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Thermal-Hydraulic Phenomena - August 22, 2001

 

                
                Official Transcript of Proceedings

                  NUCLEAR REGULATORY COMMISSION



Title:                    Advisory Committee on Reactor Safeguards
                               Thermal Hydraulic Phenomena Subcommittee



Docket Number:  (not applicable)



Location:                 Rockville, Maryland



Date:                     Wednesday, August 22, 2001







Work Order No.: NRC-389                       Pages 1-140/195-199





                   NEAL R. GROSS AND CO., INC.
                 Court Reporters and Transcribers
                  1323 Rhode Island Avenue, N.W.
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                          (202) 234-4433                         UNITED STATES OF AMERICA
                       NUCLEAR REGULATORY COMMISSION
                                 + + + + +
                 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS
                                  (ACRS)
                 THERMAL-HYDRAULIC PHENOMENA SUBCOMMITTEE
                                 + + + + +
                                 WEDNESDAY
                              AUGUST 22, 2001
                                 + + + + +
                            ROCKVILLE, MARYLAND
                                 + + + + +
                       The subcommittee net at the Nuclear
           Regulatory Commission, Two White Flint North, Room
           T2B3, 11545 Rockville Pike, at 8:30 a.m., Doctor
           Thomas S. Kress, Acting Chairman, presiding.
           PRESENT:
                 THOMAS S. KRESS, ACTING CHAIRMAN
                 F. PETER FORD, MEMBER
                 VIRGIL SCHROCK, CONSULTANT
                 JOHN D. SIEBER, MEMBER
           ACRS STAFF PRESENT:
                 PAUL A. BOEHNERT
           
                                           A-G-E-N-D-A
                      Agenda Item                          Page
           Opening Remarks
                 T. Kress, Acting Chairman. . . . . . . . . . 3
           GE Nuclear Energy TRACG Code for Anticipated 
           Operational Occurrences, R. Landry, NRR. . . . . . 6
           NRC Staff Presentation TRACG Kinetics Review
                 Tony P. Ulses, USNRC . . . . . . . . . . . .36
           Review of Uncertainty Evaluation
                 Yuri Orechwa, NRR. . . . . . . . . . . . . 101
           Conclusions, Ralph Landry, NRC . . . . . . . . . 125
           Lunch
           GE Nuclear Energy Presentation
           Introduction
                 J. Andersen, GNF, et al. . . . . . . . . . 135
           Concluding Remarks . . . . . . . . . . . . . . . 199
           
           
           
           
           
           
           
