed. 
           It's not the same ratio as --
                       MR. CORLETTI:  No, but basically you look
           at the in-surge and really the pressure outside.  It's
           dependent not only on the power, but really on the
           overall reactor coolant system volume and the changes
           in temperature.
                       MEMBER KRESS:  You didn't change it.
                       MR. CORLETTI:  That's exactly right.  We
           didn't change that 70 percent.
                       CHAIRMAN WALLIS:  So it's just thermal
           expansion of the water?
                       MR. CORLETTI:  That is -- yes.  So
           basically you would have a -- the real sizing they do
           a trip without inserting the rods and you have the
           expansion of the water and you see whether prevent
           filling it up.
                       MEMBER KRESS:  To anticipate a transient
           without a scram is --
                       CHAIRMAN WALLIS:  Just like losing a fan
           belt on a car.
                       MR. CORLETTI:  That's how we do our design
           calculations, yes.  Okay.  Thank you very much.
                       CHAIRMAN WALLIS:  We are ahead of time,
           aren't we?
                       MEMBER KRESS:  We'll be challenged on that
                       MR. SCHULZ:  Thanks, Mike.  As Mike said,
           there are several items that I am going to try to talk
           about here related to the passive safety systems
           design for AP1000.  
                       I would like to talk about the design
           changes that we've made and try to give you some
           insights and understanding as to how we went about it
           and how we arrived at the sort of curious some things
           are bigger, some things aren't.  
                       MEMBER KRESS:  What's an Advisory
                       CHAIRMAN WALLIS:  A smart one.
                       MR. SCHULZ:  It's an official category of
           engineering at Westinghouse.
                       MEMBER KRESS:  It's one of their official
                       CHAIRMAN WALLIS:  It's like an Advisory
                       MR. SCHULZ:  I wouldn't --
                       MEMBER SHACK:  He's eligible to become a
           first principal.
                       MEMBER KRESS:  Where I went to school we
           never had a category called Advisory Engineer.
                       MR. SCHULZ:  The second thing that I'm
           going to talk about is a margins assessment that we've
           done.  These are very simple --
                       CHAIRMAN WALLIS:  I was very struck by the
           simplicity.  They're extraordinary simple.  I would
           think a thing as expensive as this and as important as
           this would be something a little more sophisticated. 
           I mean it seems to be very, very crude --
                       MEMBER KRESS:  Actually, I was quite
           pleased with that approach myself.
                       CHAIRMAN WALLIS:  You liked that.  It's
           very good for a start.
                       MEMBER KRESS:  What's why --
                       MEMBER SHACK:  That's what the designer
           really did and then he went off and did the analysis
           after he had it.
                       MEMBER KRESS:  Yes.
                       CHAIRMAN WALLIS:  I would have thought
           you'd optimize it or something -- computer codes and
           say is this really the best we can do?
                       MR. SCHULZ:  It is an iterative process. 
           We already in this short time that we've been working
           on AP1000, we've gone around several times on should
           we make the accumulators bigger or not?  What happens
           if we run them faster?  What happens if we try to make
           them bigger?  What are the costs of making them bigger
           in terms of the plant impact?  We've been doing that. 
           What you see here is more of the end result of the
           iterations we've made.  
                       There is a role.  The margins assessment
           is -- a lot of this comes out of the design process. 
           What you see in the report is more of an end
           assessment of where we ended up.
                       In addition, as Mike mentioned, as I
           already showed you some, we've used the AP600 SSAR
           safety analysis codes and we've made some analysis on
           AP1000 for the purpose of assessing where we think we
           are in terms of the design changes and do we think the
           design is adequate.
                       MEMBER KRESS:  Now if Hal Lewis were here,
           he would point out to you that principals run schools.
                       MR. SCHULZ:  Yes.
                       MEMBER KRESS:  But I'll refrain from doing
                       MR. SCHULZ:  Thank you.  Mike has already
           talked about the design approach on the plant level
           and of course it's very important for us in terms of
           the economic viability of what we end up with and the
           resources it takes to get there that we minimize the
           changes to the plant.  But at the same time we need to
           make the plant safe and have adequate margins and in
           doing that margin thinking, we've been looking at both
           deterministic, which I'm going to talk about mainly
           today and also the probabilistic area.
                       Now when I'm talking about probabilistic-
           wise is more the T & H success criteria, how many ADS
           valves do we need to prevent core melt kind of thing. 
           And we have done some looking at that already in our
           process in trying to check whether the systems are
           adequately sized for AP1000.
                       And also keeping in mind as we did in
           AP600, where there is uncertainty in testing and
           analysis, we're providing margin in the systems
                       CHAIRMAN WALLIS:  Your hand calculations
           struck me as being sort of independent.  You assessed
           each part independently, but as I remember an analysis
           of AP600's behavior, it's the interaction between
           these systems which is pretty key in an accident and
           the balance between them as hydrostatic heads and
           Novak Zuber's bathtubs and things and you cannot
           really look at one by itself and say well, just look
           at how that performs because it affects the whole
           transient which changes when the next one comes on and
           how they interact and all that.
                       I think you'd have to run computer
           programs quite a bit in order to iterate to a good
           design.  I was very surprised that the hand
           calculations seemed to work out or they did work out. 
           That was your real basis --
                       MR. SCHULZ:  I think we are not making
           these hand calculations in a vacuum.  We have done a
           lot of analysis on AP600, a lot of testing and from
           that we've gained insights into what are the limiting
           points in a transient?  What are the limiting events?
                       And then with that understanding we say
           okay, if we take a snapshot in time when the RWST is
           just starting to inject, this is the delta P we have
           and if we take that same delta P which is an
           assumption, a critical one, and apply it to AP1000,
           how much more flow do we get and does that seem to
           make sense?  So yes, it is very much separate effect
           on a system, but we're using our experience and
           judgments on what we learned on AP600 analysis and
           testing to try to focus in on what we think will be
           the limiting situation for AP1000.
                       Now it's not enough to just do that. 
           That's why we've already exercised a computer code as
           a good check on the integrated effects.
                       MEMBER KRESS:  Are you going to give us
           details on the sub-bullets, the deterministic criteria
           and this PRA success criteria later?
                       MR. SCHULZ:  As I go through each feature,
           I will mention what we've looked at.  I won't really
           be presenting any analysis.  We have done some map
           analysis which is what -- what we would do to at least
           initially assess what the success criteria is.  In
           fact, I don't think we've reported any in that report
           that we gave you that we did mention that we had done
           that.  I will mention a couple of features where that
           -- where we did some work in that area.
                       So if I don't say enough about that, I'm
           sure you'll remind me.
                       So what I intend to do now is go through
           feature by feature and talk about what's different,
           what's the same and then go through the margins
           assessment and some safety analysis for each.
                       So in the passive RHR, the configuration
           is identical in terms of where it connects to the RCS,
           where the heat exchange is located, where the water
           returns to the steam generator, the valving
           arrangement is all identical.  The elevation of the
           heat exchanger is the same.
                       The changes that we made were increase the
           pipe through the system from 10 inch to 14 inch, so we
           made a significant increase in the pipe size.  Now
           originally, when we started AP1000, that's all we did. 
           We left the heat exchanger alone.
                       But then through some of our iteration
           process, into a computer analysis, that wasn't enough,
           so then we looked at making the heat exchanger a
           little bit bigger.  And so the other change that we
           made to the design is to increase the surface area of
           the heat exchanger about 20 percent.
                       When we did that by adding a few tubes, it
           turned out on AP600 on the tube sheet there were about
           9 tubes on the top and bottom rows that were left out. 
           We left them out because we just didn't need that
           surface area.
                       So on AP1000 we said well, that's an easy
           way of getting a little bit more surface area, so we
           filled in the tube sheet on the top and bottom rows
           and we also extended horizontal portion of the heat
           exchanger 3 feet.  Of course, on the top and the
           bottom.  And the total effect of that was to give us
           about 22 more percent more surface area.
                       CHAIRMAN WALLIS:  Now are the flow
           patterns in this heat exchanger are important, I mean
           the stratification and that sort of stuff in the pool
           and everything, does that make a difference to the
                       MR. SCHULZ:  One of the things that we got
           out of the testing that we've done in both the passive
           RHR, especially the passive RHR testing, we
           investigated and tried to quantify the mixing in the
           tank and what we learned from that is the tank does
           mix well horizontally.  The heat exchanger is kind of
           like a pump and it pumps water and keeps the tank
           relatively uniform.
                       The tank is not getting bigger, but we are
           adding a little bit more water on top by adding,
           putting in some more accurate low instrumentations, so
           we're gaining a foot or so of water level in the tank,
           but the tank is not getting significantly larger.  So
           it will heat up a little faster and it will start
           boiling a little sooner, but that doesn't seem to be--
                       CHAIRMAN WALLIS:  That's a well-mixed tank
           in both cases?
                       MR. SCHULZ:  Yes, it's a well-mixed tank. 
           So early on when you're trying -- worried about
           mitigating the design transient or loss of flow of
           feedline break, the tank is going to be subcooled. 
           Bulk-wise anyways.
                       MEMBER KRESS:  This tank is half moon
                       MR. SCHULZ:  Yes.
                       MEMBER KRESS:  The heat exchanger is on
           the flat side?
                       MR. SCHULZ:  It's on one end.  I don't
           know that I have a slide.
                       I've got one that shows --
                       MR. CORLETTI:  Page 42 of the slides.
                       MEMBER KRESS:  I see where it is.
                       MR. SCHULZ:  This is the tank here.
                       CHAIRMAN WALLIS:  Where is the tank
                       MEMBER KRESS:  It's that solid line.
                       MR. SCHULZ:  This is actually the
           operating deck so you can't really see the tank, but
           it's under this part here.  The heat exchanger is
           actually under this hatch.
                       CHAIRMAN WALLIS:  That sets up currents
           which mix the whole tank?
                       MR. SCHULZ:  Mix the whole tank, yes.
                       MEMBER KRESS:  That's why I was --
                       CHAIRMAN WALLIS:  That doesn't change --
                       SPECIAL AGENT WHITE:  That's the reason I
           was asking.  Over there in the corner.  You ran a test
           on a model of this with 3 or 4 tubes?
                       MR. SCHULZ:  Yes, yes.  And those tubes
           were baffled off from the rest of the tank to try to
           give us a way of assessing the mixing.
                       This is the corner -- this is where the
           pressurizer is, so it comes up through here and the
           tank wraps around.
                       CHAIRMAN WALLIS:  Do you get boiling from
           these tubes to empower the transient?
                       MR. SCHULZ:  As the transient goes on, you
           do.  Early on, you get essentially no boiling.
                       CHAIRMAN WALLIS:  And it's the same kind
           of scenario, I mean the boiling progresses and is
           there anything different about the two power levels in
           terms of boiling?
                       MR. SCHULZ:  We don't think so in the
           short term.  In the longer term, the AP1000 tank will
           heat up quicker, but in both cases, we're talking
           about more than an hour before you start boiling in
           the tank, before the tank really reaches saturation. 
           We'll get some local boiling a little before that, but
           until you get really vigorous boiling around the heat
           exchanger will be well beyond an hour.
                       MEMBER KRESS:  Now how did you know this
           tank was pretty well mixed?  Is this a calculation
           that you did?
                       MR. SCHULZ:  Well, it's based on this
           testing, primarily.
                       MEMBER KRESS:  Based on that testing?
                       MR. SCHULZ:  Yes.  We took temperature
           measures around the tank and could see that -- I mean
           the top of the tank heats up a little faster than the
           bottom of the tank, but there is this, around this
           heat exchanger there's a strong circulating current
           driven by the heat that you're putting in there, so it
           keeps putting the colder water from the bottom of the
                       CHAIRMAN WALLIS:  Is steam being involved
                       MR. SCHULZ:  Eventually, yes.
                       CHAIRMAN WALLIS:  Presumably, there's more
           steam being involved in an AP1000?
                       MR. SCHULZ:  Be more and it would happen
           a little sooner, yes.  And that gets vented to the
           containment when that starts occurring the passive
           containment cooling comes into play.
                       CHAIRMAN WALLIS:  How is this formed?  Is
           there sort of a great evolution of steam and level
           swell in this corner of this tank and --
                       MR. SCHULZ:  Yes.  I think that fluid to
           the heat exchanger --
                       CHAIRMAN WALLIS:  Will be some kind of
           bubbling and frothing and swelling.
                       MR. BROWN:  Dr. Wallis, Bill Brown here. 
           We noticed that's really more -- the real level swell
           we saw in the test was really more associated when the
           automatic pressurization system goes off.  So if
           you're thinking about swelling and things in the tank
           the real challenge to that is when the ADS 123
           discharges in here.  This is more of a bulk boiling
           situation.  So level swell is really associated with
           the ADS.
                       CHAIRMAN WALLIS:  Now this pipe goes into
           the bottom of the steam generator, it's a different
           steam generator?
                       MR. SCHULZ:  Yes.
                       CHAIRMAN WALLIS:  I think there's
           something about mixing in the bottom of the steam
           generator which they used a stratification in the cold
           leg or didn't we go through that with APU 600?
                       Didn't we worry at one stage about mixing
           it in the -- where your pipe comes out of the steam
                       MR. SCHULZ:  I believe there was some
           notice of that, especially in OSU.  When the heat
           exchanger starts working, there's still steam being
           released from the steam generator which means that
           there's still a flow going through that, through the
           loop, through the tubes of the steam generator and
           it's not just flow through the passive RHR circuit.
                       As long as that continues and it will
           continue for some time, depending on the particular
           transient, it may be half an hour or it may be an hour
           before the steaming is terminated in that steam
           generator and passive RHR has -- its capacity matches
           the decay heat.  Now after that point in time there
           will tend to be more of a stratification in the loop
           than before them when there is still circulation flow
           through the steam generator.