           
                                      P-R-O-C-E-E-D-I-M-G-S
                                                    (8:30 a.m.)
                       CHAIRMAN KRESS:  The meeting will now
           please come to order.  This is a meeting of the ACRS
           Subcommittee on Thermal-Hydraulic Phenomena.  I'm Tom
           Kress and I'm Acting Chairman of this subcommittee
           since our regular chairman can't be here.
                       The purpose of this meeting is 1) to
           review the GE Nuclear Energy TRACG realistic thermal-
           hydraulic code version, particularly for its
           application for evaluation of anticipated operational
           occurrences and, 2) review the resolution of issues
           associated with the EPRI Report TR 113594, resolution
           of generic letter 9606 waterhammer issues.
                       The subcommittee will gather information,
           analyze relevant issues and facts, and formulate
           proposed positions and actions as appropriate for
           deliberation by the full committee.  Mr. Paul Boehnert
           is the designated federal official for this meeting.
                       The rules for participation at today's
           meeting have been announced as part of the notices of
           this meeting previously published in The Federal
           Register on July 30 and on August 15, 2001.  
                       Portions of this meeting will be closed to
           the public to discuss GE Nuclear Energy and EPRI
           proprietary information.  A transcript of the meeting
           is being kept and will be made available as stated in
           The Federal Register notice.
                       It is requested that speakers first
           identify themselves and then speak with sufficient
           clarity and volume so they can be readily heard,
           particularly by the transcriber.  
                       We have received no written comments or
           requests for time to make oral statements from members
           of the public regarding today's meeting.
                       For the benefit of the members who may not
           have been here during some of our earlier reviews of
           TRACG, we did have a few problems -- or not problems,
           maybe issues, questions, related to the treatment of
           delayed neutrons, the treatment of rental stresses,
           the treatment of wall shear and heat transfer
           partitioning from the wall, flow regime transition
           treatment and interfacial shear and interfacial heat
           transfer treatment, among others.  I think those are
           just some of the more important ones.  
                       With those comments, I'll ask if our
           consultant, Virgil Schrock -- I forgot to mention the
           ACRS members in attendance are Peter Ford, Jack
           Sieber, and our consultant, Virgil Schrock.  If
           anybody wants to make any comments before we start,
           Virgil, I'll start out with you.
                       MEMBER SCHROCK:  I'm a little at a loss to
           know what to say or what depth to pursue the issues,
           but I found the SER to be a great disappointment.  I
           don't see that it has explained in any way many
           questions that were discussed at the last meeting of
           the ACRS on this topic.  Some of that may be because
           some of the things that I thought were important
           evidently had not been deemed sufficiently important
           by the full committee to make it on their laundry list
           of things to have you respond to.  
                       But I understand several of these problems
           as well as anybody in this room, and I can say to you
           that you have a superficial treatment of real problems
           in this SER.  If that's what you want, that's what you
           will have.  I think it's a disgrace to the regulatory
           process.  I'll give you as much detail as you'd like
           to have as we go along, but that's what my reading of
           it led me to believe.
                       CHAIRMAN KRESS:  Okay.  With that pleasant
           note, I'll go around this way.  Do you wish to add to
           that?
                       MEMBER SIEBER:  I don't think so.
                       CHAIRMAN KRESS:  Peter, I think you wanted
           to make some sort of statement.
                       MEMBER FORD:  Yes.  I'm a retired General
           Electric employee.  Although I had nothing at all to
           do with the TRACG code, I do have to declare a
           conflict of interest.
                       CHAIRMAN KRESS:  Okay.  With that then, I
           don't have any additional statements, so we'll proceed
           with the meeting, and I guess I'll call on Ralph
           Landry to begin the inquisition.  Did we give you a
           laundry list of comments and issues?  Since I wasn't
           chairing this subcommittee at the time, I don't know
           whether we did or not.
                       DOCTOR LANDRY:  Okay.  For the record, I'm
           Ralph Landry from the NRR staff.  
                       No, Doctor Kress, we did not receive a
           laundry list.
                       CHAIRMAN KRESS:  Did we pass Virgil's
           written thing on to you?
                       DOCTOR LANDRY:  No, I never received a
           copy of a report from Virgil.
                       CHAIRMAN KRESS:  That might explain,
           Virgil, why the--
                       DOCTOR LANDRY:  We were surprised when we
           saw some of these items.
                       MEMBER SCHROCK:  Let me just interject
           that whether you had it in writing or not, you sat in
           this room and heard the arguments.  We spent a lot of
           time.
                       DOCTOR LANDRY:  Well, somewhere between
           all of the discussion and getting the agenda for this
           meeting, we had missed a number of these points and
           did not have them down.  So this time we didn't have
           copies of the reports from the consultants, so we
           missed the specific points.  But yes, Virgil, if you
           do have specifics in addition to what's on the list
           with the agenda, we'd definitely like to hear your
           views and specific things that you think should be
           brought out.
                       What we're going to talk about this
           morning is give a real brief review of how we got to
           the SER.  The approach that the staff took in the
           review of the documentation on TRACG, the
           applicability intended for the code, what transients
           and where the code is going to be applied.  Talk
           briefly about the assessment of TRACG.  We'll talk
           about the staff evaluation and briefly about the
           thermal-hydraulics.  We'll go into a great deal more
           depth on the neutron kinetics.  Tony Ulses will
           present his review of the neutron kinetics aspects of
           the code.  Yuri Orechwa will talk quite a bit about
           the statistical methodology review which he performed,
           the uncertainty analysis.  We'll talk a little bit
           about the code user experience.  We have been running
           the code.  We've run some cases with the code and
           tried to look at a few things, so we'll talk about
           some of our experience in running TRACG.  And then
           review the conditions and limitations that we're
           suggesting for the code and the conclusions of the
           staff.
                       Okay.  How did we get to this point?  In
           the spring of 1999 and the summer of 1999, TRACG was
           presented to us in a preliminary fashion by General
           Electric and General Nuclear Fuels, GNF.  Sometimes we
           use the two interchangeably, GE and GNF.  So if we
           swap back and forth, we mean the same company.  
                       The preliminary information was to come in
           and show us how GE would propose to submit the code
           for review for AOO analyses, what material they would
           suggest that we review and how they would like to
           proceed with a review of the code for operational
           transients.  
                       In January of 2000, we began to receive
           the materials on the code.  That submittal was finally
           complete in February of 2000.  We received manuals and
           then we received the electronic version of the manuals
           and finally we received the code itself.  General
           Electric did submit to us both the source code and an
           executable version of the code.  We installed the code
           on an alpha machine, a VMS machine which we purchased,
           so that we could run the code in the same native mode
           that the applicant ran the code for their own work.  
                       We met with the ACRS Thermal-Hydraulics
           Subcommittee in middle of November of 2000.  We've
           been issuing RAIs informally as we've been performing
           this review and the applicant has been looking at the
           RAIs and responding to those RAIs informally
           throughout the review.
                       In July we finally issued the formal RAIs,
           those that have gone through our full review by
           management and have been issued formally to the
           applicant, and we have received now the formal
           response from the applicant which is really the same
           responses which we had in draft but this now puts the
           response officially on the record.
                       We prepared the draft SER on TRACG in July
           and we have discussed that draft SER with the
           applicant.  We have provided it to them for review for
           proprietary content, and I would point out to the
           committee at this point that the draft SER which you
           have received from the staff does contain proprietary
           information. The applicant has determined that there
           is proprietary information in there, so we are going
           to withhold this draft version of the SER from the
           public.  We are going to work on the SER and try to
           take the draft material which is proprietary out of
           the SER so that we can publish a non-proprietary
           version of the SER.  So at this point, the SER draft
           which you have received must be treated as
           proprietary.
                       CHAIRMAN KRESS:  What are the plans for
           going final with that?  What is your time line?  Do
           you have one?
                       DOCTOR LANDRY:  We would like to have the
           final SER ready in September.  Assuming that the
           Thermal-Hydraulic Subcommittee can report back to the
           full committee at its September meeting, we would then
           issue the final version of the SER in September.
                       MEMBER SCHROCK:  Is there an
           identification of the version of the code that you've
           reviewed?
                       DOCTOR LANDRY:  It's right at the
           beginning of the SER.  It's TRACG O2A.  
                       MEMBER SCHROCK:  What does TRACG O2A mean
           precisely?
                       DOCTOR LANDRY:  That's the specific
           version which was submitted to us for a review.  We
           realize that the applicant is working on future
           versions of the code.  They have talked with us about
           submitting a version of the code for realistic LOCA
           analysis.  So we're being very specific that the
           version we review has been designated as TRACG O2A.
                       CHAIRMAN KRESS:  Does the A stand for
           anticipated?
                       DOCTOR LANDRY:  I'd like to ask Jens
           Andersen from General Electric to answer that one.
                       DOCTOR ANDERSEN:  This is Jens Andersen
           from GNS.  The A simply just designates the computer
           hardware that it's executed on.
                       MEMBER SCHROCK:  Well, I had raised that
           question in the previous meeting, but it seemed to be
           now several different versions of TRAC as opposed to
           a version which was reviewed comprehensively in the
           past maybe, maybe not comprehensively but reviewed in
           some depth and asked and specifically the fact that
           the decay power was discussed in terms of the May-Witt
           estimate which goes back to the 1960s whereas the
           version of TRACBD1 which was developed by INEEL with
           cooperation from GE had the 1979 decay standard in it. 
           A world of difference between the two in the sense of
           the technical approach.  One recognizes that the decay
           power is not the same for different fissile muclides. 
           The other does not.
                       In any case, that led me to ask the
           question in that previous meeting.  Has the ANS
           standard been removed from TRAC and Jens Andersen was
           unable to answer the question, as I remember, at that
           time.  But I presumed that somebody would look and see
           what is the status.  Now what you have in your SER, in
           one paragraph you kiss off both that issue and the
           issue of what procedure is employed to weight delayed
           neutron fractions according to contributions from
           different fissile species.  Both of those are
           superficially essentially treated as non-issues, non-
           questions.  So if you don't understand what I'm saying
           to you, Ralph, I'll try to explain it in greater
           detail.  Is that the problem?  You don't understand
           the issue that I'm addressing?
                       DOCTOR LANDRY:  No.  I think when we get
           into the discussion of the neutron kinetics, we'll
           address that a little bit more.
                       MR. ULSES:  We will now.
                       DOCTOR LANDRY:  Tony Ulses will address
           that further when we get into the discussion of the
           neutron kinetics because he has already looked at
           that.  Yes.
                       MEMBER SCHROCK:  Okay.  Well, several
           related questions are, two technical issues I just
           mentioned plus the question of what is the code
           version?  How is it defined?  How are we understand
           what the code version is?  If it does not have the ANS
           decayed heat standard in it any longer, then it's not
           the same code that was reviewed for SBWR.  Do you know
           the answer to that?
                       DOCTOR LANDRY:  Let me ask Jens Andersen
           if he can respond to that.
                       DOCTOR ANDERSEN:  Yes, I can comment on
           that.  Most of the models in the codes are the same as
           what was reviewed for the SBWR and if you compare the
           model description TRACG 2A -- revision one to the
           model description, which was what was submitted during
           the SBWR review, and then revision two, which is what
           we have submitted for this review, there are minor
           model differences but the majority of the code is the
           same.  The decayed heat model that is being used for
           the application to transient is based on a simulation
           of decayed heat cooks and we can get into that later
           on.
                       What we have done is, realizing that there
           were minor differences in the code, is that we
           submitted a complete qualification of the code as
           submitted.  The material that's documented in the
           qualification report is all one with the code as
           submitted to the NRC.
                       MEMBER SCHROCK:  Well, it seems to me that
           there are guidelines that you have issued for code
           reviews that are not met by this submittal.  Is that
           incorrect?  You needed a starting point, but you had
           a clearly defined code that you had complete
           documentation for that clearly defined code.  It
           doesn't appear that you have that.
                       DOCTOR ANDERSEN:  Can I make a comment
           again? This is Jens Andersen.  The documentation that
           has been submitted for this review, model description,
           qualification, the user's manual, is all specific to
           the code version TRAC.  It's a two way that has been
           used and that was made available to NRC for
           installation on their computers. So it's totally
           consistent.
                       MEMBER SCHROCK:  But not the same code
           that was reviewed for SBWR?
                       DOCTOR ANDERSEN:  That's correct.
                       DOCTOR LANDRY:  That's correct.  It's been
           built on the version that was reviewed for SBWR.
                       MEMBER SCHROCK:  Of course it's been built
           on it, but unless you define changes and explain what
           the changes are, how can you expect a technical body
           reviewing it to tell you what yes, what you're saying
           is fine when you haven't even defined what the product
           is that you're reviewing?
                       DOCTOR LANDRY:  But they have defined the
           product and that is the TRACG O2A version of the code
           and the documentation which they submitted on this
           version of the code, the staff believes defines the
           code.
                       When we did the review of this code, we
           did build on the work that was done in the review of
           SBWR version of TRACG.  At that time, the contractor
           which the staff was using, Brooke Haven National
           Laboratory, did an extensive review of the thermal-
           hydraulics of the code and a review of the kinetics
           and other parts of the code.  
                       We looked at the review that was
           performed, compared that with what was being submitted
           for the review of the TRACG O2A code for AOO
           transients, and we felt that the thermal-hydraulic
           questions and concerns that had been raised during the
           SBWR review had been addressed in the material
           submitted for the TRACG O2A submittal.  
                       Because of that review and the depth that
           that review was taking, the staff made the decision
           that we would review the material and we only asked a
           few requests for additional information on thermal-
           hydraulic aspects of the code and then concentrated
           heavily on the kinetic aspects of the code and on the
           uncertainty analysis, the statistical methodology.  We
           felt that that would be a more productive use of the
           resources which we had available to us in performing
           the review.
                       You have to keep in mind what the code is
           being applied to.  The application of TRACG O2A for
           AOOs is very limited in scope.  The code is being
           applied to only transients in chapter 15.  It is not
           being applied to Atlas, it is not being applaud
           stability analysis, it is not being applied to loss of
           coolant accidents.  It's being applied only to
           increase and decrease in heat removal by the secondary
           system, a few transients in those classifications, a
           decrease in the reactor coolant flow rate.  It's being
           applied to reactivity and power distribution
           anomalies, increase and decrease in reactor coolant
           inventory.  Those increases and decreases that are
           short of a loss of coolant accident.
                       When we looked at the assessment that was
           performed for the code, the first thing we did was
           step back and look at assessment in the way we always
           do.  How has the assessment been performed?  Have they
           looked at the phenomenological tests, separate effects
           test, integral test, plant system information when
           available, so that they can assess from the level of
           correlations to the level of models to the level of
           the entire code.  
                       Of course, when you look at plant
           operational data, because of the way the data are
           taken, they're not experimental, empirical data, so
           the data set is much more limited.  But the assessment
           that is performed is a global assessment of the code. 
           Does the code adequately represent the global events
           occurring in a transient when those transients have
           been run in a plan?
                       CHAIRMAN KRESS:  How do you know when you
           have enough assessment?  I know I've asked this
           before.
                       DOCTOR LANDRY:  The big question for years
           has been how good is good enough.
                       CHAIRMAN KRESS:  Yes.
                       DOCTOR LANDRY:  In the case of the code as
           it has been submitted, since it is doing a statistical
           uncertainty analysis, has enough assessment been
           performed is determined by has a phenomena
           identification ranking table been prepared, a thorough
           PIRT, that can be reviewed and is thorough, captures
           all the phenomena.  Do we agree that the PIRT captures
           all the high and medium importance phenomena?  And
           then have those phenomena been properly assessed
           against data?  Have enough assessments been performed
           that an uncertainty analysis can be performed and
           uncertainty be placed on the important phenomena?  
                       When we look at codes, as we have in the
           past, that did not do uncertainty analysis, codes such
           as LOCA codes meeting Appendix K, we did not put a
           handle on uncertainty.  We simply said does the code
           meet these set prescriptive requirements and how good
           is good enough became a much more difficult question
           to answer because we did not have a definition of
           statistically what is enough assessment to perform and
           we would have to look at the assessment and say does
           it cover an adequate set of the data available.  Are
           there data available from the other aspect to perform
           an assessment?  
                       And we always run into the problem when we
           get into those assessments that there are events that
           can occur, there are phenomena that can occur, for
           which there are no data and for which you can not
           properly assess.  There are a number of aspects in
           turbulent flow where it's three-dimensional flow
           effects where you don't have data and you can't really
           assess the capability of the code in some of those
           areas.  So I hope this is answering your question.
                       CHAIRMAN KRESS:  Yes.  I think that was a
           good answer.
                       DOCTOR LANDRY:  When a code is submitted
           with an uncertainty analysis under a statistical or
           what we sometimes call best estimate or realistic
           application, we have a better way of saying how much
           assessment is enough because now we're zeroing in on
           the phenomena that are important.  We're saying are
           those phenomena assessed properly so that a
           statistical basis for the uncertainty can be assigned?
                       This morning later on Yuri is going to go
           through an explanation of his review of the
           statistical methodology and he'll give some of his
           views of what has been performed and has a proper
           assessment been performed.
                       MEMBER SCHROCK:  You have made the point
           in the SER that the code and its application meets the
           guidelines of the CSAU methodology.  Do you want to
           comment on how the uncertainty and decay power
           evaluated -- assessed.  -- provided assessment of the
           uncertainty.  Uncertainty indeed is dependent upon the
           details of the reactor problem that you're addressing. 
           It's impossible to assess such an uncertainty.
                       The problem may be that a good case can be
           made that decay power is pretty much a second order
           phenomenon in AAOs.  That case is not made here.  It's
           nowhere to be found in your SER that I can see.  But
           even so --
                       DOCTOR LANDRY:  Well, we'll take that into
           consideration.
                       MEMBER SCHROCK:  My recollection, as I
           said in the previous meeting, of what GE did in using
           the ANS standard first was to run a lot of Monte Carlo
           calculations to find a sort of generic decay power
           curve which they could put some sort of balance on,
           and I think they take a penalty rather than including
           that in the assessment.  The details are a little bit
           fuzzy in my mind, but I clearly remember that was the
           general pattern of what was done.  It was not a
           straightforward assessment of the uncertainty using
           the uncertainties that are published in the ANS
           standard for decay power.  That would be one way of
           approaching it.  It's not what they did.  What they
           did was found acceptable at the time.  I thought it
           was quite good.  
                       My problem with this is that what I see is
           superficial discussion of real life problems in an
           SER.  This is the government's evaluation of the
           safety of that system done in a very superficial way. 
           That frightens the hell out of me.
                       DOCTOR LANDRY:  Tony.
                       MR. ULSES:  I suppose nobody -- to talk
           about decay heat.  Let's do it rather than wait?  The
           issue of decay heat and --
                       CHAIRMAN KRESS:  Go ahead.  We'll talk
           about it now.
                       MR. ULSES:  I would say I would certainly
           agree with you, Doctor Schrock.  It was given a
           cursory discussion in the SER because I believe it has
           a cursory effect on the problem, and that's my fault. 
           I should have discussed it in more detail and that's
           a valid criticism and I will definitely change the SER
           to expand upon that point.  I definitely think you are
           right, and that's an oversight on my part and that is
           something that will be fixed.
                       MEMBER SCHROCK:  More than that, you're
           reviewing a code which is said to have been adequately
           reviewed for loss of coolant accidents and other
           purposes in the context of the SBWR review and now
           you've not called out in any sense here that what
           you're going to do is substitute for one particular
           aspect of the whole calculation, a more simplistic
           approach because it's more computationally efficient. 
           That is to invoke the Mae Witt implication for decay
           heat evaluation. 
                       MR. ULSES:  Well, again, we were looking
           at the version of the code that we were given and
           that's a beyond scope issue.  I mean this is not a
           LOCA code.
                       MEMBER SCHROCK:  Do you review something
           with blinders on or do you review it with an
           intelligent assessment of how it fits into the whole
           picture of your dealing with this code?
                       MR. ULSES:  Well, I reviewed it with the
           scope of the application in mind.
                       CHAIRMAN KRESS:  If they come back later
           and want to use this for best estimate LOCA, then you
           would face up to that problem.
                       MR. ULSES:  Yes, sir.  We will deal with
           it in excruciating detail because it is very important
           for LOCA applications.  However, for AOOs, it is not
           a significant contributor.
                       CHAIRMAN KRESS:  You're pretty much
           constrained to have to review the application as it's
           presented to you.
                       MR. ULSES:  Yes, sir.  We're not really
           allowed to go beyond the scope of the review, and that
           would have been beyond scope if we would have gotten
           into the questions about specific details of the decay
           heat model because it's not a significant contributor
           to the answer.  But your criticism is certainly valid. 
           On what's written in the SER, it is not clearly
           spelled out and that will definitely be corrected and
           for that I apologize.  The actual discussion of why it
           was not reviewed in detail is not there and I will
           definitely correct that.
                       DOCTOR LANDRY:  Let me make one other
           correction.
                       MEMBER SCHROCK:  The description of the
           code doesn't say we have different options for decay
           heat evaluation.  Those options are used in this way
           for evaluation of AOOs. We invoke this simpler thing. 
           That's not in the GE documentation.  It's not in your
           interpretation of the GE documentation.  But you're
           telling us now, after all, that is your
           interpretation, that's your understanding of it.  This
           is the limit of its utilization in TRACG.  Is that
           right?
                       MR. ULSES:  Yes, sir.  That's all that GE
           will be able to actually use the code for because the
           SER will be written not to allow them to use it for
           any other applications.  I believe we have an
           additional comment.
                       MR. HECK:  This is Charlie Heck from
           Global Nuclear Fuel.  In the documentation that was
           submitted with the application in Section 9.3 of the
           model description, it clearly describes what is the
           model we're using for decay heat and it also provides
           a comparison of the  Mae Witt curves with the ANS
           standard 5.1 and it describes the model that's being
           used.  That was part of the submittal.
                       MEMBER SCHROCK:  In order to make such a
           comparison, you have to say what the particular
           reactor state is at the point of this evaluation by
           the ANS standard.  There's not just a single
           comparison of Mae Witt.  Mae Witt is a single entity. 
           That's right.  It just relates it to the operating
           power.  But the decay heat standard gives you an
           evaluation which depends upon the operating history of
           the reactor and the composition of the fuel. So,
           Charlie, you can't argue that that was an adequate
           description.  It was a comparison but with an
           undefined set of circumstances for what the ANS
           standard part of that comparison was calculated for.
                       MR. HECK:  Doctor Schrock, the
           documentation that was provided indicates that the
           comparison was made at end of cycle conditions,
           exposures and radiation time, and enrichment values
           that are typical of the application for AOOs, and it
           was done at that point because that's where the most
           limiting conditions for AOO occur.  So a comparison
           that we did do -- and I acknowledge your point that
           it's very specific to what has been the operating
           history, what was the initial load, what are the
           fissionable materials.  We did provide the comparison
           at a representative condition for the intended
           application.  But it is a single point evaluation.
                       MEMBER SCHROCK:  Well, I think the point
           that I'm making is that the documentation of these
           issues is something that needs to be of concern to the
           NRC.  It's treated in the SER as though the problem
           would never arise.  That's what I have great
           difficulty with.
                       DOCTOR LANDRY:  Well, this is a draft SER
           and we'll take your comments back and address them.
                       In looking at the assessment that has been
           performed through the uncertainty analysis, we did
           find that all the medium and high ranked phenomena
           have been taken into account in the uncertainty
           analysis and, on that basis, we feel that the proper
           assessment has been performed that does show the
           capability of the code to represent the experimental
           and operational data as necessary for the application
           to AOO transients.
                       CHAIRMAN KRESS:  Did decay heat show up as
           important in that PIRT?
                       DOCTOR LANDRY:  No.
                       MR. BOLGER:  This is Fran Bolger from GE. 
           We did identify it as a high phenomena for the loss of
           heat water transient.
                       CHAIRMAN KRESS:  For what are the AOOs
           only.
                       DOCTOR LANDRY:  Okay.  Just to briefly
           recap some of the thermal-hydraulic aspects of the
           code because this was, as I said, more of a review of
           what was done during the review of the SBWR
           application of a version of TRACG.  This was an
           extensive review.  As I said, it wasn't performed to
           be a complete review because the code was withdrawn. 
           The whole submittal was withdrawn before the review
           could have been completed.  So it was not a complete
           acceptance review of the code.  But it was an
           extensive review for thermal-hydraulic aspects.
                       TRACG is just basically like the TRAC
           code.  It's a two fluid, six conservation equation
           code.  Has boron transport, non-condensible mass
           equation in it.  It's a two regime unified flow map
           instead of some of the other codes that we see
           typically for PWRs that will have multiple regimes. 
           The regimes that are in the code are adequate to cover
           the normal operating and anticipated regimes that
           occur in a BWR.  We're saying for AOOs the four
           regimes that are covered are adequate.  
                       There's a two phase level tracking model
           which was criticized during the SBWR review because it
           uses approximations for void fraction above and below
           a mixture level and uses a cut point for level
           detection.  We feel that because there is not a high
           degree of mixture tracking going on in AOOs that the
           shortcomings of this model are acceptable for AOOs. 
           However, to go beyond AOOs, we are going to look at it
           extensively.  
                       When the application comes back for the
           LOCA, we will look at this model again.
                       CHAIRMAN KRESS:  Could you refresh my
           memory on bullet one about the boron transport
           equation.  Is that a K epsilon turbulent transport
           model or was that empirically based on the tests that
           were done with salt and thermal?
                       DOCTOR ANDERSEN:  This is Jens Andersen
           again.  We have a boron transport model in the code
           but let me first clarify one thing is that this
           particular submittal is for AOO transients, and it
           does not include Atlas.  It does not involve the boron
           transport model.  The model does assume that the boron
           is transported with a fluid model.  Fluid velocity. 
           So it's a relatively simple model.  If we make a
           submittal of TRAC for Atlas, that's one issue that we
           would have to address in more detail.
                       CHAIRMAN KRESS:  Thank you very much.
                       DOCTOR LANDRY:  In the TRACG code, the
           kinetic energy term has been put back into the energy
           equations.  The kinetic energy term was removed in the
           TRACB version of the code that the NRC had supported,
           and that introduces energy balance errors.  By putting
           the kinetic energy back in, there's better
           conservation of energy with this version of the code.
                       CHAIRMAN KRESS:  That's merely to keep
           people from asking questions about why the energy
           didn't balance because it was a small discrepancy.
                       DOCTOR LANDRY:  -- will have it back in
           and get rid of those problems.  Reduce errors wherever
           possible.
                       MEMBER SCHROCK:  When was it removed?
                       DOCTOR LANDRY:  That was in the early
           stages of the TRACB development at INEEL.
                       MEMBER SCHROCK:  It was not in BD1, didn't
           include kinetic energy?
                       DOCTOR LANDRY:  No.  An issue that did
           come up during this review that is not a TRACG
           specific issue but came up during the power up rate
           review is an issue concerning the GEXL heat transfer
           correlation.  The NRC staff review and the power up
           rate found that data were generated using COBRAG for
           assessment of the GEXL 14 correlation rather than
           using up skew, down skew experimental data.  
                       We raised a number of questions on the use
           of artificial data instead of empirical data for doing
           a statistical analysis on the MCPR safety limit.  The
           staff is involved with the applicant in resolution of
           that issue on the power up rate concerns at this
           point.
                       CHAIRMAN KRESS:  Wouldn't your perception
           of that depend on how well you thought the other code
           had been validated?
                       DOCTOR LANDRY:  If the other code was
           truly independent and was properly validated.  Yes. 
           The staff view is we don't like using one code to
           validate another code rather than data.  If the other
           code has not been validated against data, then --
                       CHAIRMAN KRESS:  You would always prefer
           data.
                       DOCTOR LANDRY:  We always prefer data.
                       CHAIRMAN KRESS:  But if you have places
           where you don't have data, it seems like --
                       DOCTOR LANDRY:  But if there are data but
           they're owned by another entity, then --
                       CHAIRMAN KRESS:  Oh, that's a problem.
                       DOCTOR LANDRY:  This is a very involved
           question.
                       CHAIRMAN KRESS:  Yes, I can see that.
                       DOCTOR LANDRY:  This is a question that
           has come up through the power up rate reviews, but
           we're only pointing out in the TRACG review that yes,
           if the GEXL 14 correlation is applied in this code for
           a transient, this issue must be addressed and that
           whatever the resolution of the GEXL 14 issue is, we
           expect that to be applied in the TRACG application
           also.
                       CHAIRMAN KRESS:  I don't know if we have
           a statistician here or not but it seems to me like if
           you have a measure of the uncertainty for the base
           code and you can use that along with comparison with
           calculation of the TRACC, TRACG, then you can actually
           develop the uncertainty in the TRACG based on the
           uncertainty in the other code.
                       DOCTOR LANDRY:  If you have a thorough
           uncertainty analysis of the other code.
                       CHAIRMAN KRESS:  Yes.  What I'm saying, it
           seems like philosophically it's a reasonable thing to
           do is to use another code if you know enough about
           that code and uncertainty is known about it to develop
           the uncertainty in another code if they are
           independent, just as a philosophical statement.  Seems 
           like an approach that's probably reasonable,
           especially in places where you can't get access to
           real data or real experiments.
                       DOCTOR LANDRY:  We did not want to get
           into that issue--
                       CHAIRMAN KRESS:  I understand.
                       DOCTOR LANDRY:  -- other than to point out
           that there is an issue which is being dealt with
           independently of this review but will impact the
           application of this code when it is finally resolved. 
           I call that out in the SER for that purpose to ensure
           that the resolution of the GEXL 14 issue is properly
           addressed in the application of TRACG.
                       CHAIRMAN KRESS:  Yes.  I just wanted to
           give you a hint as to how the ACRS might feel about
           that issue.  I can't speak for the ACRS.  Some of the
           ACRS members --
                       DOCTOR LANDRY:  One of the ACRS members.
                       CHAIRMAN KRESS:  At least one of them.
                       DOCTOR LANDRY:  In looking at the TRACG
           code, the basic component models are very much the
           same as in the TRACB version of the code.  Models are
           used as building blocks to construct physical input
           models for a plant.  We did note that the
           applicability to isolation condensers needs to be
           demonstrated should the code be applied to transients
           for which the isolation condenser is important.  
                       We feel that the steam separator model
           that is in the code has been validated very well
           against full scale performance data.  This issue of
           steam separator/steam dryer keeps coming up whether
           we're talking about PWRs or BWRs because there's so
           much lack of data.  But here the applicant has a great
           deal of full scale data.
                       CHAIRMAN KRESS:  You'd think GE would know
           more about steam separators and dryers than anybody.
                       DOCTOR LANDRY:  Right, and they have a
           great deal of full scale performance data which they
           have used to validate their separator model.  We just
           wanted to call out that yes, they've done a very good
           job and we feel that the model is very well-
           documented.
                       CHAIRMAN KRESS:  Where does it show up in
           PWRs?
                       DOCTOR LANDRY:  We're talking about steam
           generator performance.
                       CHAIRMAN KRESS:  In generator problems. 
           Okay.  
                       DOCTOR LANDRY:  It has default, fully
           implicit integration for hydraulic equations and heat
           conduction equation is used.  Predictor -- technique
           is used.  There's implicit coupling between the heat
           conduction and coolant hydraulics and this code is
           less prone to error on phase shift in thermally
           induced oscillation.  So we feel that the numerics
           have been improved in going from the TRACB to the
           TRACG version of the code.
                       MEMBER FORD:  Can I ask a question?  I'm
           trying to come as quickly as possible onto the issues
           on this particular subject.  As I understand it,
           there's a whole lot of questions about the specifics
           of the modeling Virgil has brought up.  And also there
           could be presumably some questions about how good the
           model is to predict the observations.  Are we going to
           see any data at all today on resolving some of these
           modeling questions and are we going to see any data
           against which the model is calibrated?
                       DOCTOR LANDRY:  There will be some
           material presented by Tony.  Tony will be coming up
           next to talk about the kinetics modeling which he has
           examined.
                       MEMBER FORD:  We'll see some data points.
                       DOCTOR LANDRY:  We'll see some data
           comparisons which Tony has prepared.
                       MR. ULSES:  Ralph, I want to interject. 
           We actually aren't going to discuss the data because
           the data is proprietary to GNF.  We obviously can't
           get into it in open session this morning.
                       MEMBER FORD:  I have a fundamental problem
           then.  Again, I'm learning about this whole process.
                       CHAIRMAN KRESS:  You come into this issue
           a little late, but there is a validation part of the
           submittal that includes the data they have and their
           comparisons with the code.  We may not have gotten you
           all that information yet.  But it is part of the
           submittal.
                       DOCTOR LANDRY:  Tony is going to talk
           about some comparisons with the code which he has
           performed and the neutronics.  Yuri is going to talk
           about the statistical methodology that's been set up.
                       CHAIRMAN KRESS:  That's largely based on
           data.
                       DOCTOR LANDRY:  We're trying not to
           utilize proprietary information in our presentations,
           so we're trying to stay away from the actual data but
           by showing some analyses which we have performed how
           we feel the code is performing.
                       MR. ULSES:  And there also is an extensive
           assessment manual which was given to the staff and I
           believe the ACRS as well by GNF and that has a great
           deal of data in it.  It's like an inch and a half
           thick if I recall.  It's an extensive manual. 