                       CHAIRMAN WALLIS:  Is this the same as in
           600 or do you run into some new phenomenon of
           stratification that's different.
                       MR. SCHULZ:  I don't think it's the same
           phenomenon.  Things may occur in a little bit
           different timings and because the flow through the
           passive RHR is a little bit greater.  The temperatures
           are not lower coming out of the heat exchanger or are
           not significantly different, so and the flow is a
           little bit greater because of the bigger pipes through
           the system.
                       But I think the phenomenon is the same
           that there would be colder water running around the
           bottom of the pipe, primarily after you get to the
           point where you match decay heat.
                       The margins assessment again as we
           mentioned to start with, I had mentioned to start with
           tends to be a simple first principles calculation.  In
           this case, we tried to calculate the natural
           circulation heat removal from the heat exchanger.
                       Now this is not quite as simple as some of
           the other calculations so actually you're exercising
           the same correlations, heat transfer correlations that
           we use in our safety analysis codes that in a stand
           alone spreadsheet type of program which gives fairly
           close agreement with the safety analysis code.
                       So by putting some boundary conditions in
           terms of the RCS temperature and the temperatures we
           picked were based on the steam generator safety valve
           setpoints which are a little bit higher in AP1000 than
           AP600.  In exercising that code, we end up calculating
           did we get about 170 so percent more decay heat
           removal which is not quite equal to the increase in
           power, but very close to it.  So that's a comforting
                       Another thing that we checked in this is--
                       CHAIRMAN WALLIS:  In thinking about this,
           isn't the limiting heat transfer resistance until you
           get boiling, it's only RWST side, it's a natural
           convection in the RWST which is much less effective
           than this stuff that's whipping around your 14-inch
           pipe and going around.
                       MR. SCHULZ:  Yes.
                       CHAIRMAN WALLIS:  So that's the limit and
           that isn't going to be increased much by increasing
           the velocity or decreasing the flow path resistance.
                       MR. SCHULZ:  In terms of heat transfer
           coefficients, yes, but by having more surface area and
                       CHAIRMAN WALLIS:  There isn't 72 percent
           more --
                       MR. SCHULZ:  No, there isn't.  There's 22
           percent more surface area, but by reducing the
           resistance on the primary side, we can allow more
           water to flow with a given density difference and you
           can go through that using the same correlations which
           are more limiting on the tank side, but you still
           can't improve that heat transfer by reducing the
           resistance on the primary site.  Not so much from a
           heat transfer effectiveness point of view, but by
           giving a certain density difference, you can get more
           flow to circulate and of course, there is interaction
           there between how much flow is circulating and what
           the delta T is on the heat exchanger.
                       CHAIRMAN WALLIS:  So you've increased your
           heat flux by 30 percent, I see.
                       MR. SCHULZ:  Yes.  But we think we're
           still comfortable versus critical heat flux in the
           heat exchanger.
                       The other thing that is an important
           consideration here is as I mentioned when you first
           turn the heat exchanger on it can't match decay heat.
                       CHAIRMAN WALLIS:  I don't know why you
           worry about heat flux anyway because it's going to get
           cooled somewhere else eventually.  It's not that
           critical, is it if you get critical heat flux?  It's
           not as if it's called a heat source which kind of --
           any type of heat aspersion --
                       MR. SCHULZ:  Right, it's not critical from
           that point of view, no, no.
                       MEMBER KRESS:  That's why the design
                       MR. SCHULZ:  It's just that if you got
           less heat transfer than you thought you were getting
           from a portion of the heat exchanger, the overall heat
           transfer of the heat exchanger might be a little less
           than you thought, but what tends to happen if you ever
           got into critical heat fluxes the hot part of the
           tubes gets a little less heat temperature reduction
           and the heat moves on to the heat exchanger and these
           tubes are relatively long so eventually you get most
           of that heat out, but it would affect the overall heat
           transfer somewhat, so it's something that we look at
           and try to keep in mind in the design.
                       The other factor is how much of the steam
           generator secondary side water you boil off in an
           event and these percentages are a little confusing,
           but basically if you look at the amount of water in a
           steam generator per megawatt of core power.  The
           AP1000 has 36 percent more mass at the time of trip
           than AP600 does per megawatt.
                       And that when I say final water this is
           when you would calculate that you terminate steaming
           with the passive RHR.  So you've decreased the water
           level some, but in AP1000 basically you end up with
           twice as much water in the steam generator at the end
           of a transient than AP600.
                       CHAIRMAN WALLIS:  Does this make up for
           some of your other capacities not being increased in
           your accumulators at the same CMTs aren't that much
           bigger, but you have steam generators with a lot more
           water in them.
                       MR. SCHULZ:  It doesn't help accumulators
           of core make up tanks very much.  It helps the passive
           RHR a little bit.  Initially, we had a passive RHR
           that was maybe 25, 30 percent more capacity than the
           AP600 and this story on secondary site mass was more
           important than it is now because we've almost got
           parity with power in passive RHR.  So this is not so
           important as it was once when we were playing around
           with smaller passive RHRs.
                       CHAIRMAN WALLIS:  I guess it's only energy
           balance you care about in this phase?
                       MR. SCHULZ:  Yes.
                       CHAIRMAN WALLIS:  It's not mass --
                       MR. SCHULZ:  In fact, this -- we've toyed
           with, is it good to have more, is it good to have
           less?  When you get to the containment, having more
           mass here challenges the containment mass energy
           input, so it's not so good from that point of view,
           but it is better from say a transient mitigation point
           of view.
                       So that's the margin story.  We've also
           done some safety analysis, transients again to assess
           the AP1000 and the selection of the passive RHR heat
           exchanger changes.  Same methods as we used on AP600,
           conservative inputs and models.  We selected several
           limiting transients.  We've looked at all four of
           these events for AP1000.
                       Due to time limitations we chose to show
           you what the loss, feedline rupture looks like and the
           curves are a little confusing here, but basically the
           criteria is subcooling and maintaining subcooling and
           if you look at this dotted line versus the solid line,
           the dotted line is saturation temperature and the
           solid line is the hot leg temperature, so you see the
           hot leg temperature is dropping down to a comfortable
           level below the saturation temperature.
                       In both cases, the transients look a
           little different.  AP1000 doesn't cool down quite as
           much, as fast.  So in both cases there's a comfortable
           margin.  If you actually look at one of these
           transients for an operating plant, you would see the
           subcooling become much less in time, it tends to drop
           down, but then come back up and the margin is a lot
           less.  So AP600 and AP1000 both have a lot higher
           subcooling margins than most operating plants.
                       And so our conclusions from that is that
           from our assessment of these computer calculations is
           that the AP1000 has comparable behavior and margins to
           AP600 and so we're -- we feel comfortable with the
           sizing of the passive RHR.
                       CHAIRMAN WALLIS:  Margin, what do you
           mean, your measure of margin?
                       MR. SCHULZ:  In this case, like
                       CHAIRMAN WALLIS:  Like subcooling.  Yeah. 
           It's not a direct measure of some sort of safety
           margin.  It's an indirect measure -- it's better to
           have more subcooling therefore as an indication.  But
           it's not a very quantitative measure.
                       MR. SCHULZ:  You can go through this
           transient side about so many degrees minimum.
                       CHAIRMAN WALLIS:  Yeah, but I'm not quite
           sure what that means in terms of --
                       MR. SCHULZ:  Real safety?
                       CHAIRMAN WALLIS:  More definite measure of
                       MR. SCHULZ:  The acceptance criteria for
           feedline break is keeping the reactor subcooled.  Now
           does something real bad happens when it becomes
           saturated?  Not necessarily.
                       So it's more of a licensing criteria than
           a safety criteria.
                       I'd like to now move on to the passive
           safety injection.  And again, the configuration of the
           AP1000 in terms of numbers of tanks, the valving
           arrangement is identical with the AP600.  The
           accumulators are the same size and we'll be talking
           about each of these features in a few minutes.  The
           core makeup tank is 25 percent bigger and we increased
           the orifice that controls the CMT flow so that's flow
           rate is also 25 percent bigger.  We've increased the
           pipe sizes from the IWST to the direct vessel
           injection line.  We've also increased the
           recirculation piping and we've also increased the
           stage 4 ADS piping and valving.  The other piping has
           not been changed.
                       CHAIRMAN WALLIS:  On the ADS 1, 2 and 3
           are still the same?
                       MR. SCHULZ:  Exactly the same.
                       CHAIRMAN WALLIS:  Which I found a little
           surprising, but maybe there's a good reason for it.
                       MR. SCHULZ:  There is a reason.  We think
                       CHAIRMAN WALLIS:  You have less mass of
           water per megawatt?
                       MR. SCHULZ:  Yes.
                       CHAIRMAN WALLIS:  But your hand
           calculations emphasize flow rate.  You have bigger
           pipes and all that, so you try and duplicate the flow
           rate, but there's less mass.  So in terms of a mass
           balance you might think there's a less margin, less
           water to cool to use the RWST?
                       MR. SCHULZ:  You could say that.  We think
           that when you look at a bit more mechanistic in terms
           of specific situations that we have sufficient margin
           and I think if we try to go through in our discussion
           here, you can see what you think.
                       CHAIRMAN WALLIS:  Okay.
                       MR. SCHULZ:  In some cases yes.
                       MEMBER SHACK:  You have adequate margin,
           but by and large, it does it smaller, for things like
           peak clad temperature.
                       MR. SCHULZ:  For large LOCA yes.  That's
           not necessarily true, we don't think it's true for
           like long-term cooling.  We think we're at the same or
           better margin because we've increased things much more
           than we did in other areas.  In other words, we were
           rather selective in where we increased things and how
                       CHAIRMAN WALLIS:  But you haven't decided
           that you want to stay with the same PCT as AP600, for
           instance.  You're going to get closer to the
           requirement, the regulatory limit.
                       MR. SCHULZ:  That's right.  Again --
                       CHAIRMAN WALLIS:  So you're going to see
           how far the staff will let you go in terms of raising
                       MR. SCHULZ:  I wouldn't put it that way. 
           We're not playing a --
                       MEMBER SHACK:  There's a known regulatory
                       MR. SCHULZ:  That's right.
                       CHAIRMAN WALLIS:  Yeah, but presumably
           somebody came in here several years ago and said 1644
           was great, now you're going to tell us 1940 is great.
                       MR. SCHULZ:  When we originally selected
           the accumulator sizes for AP600, we had no idea what
           the PCT was going to be.
                       CHAIRMAN WALLIS:  It seems very strange to
           me.  I think it worked backwards.  So you have a
           design criteria and worked back to whether cumulative
           size needs to be to meet it.
                       MR. SCHULZ:  I'm sorry?
                       CHAIRMAN WALLIS:  You seem to have picked
           an accumulator and then see what you get the PCT and
           then said that's okay.  I think it worked backwards. 
           You designed the accumulator to achieve or the PCT you
                       MR. SCHULZ:  In this case, we realize what
           we're starting from a design, the AP600 equipment and
           we're saying how big does it need to be to provide
           adequate margin for AP1000.  So it's a little bit
           different than starting with a clean sheet of paper.
                       CHAIRMAN WALLIS:  But the adequate margin
           apparently is a higher PCT?
                       MR. SCHULZ:  In this case, yes.
                       CHAIRMAN WALLIS:  Why is that so?  Why is
           it now acceptable to have a higher PCT than before?
                       MR. SCHULZ:  It always was acceptable.  We
           didn't design to a particular PCT.
                       CHAIRMAN WALLIS:  But some designers
           decided 1940 is now okay as opposed to 1644.  These
           are much more important numbers than choosing the
           accumulator as the same as before or something.  If
           you had twice as big an accumulator, maybe you could
           bring that down to 1644, I don't know.
                       Someone has decided that these are okay
                       MR. SCHULZ:  Basically, all the operating
           plants in the United States have temperatures that are
           this --
                       CHAIRMAN WALLIS:  So you decided to be a
           little less conservative than you are with 600?
                       MR. SCHULZ:  That's right.  
                       MEMBER KRESS:  If that number had been
           2100 would you have felt "iffy" about it?
                       MR. SCHULZ:  Yes, I would have felt iffy. 
           If we had gotten to the point where these numbers were
           higher than most operating plants and were getting
           close to the limit --
                       MEMBER KRESS:  How do you know how close
           that is to 2100?
                       MR. SCHULZ:  2200.
                       MEMBER KRESS:  Well, I said 21 because I
           didn't want to get all the way up to 22.
                       MR. SCHULZ:  Okay.
                       MEMBER KRESS:  Because I was seeing the
           uncertainty on the number.
                       CHAIRMAN WALLIS:  It's with uncertainty.
                       MR. SCHULZ:  With uncertainty.
                       MEMBER KRESS:  That's with uncertainty?
                       MR. SCHULZ:  With uncertainty.  We're down
           at 1670 without, approximately.
                       MEMBER KRESS:  What's that, two sigma of
                       MR. SCHULZ:  This is the -- I don't know
           what -- maybe Bob Kemper can help me out, but these
           are the uncertainties that were calculated basically
           for AP600 for both co-retract and the PCT uncertainty. 
           So the plant parameters and the models both are
           accounted for in here.
                       MR. KEMPER:  Bob Kemper here.  What Terry
           is showing as the reflood PCT with uncertainty would
           be our assessment of the 95th percentile value as
           obtained with our large break LOCA EE methodology. 
           And that's the assessment we have at this time for
                       MEMBER KRESS:  So 99 percentile might have
           been about 2200?  Why is 95 percentile acceptable is
           my question?
                       MR. KEMPER:  That is the basis for the
           large break LOCA methodology with best --
                       MEMBER KRESS:  Using best estimate.
                       MR. KEMPER:  COBRA track best estimate.
                       MEMBER KRESS:  So this was a best estimate
           calculation rather than Appendix K?
                       MR. KEMPER:  The AP600 was done with the
           approved methodology for large break LOCA.