           Unfortunately, I don't have it here.
                       MEMBER FORD:  I can see some of the
           problems.  I personally would not like to see some of
           that data.
                       DOCTOR LANDRY:  We'll try not to show it
           to you then.
                       DOCTOR LANDRY:  The next person to talk is
           going to be Tony Ulses.  Tony will talk about the
           neutron kinetics analysis which he has performed, and
           then Yuri Orechwa will follow Tony and talk about the
           statistical methodology, and then I'll come back up
           and talk a little bit about some of the user
           experience with the code and the conditions and
           limitations on the code and our conclusions.  I would
           ask during the next two presentations if GE sees stuff
           coming up that they think is proprietary to alert us
           so that we can take appropriate action.
                       MR. BOEHNERT:  Yes.  We can close the
           meeting if we need to.
                       DOCTOR LANDRY:  We don't think that what
           we're going to say is proprietary, but if it looks
           like we're getting in a proprietary area, let us know.
                       MR. ULSES:  As Ralph said, I'm Tony Ulses
           of the staff.  What I'd like to do is I'd like to try
           and address your concerns, Doctor Schrock, before I
           get into the actual details of my presentation because
           I don't have any specific discussions in there about
           your questions.  But I'd like to make sure that I
           address them.  There's one question you had about beta
           that I know we haven't discussed.  We can talk about
           decay heat more if you'd like and if there's anything
           else you'd like to discuss, I'd like to do that now
           just to make sure I address your questions before I
           get into the presentation, just to make sure they
           don't get lost.
                       MEMBER SCHROCK:  You can explain that now
           or you can explain it wherever you plan to if you did
           plan to.  But I would like to hear it.
                       MR. ULSES:  It's not in the presentation.
           That's why I'd like to discuss it now.
                       MEMBER SCHROCK:  How you deal with the
           calculation of beta for -- fissile fuel.
                       MR. ULSES:  This actually goes back to the
           discussion we had in the past in the RETRAN review. 
           The question of beta within the scope of this review
           is that it's viewed as input value into TRACG.  It's
           calculated by the upstream codes and it's going to be
           fuel type specific.
                       MEMBER SCHROCK:  You haven't read my
           December report and, therefore, you couldn't have
           responded to that but in that report I said, and I
           believe this to be absolutely essential in what you do
           in the regulation, that you have to know what the
           source of information is for inputs.  You can't
           extract a physical problem from a computer code and
           say, now, this code doesn't deal with that issue any
           more because it's input.  The fact is it has to be
           evaluated in order to get a completed calculation
           using this code and, in fact, the input or whatever is
           preparing the input has to be based upon the
           conditions that you're doing the calculation--
                       MR. ULSES:  You're certainly correct,
           Doctor Schrock, and the reason why it's not reviewed
           in these contexts is that GE has and uses a licensed
           code which has been reviewed and approved by the staff
           for doing lattice physics type calculations and also
           core analyses.
                       MEMBER SCHROCK:  What I heard is an
           oblique way of telling me it's not my business to know
           this.  What I'm saying to you is that you, the NRR,
           has gone on record as saying you have conditions for
           review of computer codes and those conditions we've
           reviewed.  A lot of time has been spent on that. 
           You're not following the advice that you prepared for
           industry.
                       MR. ULSES:  I'm not particularly sure I
           know what advice we're not following.
                       MEMBER SCHROCK:  This is a part of the
           calculation.  I raised the issue because I read things
           in some other documents, as I explained previously,
           that planted the seed of the possibility that maybe
           this distinction is ignored in such calculations which
           seems incredible.
                       MR. ULSES:  Well, I can assure you that it
           is not ignored in the GE analysis.  We do specific
           fuel type analysis based on exposure.
                       MEMBER SCHROCK:  I don't think it is
           either, and Fran Bolger and Charles Heck gave a lot of
           assurance last time that it is done and it's done
           well.  I'm not challenging that.  What I'm saying is
           that if you're going to review the code, if you're
           going to ask us to review the code, if you're going to
           ask me to review the code, don't tell me it's none of
           my business how this gets calculated.
                       MR. ULSES:  If that's the impression I
           left with you, I apologize.  That was not my point. 
           The issue  is is that we have a scope of review which
           has been defined for us and it's very difficult for us
           to go beyond that scope and if you look at the
           application that we were reviewing, it was for one
           code -- in this case, the TRACG code, which uses beta
           as an input value.  We know because we have access to
           all the previous reviews that the staff has done that
           there is an approved code that GE uses for doing those
           types of calculations and that they do treat all the
           relevant physics, all the relevant parameters. 
           Unfortunately, that information was not made available
           to you and actually, I don't know if we could have
           made it available to you or not.  I really don't know
           actually in this context because again, it really is
           beyond the scope of the question we were asked to
           answer.  Other than to assure you that it is dealt
           with and it is dealt with through all the relevant
           parameters.
                       CHAIRMAN KRESS:  How do you determine
           what's in scope because it seems to me like the
           determination of any input value in the code could
           reasonably be said to be in scope.  I don't know how
           you determine what's in scope.
                       MR. ULSES:  In this case, it's determined
           because we know that GE has an approved method which
           the staff has already reviewed and approved.  There's
           an SER written on it that says it's acceptable for
           doing those types of calculations.
                       CHAIRMAN KRESS:  Okay.
                       MR. ULSES:  That's the finding the staff
           has made.
                       MR. CARUSO:  Doctor Kress, this is Ralph
           Caruso from Reactor Systems Branch.  I think there may
           be a little bit of concern here that in the regulatory
           context there's no opportunity for the staff to review
           these inputs that are generated for these codes. 
           Realize that reviewing the code itself is just one
           part of the regulatory fabric.  We do, as we've been
           doing for the power upright reviews, we've been doing
           a number of audits of the actual calculations where we
           send people like Tony out to GE to look at the actual
           design record files to look at the actual input values
           that are put into these codes and that is the context
           in which we would verify that they were using the
           appropriate value of beta, if they were calculating it
           appropriately with the lattice physics code and then
           appropriately inputting it into TRACG.
                       The code review itself does not
           necessarily include a review of all of the steps of
           the surrounding methodology because we just don't have
           the resources to completely review a methodology every
           time we do a review of a particular part of it.  We
           understand that the other parts are there and we take
           them into consideration as we do the review, but we
           don't necessarily review them entirely.  We have other
           regulatory means to verify that they will be done
           properly.
                       CHAIRMAN KRESS:  You can review it at the
           time of an application.
                       MR. CARUSO:  We can review it when an
           individual licensee applies for permission to use this
           code for their plant.  We can review it when we --
                       CHAIRMAN KRESS:  Will part of the
           limitations on the use of this code for this
           particular aspect specify that the -- I guess it's the
           ODYN code must be used to determine this beta.
                       MR. ULSES:  No.  Actually, the lattice
           code G uses is called TGBOA.  I don't know where that
           came from, but that's what they call it.
                       CHAIRMAN KRESS:  But will you specify in
           your limitations that to determine this input you will
           have to use that code or if somebody uses a different
           code to determine that input, you'll have to review
           that one at the time of the application.  Is that the
           approach?
                       MR. ULSES:  Well, at the time of the
           application, what'll happen is the applicant in this
           case -- it would actually be the utility coming in for
           the proposed application -- they would have to
           identify what methods that they used.
                       MR. ULSES:  And if they had a method that
           was not reviewed and approved, we would have to make
           the choice of whether we're going to review it or
           whether we're going to say we don't have the resources
           to review it because it would require an additional
           code review.
                       CHAIRMAN KRESS:  Does the code have a
           default value for this particular input? 
                       MR. CARUSO:  Does TRACG have a default
           value?  Is that what you're asking?
                       CHAIRMAN KRESS:  Yes, because I understand
           part of the problem is you have to -- the input value
           depends on the power history and the loading of the
           code and so forth, so you can't just have one input
           value.  You have to know what the particular state of
           the core in order to get it.
                       MR. ULSES:  Sure.  Well, there certainly
           will be default values in the code.  However if you
           look at the application of this particular code -- in
           this case, TRACG -- it's not really designed to be
           used outside of the automation mechanism that they use
           at GNF which basically would require that you have
           input files which are calculated to the appropriate
           exposure points for the appropriate reactor being
           analyzed and, therefore, that's going to be imposed by
           their QA program which is going to require them to do
           the analysis with the correct input.
                       MR. CARUSO:  And this actually applies to,
           I would think, any calculation that is done.  The QA
           procedures Appendix B requires there to be a
           documented description for every input value that goes
           into the code and the way we regulate that is we do
           inspections, we do audits to verify that they have
           chosen the appropriate value and that they have a
           basis for it.  So even though there may be a default
           value in the code, if they use that default value
           without a basis, then they subject themselves to the
           possibility of this being discovered during an audit
           or an inspection and appropriate regulatory action can
           be taken for noncompliance with Appendix B.
                       MR. ULSES:  As an example, what I would
           expect is--
                       CHAIRMAN KRESS:  Aren't things like that
           flagged in the SERs and when you get around to --
                       MR. CARUSO:  Because of the large number
           of input values, we don't flag in the SER every
           individual input.  That's a requirement of Appendix B
           is that every value that's used in a calculation
           should have a basis for it.
                       CHAIRMAN KRESS:  Okay.
                       MR. ULSES:  Just as an example, I would
           expect when I would go down to, say, the GNA offices
           in Wilmington and I would audit a design record file,
           I would expect to see a discussion in there if the
           analyst, say, made the choice to use the default
           values and they would say why they did it, why it has
           no impact, and then the reviewer of that design record
           file would have to either say I agree with this, I
           challenge you on this, and this is why I think this is
           right or wrong.  That entire deliberation ought to be
           documented in the records that are kept on the
           analysis.  That's the QA trail for those types of
           questions, and those are things that we will audit
           when we go down to the site.
                       MEMBER SCHROCK:  What is the required
           detail of the input data?
                       MR. ULSES:  I don't think I understand the
           question.
                       MEMBER SCHROCK:  Does the input provide
           spatial distribution of beta?
                       MR. ULSES:  It's handled on a fuel type. 
           Yes, it does.  Let me just say yes to that question. 
           I can go into more detail if you want as to how it
           actually works.  Hopefully, I won't tread on any
           proprietary information here.  But it certainly does. 
           You have the information on a node-wise basis which
           basically means it's a six inch by six inch by six
           inch square portion of the reactor.  Each one of those
           nodes will have individual values of beta which are
           appropriate for the exposure points that are being
           analyzed.  That's correct.  Yes.  
                       Do you have another question, Doctor
           Schrock, or shall I go ahead and proceed here?  Okay. 
           Let's see.  I think I'll skip my name because I think
           we all know who I am now.
                       What I'd like to do in this discussion is
           I'd like to focus really and discuss basically the
           conclusions of the review and then I'd like to go
           through what I call sort of a lessons learned on this
           particular review because this review was very
           challenging.  There were some areas where I ran into
           some difficulties, and I'd like to discuss those and
           I'd like to go through some areas where I think I can
           do a better job the next time and areas where we can
           improve upon what we've done.  That's essentially what
           I'd like to try and do today.
                       These are the areas where the review was
           focused.  We obviously reviewed the documentation
           which was given to us by GE.
                       CHAIRMAN KRESS:  Did you find the
           documentation sufficiently good and detailed for you
           to make your reviews?
                       MR. ULSES:  Well, the documentation is
           acceptable for use internally by GNF.  It's not
           information that I would consider to be acceptable for
           public dissemination because it's not a discussion
           from the cradle to the grave on how this code works. 
           But if you use it in the context of the organization
           that's actually using it, I feel the documentation is
           acceptable.  There actually are some areas where it
           was kind of disjointed and actually, I plan on
           discussing those a little later.  There were some
           models that were described in one document whereas I
           think they should have been in another one, etcetera,
           etcetera.  There were some areas where there were some
           difficulties, but I think if you put it in the context
           of the application and who's going to be using this
           code, I feel that it's acceptable for internal use by
           the applicant.
                       As part of the documentation review, we
           went through a discussion of the actual model
           development itself, the theoretical development.  What
           I refer to as an auxiliary model is, say for example,
           like moderator heating effects, heating of structure,
           that those are discussed in the documentation and, of
           course, we also reviewed the validation that was
           presented and we also went through a sample problem
           which was derived -- this is very similar to what we
           did in the RETRAN review.  
                       Basically we derived a problem on which we
           ran the TRACG code.  This is actually the staff ran
           the code and we also ran our own methods and then we
           tried to do a comparison.  Essentially, what we're
           trying to do there us we're trying to sort of bridge
           the gap between the data that we have available which
           is very old data.  It's on reactor designs and fuel
           designs that aren't really in use any more.  I wanted
           to sort of bridge the gap there and try and get an
           understanding of how the code will perform if we use
           a more modern fuel design.  That's effectively the
           point of the data analysis.
                       MEMBER FORD:  Just for clarification, your
           use of the word validation is not validation of a code
           to make sure that operator A gets the same results as
           operator B on the code.  It's on how well the code
           predicts experimental observations.
                       MR. ULSES:  Yes, sir.  Right.  This is a
           mixture of experimental data and there's also some
           plant transient data as well which has been validated
           against it.  Again, it's all in that report which I
           understand you haven't seen so it's very difficult to
           get into and it's certainly proprietary so I can't get
           into the details of the actual results.  I don't know
           if we want to maybe do it this afternoon.  I don't
           know if that's possible and if it would be interesting
           to anybody, we could put some cards up this afternoon
           in closed session just to show you some of the
           information.  That's something you can think about.
                       CHAIRMAN KRESS:  I think for Peter's
           benefit and even Jack, he hasn't seen that either, it
           might be worthwhile to do some of that.  I don't know
           how much time we've got.
                       MR. ULSES:  Perhaps we can think about it
           and if we have enough time, we can maybe do it this
           afternoon.  That would obviously be up to GNF if they
           want to do that because it's their data.
                       MEMBER SCHROCK:  Also, I had understood
           that you had difficulty matching GE calculations in
           some instances.
                       MR. ULSES:  And that's something I want to
           discuss.  Yes, that's exactly one of the things I
           wanted to discuss which is why I constructed the
           presentation as I have.  I want to get to the bottom
           line, and then I want to discuss the problems that I
           had which basically have been resolved.  There were
           some issues where basically I made a mistake is what
           happened, and that's why there were differences.  I'll
           say my mea culpa right now.  That's what I want to get
           into, and I want to discuss how that happened, and I
           want to discuss some areas where we can improve in the
           future.
                       So let me move on here.  I think I've
           already discussed most of this.  Basically, what we're
           doing now in these days when we're actually reviewing
           the code by having the code and executing the code is
           we're focusing more on the performance of the code
           rather than just looking at the presented written
           material.  This is a model that we found has worked
           well for us in the past, and I think it actually
           worked well in this case, I'd say even when one
           considers the difficulties that we had along the way. 
           I'd say this was an effective review model.  I don't
           know if GNF would agree with that, but I think it was
           an effective review model from the staff's
           perspective.
                       CHAIRMAN KRESS:  That's interesting to
           know because ACRS has pretty much been advocating that
           approach for a long time.
                       MR. ULSES:  One thing that was certainly
           useful with the way we did it this time is it actually
           led us into reviewing some models that we probably
           wouldn't have reviewed which actually were more
           important than I originally suspected.  So I guess in
           a sense that was certainly an effective outcome of
           this review process and again, I'll discuss that in
           more detail after we get to the SER conclusions.  
                       Basically, all the information at the
           beginning of the presentation is all contained in the
           SER.  It's just sort of ground out of there.  
                       These are the validation studies that are
           in the assessment manual.  These are the areas where
           they have data.  Obviously, the Peach Bottom turbine
           trip tests which are validated against.  And the rest
           of this information is -- there's start-up testing in
           there and there's also some data from planned events
           which has been assessed and it is in the manual.  I
           just wanted to put this up here to show you that they
           do have actual data that they compare their code to. 
                       CHAIRMAN KRESS:  Is this the proprietary
           data?
                       MR. ULSES:  Yes.  If we actually wanted to
           show the actual results, that would be proprietary.
                 