                       MEMBER KRESS:  Which was Appendix K?
                       MR. KEMPER:  No.  It uses the uncertainty
           determination and that would be essentially best
           estimate decay heat and then the decay heat
           uncertainty is rolled in with the other uncertainties
           in CSAU type methodology to obtain the result.
                       MEMBER KRESS:  Okay.  That's very helpful.
                       CHAIRMAN WALLIS:  So it looks as if
           somebody said let's go with the same accumulator and
           see what we get for PCT?
                       MR. SCHULZ:  Yes, and there are several
           considerations here.  One, we actually studied taking
           the same accumulator and readjusting the flow orifice
           to get more flow.  And by doing that we can reduce the
           large break LOCA PCT.
                       However, there are other events that the
           accumulator plays a role in, small break LOCAs and in
           particular small LOCAs that are involved in multiple
           failure PRA-type events where say the accumulator --
           not accumulator, the core makeup tanks have been
           failed due to some common mode failure that would be
           considered in the PRA.  And having accumulators empty
           quicker in those kind of events is not good, so it's
           not safer.
                        So we in the balance between those two
           events, the large break LOCA which is a very low
           probability event and in fact some day maybe
           eliminated from consideration, we felt that the safety
           was better balanced by maintaining the small break
           LOCA-type performance where the accumulator runs a
           little bit longer.
                       Now we also could have made the
           accumulator bigger.  However, it's buried in concrete,
           basically, surrounded by concrete.  It's already a
           sphere, so we've maximized the volume in the space
           available.  So it would have been rather disruptive to
           the plant design and structures to make the
           accumulator bigger.
                       CHAIRMAN WALLIS:  So now you've got a
           sensible argument.  It seems from a spherical
           perspective, it's not a very expensive thing
           comparatively speaking.  The obvious thing would be to
           make the accumulator bigger, but if they've got some
           good reason for space constraints, then that makes
           some sense, but in terms of 
           thermal-hydraulics, it seems to be very arbitrary to
           say well, choose the same size.
                       MR. SCHULZ:  Yes, yes.
                       CHAIRMAN WALLIS:  So there is some reason
           for it.
                       MR. SCHULZ:  The tank itself is not that
           expensive, so we have had space to make it easily
           bigger, that would have been a different story.
                       In the core makeup tanks, we actually did
           choose to make the tank bigger.  This tank does have
           constraints vertically.  It's located on a concrete
           floor so we can't go down very easily.  The operating
           deck is fairly close to above the tank so we can't
           really make it bigger.  We did choose to make it a
           little fatter, 25 percent increase in volume.  
                       This is a very expensive tank.  It's a
           full system design pressure, Class I vessels.  It's a
           very expensive tank, so it's something that we have to
           keep in mind.  Now the cost of the tank is not so
           significant relative to the cost of the plant.  I want
           to imply that, but it is an expensive tank.
                       Why 25 percent?  That's kind of a curious
           number.  Let me try to explain what we did.
                       MEMBER KRESS:  You knew we would ask that,
           didn't you?
                       MR. SCHULZ:  Yes.  We asked ourselves too. 
           In our looking at the range of accidents that the core
           makeup tank deals with, we think one of the more
           limiting events is a direct vessel injection line
           break which eliminates one of the tanks, in fact, half
           of the injection system. 
                       And at the point in time where the
           accumulator is empty which of course happens first in
           a transient, the accumulators start running and when
           they run fast as the plant depressurization occurs,
           the core makeup tanks don't inject because of the way
           the systems interact, the tanks interact and when the
           accumulator empties then the core makeup tank is
           basically relied upon to maintain core cooling.  That
           occurs in about 10 minutes after the accident.
                       Now if you look at that period of time and
           take decay heat and some instrument of sensible heat
           coming out of the fuel in the reactor vessel, you can
           estimate a heat that you should be removing and back
           calculate a safety injection flow.
                       Now it turns out that when you do that
           AP600 had a significant margin relative to that flow
           requirement, basically 38 percent margin.  
                       MEMBER KRESS:  And you want to remove that
           amount of heat over some time period?  There's a
           window in there, I seem to remember --
                       MR. SCHULZ:  I'm looking at an instant in
                       SPECIAL AGENT WHITE:  You were looking at
           an instant in time.
                       MR. SCHULZ:  I'm looking at an instant.
                       MEMBER KRESS:  But you want to continue
           that removal, have enough water to continue that
           removal --
                       CHAIRMAN WALLIS:  That is why the flow
           capability and the volume are up by 25 percent?
                       MR. SCHULZ:  Right.  There's two questions
           here.  I'm addressing right now the flow rate question
           and then I should speak separately about the volume
           and duration question because we actually separately
           looked at those two.
                       In thinking about the flow rate question,
           it turns out that if you take the AP600 core makeup
           tank, it would just about match the AP1000 calculated
           requirement, but it would have very little margin to
           it.  And we were uncomfortable with that.  So that's
           part of where the 25 percent increase in flow rate
           comes from.
                       The other place where that comes from is
           looking at some multiple failure scenarios where we
           don't have any accumulators and in that case having
           some more flow rate out of the core makeup tanks is
           also beneficial.
                       CHAIRMAN WALLIS:  Now these numbers, this
           requirement per flow is based on an energy balance, do
           you know the core, the decay heat --
                       MR. SCHULZ:  Decay heat --
                       CHAIRMAN WALLIS:  There are very few
           uncertainties in those numbers?
                       MR. SCHULZ:  Decay heat there's very
           little uncertainty.  There's a little more uncertainty
           maybe in the sensible heat that's also 
                       CHAIRMAN WALLIS:  Those are pretty hard
           numbers, not much uncertainty, so you don't need a
           huge margin.  You need some margin.
                       MR. SCHULZ:  That's right.  I would agree
           with that.
                       CHAIRMAN WALLIS:  So the rationale thing
           probably would be to match your margin to your
           uncertainties in some logical way so it would be
           explainable to a committee like this one?
                       MEMBER KRESS:  Where have I heard that
                       CHAIRMAN WALLIS:  That is to make Dr.
           Kress happy.
                       MEMBER KRESS:  Yes.  I would be ecstatic,
           wouldn't I?
                       MR. SCHULZ:  I am not sure I could do
                       The other thing that we factored in here
           in terms of volume is that we did not want the tank to
           have a shorter duration of injection.  That plays into
           ADS sizing and RWST injection capability which we feel
           that that is an area where we really want to keep
           margin and not reduce margin versus AP600 and by --
           with the power increase that we already need to deal
           with, shortening the CMT injection would add to the
           burden that ADS and RWST injection would have to
                       So one of our sort of internal guidelines
           was not to shorten that initial cut in requirement for
           when RWST injection should start.  And by maintaining
           CMT duration of injection that helped us in that
           mission.  That's kind of a soft requirement, but
           that's the way we kind of approached it and why we
           kept the CMT, increased its volume when we increased
           the flow rate.
                       What I'm going to go through is the ADS
           margin assessment and then RWST margin assessment and
           then show you a small break LOCA which kind of looks
           at the integrated effects of those three elements.
                       In ADS we increased the size of the four
           stage and again the ADS four stage is obviously one of
           the most important features in getting to the low
           pressure where you can get RWST injection.  So we feel
           that that is a very important feature.  It's important
           to have this adequate capacity.
                       CHAIRMAN WALLIS:  But did you increase it
           because you didn't want to change 1, 2, 3 -- 1, 2 and
           3 are the same so you're getting less depressurization
           from 1, 2, 3 proportionally or the bigger system?  In
           order to catch up, then you have a bigger ADS fall? 
           Is that the way that I should think about it?
                       MR. SCHULZ:  There's a couple of reasons
           why we didn't change stages 1, 2 and 3.  One of them
           is 1, 2 and 3 is not very useful at the RWST cut in
           point because you end up, according to the testing and
           analysis with water in the pressurizer which severely
           limits the amount of flow that you get through the
           pressurizer.  And so making 1, 2 and 3 bigger we
           didn't think would help very much.  So it was much
           more effective and probably necessary to increase four
           stage --
                       CHAIRMAN WALLIS:  What about 1, 2, 3 and
                       MR. SCHULZ:  To basically get you to --
                       CHAIRMAN WALLIS:  To depressurize and to
           depressurize along the same sort of curve, you
           presumably need a bigger 1, 2 and 3 for a bigger
                       MR. SCHULZ:  If you wanted to depressurize
           along the same curve.
                       CHAIRMAN WALLIS:  Do you depressurize a
           little slower at the beginning and faster later on, is
           that what you --
                       MR. SCHULZ:  Yes, and where you notice it
           is at the lower pressures.  At the higher pressures,
           it doesn't make a lot of difference because you
           depressurize fairly rapidly when you're say above 100
           psi or something.
                       CHAIRMAN WALLIS:  This doesn't quite
           follow the same scenario time-wise as an AP600.  You
           would have actually increased the size of 1, 2 and 3
           and 4.
                       MR. SCHULZ:  If you wanted to scale it up,
                       CHAIRMAN WALLIS:  Right.
                       MR. SCHULZ:  Exactly.
                       CHAIRMAN WALLIS:  So you've changed the
           sequencing of things a bit, presumably, with this
                       MR. SCHULZ:  A little bit, yes.  And we
           have even thought, if we started with a clean sheet of
           paper, which we aren't, that maybe we'd even take out
           the third stage because it's not so useful.  One of
           the things we've learned in all our testing and
           analysis is it's much more effective in terms of
           getting to the lower pressures to have hot leg venting
           than pressurizer venting because there's things that
           happen in the pressurizer that interfere with its
           effectiveness at low pressures, not high pressures,
           but low pressures.
                       MEMBER KRESS:  I would have thought when
           you depressurize this vessel that the most important
           thing was the stored energy in the water and how much
           water is in there and the volume and not the power. 
           So the 76 percent, various size, bothers me a little
           because I don't think the total volume of water in the
           primary system changed that much and I think don't
           it's internal energy at the start changed that much.
                       So it seems to me like -- I'm disagreeing
           with what Graham said because I would have thought the
           thing would have just depressurized about the same as
           the AP600 with the 1, 2, 3 as it's sized.  And even
           with the 4 as it's sized.  I may be wrong there --
                       CHAIRMAN WALLIS:  It's a bit bigger, but
           it's not bigger proportionately.
                       MEMBER KRESS:  No, it's not 76 percent
           bigger internal energy.  So I'm still not quite sure
           of the choice.
                       MR. SCHULZ:  I think there's an element,
           if you think about large LOCAs, I think that's much
           more true, when you're blowing down the system very
           rapidly, how much you're starting with is very
                       Our EDS is sequenced and blows -- it's a
           more protracted blow down.
                       MEMBER KRESS:  If you're right -- you're
                       MR. SCHULZ:  Probably more important.
                       MEMBER KRESS:  Yes.
                       CHAIRMAN WALLIS:  Anyway, it's all going
           to be clarified by some computer runs of how they
           really work, not just the hand calculations.
                       So you have a new ADS 4 valve that you're
           going to test at full scale?
                       MR. SCHULZ:  We need a new ADS stage 4
           valve yes.
                       CHAIRMAN WALLIS:  Are you going to test it
           at full scale?
                       MR. SCHULZ:  When we build the plant we'll
           -- when we build the valve, we will test the valve.
                       CHAIRMAN WALLIS:  Yes.
                       MR. SCHULZ:  In a test facility.
                       CHAIRMAN WALLIS:  You don't need the plant
           to test the valve.
                       MR. SCHULZ:  Right, in fact, it's a little
           difficult to do that.  Right.
                       MR. GAGNON:  What I provided Terry is
           basically the depressurization response.  I'm Andy
           Gagnon from Westinghouse.  
                       That's just a depressurization response
           for an inadvertent ADS small break LOCA situation.  As
           you can see, the depressurization characteristics are
           very similar with the common ADS 1 to 3.
                       MR. SCHULZ:  And you're right, it does
           come down a little slower, but still, this is pretty
           rapid depressurization.  I think is this where the
           fourth stage opens up?
                       MR. GAGNON:  Yes.
                       MR. SCHULZ:  So we come down here and hold
           until the fourth stage finally opens up near the end
           -- later in the transient.
                       CHAIRMAN WALLIS:  Now do you put on there
           things like CMT training, would they occur about the
           same time?
                       MR. SCHULZ:  I think so, as I recall.
                       MR. GAGNON:  For the inadvertent ADS, yes,
           it's approximately the same time.
                       MR. SCHULZ:  And about the same duration
           as it was designed to do. 
                       The other assessment that I wanted to talk
           about before we showed the small break analysis was
           the IRWST.  And we basically did two things here to
           improve the injection capability.  One is to raise the
           initial water level.  Now we didn't raise the maximum
           water level.  What we did is compress the operating
           band and a lot of that operating band was given up to
           errors in level measurement because we only had a wide
           range level measurement in the tank and it's like 30
           feet.  So that ended up giving us some significant
           possible errors in measuring the level and what we are
           doing at AP1000 is putting in a narrow range level
           instrument that will cut that error down quite a bit
           and end up giving us one and a half more feet initial
           water level.
                       The more significant thing was increasing
           the line size, basically that's the injection line
           size from the IRWST from 6 to 8 inches which
           significantly reduces the line resistance and if you
           run through the numbers, assuming some RCS pressure,
           containment pressure and with the initial hit of water
           in the tank, you'll get like an 84 percent more
           injection flow which is a little bit more than decay
           heat.  So again, this is an area where we think it's
           important to maintain AP600 margins without reducing
           them, and in fact, increasing them slightly.
                       CHAIRMAN WALLIS:  Now again you're talking
           about flow rate and not just the overall capacity. 
           The IRWST is not much bigger?
                       MR. SCHULZ:  It's not much --
                       CHAIRMAN WALLIS:  Same amount of water.
                       MR. SCHULZ:  Well, you get a little bit
           more water.