                       These are effectively the conclusions that
           are in the SER.  We felt that the theoretical
           development captured the relevant physics necessary to
           predict an AOO type transient.
                       CHAIRMAN KRESS:  It captures them to
           sufficient degree?
                       MR. ULSES:  They provided reasonable
           assurance that the code will accurately predict these
           answers for application to licensing.  
                       And again, what I refer to as auxiliary
           models which are basically gama heating of the liquid
           in the structure.  I felt them to be very well
           developed, and that they would be effective in the
           proposed application.  And again, the decay heat
           modeling.  I felt it was adequate for the proposed
           purpose and, again, Doctor Schrock, I definitely think
           your criticism is valid, and I will definitely change
           what's written in the SER to describe the constraints
           on the review.
                       MEMBER SCHROCK:  I don't know what you
           mean by you feel it's adequate.  I mean you need some
           quantitative --
                       MR. ULSES:  Well, let me say that it is
           adequate for the proposed application because decay
           heat is at best a second order effect, perhaps even a
           third order effect, for the application that's been
           proposed.
                       MEMBER SCHROCK:  Well, I don't know that
           it's a third order effect but --
                       MR. ULSES:  It's definitely a second order
           effect, at best.
                       MEMBER SCHROCK:  Yes.  What I'm saying is
           that we haven't heard evidence of such conclusions,
           and I think we should.
                       MR. ULSES:  Interesting.
                       CHAIRMAN KRESS:  What do you do about loss
           of feed water with respect to that?
                       MR. ULSES:  Well, it's A) not a limiting
           transient.  It's one that's analyzed because it's
           required by Chapter 15.
                       CHAIRMAN KRESS:  It's a low frequency.
                       MR. ULSES:  It's usually a low effect
           transient.  Correct me if I'm wrong here.  I think
           it's usually not one that sets any limits on the plant
           and, therefore, the decay heat, if it's high for that
           particular scenario, the uncertainty in the model
           would not have a significant effect on plant
           operations.  Again, correct me if I'm wrong but I
           believe that's correct.  And that again would be why
           that was dispositioned as it was.
                       Again, this goes back to a discussion of
           documentation we had earlier, Doctor Kress.  It's
           acceptable for use by the applicant, and that's
           obviously the intended audience of the documentation. 
           It certainly isn't documentation that I would expect
           somebody who didn't have a great deal of knowledge of
           the methodology to pick up and be able to fully
           understand it.  But again, that's not the intended
           audience of the documentation.
                       This goes on to our test problem that we
           derived.  Essentially, like I said, what we were
           trying to do here is we were trying to bridge our
           understanding of the code's ability to handle the
           reactors that are being run and used right now in this
           day and age.  The core is based on an ABWR reactor. 
           It was designed to be as easy a model as we could.  A
           zero exposure so we didn't have exposure effects.
                       MEMBER SCHROCK:  That may be because in
           the SER you do not include ABWR as the reactor types
           to which the code may be applied.
                       MR. ULSES:  Well, the issue though is that
           that was a model that GNF already had available and it
           was based on modern GE fuel.  That was the reason that
           was chosen.  And all we modeled there was the reactor
           core itself.  We did not model the rest of the steam
           supply system at all.
                       MEMBER SCHROCK:  Well, I asked myself the
           question in the opposite sense as I read that.  Why is
           ABRW excluded from what the code is approved to do?
                       MR. ULSES:  Well, I'd say right now off
           the top of my head we're not running any ABWRs in the
           United States and plus that's a good question.  I
           think that's something that we were asked to review
           and approve more than likely.
                       MEMBER SCHROCK:  Is it necessary to call
           it out?
                       MR. ULSES:  Well, it's going to be trying
           to identify the source.
                       MEMBER SCHROCK:  Or exclude it from the
           list of those for which it could be applied.
                       DOCTOR ANDERSEN:  Jens Andersen from GNF. 
           When we made the submittal to the NRC, we made the
           submittal to be valid for operating BWRs in the United
           States.  There are no ABWRs in the United States. 
           Clearly, the difference --
                       MEMBER SCHROCK:  So it's GE's choice, not
           NRC's choice.
                       DOCTOR ANDERSEN:  It is our choice.  The
           difference in the ABWR design and the conventional BWR
           design is mostly in the recirculation system.  There's
           clearly no relevant significant differences in the
           core design.  We chose NABWR core design because it
           would simplify the process of generating the nuclear
           input that would allow us to do the comparisons
           between the NRC codes and the GE codes because it was
           an initial core at zero exposure.  It greatly
           simplifies the process.
                       MR. ULSES:  And it's just discussed in the
           SER because we were trying to identify it.
                       MEMBER SCHROCK:  You could manage to have
           the approval cover the SBWR, but that's your business,
           not ours.
                       MR. ULSES:  I was just simply trying to
           identify the source of the model.  That was the reason