                       CHAIRMAN WALLIS:  Little bit.
                       MR. SCHULZ:  But not much.
                       CHAIRMAN WALLIS:  And it's going in
           faster, it's going in much faster.
                       MR. SCHULZ:  Right, now that will affect
           when you get to recirculation --
                       CHAIRMAN WALLIS:  Yes.
                       MR. SCHULZ:  Which is long term cooling
           which I'll get to in just a little bit.
                       Now if you take those effects and then
           look at a small break LOCA transient and then again
           using for assessing purposes the AP600 SAR analysis
           and this is NO TRUMP, Appendix K type approach, we
           looked at several different events, a 2-inch curve leg
           break which is sort of a reference one we look at. 
           DVI break which tends to be challenging from
           accumulator core makeup tank early injection
           capability and inadvertent ADS which tends to be more
           challenging in terms of ADS and IRWST cut in a little
           bit later.
                       This shows you the core mixture level and
           tries to compare AP600 to AP1000 for DVI line break. 
           You see initially AP600 has a dip and AP1000 doesn't. 
           And the main reason for that is this is the same break
           size in both plants and it's limited by a Venturi in
           the nozzle to about 4 inches ID and so since AP1000 is
           a better plant with the same break, it has a little
           bit less of a blow down effect early on.  So that's
           the main reason why AP1000 actually doesn't have this
                       Later on, the trends are pretty similar. 
           There's some minor variations of AP1000.  This is when
           IRWST is starting to inject and shut off and inject
           and shut off until out in the 2800, 2900 seconds RWST
           comes on and stays on and the level goes up a little
                       CHAIRMAN WALLIS:  What's the top of the
           core on this?
                       MR. SCHULZ:  This dotted line.
                       CHAIRMAN WALLIS:  That's the top of the
                       MR. GAGNON:  The vast line is the top of
           active fuel and they've been offset to represent the
           difference in vessel lengths.
                       CHAIRMAN WALLIS:  So the zero for the
           level is different than the two?
                       MR. GAGNON:  Yes, that's correct.
                       MR. SCHULZ:  And from this, we basically
           conclude that from the three basic transients that we
           looked at, we didn't see any core uncovery, the
           behavior of the plants were similar.  We didn't see
           any phenomenon that was different.
                       CHAIRMAN WALLIS:  Now this is a mixture
                       MR. SCHULZ:  Yes.
                       CHAIRMAN WALLIS:  The collapsed level is
           somewhere else, so there's some kind of a two-phased
           flow level which says how much the expansion due to
           the presence of the vapor is that we can rely on?
                       MR. SCHULZ:  Of course.
                       MR. GAGNON:  That's the core fraction
                       MEMBER KRESS:  The collapsed level would
           be a lot level for --
                       CHAIRMAN WALLIS:  There's a good
           verification of this, whatever the model is for the
           level swell, whatever you call it?  Because some of
           the models they use are not very good, over rise
           glossing or whatever it is that governs the level
           swell.  Maybe yours is.
                       MR. GAGNON:  It's the same model as in our
           approved valuation model. 
                       CHAIRMAN WALLIS:  That's for AP600.
                       MR. GAGNON:  Yes.
                       MR. BOEHNERT:  Is this calculated using NO
                       MR. GAGNON:  Yes.
                       MR. BOEHNERT:  Both of these?
                       MR. GAGNON:  Yes.  Same methodology.
                       CHAIRMAN WALLIS:  The staff has this code?
                       MR. GAGNON:  The staff does not have this
           code at this point.
                       CHAIRMAN WALLIS:  Is the staff going to
           get the code?
                       MR. GAGNON:  Uh --
                       MR. SCHULZ:  Mr. Gresham will address that
                       CHAIRMAN WALLIS:  It's interesting, I
           think, for people to run sensitivity studies on these
           sorts of questions about how is the collapse level
           related to the mixture level and so on, what's the
           sort of certainty with which you can make these
           predictions and what are the uncertainties and what's
           the sensitivity to some assumption of its own.
                       MEMBER KRESS:  Particularly with respect
           to this item here, because that's one of the things
           that gave us comfort was that the level never got down
           below the top of the core, except in one little period
           there it was, but --
                       MR. BOEHNERT:  There was also a problem
           using NO TRUMP from the standpoint the staff said, I
           think, said you could only use it on AP600 and there
           was an issue there about applicability to AP1000.  
                       CHAIRMAN WALLIS:  All the more reasonable
           why it needs to be tested in some way.
                       MR. BOEHNERT:  I would think.
                       CHAIRMAN WALLIS:  Does the staff have any
           intention to get this code and run it and then look at
           the kind of sensitivity questions?
                       MR. WILSON:  Jerry Wilson, NRR.  We made
           a request of Westinghouse to have the codes as part of
           our review.  And we expect -- you'll notice earlier
           there was a discussion about an additional report to
           be submitted and that's the code report and we expect
           to discuss this issue when that report is submitted.
                       CHAIRMAN WALLIS:  It's just going to be
           something you insist upon?  Just discussing it doesn't
           give me a good feeling.  Are you going to insist upon
           getting this code?
                       MR. WILSON:  I don't want to prejudge it. 
           As I said, we made a request and we'll see that
           Westinghouse has to say.
                       CHAIRMAN WALLIS:  Would it help if the
           ACRS said that you should insist upon it?
                       MR. WILSON:  It always helps to hear from
                       MEMBER KRESS:  Do they teach you guys
                       MR. WILSON:  It's part of the job.
                       CHAIRMAN WALLIS:  Okay.  
                       MR. SCHULZ:  The last part of the safety
           injection system that I want to talk about is that
           involving the long term cooling or the containment
           recirculation part.  And so what we have here is again
           a margins assessment looking at this aspect.  The line
           resistance has been significantly reduced by again
           making pipe sizes bigger.  
                       Another factor in that that is important
           is when do you get to recirculation?  And we have, as
           you noticed, kept the RWST about the same volume. 
           We've increased the injection lines which is helpful
           in terms of getting water into the reactor, but it
           also increases the spill rate, if you have a direct
           vessel injection line.  So if you look, for example,
           this DVI case without the RNS as the pumped RHR system
           which can interact in this event, so we have to keep
           account of whether it's operating or not.  But if you
           look at the case without RNS, this is just with the
           gravity passive systems working, in AP600 you would
           get to recirculation in 4.7 hours.  With that same
           event for AP1000, you get there soon, 2.6 hours and
           the main reason for that is that you've got a bigger
           line that's spilling so it helps drag down the level
           and get you to recirculation sooner.
                       CHAIRMAN WALLIS:  And you've got more
           decay heat then because it's sooner.
                       MR. SCHULZ:  And you've got more decay
           heat then, so we have to deal with that.
                       Now it turns out on AP600 that the
           limiting case was not the gravity case.  It was, in
           fact, the case where these RHR pumps were running. 
           The operators in the plant are instructed that if you
           have a LOCA and the ADS goes off, turn on these RHR
           pumps, even though they're not safety, they can help
           you.  Well, if you have a DVI line break, it actually
           can hurt you in some respects and that is instead of
           having recirculation occur in four some hours, it's
           2.1 hours. 
                       What we analyzed in AP600 SAR is the
           limiting recirculation cut in or initiation time was
           the 2.1 hours.  
                       Now if we take that same event for AP1000,
           it would even be short than 2.1 hours.  And we didn't
           want that to occur.  So what we ended up doing is
           changing the RHR pump design so that initially it will
           not take water out of the RWST.  It takes water from
           outside of containment, like a more conventional
                       MEMBER KRESS:  There's another tank out
           there somewhere?
                       MR. SCHULZ:  Yes.  We're going to take
           water out of the spent fuel, CAS loading pit or
           something.  We will not take water out of the RWST.
                       MEMBER KRESS:  So you've essentially added
           another source of water to your system?
                       MR. SCHULZ:  Yes, so if the nonsafety
           system works, it cannot make the event worse.  And in
           fact, will make it better because it will put extra
           water in the containment.
                       So now for this event, the limiting case
           is, in fact, without the RNS working because that adds
           extra water and we end up with additional margin, in
           fact, more than twice as much flow as AP600.
                       MEMBER SHACK:  Isn't there something where
           you change that alignment in some situation?
                       MR. SCHULZ:  Yes.  What would happen as
           this event would continue is the event that's talked
           about here is you run the RNS at pump until you get to
           recirculation and then it magically fails.  That's the
           worse design basis deterministic type assumption.  So
           this case here is not what the RNS pump continuing to
           run indefinitely, it runs until recirc. and then it
                       Now in the AP600, once you get the system
           lined up and you start it running, it just -- it just
           keeps going in the same mode of operation.  You don't
           have to realign it. 
                       For AP1000 when the outside water supply
           gets depleted, we have to switch to the inside water
           supply of the RWST.  We'll have valves to do that and
           it will be manual operation, but it's again, not a
           safety.  It doesn't have to be done to make the plant
           safe.  It's an extra level of defense.
                       So we've done some things to increase the
           water level in terms of the initial water level in the
           tank and avoiding flooding of the refueling cavity. 
                       We've changed RNS alignment so it takes
           water from outside.  We've increase the line
           resistance.  So we've done a number of things that
           significantly improve the situation.
                       We've also done the long-term cooling
           calculation again using the SAR methodology which is
           COBRA/TRAC in this case.
                       CHAIRMAN WALLIS:  Your ultimate heat sink
           is --
                       MR. SCHULZ:  The passive containment
           cooling and the air.
                       CHAIRMAN WALLIS:  Containment.
                       MR. SCHULZ:  Yes.  Just like in the AP600.
                       Now if the RNS pumps were running, which
           they may be, they have big heat exchangers and if the
           CCW is running that's where the heat will go, or most
           of it.  But again, that's not safety.  We don't really
           on that to work, but it is another level of defense.
                       So in this case we've looked at this
           limiting DVI break case for AP1000, running the same
           methodology as we did with AP600.
                       CHAIRMAN WALLIS:  This nonsafety system
           that's pumping water in from outside, it's not
           recirculating, it's just pumping it in?
                       MR. SCHULZ:  Initially, pumping it in. 
           When the outside water supply gets depleted, we'll
           realign it to inside containment, much like you do in
           today's plants.
                       CHAIRMAN WALLIS:  But you're not taking
           another path for taking contaminated water out with
           this system?
                       MR. SCHULZ:  If you continue to run the
           system, you will.
                       One of the restrictions on running this
           system in terms of the operating procedures is that
           the activity levels are not very high in containment. 
           If you get to a situation where you've really damaged
           fuel and you have high activity in containment, you
           would normally not run the RNS unless you're in a core
           melt scenario or you're in one of those kind of
                       The first guideline would be turn it on,
           but if the activity goes up, turn it off or don't run
           it.  And that's the same situation as AP600.
           In fact, AP600, when you initially start the RNS, it's
           pulling water from inside containment to inject it
           back in.
                       So when we look at the results of the
           COBRA/TRAC we see similar behavior, no core uncovery
           relative to AP600.  So looking at the COBRA/TRAC
           results, they look like we were successful in sizing
           ADS and recirculation.
                       CHAIRMAN WALLIS:  How close does it come
           to uncovery?  It always could be within a micron or
                       MR. SCHULZ:  No.  I think feet.
                       CHAIRMAN WALLIS:  More reassuring than
                       MR. SCHULZ:  I don't know -- do we know
           the comparison?
                       CHAIRMAN WALLIS:  Maybe we could see that
                       MR. GAGNON:  The behavior is comparable as
           I recall in terms of margin.
                       CHAIRMAN WALLIS:  So when we see the
           details it will look just like AP600?
                       MR. SCHULZ:  Or better.  In summary, for
           the passive core cooling system, we've retained the
           configuration of the design.  We selectively increased
           features in terms of the capabilities.  We've done
           these independent hand calculation margins assessments
           which are actually part of the design process to give
           us a feeling for how much we've increased the
           capacities and where we've done that and we've done
           some checks using the SAR codes to look at the
           integrated effects.
                       I'd like to now move on to containment. 
           Mike showed you a little bit of containment and talked
           a little bit about what we've done to the pressure
           vessel.  The shell thickness gets a little bit
           thicker, the 1-3/4s is the limit to avoid 
           post-weld heat treatment which we don't want to do, so
           we've gone up to that limit. 
                       The total free volume is actually
           increased 20 percent or so.  The total volume has not
           increased that much, but there's a lot of structures
           in there and we've accounted for those.  And so most
           of the increase that we made goes to free volume,
           although we do have bigger steam generators in there.
                       The design pressure has gone up.  In order
           to account for that design pressure --
                       CHAIRMAN WALLIS:  How much does it grow
           when it gets to 59 psig?
                       MR. SCHULZ:  How much does the --
                       CHAIRMAN WALLIS:  How much does it grow in
           terms of inches?
                       MR. SCHULZ:  I don't know the answer to
                       MR. CUMMINGS:  Ed Cummings.  On AP600 it
           was about an inch and a half.  I guess this would be
           just a little bit larger than that.
                       MEMBER SHACK:  When I went to my friendly
           ASTM handbook, I couldn't see where you'd get a whole
           lot more design strength under the SA738.  You have to
           put a code case together for that.
                       MR. SCHULZ:  Yes.  We have to put a code
           case together for that.  I don't remember.  I thought
           it was significant, but not -- the other thing that
           we've done in the containment cooling area is we made
           the water storage tank bigger and this is the maximum
           water at the overflow point that we're using as a
           reference point here.  And we increased it from
           540,000 gallons to 800,000 gallons.  We also increased
           the water flow rate.  
                       Now the initial water flow rate didn't
           increase very much.  We run 400 or so gallons for
           about 3 hours to cover the containment shell, to form
           the film quickly, relatively quickly.  And since the
           containment dome is the same shape in diameter and
           it's just a little bit taller, we've maintained that
           flow rate, increased it a little bit, but not very
                       After that three hours, the flow rate
           increases more proportional to the power increase.  So
           it's 70 some percent.
                       CHAIRMAN WALLIS:  Your concrete wall is
           thicker, is it?
                       MR. SCHULZ:  It's not thicker.  It may
           have or probably will have more rebar.
                       CHAIRMAN WALLIS:  More rebar, has
           something in it to hold up that water at a higher
                       MR. SCHULZ:  Yes, it's higher and it's a
           little bit heavier.
                       CHAIRMAN WALLIS:  Do we get into seismic
           considerations, the whole thing shakes?
                       MR. SCHULZ:  We will have to demonstrate
           that.  I think this is one of the issues with the
           staff is how much demonstration we will be doing and
           I believe we'll be doing one site, one calculation for
                       MR. CUMMINGS:  This is Ed Cummings.  We're
           providing hard rock seismic analysis case and we have
           done an assessment of the roof structure to show
                       MR. SCHULZ:  We have also again, as we've
           done in the other features, taken the SAR analysis
           codes and methods which is GOTHIC in this case and
           analyzed the containment.  One thing that was a little
           different than -- at least the SAR reference case, was
           using a more realistic large LOCA steam generator
           energy input.  We had used a very conservative
           arbitrary input forcing the generator energy to go
           into the reactor coolant system very quickly which
           gave us a second peak in pressure that was kind of
           unrealistic.  So we're using this as what we think is
           a more realistic scenario.  But otherwise, the codes
           and methods and conservatisms in the code is the same.
                       We looked at two limiting cases, the
           double ended large LOCA and a large steam line break.
                       MEMBER KRESS:  Now when you're
           transferring heat condensing steam on the wall of your
           containment, I recall there was some question about
           the model we had in there on how it dealt with the
           surface area.  It might be covered by liquid and the
           part might not be -- did that ever get resolved,
                       MR. SCHULZ:  In terms of the outside of
           the containment, the water coverage for AP1000 should
           actually be a little better at least around the dome
           and the upper part of the shell because the geometry
           is the same in terms of the diameter and the shape of
           the head and we're in the longer time, anyways, we're
           putting more water flow on.
                       MEMBER KRESS:  That was one of the issues. 
           The one I was recalling though was all on the inside.
                       MR. SCHULZ:  Okay.
                       MEMBER KRESS:  That's a different --
                       CHAIRMAN WALLIS:  Doesn't etching, surface
           behavior, if it gets dirty and it doesn't wet so well
           or what's better and things --
                       MR. SCHULZ:  That's important on the
           outside, not so much on the inside.
                       CHAIRMAN WALLIS:  On the outside.
                       MR. SCHULZ:  The wetting and the spreading
           of the film.
                       CHAIRMAN WALLIS:  This thing is going to
           rush, isn't it?
                       MR. SCHULZ:  No.
                       CHAIRMAN WALLIS:  Things happen to it.
                       MR. SCHULZ:  Well, it's got a coating on
           it that is -- has a safety function and it will be
           inspected during the life of the plant and in fact,
           we'll be running some tests, running water already
           outside periodically which will have a couple of
           purposes.  It will tend to wash the outside and it
           also will demonstrate the fact that the water film
           forms.  So we can test that part of it, in fact.
                       CHAIRMAN WALLIS:  Do you have any wetting
           agent you add to the water to help it spread?
                       MR. SCHULZ:  No, we don't.  The coding is
           an important factor that we do take credit for and
           that's why it has some safety function, btu we don't
           add anything to the water.
                       MEMBER SHACK:  But you did up the rate as
           well as the total volume of water, as I recall.
                       MR. SCHULZ:  Yes, yes.  And I think the
           issues with curbage were more in the lower flow rate
           regimes, not so much in that initial 400 GPM flow
           rate.  When we slowed down later in time and there's
           where we'll have some more water flow.
                       MEMBER KRESS:  We had some questions about
           the GOTHIC assumption of well-mixed flow inside the
           containment.  And now you've got a slightly worse case
           for mixing, maybe, I don't know, because you've got
           more heat but how have you dealt with that issue of
           whether or not it's well mixed in there?
                       MR. SCHULZ:  I think it's something that
           Bill Brown will probably get to, maybe, maybe not. 
           Would you like to address that now?
                       MR. BROWN:  Bill Brown.  If you remember
           the last time we went through this, one of the things
           that was suggested by the Committee was to do some CFD
           and included in this report you'll see a comparison
           between AP600 and AP1000.  We took a little 2-D slice
           through the hull of containment and the results that
           we see from it is that it looked similarly mixed to
                       MEMBER KRESS:  Good move.
                       CHAIRMAN WALLIS:  Do we get to talk to you
           about that later on today?
                       MR. BROWN:  Yes, if you feel good about
                       CHAIRMAN WALLIS:  Well, the obvious
           question is why you take a slice instead of a --
           whatever the cylindrical symmetry, a slice really
           isn't very typical of a cylinder, but we'll get to
           that later on, perhaps when you are standing up there.
                       MR. BROWN:  Yes.
                       MEMBER KRESS:  I thought the slice was
                       MR. SCHULZ:  It is.
                       MEMBER KRESS:  That seems to me like it's
                       CHAIRMAN WALLIS:  Well, we'll talk about
                       MEMBER KRESS:  Okay.
                       MR. SCHULZ:  The large break LOCA
           transient looks like this for AP1000.  You see the
           higher design pressure.  The actual margins in terms
           of PSI and even percentage are even greater on AP1000
           than they are on AP600.
                       CHAIRMAN WALLIS:  This is with
           conservative assumptions?
                       MR. SCHULZ:  This is with conservative
           assumptions, AP600 methodology margins.  The only
           difference is in the rate of steam generator energy
           input which affects the second peak there.
                       The other event which we looked at which
           is actually limiting is the main steam line break. 
           And it does with the large steam generators that we
           have in AP1000, it is understandable why this is
                       CHAIRMAN WALLIS:  Well, you need some
           uncertainty analysis.
                       MR. SCHULZ:  Well, I'm not so sure. 
           Passive containment cooling is not very important
                       In fact, we've run the same transient
           without passive containment cooling and the peak is
           barely larger --
                       CHAIRMAN WALLIS:  No, I mean I just wonder
           how certain -- do you have conservative assumptions in
                       MR. SCHULZ:  Yes.
                       CHAIRMAN WALLIS:  So the real thing should
           be less than that?
                       MR. SCHULZ:  Yes.  That is correct.
           So our conclusion on the containment is that we expect
           margins to increase, to be better on AP1000
                 .  We've increased the capacity of the
                       CHAIRMAN WALLIS:  It's a very funny code,
           that one.  It goes up linearly and just before it
           reaches disaster it stops.
                       MR. SCHULZ:  That's not too surprising. 
                       CHAIRMAN WALLIS:  That's what I always
                       MR. SCHULZ:  This is what happens when you
           get designers working with the analysis, you figure
           out how big you have to make the containment and this
           was really limiting.
                       The other thing is that design pressure is
           not a disaster either.
                       CHAIRMAN WALLIS:  No.
                       MR. SCHULZ:  You can go above that --
                 DR. WALLIS:  But you'd expect something which
           would have a gentler approach to the maximum or
           something instead of going up linearly and coming down
                       MEMBER KRESS:  That's probably just an
           artifact of the plotting routine.
                       At some point up there is where you empty
           out the steam generator, I guess.
                       MR. OFSTUN:  This is Rick Ofstun.  That's
           correct.  The time that the steam generator empties or
           SVIs are closed at 600 seconds, that's when the break
           release --
                       CHAIRMAN WALLIS:  So if something happens
                       MR. OFSTUN:  After the break release stops
           then the containment heat sinks continue to soak up
                       CHAIRMAN WALLIS:  So it does turnaround
           for a good reason.
                       MR. OFSTUN:  Right.
                       MR. BOEHNERT:  What's the peak pressure
           you calculate?
                       MR. OFSTUN:  It looks like around 70 or
           70.5 psi.  I think we're about 2 or 3 psi from the
           design limit.
                       MR. SCHULZ:  Three and a half or four.
                       MR. OFSTUN:  Okay.
                       MR. SCHULZ:  Again, we didn't see anything
           that was really different form AP600 in terms of the
           phenomenon involved.  The margins look larger.  Main
           steam line break is the limiting event and the
           performance of the PCS is not very important in that
                       CHAIRMAN WALLIS:  When we look at this 2.5
           psi between design pressure, this is where
           stratification might be important.  It may be well
           mixed but not that well mixed.  It makes a difference
           to the pressure.
                       MEMBER KRESS:  Yeah, but in the worse
           case, it's well mixed.
                       CHAIRMAN WALLIS:  Well, maybe if that's
           the case you can reassure us.
                       MEMBER KRESS:  If you're stratified or not
           well mixed, you actually get to a lower pressure.
                       CHAIRMAN WALLIS:  I don't, but the
           containment does.
                       MEMBER KRESS:  The containment.
                       MR. BROWN:  Bill Brown, Dr. Wallis.  We
           would love it if all the steam could go up and get
           with that nice cold water up there and we've actually
           taken the worse case and actually assume it would be
           well mixed.
                       CHAIRMAN WALLIS:  Are you finished now?
                       MR. SCHULZ:  Yes sir.  That was our last
                       CHAIRMAN WALLIS:  We're a little bit
           behind in time, I think.  
                       I'm wondering -- we're going to take a
           break now, but when we come back probably we'll accept
           fairly briefly the reports are going to look about the
                       MR. SCHULZ:  Yes.
                       CHAIRMAN WALLIS:  I noticed that some of
           your advisors recommended such phenomena be upgraded
           in the PIRT.  You might want to mention one or two of
           those if they're important, but then we should really
           move on to the scaling approach, but we're going to
           take a break and I think we should have at least 10
           minutes.  Let's same come back at 5 after.
                       (Off the record.)
                       CHAIRMAN WALLIS:  Let's come back in
           session.  We're looking forward to hear some more.
                       MR. BROWN:  PIRT and scaling assessment.
           To give you an idea of the outline here, I want to
           briefly go over the PIRT assessment, not the PIRT
           itself, there really wasn't much changes.  And I want
           to spend most of my time in the scaling assessment
           which will consist a little bit of trying to identify
           the things in which we really assessed relative to
           actually did an analysis, I guess.
                       And a little bit on our approach and then
           I want to get into some of the major areas, the ADS-
           IRWST transition phase, the ADS phase, the sump
           injection phase and go over briefly as to what we did
           and what the results were, try to give you a summary
           overall for what that meant to the integral effects
           test facilities of SPES and OSU, and then move on to
           the PSS scaling for containment which will large
           address the separate effects test and the containment
           mixing and stratification.
                       The main goal, of course, for our part in
           scaling assessment was to try to determine the extent
           to which the AP600 experimental test data base was
           applicable to AP1000 to support our safety analysis
           code validation in accordance with 10 CFR part 52.
                       So a real simple two-step process we went
           through, was the first -- take our AP600 PIRTs as they
           were and then have them reviewed by several industry
           experts for application to AP1000 and then once we got
           the results from that we could then look at the import
           of the high rank phenomenon and then use that to
           assess these phenomenon relative to AP1000.
                       MEMBER KRESS:  How many of these experts
           did you have?
                       MR. BROWN:  Several.  I'll show you in a
           list here in a second.
                       MEMBER KRESS:  Oh, you've got a list.  I'm
                       MR. BROWN:  Yeah, I'm going to give you a
           list here.
                       MEMBER KRESS:  Okay.  The usual suspects.
                       Who is this Hochreiter person?
                       MR. BROWN:  This guy?
                       He's a big target back here at one point
           with the ACRS.  Not a big target at Penn State.
                       Dr. Bajorek from Kansas State, Dr. Bankoff
           from Northwestern, of course, Dr. Hochreiter, Dr.
           Larson from INEEL, Dr. Peterson and Mr. Wilson, those
           were our primary peer reviewers.
                       Primarily, Dr. Bankoff and Dr. Peterson
           had been involved with our containment PIRTs so they
           primarily focused on containment for us and they
           looked at the others, and the other four looked at our
           other events, our large break LOCAs --
                       CHAIRMAN WALLIS:  I am surprised that
           these four academics used industry as an adjective to
           describe their expertise.
                       MR. BROWN:  Well.  Certainly they worked
                       MEMBER SHACK:  Discipline experts.
                       CHAIRMAN WALLIS:  Because usually
           academics are regarded as in other world from
                       MEMBER KRESS:  Independent, right?
                       CHAIRMAN WALLIS:  I'm glad to see that --
           well, in a way I'm glad to see at least they're
                       MR. BROWN:  Are you disappointed you're
           not on the list?
                       CHAIRMAN WALLIS:  Why do you call them
           industry experts?
                       MR. BROWN:  Well, I should say perhaps
           academic experts who are certainly familiar with our
           industry history issues.
                       MEMBER KRESS:  I thought maybe you'd have
           Ivan Katten on there.
                       MR. BROWN:  I did talk to Ivan, but I
           didn't get a hold of him quite frankly, early enough
           to do that, but when we went through this process,
           this was really the starting list and what I sort of
           decided was I would send them out to this group and if
           I got anything significantly different or got a lot of
           comments, then we would continue on with this, but
           quite frankly the real result of this was there wasn't
           a significant different by most of the reviewers.
                       And here, gives you an idea of what the
           summary of the major changes that they came up with. 
           A large break LOCA, the core entrainment was increased
           a little bit from 6 to 7 from a median to a high.  We
           addressed this via our BE LOCA methodology. 
                       MEMBER KRESS:  Was that because you have
           a higher steam flow?
                       MR. BROWN:  Yes, right.  Because of the
           higher power and the higher steam flow, they expected
           additional entrainment than they had up in the upper
           plenum area, right.
                       Small break LOCA, same type thing again. 