           it was discussed in there.  And again, obviously we
           looked at the steady state results to make sure that
           we didn't have any gross discrepancies between the
           application in TRACG and the application with our
           methods, and we didn't see any differences.  Well, we
           didn't see any large differences.  The codes compared
           well.  And we also ran some small perturbation
           transients to look and make sure that we didn't see
           any gross discrepancies in the way the model would
           respond to, say, a small perturbation in pressure, a
           small perturbation in flow.  
                       I just want to briefly put up again.  This
           is all in the SER.  This is the initial steady state
           power distribution out of the two models, the two
           codes, and they compare very well.  There are some
           discrepancies on the periphery due to the handling of
           the modeling of the reflector.  However, for this
           case, we feel that this is a pretty good comparison
           and that the model is working very well in both cases.
                       MEMBER FORD:  You said the model was
           working well.  What is your definition of working
           well?
                       MR. ULSES:  Well, in this case, since
           we're trying to compare one code to the other, if we
           get good comparison, we feel that both codes are
           modeling the problem in the same way and giving the
           same answers.  That was a figure of merit.
                       MEMBER FORD:  Validation of those models
           is based presumably on data from off-shore reactors?
                       MR. ULSES:  Actually, the data for TRACG
           is based on all data, I believe -- actually, there's
           a couple of data stats from overseas reactors but, for
           the most part, it's based on U.S. data.
                       MEMBER FORD:  That's not ABWR.
                       MR. ULSES:  Right.  Again, it was just
           intended to make everyone's life easy.  That's the
           reason why that reactor was chosen, because it was
           available, there was zero exposure, and all we're
           trying to do here is examine the response of the code
           to a perturbation, not necessarily the ability to
           actually model the steady state characteristics of the
           reactor which would be burn-up, for example.  That's
           basically a steady state response, and that's not
           really modeled in TRACG.  I mean it's handled as an
           input parameter to the code.  So what we're trying to
           do is we're trying to examine the code's ability to
           model the effect of a pressure perturbation.
                       MEMBER FORD:  The number of ABWRs against
           which this prediction would be compared were not
           large.
                       MR. ULSES:  But this reactor will never
           exist.  This is a hypothetical reactor that we made
           up.  This is a sample problem.  This reactor will
           never exist.
                       MR. HECK:  Excuse me.  This is Charlie
           Heck from Global Nuclear Fuel.  The loading, the core
           specification bundle designs here, one of the
           constraints was that it be an initial core so that
           there would be no issues regarding how exposure
           differences possibly in lattice physics.  And that was
           Tony's specification. He said initial core as
           realistic as possible, so we chose a real design which
           was an ABWR core.  
                       The only initial core we have these days. 
           And we took it and we trimmed it so it's really not
           ABWR core per say.  This is actually a 560 bundle
           core.  ABWR is much larger than that.  Eight hundred
           and twenty, I think.  We trimmed it to the right size
           maintaining the same proportions and the calculation
           that's being done here is just for the core model
           hydraulics.  The vessel boundary conditions above and
           below the core are specified.  So this is a problem
           designed specifically to focus on the neutron kinetics
           and coupling of that with the hydraulic models.
                       CHAIRMAN KRESS:  Tell me what I'm looking
           at.  This is one quarter of the core.
                       MR. ULSES:  It's one quarter steady state
           power distribution.
                       CHAIRMAN KRESS:  Steady state full power
           distribution and if I were to ask how to compare the
           two code calculations in terms of some figure of
           merit, would I be asking what the differences were in
           terms of some root mean square area or would I be
           asking how the differences affect peak clad
           temperature of the hot model?  How do you compare two
           curves like this and ask yourself whether they're the
           same or close enough?  I see very little difference. 
           I can see the parts around the periphery where you say
           there's some difference but it's a little hard for me
           to figure out how good the comparison actually is.  It
           looks almost identical.
                       MR. ULSES:  Well, the real figure of merit
           for this study was the energy deposition which is
           calculated by this code following a simulated
           pressurization transient.
                       CHAIRMAN KRESS:  You started at steady
           state and then you ran through --
                       MR. ULSES:  What effect are any
           discrepancies you see here going to have on the effect
           of the analysis with these two codes on the energy
           deposition following a pressurization transient.
                       CHAIRMAN KRESS:  It's a total energy
           deposition.
                       MR. ULSES:  Right.  That's what's going to
           lead to changes in MCPR.  That's going to lead to
           changes in the calculated changes in critical power
           ratio which are clearly the figure of merit for an AAO
           analysis.  So that's basically the bottom line. What
           we're trying to do here is make sure that the models
           had no gross discrepancies at the steady state point. 
           That was the only point of doing this particular
           figure.
                       MEMBER SCHROCK:  TRAC/Nestle has been used
           previously for AOOs.
                       MR. ULSES:  No.  It was used -- the staff
           code that we used for these types of simulations, we
           used it in the RETRAN work where we worked on RETRAN
           3D.  And it's a code that's used by the staff for
           these types of audit type of calculations.  It's not
           a licensing code.  It's not an industry code.  
                       MEMBER FORD:  I shouldn't be reading
           anything more into that draft than to say that there's
           little difference.  Whatever the difference between
           those two models are if it's an input -- it has no
           impact at all on the resultant prediction.
                       MR. ULSES:  I wouldn't say no impact but
           there's a small impact on the final bottom line.
           That's the only point of this curve is to make sure
           that there are no gross discrepancies in the initial
           conditions.
                       MEMBER FORD:  I may be a devil's advocate
           here but the model could be completely wrong because
           I don't see any data, observed data.
                       MR. ULSES:  Right.  Both codes have the
           potential to be completely wrong.  You're correct. 
           And that's why you need to fold in the existence of
           experimental data into these types of studies.
                       MEMBER FORD:  For ABWRs, whatever the fuel
           configuration is, there's very little data existing.
                       MR. ULSES:  Well, I can ese it was a
           mistake to put ABWR on here.  The only point of this
           study, this reactor, like I said, is hypothetical.  It
           will never exist.  It will never run.  It's just on
           paper.
                       MEMBER FORD:  I'm trying to understand
           what may take away from that
                       MR. ULSES:  What we're trying to do is
           we're trying to design a sample problem which would be
           easy for both organizations to set up and what we want
           to do is we want to isolate the kinetics modeling from
           the reactor system modeling as much as we can. 
           Obviously we can't do it entirely.  So we stripped out
           all the rest of the vessel model.  There's no
           separators.  There's no recirc flow.  There's nothing. 
           All it is is the reactor model and it's got a velocity
           boundary condition at the lower tieplate and the
           pressure condition in the upper plenum.  
                       So that's the point in this.  The
           existence of this model was used because it already
           existed and they were able to take it, they were able
           to scale it down and make a smaller core out of it
           without doing a great deal of work.  That was the only
           point of using this model.  It's not intended to
           validate against the ABWR at all.  It was used because
           we were able to isolate the kinetics modeling from the
           rest of the reactor system.  That's the point of this
           study.
                       MR. BOLGER:  This is Fran Bolger from GE. 
           I just wanted to point out that the model that you see
           under the TRACG is based on the GE steady state
           simulator.  Now that steady state simulator is the
           same simulator that is run at the plants and those
           simulators are compared to LPRM and trip data
           regularly.  So that's the same model that's validated
           on a day to day basis in the fleet.
                       MR. ULSES:  Let me move on here.
                       MEMBER SCHROCK:  Let me make one last
           point.  The TRAC/Nestle is what version of TRAC?
                       MR. ULSES:  It's using the NRC version of
           TRACB which we all know and hopefully love or don't
           love.  It's the version that came out of INEEL.
                       MEMBER SCHROCK:  But you have other
           experience to tell you how good or not good that
           should be expected to do on a typical problem like
           this.
                       MR. ULSES:  That's correct.  TRACB itself
           has validation.  It's not an unvalidated model. 
           Obviously it's not validated against the same data
           that they validated TRACG against obviously because
           most of the data they use is going to be GE
           proprietary information.  But it is a validated method
           for things like, say, void fraction predictions,
           density predictions, fuel temperature predictions,
           things that are going to be relevant for this
           particular study.
                       MEMBER SCHROCK:  But you don't use its
           kinetics model.
                       MR. ULSES:  No, not using its kinetics
           model.
                       MEMBER SCHROCK:  Because it's not multi-
           dimensional.
                       MR. ULSES:  It has a one-dimensional
           model, but it's not being used.  All it's doing is
           it's giving Nestle density fuel temperatures.  That's
           it's only function for this study.
                       I just wanted to put up again the axial
           void fraction profile radially collapsed, one-
           dimensional.  The only difference is this little
           change here and that comes in because of the existence
           of the part length rods and that's the TRACB modeling. 
           There's a difference.  You could go into the part
           length rod and region.  But again, as you'll see, it
           does not have an effect on the overall bottom line
           answer.
                       CHAIRMAN KRESS:  Is this integrated
           radially across the core?
                       MR. ULSES:  Yes.  This is radially
           collapsed, one-dimensional average axial power
           distribution.  I'm sorry.  Average in channel void
           fraction.  Okay.  
                       This is just a brief description of how we
           set the problem up.  What I did was I ran an input
           deck that had the entire reactor system model to get
           the boundary conditions which were then imposed on our
           simpler model and that enabled us to do the transient
           modeling.  And then we modeled the case in TRACG using
           multiple options available in the code.  We turned
           switches on and off to see if they had effects on the
           results.  
                       MEMBER FORD:  Again, I keep coming back to
           this and you gave the key answer.  This tells me
           nothing at all how good the model is.
                       MR. ULSES:  Right.  All this is telling us
           is -- well, it's telling us that we're able to bridge
           the gap and that we have an understanding that we have
           multiple codes which can model a reactor using modern
           GE fuel.  It's telling us an area where we do not have
           any data because there is no data that exists.
                       MEMBER FORD:  But the critical question is
           any of these codes, they all seem to give the same
           results.  Are there operational data against which you
           can have a one to one comparison between the
           prediction and the observation?  What you've told me
           is there is.
                       MR. ULSES:  For pressurization transients
           with modern fuel, it's my understanding that there is
           no data available.  We have data from the '70s using
           fuel that's no longer run in reactors which allows us
           to do validation against or verification if you want
           to look at it.  The only point of this particular
           study was to attempt to understand the ability of
           TRACG when compared to another method, whether there's
           anything unique about modern fuel designs which will
           lead the staff to believe that the code is not capable
           of modeling a modern reactor.  That's the only point
           of this study because there is no data with modern
           fuel, as I understand it, for pressurization
           transients.  Correct me if I'm wrong here.
                       DOCTOR ANDERSEN:  This is Jens Andersen
           from GNF.  I understand that you're a little at a
           disadvantage but if you remember from Ralph Landry's
           presentation, we have one of the reports that was
           submitted to the NRC and also to the ACRS was the TRAC
           qualification report which is about an inch and a half
           thick and it has an extensive qualification consisting
           of basically four sets of qualifications.  
                       One was a set of separate effects test
           where we had isolated individual phenomena and tried
           to qualify those phenomena like could we predict a
           given heat transfer core regime?  Could we predict a
           void fraction in the fuel bundle?  Then it has more a
           complicated section on component performance like how
           well do we predict a steam separator performance?  How
           well do we predict a jet pump performance?  This is
           all based on data and full scale data wherever full
           scale data was available.  
                       Then we have a section in the report which
           is what we call integral system effects test which is
           basically scale simulation of an entire BWR typically
           scaled down to a few bundles that are simulated
           through electrical heating.  That gives us a
           qualification of how well the code predicts system
           interactions between various components in the
           systems.  And then we have the final section is a
           section of comparison against plant data where we have
           full scale plant data, typically data taken during
           plant start-up tests.
                       That includes data like the Peach Bottom
           turbine trip test.  Those are, as Tony Ulses
           mentioned, all the data based on 7 X 7 and 8 X 8 fuel. 
           We have later data with more modern fuel types like
           the Nine Mile Point pump up-shift test which contains
           predominantly GE11 fuel which is typical of the modern
           fuel with a large central water rods and the part
           length rods.  So we do have qualifications for modern
           fuel types, and it shows how the kinetic reacts to
           changes in the hydraulic conditions in the core.
                       So all of that is in the qualification
           report and it's based on comparison to actual plant
           data.  Now, we have taken that a step further in the
           application methodology report, and that's where we
           apply the statistical methodology is that we have gone
           in and done a statistical analysis of all the
           qualification data and quantified what are the
           uncertainties in predictions of the individual data so
           that we can properly account for this uncertainty in
           the application methodology. 
                       So all of that is in the report and,
           unfortunately, I understand you haven't seen these
           reports, and we'll be happy to show one of the
           reports.  We can do it during the break.
                       MEMBER FORD:  I'll look at it like this. 
           (Indicating blindness with his hands.)
                       MR. ULSES:  Well, anyhow, I'd like to move
           on to the next slide.  Basically the next slide is the
           results of the sample problem.  Again, the ABWR
           problem which is not a real reactor which is intended
           just to allow us to bridge the gap between the areas
           where we have data for the pressurization transients
           which are typically limiting AOOs and BWRs to the
           reactors that are operated in the year 2001. That's
           the only point of this problem, again.
                       Actually, what I'm going to do is put up
           another slide that's not in your handout.  I apologize
           for this.  I'll get to this to you, Paul.  This is a
           slide that actually is in the SER.  Essentially, these
           are the results.  These are the relevant results. 
           What you see here is the power on the top one, the
           total power from the reactor.  Obviously, there are
           some discrepancies there between the codes.  We have
           a couple of hundred megawatt difference in the peak
           power between the TRACB calculations and the TRACG
           calculations.  But if you look at the effect --
                       CHAIRMAN KRESS:  Under a pressurization
           transient without scram, you're basically checking the
           void coefficient effect and the temperature
           coefficient effect.
                       MR. ULSES:  That's correct.  That's what
           we're doing.  What we're doing is looking at the
           balance of the reactivity from the void effect and the
           fuel temperature effect.
                       CHAIRMAN KRESS:  The voids get collapse
           and that adds power and the temperature goes up
           because of the increased power and it turns it around.
                       MR. ULSES:  That's exactly what happens
           and you also have a trip of the recirculation pumps as
           well.
                       CHAIRMAN KRESS:  Okay.  
                       MR. ULSES:  Which will also significantly
           drop the power.  That's what's going to happen.  But
           if you look at the bottom curve, which is just simply
           the interval of the top of the curve, what you're
           going to see is that the effect on the energy, which
           is really the figure of merit for an AOO transient, is
           effectively -- well, it's not nil.  It's obviously
           very difficult to see on this scale.  But it's very
           small which would mean that the actual calculated
           change in the critical power ratio from these multiple
           simulations would be very small which tells us that
           these two codes obviously are able to predict that
           this model is the same, if you will, in effect. 
           Obviously, there are some differences.
                       CHAIRMAN KRESS:  What are the differences
           between the blue and the red?
                       MR. ULSES:  That's using a different model
           in the TRACG code which I'd like to discuss next
           actually.  That's one of the things that I discovered
           going through this review which was very intriguing.
                       CHAIRMAN KRESS:  What's the cause of that
           little plateau on the right?
                       MR. ULSES:  Right here?
                       CHAIRMAN KRESS:  Yes.
                       MR. ULSES:  This is, in effect, the
           competition of the void reactivity and the fuel
           temperature reactivity and how it's affecting the
           power.  That's what's causing that.
                       I'd like to just move on to the review
           conclusions which again are in the SER.  Effectively,
           what we concluded is that we have reasonable assurance
           that TRACG can model AOO transients.  This is based on
           obviously evaluation of the GNF validation,
           benchmarking, if you will, comparison to actual plant
           data and also based on the sample problem which we
           derived.  And again, this is just simply stating what
           we've already stated, that the code that's being