           Same issue, really with increased entrainment and
           recommended a high for RWST and sump injection and
           I've addressed this via some bottom up scaling on
           liquid entrainment inception from the hot leg into
           ADS-4 and the scaling report.  And then the ADS-4 two-
           phase pressure drop was increase the High from IRWST
           and sump injection as well.  And I've addressed this
           from more a top-down perspective during the IRWST and
           sump two-phase natural circulation.
                       In containment, we had no changes
           whatsoever.  The only issues or comments that came up
           there were with respect to comments that you made
           similarly earlier, Dr. Kress, with the increased
           height of the 25 feet in containment, what would that
           do to mixing and later on in our report we have some
           CFD analysis to try to address that.
                       In non-LOCA, there were no important
           changes either, so the primary changes were really in
           the small break LOCA.  So we took these changes in
           addition to the things that were already ranked as
           high and important from AP-600 and we addressed this
           in the scaling assessment.
                       CHAIRMAN WALLIS:  What effect does it
           have?  Suppose you change a number from 6 to 9 or
           something, what difference does it make?  What the
           procedure for making it actually make some difference? 
           It's nice to see lots of numbers.
                       MR. BROWN:  I think in the case of the
           large break, it really doesn't mean a whole lot
           because you're going to really, you're going to end up
           doing the analysis anyway, where you're varying each
           parameter and going through some uncertainty.
                       CHAIRMAN WALLIS:  I've always been curious
           about PIRTs.  You have these numbers and medians and
           high and all that, that ought to mean that you assign
           some weighting factor to sensitivity or uncertainty in
           your later analysis where you somehow complete the
           loop and come back and see whether you really did a
           good job or -- I'm never sure that that's actually
                       MR. BROWN:  I think you could go through
           a numerical validation of that after the fact.
                       CHAIRMAN WALLIS:  Otherwise, what's the
           exercise for except to put a lot of numbers on the
                       MR. BROWN:  I think it certainly gives you
           an idea which I used to make sure that these are
           certainly a checklist of items that you should have
           included and addressed either in scaling and/or test
           facilities, certainly it's a good place to start.  I
           agree.  I don't think it's something -- I think it's
           a tool to get started with. 
                       CHAIRMAN WALLIS:  You might say, if you
           have a 9 you need to have independent assessment from
           three facilities and if you have 6 you only need one. 
           There's got to be some sort of tie in between the
           numbers in the PIRT and what you actually do.
                       MR. BROWN:  Right.  It sounds like you
           could write a paper on that.
                       CHAIRMAN WALLIS:  This PIRT, is it an
           empty exercise or does it really --
                       MR. BROWN:  Well, as I said I think it
           helps me to focus on what needs to be looked at as far
           as scaling.  I mean certainly in the areas where if
           you initially didn't have a test program before we had
           the AP600 test program, I think this was probably much
           more valuable, where you said look, I really don't
           know how this is going to react.  Nobody knows.  I
           mean the experts here probably don't know how it's
           going to react, so we need to do the test.
                       Yes, now that we've been through the
           testing process, quite frankly, these particular items
           here are really more -- came out of -- now that I know
           what happened in the tests I would have ranked these
           higher than I would have initially in AP600.  So
           really, if I was going back to the AP600 PIRT I would
           have increased these a little high as well.
                       Maybe here if we were using numbers, maybe
           this was a 9 in the AP600 and maybe it was a 10 in the
           AP1000, but you would have gone back to do it.  So I
           think when you're initially starting a test program,
           I think it's pretty helpful.  I think once you have
           done a test program, it's probably not quite so
                       CHAIRMAN WALLIS:  It might guide the
           staff, if the staff ever gets hold of your codes and
           they see that these are 9s, then they might focus on
                       MEMBER KRESS:  It gives you a place to
           focus on your sensitivities and things of that nature.
                       MR. BROWN:  I think that helps you as to
           where you should spend your effort mostly.
                       CHAIRMAN WALLIS:  There's no check that
           you actually did spend your effort.  That's the thing
           that bothers me.  It needs to be a loop, a complete
           loop of the PIRT so it leads to some actually
           quantitative result in some way.
                       MR. BROWN:  Certainly in the code reports
           we do identify, I mean all the PIRT items are -- we
           make sure that we have certainly a model and I think
           that the scrutiny when looked at the model, the
           validation as to how does the prediction of the code
           compare to the test facility is much higher,
           scrutinized much more heavily when it's a higher
           ranked item.
                       CHAIRMAN WALLIS:  If we scrutinized we
           would find that correlation.
                       MR. BROWN:  You should.  And for the
           passive core cooling system then this became the list
           to include a couple of items which were increased for
           AP1000 as well as those which were already ranked
           high.  And what I did was I tried to lump these into,
           especially for the passive core cooling system, I sort
           did top-down versus what I did bottom-up and some of
           the things that were mentioned like the ADS two-phase
           pressure drop and so on are listed in here.  And this
           gives you an idea of the type of things that I tried
           to do from a system level and quite simply I ended up
           with something that's of much more local phenomenon
           that was difficult to include top-up such as
           entrainment or phase separation and so on.  These are
           bottom-up.  So this kind of gives you a list of what
           were the high ranked or most important.
                       CHAIRMAN WALLIS:  Is there something here
           about this level swell we were talking about earlier?
                       MR. BROWN:  Level swell in the IRWST?
                       CHAIRMAN WALLIS:  No, in the vessel.
                       MR. BROWN:  In the where?
                       CHAIRMAN WALLIS:  In the vessel.
                       MR. BROWN:  In the vessel.  Well, the
           closest, I guess, you could look at it as one as I
           have a reactor vessel inventory scaling and then also
           try to look at the core exit void fraction using the
           A correlation.
                       CHAIRMAN WALLIS:  It makes a big
           difference now that you carry out into the rest of the
           system and a difference in how the actual masses
           related to whether or not the two-phase level covers
           the core, pretty critical how you model that phase
           behavior in the vessel.
                       MR. BROWN:  Yeah, you certainly get into
           an area though certainly more important, I think,
           certainly the codes right in their answers as opposed
           to I'd say scaling where you're not so much after a
           best estimate answer, but trying to make a relative
           comparison between a facility and a plant.
                       Okay, this is a list of the phenomena for
           the passive core cooling system.
                       CHAIRMAN WALLIS:  How would you scale up
           to a vessel the business of level swell in the vessel?
                       MEMBER KRESS:  I don't think what you
           measured was collapse level.  When you measure it in
           the test, I don't think they had a swell level.
                       MR. BROWN:  Right, right.  The DP cells --
                       MEMBER KRESS:  The DP cells.
                       MR. BROWN:  -- we had were really
           measuring a collapsed liquid levels.  That's why we
           know it's much better.
                       CHAIRMAN WALLIS:  So we don't have a
           measure of these --
                       MEMBER KRESS:  You can do some inferring,
           but I don't think you have a direct measure.
                       MR. BROWN:  Yes, I think essentially we
           have the -- certainly you have an idea of what that is
           based on, the DP cells, but we don't have, again
           tensitometers sitting in there in the vessel, looking
           at the level.
                       MEMBER KRESS:  What you have is a heat
                       MR. SCHULZ:  This is Terry Schulz.  We had
           heated rods.  If the rods were not adequately covered
           and cooled, we would see that in temperatures --
                       MEMBER KRESS:  But generally it's hard to
           see with the level swell.  It cools the rods pretty
           doggone good and it's hard to see it break between 
           -- where a collapse would be and -- it's hard to find.
                       MR. BROWN:  Unfortunately, in the small
           break area we don't get the kind of level swelling
           that you certainly would get in the large break on the
           initial blow down.
                       Okay, with that I'd like to move on to the
           scaling assessments.  There's a lot here.
                       The scaling assessment really focused on
           the high-ranked phenomenon.
                       CHAIRMAN WALLIS:  Will you let us know
           when this gets to be priorities?
                       MR. BROWN:  Yes, we're getting there,
           we're almost there.
                       We really tried to focus on the small
           break LOCA with respect to core cooling and vessel
           inventory and then things like the steam line break
           for containment pressure.  So that was our focus.
                       And the assessment, looking at the scope
           of the scaling assessment, phenomena that we find in
           conventional plants for which there's test data bases
           that already exist, we did not scale for AP1000 and
           that includes the large break LOCA, blowdown steam
           generator circulation phases for the small break LOCA
           and non-LOCA with the exception of CMT and passive RHR
           which are items that are unique to passive plants.
                       And things that were low ranked or medium
           ranked in the AP600 scaling effort that were already
           scaled we did not rescale those.
                       So our basic approach then was starting
           from the AP600 scaling analysis, using that as a basis
           for AP1000.  We tried to use the insights and lessons
           and so on and we did not, as I said, reinvent the week
           completely here.  Processes that were not important or
           minor were not scaled and we certainly tried to use
           simplified models to try to highlight these
           differences or features in AP1000 such as core power,
           volume, ADS vent area and things like that so that we
           could see what the real differences were and try to
           root those out to be more obvious in looking at the
           assessment in AP1000 relative to the AP600.
                       So we sort of did two types of
           assessments, if you will.  One, we examined the range
           of operating conditions, geometry, those types of
           things between AP1000 in each test facility.  And
           usually in those many cases, the AP600 scaling
           analysis was already sufficient.  This typically
           covered the separate effects test.  However, when we
           tried to look at AP1000 relative to for example
           integral effects test facility, we definitely needed
           to be able to supplement this with a scaling analysis,
           so that's what you'll see here very shortly as some
           examples of what we did in the integral effects tests
           to try to assess AP1000 relative to AP600.
                       So I'm going to give you an idea briefly
           as to what's covered.  In the integral effects we
           looked at an assessment of both SPES, OSU, ROSA, the
           ADS test, CMT, PRHR and our DNB tests.  And we did an
           additional new scaling analysis for both SPES and OSU
           for the integral effects test.
                       In the area of containment, we did the
           scaling analysis for the LST, or condensation and
           heated flat plate tests, water distribution and water
           fill formation tests.
                       Now we're going to get into the scaling
           assessment part which is going to be the priority part
           of the meeting.
                       (Whereupon, at 3:21 p.m., the open session
           went into closed session.)
                       (Off the record.)
                       (Open session resumed at 4:49 p.m.)
                       CHAIRMAN WALLIS:  Let's come back into
           session again.
                       MR. BOEHNERT:  We are in open session.
                       MR. GRESHAM:  My name is Jim Gresham and
           I'm going to talk about the computer codes used for
           AP1000, but I'm not going to get into the details of
           the codes.  Rather, I'm going to talk about the
           approach that we're going to use on the analysis for
                       And pretty simple, you start with the
           codes that were approved for AP600, our starting point
           for the assessing the codes for the analysis and used
           those as much as possible.  Of course, to do that we
           have to confirm that they're adequate for performing
           the safety analysis for the AP1000 design and address
           the concerns that were identified on the AP600
           application and make sure that we've reached agreement
           on applicability after addressing those and then reach
           consensus with the staff and then when we do that,
           then we'll use those codes for the FSAR analysis to
           complete the safety case.
                       The advantages of doing it this way is we
           step through in an orderly fashion in the review
           process which we believe would make it more efficient
           for us and for the staff in doing that.  
                       We can identify the major deficiencies in
           the codes and address those prior to the final review. 
           And also, through this we focus on the most important
           issues, so with the guidance of the PIRT, the scaling
           and test comparisons and then we can really focus our
           energies on the important phenomena in evaluating the
           code acceptability.
                       CHAIRMAN WALLIS:  So how do we resolve
           these major deficiencies or find out major
           deficiencies?  I'm just wondering where the starting
           point is.  When we had AP600 we started asking
           questions and eventually got some code documentation
           which had deficiencies in it.  I guess they're not the
           kind of deficiencies --
                       MR. GRESHAM:  I'm talking about code
           deficiencies.  There may be --
                       CHAIRMAN WALLIS:  Code.  Code is whatever
           this magical thing is that is quite different from all
           of the --
                       MR. GRESHAM:  I think in a few slides
           we'll get to this topic a little more and then maybe
           we can -- there are different ways that we may address
                       CHAIRMAN WALLIS:  I think there's a real
           question about whether Westinghouse can assess
           deficiencies in its own code.
                       MR. GRESHAM:  I believe we can.  I don't
           believe that will be adequate and we will have to
           discuss that with the staff and reach agreement on
           that.  But I think we're the first ones to address the
           deficiencies and then our reviewers will decide how
           well we did.
                       The code, the major codes that are used
           for the Chapter 15 analysis, I won't dwell on these,
           but the COBRA/TRAC is used for the large break LOCA
           and the long term core cooling.  NOTRUMP for the small
           break LOCA.  LOFTRAN is used for non-LOCA transients
           and for steam generator tube rupture and there is a
           kind of a derivative code, LOFTTR2 which models some
           of the operator actions and other phenomena for tube
           rupture that was within that umbrella.  And then
           WGOTHIC for containment integrity.
                       In terms of identifying the adequacy of
           these codes for a performing analysis for AP1000. 
           First step in the process is to identify the important
           phenomena which is done through the PIRT that need to
           be addressed and these phenomena have been presented
           in the PIRT and the scaling and so that task in this
           process for AP1000 is complete.  And then identify the
           correlations and models used in the code to address
           the important phenomena and that really was done under
           the AP600 application and again, we are planning to
           use the same codes for that.  So those have been done. 
           What remains is to demonstrate that they're adequate. 
           And that is done through the scaling to demonstrate
           that the test data base that we have is adequate for
           code validation and then to rely on that.  And that
           has also been done through the -- is provided in the
           scaling report, the determination of the adequacy for
           both the integral effects test and separate effects
                       And then the remaining thing is
           demonstrate that the limitations that were identified,
           what we just talked about for AP600 are addressed on
           the next slide.
                       The first is just to acknowledge what I've
           already said that there were things identified in the
           AP600 that there were some concerns about and as
           already mentioned today, the approval was restricted
           to the AP600 application.  So we, I think the burden
           is on us to present the case on why the codes can be
           used for the higher power plant and that's what we
           intend to do.
                       And again, we have to evaluate those
                       There are several ways that we think that
           this can be done.  One would be to make some
           modification to the design to increase margin in the
           area of the deficiency, to demonstrate more margin. 
           There may be other test validation that can be done to
           demonstrate that the code is adequate to model that
           phenomenon.  Again, we may just -- maybe additional
           evaluation margin may demonstrate that yes, there's a
           lot of margin in this area and therefore the code is
           adequate to demonstrate safety relative to that
                       We may do analyses with other codes, for
           instance, in the containment analysis example that we
           already talked about where we did some CFD
           calculations to confirm the mixing in the AP1000 and
           the AP600.  It would be that kind of analysis or maybe
           other systems analysis code to provide independent
           confirmation of some portion of the transient or all
           the transient.
                       And it may be necessary to make some
           changes to the code also.  Any of those five we may
           use or some combination of those five to address
                       We intend to document this work in the
           Code Applicability Report which is targeted to be
           complete in April.  The key contents of that report
           will be a discussion of the importance of the
           important AP1000 phenomena referencing back to earlier
           reports that we've done, a description of the code
           that is being used for AP1000.  A lot of it is by
           reference to the AP600 work, but we'll also discuss
           anything different about it, relative to the work that
           was done there.
                       A discussion of the limits of
           acceptability or acceptability for AP600.  We intend
           to go through the FSER from AP600 and address the
           major items on the codes that the staff pointed out
           and I believe that's a good systematic way to make
           sure that we've addressed all of the items that were
                       And for each limitation we'll say how that
           limitation is addressed and there will be some of
           those components that I mentioned on the prior page.
                       CHAIRMAN WALLIS:  So how do we determine
           what is a code limitation?  Do you look up the SERs,
           is that what you do?  It was not identified then as
           the code limitation?
                       MR. GRESHAM:  Those are -- we're not aware
           of any other code limitations that we're addressing,
           other than those items that were in the FSER.  We were
           holding that open for something that happened in
           scaling that came out.  Nothing did pop out from
           either the PIRT or the scaling that we thought had to
           be added to that list.
                       Just quickly on how uncertainties will be
           addressed for AP1000.  Again, we've talked about all
           afternoon is that the phenomena are similar to AP600
           and the scaling demonstrates that the validation basis
           for the codes is adequate.  We intend to deal with the
           uncertainties the same way that they were for AP600. 
           For the large break LOCA we are using our best
           estimate methodology and 95th percentile will be
           identified as stipulated in the FSER.  The reason we
           said it that way, I believe it was for the passive RHR
           and the CMT -- it was the CMT.  The staff said if the
           PCT goes higher you may have to do more for
           uncertainties in looking at those phenomena.  So we
           will factor that in.  Otherwise, the methodology will
           be the same.
                       For the other codes, we're doing a
           bounding analysis as we did for AP600.  And we will
           ensure that the assessment is conservative, rather
           than quantify the numbers in our best estimate.
                       CHAIRMAN WALLIS:  Your AP1000 has higher
                       MR. GRESHAM:  That's correct.
                       CHAIRMAN WALLIS:  It's not clear to me
           that you're doing necessarily with the same
           uncertainties as you dealt with before with AP600.  I
           know that the phenomena are the same, but you're
           pushing them to --
                       MR. GRESHAM:  The numbers may be
                       CHAIRMAN WALLIS:  For reason of the
           envelope.  It may be that -- so the way in which
           uncertainties work, there isn't quite the same as the
           way they did before.
                       MR. GRESHAM:  A good example of that is
           the oxidation.  Down below 1700, the oxidation is
           pretty minor and as you start to increase and
           oxidation becomes more important and that is one thing
           that will have to be dealt with on the AP1000 that we
           didn't on AP600.  So your comment is correct.
                       CHAIRMAN WALLIS:  They're not so similar
           when you're talking about oxidation.  You're actually
           going to a much higher degree of oxidation than
                       MR. GRESHAM:  Yes.
                       CHAIRMAN WALLIS:  So it's qualitatively --
           you could almost argue it's no longer similar.  It's
           almost different from an extrapolation, but
           significantly --
                       MR. GRESHAM:  Okay.
                       CHAIRMAN WALLIS:  Different.
                       MR. GRESHAM:  Valid point.
                       MEMBER KRESS:  What exactly does your 
           sub-bullet up there mean?
                       MR. GRESHAM:  That we will -- the
           transients will be analyzed in a way to make sure
           we're on the conservative side.  For instance, in the
           containment where we use test data for the hidden mass
           transfer correlations and we do a bounding treatment
           of those --
                       MEMBER KRESS:  I understand you use the
           conservatisms that are specified in approach.  I don't
           know what it mean as to say that those bound the
                       Does that mean to say that if I use those
           conservatisms and I will be -- have a value that's
           close to the 95 percentile if I did a real
           uncertainty?  What does it mean to say bound the
           uncertainties?  I don't understand the statement.
                       MR. GRESHAM:  Actually, we haven't defined
           the 95 and won't define the 95th percentile
                       MEMBER KRESS:  I understand that.  Nobody
           has is the problem.
                       MR. GRESHAM:  That's right.
                       MEMBER KRESS:  That's why I always have a
           problem with this.  I know those uncertainties are
           there, I just don't know how much margin they provide
           you with respect to the uncertainties.
                       MR. GRESHAM:  I'm using the small break
           LOCA example we talked about to comparison to the test
           data on a realistic basis and show that we can model
           the phenomena and then we'll add the appendix K
           uncertainties on top of that to ensure it's a
           conservative assessment.  That's the idea on that.
                       MEMBER KRESS:  We'll look at that
           difference and say there's some sort of margin there.
                       MR. GRESHAM:  Yes.  And that margin covers
           the uncertainty and I know when I say that you can't
           quantify --
                       MEMBER KRESS:  It doesn't add any meaning.
                       MR. GRESHAM:  The magnitude.
                       MEMBER KRESS:  Bounding the uncertainties
           has no meaning to me.
                       MR. GRESHAM:  Perhaps it's just better to
           say we're doing --
                       MEMBER SHACK:  If the analysis is
           conservative then you've bounded the uncertainties. 
           It's hard to demonstrate that analysis is actually
                       MEMBER KRESS:  If you believe it's
           conservative you believe it's conservative enough to
           have a confidence level in your calculation that's
           acceptable, but they're saying something than bounding
           uncertainty.  I'm just having trouble with semantics
           and actually it means to do such a calculation.
                       CHAIRMAN WALLIS:  What do you mean by
           that?  If you have a break, you assume that there was
           no flashing and it simply came out as pure water, the
           maximum flow rate you could possibly have is all, is
           that what you mean by a conservative analysis,
           bounding something?  Look at some extreme assumption
           which takes you right to the end of what's imaginable
           and you use that?
                       MR. GRESHAM:  No, I'm not saying that. 
           There's a bound on how we're going to be.
                       That's the idea.
                       CHAIRMAN WALLIS:  Dr. Kress is right then.
                       MR. GRESHAM:  Yes, Dr. Kress has a very
           good point.
                       CHAIRMAN WALLIS:  I think also when you
           talk about realistic, I don't know what the criterion
           is for realism.  Just that you look at some data and
           the curve isn't too far away from them?  Once you
           start to quantify these things in statements like
           realistic and uncertainties, conservative, you've got
           to be quite careful in your definitions so that we're
           all speaking the same language and we can agree on
           criteria for evaluation.
                       That's all going to be cleared up.
                       MR. GRESHAM:  You're right.  There are
           different ways to do comparisons and you have to all
           agree it's a rational approach.  I agree.
                       CHAIRMAN WALLIS:  Sometimes it becomes
           more persuasion.
                       MR. GRESHAM:  Yes.  And then the final
           step in my process was to reach consensus and this is
           -- again, we're starting from codes that were approved
           for AP600 and we certainly want to stand on the
           foundation of that effort and not repeat anything that
           we don't need to, recognizing that there are still
           issues that we need to reach agreement on.
                       We're providing the reports.  We've talked
           about them several times, to the staff for their
           review, to help to make our case and we will be having
           discussions with them.
                       CHAIRMAN WALLIS:  You say you're supply
           reports.  Are you supply codes?
                       MR. GRESHAM:  We need to go through these
           steps before making the decision on that.
                       If we reach agreement that there have
           been, yeah, the codes are also applicable to AP1000
           and you've covered all the phenomena and the
           validation is okay and we don't have to change the
           code, then it's not clear that we need to provide the
           code to the staff or the staff needs to exercise those
           codes in their review.
                       MEMBER KRESS:  Part of that decision may
           be based on exercising the codes.
                       CHAIRMAN WALLIS:  It's all quite possible
           for people who exercise a code to do things to get
           what they want to get, like this business of the
           homogeneous assumption.  Until you really dig into an
           issue you're running yourself, you don't know how it
           is you manage to get this answer.  One might feel a
           little queasy if the answer only comes from
           manipulations performed by Westinghouse.  Dials and
           things can be changed in a way which always
                       MR. GRESHAM:  I guess my answer to you is
           that we need to work with the staff to decide where
           they need to have the codes and where they don't.  And
                       CHAIRMAN WALLIS:  Work with them or you
           need to give whatever they ask for?
                       MR. GRESHAM:  We won't do that without
           assessing --
                       CHAIRMAN WALLIS:  Is there a negotiation
                       MEMBER SHACK:  Persuasion.
                       CHAIRMAN WALLIS:  Yes. Persuasion.
                       MR. CORLETTI:  This is Mike Corletti. 
           Starting with the basis of the approval of AP600,
           there was quite an extensive review of the codes.  I'd
           really like to start there.  We don't want to go back
           to 1992 before we submit -- before when we sent in all
           the code documentation.  We're really looking to start
           where we left off building on that.  The best way we
           see that is what did we learn from that 8-year
           certification review, what were the hard issues with
           each of the codes and the way we resolved each of
           those issues.  How does that apply to AP1000 and can
           we address that?
                       I think that's -- that is our approach.
                       CHAIRMAN WALLIS:  But a question I think
           someone raised before is whether the staff is capable
           of knowing what the issues are with the code unless
           they actually exercise it themselves because the real
           issues of a code can be so hidden that it's hard to
           take what they are.
                       MR. CORLETTI:  I certainly think there's
           an onus on us to provide them with the documentation
           necessary for them to make the determination that the
           methods that we employ, that the methodologies that we
           employ are sound and acceptable and I think that onus
           is on us to give them that sort of documentation. 
           Whether that specifically requires them to exercise
           the codes, it's not clear to us at this time.  I think
           maybe perhaps as we go through this code applicability
           report, we understand the phenomena.  We understand
           how the test data applied to AP1000.  At that time,
           we'll have a clear understanding of where such --
           where that would be beneficial and where it would not
           be.  At this time it certainly is not clear, the first
           thing you don't do is jump into exercising the codes. 
           I think we think that would be the last thing we would
           do eventually.
                       MR. GRESHAM:  On my third bullet, we're
           asking the staff to agree on the acceptability of
           these codes for analyzing the AP1000 transients.  Now
           we fully expect that they're going to need some good
           information to be able to make that decision and we
           believe much of that is in the documentation already
           mentioned and if there are changes to the codes there
           are other significant things it may involve their
           running the codes, but we need to be looking at this
           -- we need to get further in the process before
           knowing the answer to that question on each of the
                       MEMBER KRESS:  What is it -- is it a
           difficult thing to transfer a code over to NRC?  Does
           it cause you heartburn for some reason?
                       MR. GRESHAM:  It will add a lot more time
           to the review process, that's one concern we have.
                       CHAIRMAN WALLIS:  Our contention might be
           that it would simplify everything and make it a lot
           more efficient.
                       MEMBER KRESS:  Save time.
                       CHAIRMAN WALLIS:  Save time.  You simply
           are open and say here is it.  We think it's robust and
           you won't find any problems with it.  Here it is.  But
           if one has to dig.  If one has to say well, I'm a
           little suspicious about this and Westinghouse has to
           go away on some things and has come back, and then you
           say well, maybe this other thing is something we have
           to worry about and then Westinghouse has to go away
           and answer that, that might be a very inefficient way
           of answering concerns.  But you don't really know some
           concerns.  They may get revealed as you begin that
           becomes something that is much quicker to resolve by
           having the code.  This to and fro, taking months every
           time a question gets asked before you get an answer.
                       MR. GRESHAM:  We certainly don't want
                       CHAIRMAN WALLIS:  I think the ACRS has
           been saying we really support the idea of the staff
           wanting code and we think that's the most efficient in
           the long run, the most efficient way there is to
           assess a code.
                       MR. CORLETTI:  This is Mike Corletti
           again.  The other thing that we have seen that was
           very successful in us resolving issues on the AP600
           was the staff's independent calculations of their
           independent codes.  And those tended to both our
           analysis and their analysis demonstrated the real
           large margins of the AP600.  We're not in the
           situation where we have the PCT of 2175 and it's
           really critical do we get -- are we at 28, 25 degree
           margin to cut this or not.  Kind of where we are with
           AP600 for most of the small break LOCA no core
           uncovery.  We really are far away from a lot of the
           limits that historically we've been concerned about.
                       CHAIRMAN WALLIS:  I think that's also in
           the ACRS letters you'll find that we also support the
           idea of the staff having its independent code.
                       It really helps with the public confidence
           that someone else is running something independently
           and gets the same answer.  It's something --
                       MR. GRESHAM:  That's right.
                       MR. BOEHNERT:  I was just going to comment
           on what Mike said.  My recollection is a little
           different from Mike's and that is that there was a lot
           of problems with the codes, particularly NOTRUMP. 