           applied to Chapter 15 transients and that is the scope
           of the SER.
                       MEMBER SCHROCK:  In the SER you address
           difficulties that you had in predicting results from
           the SPERT 3 tests.  You've not commented on that.  Is
           that because you're excluding RIAs?
                       MR. ULSES:  That's basically  the bottom
           line.  RIA is not included in the scope of review, but
           actually I do plan on discussing -- 
                       MEMBER SCHROCK:  Why is it in the SER?
                       MR. ULSES:  Well, because it was in the
           validation documentation which was given to us by GNF
           and, therefore, I wanted to discuss it.  And that's
           one of the things I plan on discussing in the
           discussion of review challenges which is what I'd like
           to go to next.
                       CHAIRMAN KRESS:  I was wondering.  We need
           to take a break some time right about now.  Would this
           be a good time?
                       MR. ULSES:  This would be a great time. 
           This is sort of a change in the focus, but I do plan
           on discussing really the why.  I didn't discuss the
           SPERT test and the SER because it really is not
           relevant for the proposed application.  You are
           correct.
                       MEMBER SCHROCK:  Well, if I read your SER
           conclusions correctly, you have a very different view
           of that than I have.  It seems to me that SPERT 3's
           very small core has essentially nil spatial
           difficulties.
                       MR. ULSES:  Very little, if any.
                       MEMBER SCHROCK:  It's practically a point
           reactor calculation and for what reason, I can't
           imagine that a more sophisticated code shouldn't be
           expected to give good results on that.
                       MR. ULSES:  And that's a very good
           question and that's the question that I had in my mind
           and that's one of the reasons why I decided to discuss
           it, and I do plan on talking about that in this
           presentation a little bit later.
                       CHAIRMAN KRESS:  In that case, I'm going
           to declare a recess for 15 minutes.  So be back 20
           minutes after 10.
                       (Off the record for a 15 minute recess at
           10:07 a.m.)
                       CHAIRMAN KRESS:  I think we can go back in
           session now.  Talk about challenges.  Is that what you
           were going to do?
                       MR. ULSES:  Right.  This is basically the
           mea culpa I referred to earlier in the presentation. 
           Effectively, the differences that you were talking
           about, Doctor Schrock, in that one draft RIA that I
           prepared which showed those major discrepancies in the
           code results.  Basically, the bottom line of why that
           was there is I made a mistake in the input stream of
           my analysis.  It was discovered, and the differences
           went away. The mea culpa is that I made the wrong
           conclusion based on what I saw and that's what led to
           that draft RIA which hasn't made it into the final
           RIAs, by the way, because it was not pertinent because
           it was incorrect.  But that's basically the issue.  If
           you want, I can go into more detail as to why the
           differences were there or we can leave it at that.  I
           will pose that as a question.
                       CHAIRMAN KRESS:  Are you asking Virgil or
           me?
                       MR. ULSES:  I'm asking any of the members
           and consultants if they have any interest in going
           into more detail as to why there was a large
           discrepancy in the initial analysis.
                       CHAIRMAN KRESS:  You know, I think in the
           interest of clarity, I would like to hear a little
           more.  Yes.
                       MR. ULSES:  Well, basically what it really
           boils down to is the way the moderator density is
           handled in the TRACG code versus in the methods that
           I used traditionally.  I think I'm probably going to
           tread on proprietary ground here.
                       CHAIRMAN KRESS:  Yes, be careful.  
                       MR. ULSES:  With the modeling, you will
           halt me.  Okay.  Basically, the way GE handles the
           modeling of moderator density is they use a weighted
           average of the in-channel density.  In other words,
           the water that's inside the box with the water that's
           in the bypass region where the control blades run. 
           That's an average parameter which is passed between
           the kinetics and the thermal-hydraulic solver. 
           Hopefully, that wasn't proprietary.  That's not the
           way I traditionally model that in the methods that I
           use.  I usually base it on the in-channel density
           alone which for AOO analysis is perfectly adequate
           because you don't expect to see any changes in the
           bypass.  It's going to start off as water and it's
           going to stay solid water throughout the transient.  
                       What I had to do was go into the codes
           that I had and modify the algorithm to handle that and
           I made a mistake in the way that was done and that was
           discovered and the error went away.  That was the
           bottom line.
                       CHAIRMAN KRESS:  So the difference was in
           the void coefficient effect --
                       MR. ULSES:  Right.  And that's what was
           leading to that huge discrepancy which one would
           expect because obviously this transient is definitely
           void dominated.
                       CHAIRMAN KRESS:  Okay.  
                       MEMBER SCHROCK:  So that part of the SER
           will be corrected.
                       MR. ULSES:  I don't think it's in the SER.
                       CHAIRMAN KRESS:  It was an RAI.  
                       MR. ULSES:  It was an RAI.  It was a draft
           RAI which is not going to be in the final RAIs because
           it was incorrect.  That's basically the bottom line. 
           Anyhow, one thing that I think was good out of all
           this is that it did lead me down a path that I
           wouldn't have gone into originally which leads me to
           the next slide which discusses how GE and I would say
           probably every other organization in the United States
           uses the MCMP code for validation and verification of
           lattice physics methodologies.  It's widely used,
           widely accepted in most organizations that I'm
           familiar with and probably the ones that I'm not
           familiar with.   It's used to check the results from
           lattice physics calculations in the absence of data if
           the MCMP is accepted as a very accurate methodology
           and it's used for that purpose.
                       CHAIRMAN KRESS:  That's a Monte Carlo.
                       MR. ULSES:  Right.  It's a Monte Carlo
           solver which was written by Los Alamos and has been
           extensively used for these types of applications over
           the years.
                       This leads mein to a discussion of what --
                       MEMBER SCHROCK:  I ask you to look at page
           eight of your SER.
                       MR. ULSES:  I'm going to have to ask you
           for a copy of it.  I don't have one in front of me
           here.  Okay.  
                       MEMBER SCHROCK:  I mean you don't need to
           review it now but I mean --
                       MR. ULSES:  If there's something in there
           that I have an error in, I'd like to see it.
                       MEMBER SCHROCK:  The paragraph that
           addresses the SPERT 3 report.
                       MR. ULSES:  And that I'm going to discuss
           more in the end of this presentation, Doctor Schrock. 
           I have a slide on it.  I'd like to discuss that. 
           Certainly you are right.  I agree with you that I
           would expect a more modern accurate method to be able
           to handle the E-core experiment because if you look at
           the documentation that was written up on that
           experiment back in the '60s, they were using point
           kinetics models and they were very sufficient to model
           that reactor.  But I'd like to defer that until a
           couple of slides from now if that's possible because
           I certainly think that needs to be discussed.  
                       Basically what this led me to was the
           discovery of a model that I've dubbed the PIRT 18
           model for lack of a better word.  I don't think that's
           what GE calls it, but I sort of made that up because
           I needed a word to write in the SER.  And what that
           basically does is using MCMP and then based on MCMP
           results they have a model in TRACG which effectively
           modifies the void reactivity which they would have
           calculated out of their licensing basis tool to better
           compare to the MCMP results.  That's effectively how
           the model works in a nut shell.  I hope that's a
           correct characterization of the model.
                       DOCTOR ANDERSEN:  This is Jens Andersen. 
           If I can just make one comment.  You are right in this
           characterization.  This particular model is described
           in the application methodology report and the reason
           it's described there is that this was part of the
           effort that we undertook to quantify the accuracy of
           the various models in TRAC to determine what is the
           bias and what is the uncertainty of all the models in
           TRAC in order to know what these uncertainties are in
           order to apply these uncertainties in the application
           methodology.  
                       We have quantified all the model
           uncertainties for the models that we thought were
           either of high or medium importance based on our
           tables.  The void coefficient is one of these models
           and the benchmarking against the MCMP calculations
           were how we quantified the uncertainty in the void
           coefficient.  So this is part of the process of
           quantifying what bias and uncertainty of the models
           are so we could account for it in the application
           methodology.  
                       We can go into details on that particular
           model, but we probably would want to do that as part
           of the proprietary session in the afternoon.
                       MR. ULSES:  Sure.  Well, one thing I
           definitely want to point out though is I just want to
           point out the area where the staff had difficulty with
           the model, as we understand it.
                       DOCTOR ANDERSEN:  Yes.
                       MR. ULSES:  And the issue basically boils
           down to the fact that when you run a Monte Carlo code,
           as I'm sure you're all well aware, you don't get a
           point answer out of that code.  You don't get an
           answer.  You get a range of answers.  And the way GE
           has applied the MCMP results within this uncertainty
           methodology, they're using the mean value of the
           predicted eigen value without consideration of the
           error or of the uncertainty in the analysis.
                       The issue that I had with that, I mean
           let's go to a couple of plots here.  I don't think any
           of this is going to be bad.  This is basically --
           these are the comparisons of the lattice physics
           results of the code that I used compared to the one
           that GE used for the sample problem.  In other words,
           the ABWR test reactor that's fictional that's never
           going to be run.
                       And then these are some calculations that
           I did with MCMP myself here at NRC looking at the
           lattices that were used in that problem with the
           uncertainty bounds.  These are the 95 percentile
           confidence intervals which are plotted here as error
           bars.  And again, that has it on there.  The issue
           that I really had with this model is that let's say we
           choose a mean value to do our comparisons with the
           TGBLA results and we say that there's a difference
           between the results and let's say we're going to
           believe the MCMP results and what we're going to do is
           we're going to change the TGBLA results to match the
           MCMP results.  
                       But if you look at this plot, it would be
           equally valid to take the prediction down here versus
           the prediction up here because again, this is a value
           which is not a point value.  All these values here
           have been deemed to be effectively the same number
           within the way that MCMP is usually applied.  And if
           you take this difference and you span this across this
           curve, it will have an effect on the predicted power
           response.  
                       It's not going to be significant, but
           there'll be an effect, and that's not accounted for in
           this model and that's basically the problem that I had
           with it, and that's why the SER is written as it is on
           this particular model.  It doesn't have a significant
           effect on the bottom line answer, which is energy
           deposition, but I don't believe that it's well enough
           quantified in this context simply because of the lack
           of the consideration of this uncertainty band.  
                       MEMBER SCHROCK:  Isn't there a probable
           value in some distribution?
                       MR. ULSES:  That's basically what this is
           but the way these codes are usually applied is that
           you don't simply take the most probable value.  Let's
           say I was going to use this and I was going to do like
           a criticality safety analysis, for example, which
           obviously is not really applicable here but that's
           just an example.  What I would do is I wouldn't take
           this as the answer.  I would usually take the upper
           bound because what MCMP is telling me is that it can't
           give me an answer with any better accuracy than with
           what's within this error bar.  That's what I'm getting
           out of MCMP.  And the point, that's just simply a mean
           value, but the code is really telling me that I can't
           give you an answer with any more accuracy than what's
           within the error bound and, therefore, I question why
           the mean value was chosen as opposed to the upper
           bound versus the lower bound.
                       CHAIRMAN KRESS:  Those error bands, are
           those one sigma, two sigma?  
                       MR. ULSES:  I actually don't recall when
           I plotted here.  I apologize for that.  I should have
           had that in front of me.
                       CHAIRMAN KRESS:  It's probably one sigma.
                       MR. ULSES:  It probably is, I think.  Yes.
                       CHAIRMAN KRESS:  Standard.
                       MR. ULSES:  That's what usually is
           plotted.
                       MR. HECK:  Excuse me, Tony.  This is
           Charlie Heck, Global Nuclear Fuel.  I think you said
           those are 95 percent confidence bands.  Those would be
           equivalent to two sigma.
                       MR. ULSES:  That's right.  This is the
           confidence interval.  You're right, Charlie.  Thank
           you for correcting me.
                       MEMBER SCHROCK:  So they're not bounds at
           all.
                       MR. ULSES:  This is the confidence
           interval which is what's applied or which is what's
           usually used as the output for Monte Carlo codes.
                       MEMBER SCHROCK:  You're calling it bounds
           and they're not bounds.
                       MR. ULSES:  Well, that's probably the
           wrong choice of terminology.  You're correct.  But
           this is a confidence interval which is what the code
           is telling us.  This is the highest level of
           confidence that the user should put obviously on any
           number that's in that range.  And the way these
           methods are usually applied is they're not used to
           derive a point value.  If I was simply going to run my
           lattice code and I wanted to compare it to MCMP, then
           I would say if I had an answer which landed anywhere
           within this error bound, I'd say I'm happy with that. 
           But I wouldn't go in and modify the results of my
           lattice code based on that comparison.  That's the
           area where the staff is a little uncomfortable here. 
           Everybody goes out and they modify and they actually
           validate their code against this number with the error
           bars on it and if they say that the answer landed in
           the error bars, I'm satisfied with that.  But this is
           the first application that the staff has come across
           where they actually use this result to go in and
           modify the results of the licensing tool within the
           framework of a code application.  And that's the area
           where we had some questions.  And this was the fist
           what I would call challenge of this review.
                       CHAIRMAN KRESS:  So what was the final
           resolution of this challenge?  
                       MR. ULSES:  Well, the final resolution is
           that it does not significantly effect the energy
           deposition.  However, I do not feel that the model has
           been adequately justified and I wanted to make sure it
           was pointed out in the SER as such in case it's ever
           reviewed again.  If in the context of that review it's
           determined that the model would have a significant
           impact on the result, then a future reviewer would
           know to look at it.  That's the reason why it's
           documented in the SER, for future reference.
                       CHAIRMAN KRESS:  I was trying to figure
           out how I would use that distribution and convert it
           into an uncertainty on the other calculation.  I'm not
           sure how I would do that.  But that's what you said
           you did.  You used this distribution to determine the
           uncertainty in the other calculation. 
                       MR. HECK:  This is Charlie Heck, Global
           Nuclear Fuel.  We did use the mean value from MCMP. 
           Those do not get used directly.  It's rather the slope
           of the value versus a void fraction which is what
           defines void coefficient and we use that to quantify
           the bias in the void coefficient and the uncertainty
           in the void coefficient as a function of two
           parameters that are proprietary in nature that we'll
           discuss this afternoon.
                       CHAIRMAN KRESS:  But basically you're
           saying the MCMP is truth and you use that to look at
           a bias in the thing you got then.
                       MR. HECK:  I acknowledge the point that we
           are using the mean value from MCMP as the basis for
           quantifying the void coefficient that MCMP would get
           for purposes of comparing it to the void coefficient
           that our TGBLA lattice physics method would predict
           for the same conditions.
                       CHAIRMAN KRESS:  Okay.  I'm not sure I
           have a problem with that.  I'll have to think about it
           a while.
                       MR. ULSES:  I don't think I have a problem
           with using it to validate.  The issue I had a problem
           with is using it to modify the output of the licensing
           basis tool.  That's the area of contention.  I have no
           problem actually using MCMP as a validation tool
           because I believe it's a very accurate code.  The
           issue the staff had was that those results are used
           then to actually modify the output of the TGBLA
           results for application in TRACG. That's the area
           where we had contention.  It's not the application of
           the code as a validation tool.  I think that's very
           acceptable.
                       MR. HECK:  This is Charlie Heck again. I'd
           just like to put this a little bit in perspective. 
           What we're talking about here is about a three percent
           bias in void coefficient and about a five percent
           standard deviation in void coefficient and the results
           of that on the impact for calculating CPR.  So I think
           we need to consider it within that framework.  We're
           looking at basically the bias and the uncertainty
           associated with these inputs.  In this case, the
           lattice physics captures these inputs and it
           propagates from upstream so it's really looking at the
           variability and the inputs.  
                       I want to emphasize that the variation
           lattice to lattice across the fleet and the different
           kinds of lattice configurations.  This is just one of
           hundreds of thousands that that variation that's
           accounted for on an exposure point by point for each
           specific core condition is much greater than any sort
           of bias that we're seeing here on a particular lattice
           by lattice.  It's much, much larger.  
                       And so I would contend that consideration
           of the fact that the Monte Carlo variation is
           uncertain within this band is more than washed out by
           much larger and more important variations associated