           There was a lot of back and forth and a lot of
           questions from both the staff and the ACRS and the
           code and I think it would have been much easier,
           quicker, if the staff had the code to resolve some of
           those issues.  It turned out to be a very difficult
                       MR. CORLETTI:  And I think at the end all
           of our codes predicted the same thing, no core
           uncovery and we weren't anywhere near any regulatory
           limit, so really, were we talking about the importance
           of that code in measuring plant safety?
                       MR. GRESHAM:  We do appreciate your
           feedback on that and we did listen. 
                       Just to summarize, building on AP600 codes
           that were approved for AP600, we'll confirm the
           adequacy for AP1000 and address the concerns and
           there's a number of ways that that could be done.  And
           culminating and confirming they're acceptable and
           getting some NRC agreement with that and proceed with
           the safety analysis.  That's all I have.
                       I'll turn it back over to Mike for a brief
           wrap up.
                       MR. CORLETTI:  That really does conclude
           our presentation today.  I think it's worthwhile to
           summarize.  Again, we've been working on this for
           quite a while, but I think this is certainly the
           beginning for you all and going on, I expect at least
           one more of these after the staff has had a chance to
           review our submittals.  Again, the summary of our
           proposed approach, we really focused most of our
           efforts so far on how are the plants different and how
           are they the same for the important phenomena and
           really asses how well does the test data support an
           AP1000 Design Certification.  How we used it on AP600
           provided us the data to validate our codes.  We're
           hoping that you'll agree that the test data base is
           sufficient, that it will provide an adequate data base
           for code validation, then we can concentrate on the
           validation of those codes and the issues related to
           those and how we actually would apply --
                       CHAIRMAN WALLIS:  Why would it be any
           different from what we did for AP600 if the data that
           you're going to use are the same data and it's the
           same code, then why should there be anything different
           from what you did before?  Is there something
           different about AP1000 that would make things
                       MR. CORLETTI:  We're certainly starting
           there.  We think it does deserve a review to make sure
           that there wasn't, like some of these residual issues
           that have been raised --
                       CHAIRMAN WALLIS:  Well, what would you do,
           you're running the code to say compare with a ROSA
           test.  You did that for AP600.
                       MR. CORLETTI:  Yes, we did.
                       CHAIRMAN WALLIS:  And you get some data
           points.  Now what's going to be different about what
           you do now?  You've got the same tests and the codes,
           what's different?
                       MR. CORLETTI:  That is generally, we had
           to wait until we confirmed that the test was
                       CHAIRMAN WALLIS:  Then you don't need to
           do any more.
                       MR. CORLETTI:  I think we owe it to the
           staff to go through some of the conditions, especially
           on like what was mentioned on the oxidation model.  We
           have to commit to that kind of thing.  If there is
           anything else that maybe was the way we resolve
           certain issues or certain REIs and are they still --
           the way we resolve that still applicable?  I think it
           deserves that it's really going to be the content of
           our Code Applicability Report.
                       But that generally is our approach and
           that is the approach that we're --
                       CHAIRMAN WALLIS:  Do you expect some new
           comparisons between codes and data or just use the old
                       MR. CORLETTI:  I think we would only use
           new comparisons if we had new test data or if there
           was test data that was new that was suggested that we
           use.  There were additional tests that we didn't look
           at before because it was not available to us.  There
           was the ROSA test.
                       CHAIRMAN WALLIS:  You claim you can use
           the AP600 test program for AP1000.
                       MR. CORLETTI:  Yes.
                       CHAIRMAN WALLIS:  The AP600 is already
           being used to confirm that you can use the codes and
           you're going to use the same codes, what is left to
           do, except run the code?
                       MR. CORLETTI:  We'll have to hear from the
           staff.  I agree with your approach.
                       MR. CUMMINGS:  I might comment.  This is
           Ed Cummings.  In a few cases, the staff accepted our
           codes.  Our use of the codes on the AP600, because of
           their assessment of the plant safety rather than their
           love of the code.  And you have to revisit those
           places where they accepted the use of the code because
           of the clear safety of the plant, to make sure you
           still have the same condition of acceptability.
                       MR. CORLETTI:  Yeah, the core uncovery
           issue with some of the models that were employed in
           NOTRUMP and I'm not going to go any further than that,
           but I know there were some that we didn't have to
           evaluate because we didn't have core uncovery and it
           may -- if we had core uncovery or if we would get into
           that situation, maybe that would be something that
           we'd have to address.
                       MR. BROWN:  Bill Brown.  Dr. Wallis, a
           good example, to come back to what Paul Boehnert said
           was a NOTRUMP, for example, there was not a momentum
           flux model, okay?  This was something that was
           identified by the ACRS.  It's in the FSAR.  If for
           some reason in AP1000 it was deemed that this model
           needs to be improved for acceptance of the code, then
           we would need to go back to just check that model and
           specifically validate that.
                       CHAIRMAN WALLIS:  How would the staff know
           that?  They'd have to really run the code with and
           without the momentum flux and find out if it mattered. 
           They'd have to do it.
                       In other words, they wouldn't know if it's
           an important issue or not, would they?
                       MR. CORLETTI:  I think there's other ways
           of doing that.  There's independent type of
           evaluation, a phenomena with either a different
           independent code that says is this important or not. 
           I guess it would be fully best not to get into too
           many what ifs until we really submit our report, but
           that's the nature of the kind of assessment we're
                       CHAIRMAN WALLIS:  So what's our role in
           all of this, ACRS, we're observing this.
                       MR. CORLETTI:  I guess we would be
           interested in feedback on our overall approach.  Are
           we doing the right thing in regards to our approach
           with looking at the test data, the kind of scaling
           approach that Bill has outlined, looking at the PIRT,
           looking at the scaling and then how we plan on our
           application of the codes.
                       MEMBER KRESS:  I think we have a legal
           responsibility to sign off on the certification
                       MR. CORLETTI:  That would be the later
           phase.  I think in this pre-certification --
                       MEMBER KRESS:  Not now, but then.
                       CHAIRMAN WALLIS:  So you're going to make
           a presentation to the full Committee?
                       MR. CORLETTI:  In April, there's a
           presentation of the full Committee.  I think we only
           have two hours there.
                       CHAIRMAN WALLIS:  They're liable to ask
           questions, so you have to be pretty brief.
                       MR. CORLETTI:  And it will be on the whole
           -- there's a couple of issues we really didn't speak
           of today, so we'll give you a good -- an overview of
           the Phase 2 process and where we are in that process. 
           We won't probably go into as many of Bill's scaling
           equations, but we'll probably give a higher level --
                       CHAIRMAN WALLIS:  You need a matrix or
           something showing that the numbers come out all right.
                       MR. CORLETTI:  Some of the members aren't
           probably familiar enough with AP600 either and we'll
           have to at least tell them how big of a test program
           that we did do.  I mean they don't realize we did a
           $40 million test program on the AP600.
                       CHAIRMAN WALLIS:  Let me ask you a
           question, a lot of it, you say, has to be resolved
           with the staff.  So I wonder how we can give the
           Commission advice until we see how your discussion
           with the staff works out.  We haven't really seen
           that.  We've just seen something that you've presented
           and you say now we have to discuss with the staff.
                       Should we be giving the Commission advice
           until we find out how the staff responds to that?
                       MR. CUMMINGS:  I don't think we can
           comment on that.
                       MR. CORLETTI:  We were interested in what
           you had to say about our approach so far, that's
           probably -- and maybe the staff is also.  I don't want
           to speak for the staff.
                       CHAIRMAN WALLIS:  Well, then I think we've
           seen some scaling analysis or that's most of what we
           saw.  We might be able to respond to that.  The
           question about whether or not the staff should accept
           these codes without further requirements, I'm not sure
           we're in a position to reach any conclusion about that
                       MR. CORLETTI:  Without having seen our
           code applicability report.  I guess some of this
           starting with where we left off on AP600, addressing
           the major issues from that and that's sort of an
           approach question.  
                       MR. CUMMINGS:  This is Ed Cummings. 
           Within this Phase 2, however, you will have the code
           acceptability report.
                       CHAIRMAN WALLIS:  Right.
                       MR. CUMMINGS:  Applicability report and at
           the end I think we'd like the NRC to address our
           request which is can we do AP1000 without incremental
           tests and with the existing codes as modified by our
           mutual agreement.  That's where we'd like to end up
           with in Phase 2.  It says nothing, by the way about
           what the acceptability of the safety analysis is. 
           That's a Design Certification.
                       CHAIRMAN WALLIS:  We might agree that the
           AP1000 phenomena is similar to AP600.  I think we
           might be able to agree to that.  We might be able to
           agree that you've given some demonstrations of
                       Whether or not the scaling represents
           adequate validation basis for codes, I wouldn't be
           sure, myself, until I found out what I needed to know
           in order to get these adequate validations.  So until
           you actually start doing some things with the codes,
           I'm not quite sure what is an adequate validation
           basis.  It's a carte blanche that says because you've
           demonstrated some scaling you've got an adequate
           validation basis for code.  It may be a little hard
           for us to give you.
                       MR. CORLETTI:  That is based on that data
           base was sufficient to validate codes for AP600.
                       CHAIRMAN WALLIS:  We don't know what the
           questions are for AP1000.  There may be different
           questions that come up for AP1000.  It's not clear
           that --
                       MR. BROWN:  I think one example of that
           which worked out well was -- maybe I shouldn't say
           well, one example was when we got down to the end to
           focus on the ADS to IRWST injection phase and we had
           done, obviously -- we had already done a large bulk of
           scaling, but for example, this is where that momentum
           flux issue had come up and in fact, I had gone back
           and Mike Young from Westinghouse and we had looked at
           scaling in more detail to come up with the largely
           hated level penalty approach in NOTRUMP.  But again,
           we went back to scaling for that purpose.  So that's
           probably a good example of something that you're
           talking about, Dr. Wallis, that we did in AP600.  It
           could come up later.
                       CHAIRMAN WALLIS:  Are you expecting a
           letter from the Committee or are you expecting to just
           inform the Committee and wait until we meet again?
                       MR. CORLETTI:  For today's meeting?
                       CHAIRMAN WALLIS:  No, for the full
           Committee.  Do you expect the Committee to write a
           letter based on what you told them or would you --
                       MEMBER KRESS:  For the April meeting, you
                       CHAIRMAN WALLIS:  View the meeting as
           being more informative to say this is -- now you can't
           dispute about where we are.
                       MR. CORLETTI:  We didn't have expectations
           of a letter, nor did we have expectations of a letter
           for this meeting.
                       CHAIRMAN WALLIS:  I think it's a little
           difficult again to write a letter without some
           substantial input from the staff.  In other words,
           we'd be short-circuiting them.  We don't know what
           their questions may be.  They may have concerns we
           don't know about.  
                       MR. CORLETTI:  We agree.
                       CHAIRMAN WALLIS:  Other Members have
           points you want to raise before you hear form the
                       MR. CORLETTI:  That ends our presentation.
                       CHAIRMAN WALLIS:  I'd like to thank you
           for a pretty clear and professional presentation and
           being very willing to respond to our questions.
                       MR. CORLETTI:  Thank you very much.  It's
           been our pleasure.
                       CHAIRMAN WALLIS:  Can we now hear from the
                       MR. WILSON:  This is Jerry Wilson with
           NRR.  I don't have a formal presentation.  I just want
           to say that staff hasn't officially started its review
           yet.  We're waiting for the remaining submittal from
           Westinghouse.  At that time we're going to do an
           acceptance review to determine if there's sufficient
           information to start an efficient review at this time. 
           If there is, then we're going to establish a review
           schedule, review the information, prepare
           recommendations on responses to the report questions
           that Westinghouse has asked and we're going to send a
           report to the Commission telling the Commission how we
           plan to answer those questions.
                       Now we -- I anticipate that the Commission
           is going to hear from the ACRS on that so we'll be
           prepared to come and brief the ACRS on our response to
           the questions that Westinghouse has asked us.
                       MEMBER SHACK:  Will this response be in
           the form of an SER, for example, on these reports?
                       MR. WILSON:  I wouldn't call it an SER,
           but it's some sort of a NUREG report and it's kind of
           like a traditional SER.  We're going to have a report
           and it will be transmitted via a SECY paper.
                       CHAIRMAN WALLIS:  What about the issue of
           exercising the codes themselves?  Do you have a
           position on that?
                       MR. CARUSSO:  This is Ralph Carusso.  I
           just reiterate the point that Jerry made earlier that
           we have sent the letter to Westinghouse asking for
           these codes and we're prepared to run them.  And if
           they've not made the decision yet to provide us with
           the codes then that's something we'll have to talk to
           them about.
                       CHAIRMAN WALLIS:  It seems to me we're
           fairly early in the process.  You haven't started a
           review yet.
                       MR. WILSON:  That's correct.
                       CHAIRMAN WALLIS:  It's premature for us to
           reach any conclusions at this time.
                       MR. WILSON:  Right.
                       CHAIRMAN WALLIS:  That's it from the
                       MR. WILSON:  Yes, it is.
                       CHAIRMAN WALLIS:  Do you have anything
           more to say about any  --
                       MR. WILSON:  I don't anticipate that we
                       CHAIRMAN WALLIS:  Do my colleagues have
           questions to raise?
                       MEMBER KRESS:  No questions at this time.
                       CHAIRMAN WALLIS:  Could we meet perhaps to
           discuss this before we go home, go to dinner?
                       MEMBER KRESS:  Sure.
                       CHAIRMAN WALLIS:  Compare our thoughts and
                       MEMBER KRESS:  Yes.
                       CHAIRMAN WALLIS:  Is there any reason why
           I shouldn't declare the meeting closed?
                       MEMBER KRESS:  I think it will be a good
                       CHAIRMAN WALLIS:  I'll do so then.
                       (Whereupon, at 5:33 p.m., the open meeting
           was concluded and the closed meeting commenced.)


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