           with modeling the specific problem.
                       MR. ULSES:  What I'd like to do is move on
           if there's no other questions, comments.  
                       MEMBER SCHROCK:  Have I got the right
           interpretation of the Monte Carlo code?  It's a
           transport theory level code?
                       MR. ULSES:  Yes.  You could characterize
           it as such.  Yes.  Without going into painstaking
           details, yes.
                       That's a good lead-in to the next
           discussion of the validation which is where I'd like
           to discuss the SPERT question that you raised, Doctor
           Schrock.  The emphasis in the review was on the
           validation which was presented against the
           pressurization transients because those are what are
           typically limiting.  We certainly considered all the
           validation, but if you look at the SER you're going to
           find a discussion only on the pressurization
           transients mainly because that's where the emphasis
           was placed in the review.  
                       And we discussed the SPERT results in the
           SER and obviously those are like an RIA type of
           experiment.  They're not really applicable to AOO. 
           They're really beyond scope.  But the point of
           discussing them in the SER was to ensure that if TRACG
           is ever applied to a situation where they would be
           significant, that they're reviewed in detail because
           I agree with you, Doctor Schrock, I believe that with
           a code like TRACG you should be able to accurately
           model the SPERT tests, and that's the reason why it's
           in there.  To make sure that in the future if this
           code is ever reviewed for an RIA type application that
           it is reviewed and also point out that the staff right
           now would not be satisfied with those results in that
           application. 
                       As an example, we've demonstrated that you
           can model.  Let me just put a slide up here.  This is
           from our RETRAN work where we modeled SPERT.  You can
           model the SPERT reactor experiment.  This is what I
           was showing you before.  This is what the Nestle code
           comparing to a SPERT test.  It's possible to model
           that test very accurately with these types of codes. 
           These are the kinds of results that I would have
           expected to see and that's again why it was pointed
           out in the SER.  Simply to ensure that if it's ever
           reviewed in the future that it's looked at in greater
           detail than what it was looked at in this case because
           it was considered beyond the scope.
                       CHAIRMAN KRESS:  The SPERT just pulls out
           a control rod and--
                       MR. ULSES:  Right.  Yes.  It was a rod
           ejection type experiment.  It was a very small
           reactor.  There were no spatial effects.  Basically
           what you're modeling is the ability to balance the
           reactivity of the system.  That's really all you're
           after here.  Which is why point kinetics models do
           very well on SPERT because the reactor is very small. 
           But the point here is simply that these types of
           modern, multi-dimensional methods can and ought to be
           able to model this reactor.  That's the point.  And to
           make sure that in the future it is reviewed.
                       CHAIRMAN KRESS:  What did the results look
           like with the GE code?
                       MR. ULSES:  Well, they're proprietary
           obviously, but they did okay on the energy.
                       CHAIRMAN KRESS:  The bottom line.
                       MR. ULSES:  Right.  Did okay but the power
           curve was off.
                       CHAIRMAN KRESS:  Shifted?
                       MR. ULSES:  I think it had the peak, if I
           recall, in the right point but they missed the
           magnitude by a pretty large percent and then they
           undershot the tail which is why the energy came out
           okay in the long run.  And again, I can't put the
           curve up here because I'm sure it's proprietary.  But
           that's the recollection that I have in generalities.
                       MEMBER SCHROCK:  I'm afraid I still have
           to contend that this paragraph on page eight in the
           SER--
                       MR. ULSES:  Let me look at this.  I
           apologize.  I haven't actually looked at it yet.
                       MEMBER SCHROCK:  It's a totally different
           picture than you've just described.  It's attributing
           difficulties that you were unable to resolve to the
           challenging nature.  I mean SPERT 3 E-core is a
           challenging experiment to model.  That's what you just
           said.
                       MR. ULSES:  And the reason why I put that
           in there is because it is a challenging experiment to
           model.  There was a great deal of effort that went
           into the results I'm showing you right here.  It's not
           something that you can sit down and model just right
           off the bat.  You're going to have to do code changes
           in order to do it.  It's not going to be something
           that you're going to be able to handle very easily. 
           It's a very challenging model.  It's very challenging
           to set the input up generating cross-sections. 
           They're very challenging.  This thing used control
           rods.
                       MEMBER SCHROCK:  You could say that of any
           calculation.  I mean if you don't have the proper
           inputs to match the experiment, you're not going to
           get --
                       MR. ULSES:  Right, but if you try to apply
           say like a licensing basis lattice physics tool which
           you use to model a standard in a light water power
           reactor, it's going to have a very hard time trying to
           model this reactor because it used control rods that
           are the flux trap style.  Very difficult to model. 
           And that's going to be a very large challenge for code
           model.  It's not very easy to do.  
                       MEMBER SCHROCK:  I don't find any
           relevance of that to your purpose in review.
                       MR. ULSES:  Well, the intent of the
           sentence was to concede the fact that it is a very
           difficult and challenging experiment to model. 
           However, the point that I'm trying to make here and I
           believe I make in the end here is that we expect that
           they should have been able to do a better job and that
           we would expect to see a better job if we ever had to
           do a review where we had the results of the
           discrepancies between TRACG and SPERT which in this
           case we felt we did not because of the scope of the
           application.
                       MEMBER SCHROCK:  I read this paragraph and
           I came away with the interpretation that you're saying
           that you got poor results and you're not sure why you
           got poor results but there may be something here for
           investigation.
                       MR. ULSES:  Right.  That's basically the
           point of this paragraph.  To make sure that in the
           future if the scope of review or whatever include
           these types of simulations, that the staff would give
           it the level of review necessary and would then have
           to resolve the question of why TRACG predicted one
           thing and the experiment was something else.  There
           are literally a whole host of possible explanations
           which we didn't delve into in this review because we
           didn't need to because this was beyond the scope.  But
           I wanted to make sure we reenforced it because it was
           in the documentation which we reviewed.  I wanted to
           make sure that it had the proper emphasis.
                       MR. HECK:  This is Charlie Heck, Global
           Nuclear Fuel.  I'd just like to comment a little bit
           more on what you're saying, Tony, about the
           difficulties in modeling this SPERT core.  I'll first
           of all make the point that it's a code core, so any
           comparison relative to AOO applications would be
           questionable at best.
                       Secondly, it has a much different rod
           configuration than anything in light water reactors so
           that again introduces variability.  Also, I'd make the
           point that modeling it in point kinetics where many of
           the things are of unknown nature and are collapsed
           down to a single point is perhaps easier than trying
           to actually model the lattice physics, especially, as
           you pointed out, Tony, the lattice physics codes
           themselves have to be modified to handle this
           particular geometry.  In which case you'd have to
           question whether or not -- well, certainly they're not
           the same code that's being used to model the AOO
           events.  
                       Thirdly, I think you make the point right
           up there on your very slide where you indicate the
           control rod worth for this particular experiment plus
           or minus five percent.  That's probably very
           optimistic when you take a look at the data and not
           even knowing how quickly the rod was ejected and some
           variations on the speed.
                       I make the point that the experimental
           description itself is not of a fidelity that allows it
           to be terribly useful.  Plus or minus five percent is
           probably a pretty low number.  One of the reasons we
           over-predict the peak in TRAC is because our control
           rod worth is $1.23 instead of $1.16 or .17 as you show
           there.  We get a higher peak and a narrower pulse. 
           And that thing depends on a lot of conditions all
           specific to the lattice physics, all of which have
           been modified in order to accommodate this particular
           problem.  I question its validity for application to
           AOO events and, in fact, I question its validity for
           purpose of quantifying rod drop backs events, but it's
           all we have.
                       MR. ULSES:  Well, I don't think I question
           the validity for RIAs myself personally but I don't
           really want to get into that discussion right now. 
           This experimental uncertainty is out of the
           documentation from the experimenters.  I'm not in a
           position to question that, whether or not it's
           accurate or not at this point.  As for control rod
           speeds, when I took a look at the documentation, I was
           able to derive a number that I used for this
           particular case.  This was not an easy experiment to
           model.  This represents a couple of months worth of
           work.  
                       CHAIRMAN KRESS:  The actual rod worth
           doesn't depend on speed, does it?
                       MR. ULSES:  No.  The actual instantaneous
           value will but the actual final value will not.  It's
           a static analysis.  
                       The point I wanted to make here is that I
           believe that this particular reactor can be
           successfully modeled with these methods and at this
           point, if I was reviewing TRACG for RIA calculations,
           I would not have been satisfied with those results. 
           But in the context of an AOO review, I believe that
           it's not applicable for this particular point but I
           wanted to be sure and emphasize the fact that it would
           need to be looked at in further detail if the
           application for RIAs was ever proposed.  That's the
           bottom line.  That's the bottom line conclusion and
           that's the point of having it in the SER because it
           was in the documentation that was given to us by GNF.
                       CHAIRMAN KRESS:  Does this put into
           question stability analysis at all?
                       MR. ULSES:  No, I don't think.  I think
           what you're seeing here is I think you're seeing an
           issue of the rod speed that was used in the analysis
           myself personally.  That's the place that I would look
           first if I was --
                       CHAIRMAN KRESS:  It would affect the
           whole--
                       MR. ULSES:  If I was GNF trying to
           evaluate this, I would look at the assumed rod speed
           myself.
                       MEMBER SCHROCK:  Because you haven't show
           us how different your result was from the experiment.
                       MR. ULSES:  Well, these are my results
           here.  This is experimental data.  The Xs are
           experimental data and the red is the Nestle prediction
           for this particular experiment.  What I haven't shown
           you are the GNF results which are proprietary and I
           can't put up here right now.
                       CHAIRMAN KRESS:  But you know the peak is
           higher and the tail is lower.
                       MR. ULSES:  Tail is lower so the energy is
           in reasonable agreement with the experiment.  The only
           point of putting this particular curve up here is to
           emphasize the point that the staff believes that it is
           possible to model this reactor.  That's the only point
           of putting this up here.  
                       CHAIRMAN KRESS:  With the same kind of
           neutronics actually that's's in the GNF code.
                       MR. ULSES:  Well, I'd say generally
           speaking that's true.  This method here is a little
           newer than the GNF methodology but generally speaking,
           they're similar.
                       CHAIRMAN KRESS:  Yes, but my conclusion
           may be different than everybody's.  I'm looking at
           Nestle and I'm saying this has got basically the same
           kind of neutronics as GNF.  Therefore, GNF ought to be
           usable for these kind of transients.  There's just
           something wrong with the way they model it.
                       MR. ULSES:  Exactly.  That's basically my
           conclusion.  That's what I would have concluded had I
           had the need to get into it in further detail.  That's
           the only point of putting this curve up here is just
           simply to emphasize that point.
                       MEMBER SCHROCK:  You talked about the
           uncertainty in the rod worth.  HaVe you done the
           calculation for the limits on how much effect would
           Nestle tell you it has?
                       MR. ULSES:  No, I have not but it would be
           very large.  This reactor is very small and very
           sensitive to rod worth.  Extremely sensitive to rod
           worth.  
                       CHAIRMAN KRESS:  Well, your Nestle
           predicted $1.16 rod worth.
                       MR. ULSES:  Right.
                       CHAIRMAN KRESS:  So you did calculate it.
                       MR. ULSES:  Well, I calculated the value
           but I didn't assess what would be the effect if I
           actually increased it by five percent.
                       CHAIRMAN KRESS:  You didn't do a
           sensitivity analysis.
                       MR. ULSES:  Right.  I didn't do a
           sensitivity analysis because that was not the point of
           this study.  This was simply to see whether or not the
           code could model the reactor.  Again, this was out of
           the context of the RETRAN review where they were
           trying to do RIA analysis.  That was the point of that
           review.
                       CHAIRMAN KRESS:  I would have guessed
           about a five percent effect on the --
                       MR. ULSES:  I don't know whether it would
           be linear or not but it would definitely be there.  It
           should be there and it would be fairly significant. 
           Anyhow, I'd like to not dwell on this because this is
           just simply to emphasize a point.
                       CHAIRMAN KRESS:  But the message I get out
           of that is that this kind of code can calculate SPERT.
                       MR. ULSES:  And that was the point.
                       CHAIRMAN KRESS:  And the GE code ought to
           be able to do it, too. They just did something wrong
           with the analysis somewhere.
                       MR. ULSES:  And again, we're just simply
           trying to emphasize the point for future if it's ever
           looked at again.
                       This is almost some philosophy as much as
           anything else.  Obviously, difficulties in this case
           led to a success, I would say, in that we actually
           were able to get into the MCMP modeling which is
           something that I wouldn't have looked at had I not had
           these problems.  Obviously, this is almost a personal
           pep talk.  Work harder at trying to define a problem
           where we can eliminate any of these cross-section
           issues at all.  That was not something I was
           successful at in this case, and that's what led to a
           lot of these issues.  I was trying to find a problem
           where I can give the applicant cross sections.  So
           that is not a question at all.  So all we're doing is
           looking at the results of the diffusion theory solver
           with absolutely no effect on the input stream which
           was an effect here that was very difficult to try and
           resolve.  
                       And I think it would be very important for
           the staff when we're trying to review these codes --
           like, for example, TRACG -- to have access to the up-
           stream codes which are used to generate input.  That
           would allow the staff to do further sensitivity
           studies and to try and answer some of these questions
           about the input stream as well as it would also help
           us to eliminate input stream issues which is really
           the bigger reasons.
                       And obviously the bottom line conclusion
           is think before I jump to conclusions and write out
           these RIAs which end up being incorrect.  So that's
           the bottom line philosophy.  And that's really all I
           had to say today.  If there's any other questions, I
           certainly can entertain them now or we can talk later. 
           But that's the bottom line conclusion of the staff
           review of TRACG kinetics.  And I believe now we're
           going to hear from Yuri to discuss statistics.
                       CHAIRMAN KRESS:  That ought to be
           interesting.  Thank you, Tony.  Appreciate it.
                       MR. ULSES:  I didn't know your water over
           or hit my head on your television screen.
                       DOCTOR LANDRY:  Doctor Kress, while Yuri
           is getting set, I think this has again shown us that
           this move to insist on the applicant's code being in-
           house for our own use has been a good move to make.  
                       CHAIRMAN KRESS:  Yes, I agree with you.  
                       DOCTOR LANDRY:  Much of this would not
           have occurred had we not had the code and done this
           experimenting with the code.  If we had not done this
           experimenting with the code, we would not have seen
           much of this.  Whether you go down the right path or
           the wrong path, you're learning something about the
           code and the methodology that's being used and we've
           been gaining experience through this whole process. 
           This has in some ways been a little painful.  Tony
           said mea culpa.  But it's been good in that we have
           learned a great deal in the process.  I think that,
           all things considered, it has enabled us to perform a
           better review than simply looking at documentation.  
                       CHAIRMAN KRESS:  I think that's a good
           perspective.  I'm glad to hear you say that.  We'll
           continue to support that type of review.
                       Yuri, I don't think we've met you before.
                       DOCTOR ORECHWA:  No.  I'm a new kid on the
           block.  My name is Yuri Orechwa.  I'm from NRR in the
           Reactor Systems Branch and the staff.  
                       What I want to review is the uncertainty
           evaluation that was presented to us for evaluation
           with TRACG analysis of anticipated operational
           occurrences.  What I'm going to focus on is the
           methodology.  I can't repeat all their calculations. 
           So the question is if they did the arithmetic
           according to the rules which they presented, then we
           can judge the results accordingly.
                       So what we're going to look at, the review
           topics that were requested, was to look at the model
           uncertainties and biases.  TRACG is a deterministic
           code.  So what we're saying is the models are
           imperfect.  Those imperfections, we need to express
           them somehow in the results.  Once that's established,
           how do we combine that in order to make statements
           concerning design limits and operating limits?  
                       Let me give a heuristic overview so that
           you see where I come from, where I'm going, and some
           of the notation that I'm using.  I have to apologize. 
           I'm of the old school.  I still write things down.  I
           have a tough time with the modern software which is so
           helpful that it takes you an hour to find one symbol
           that you need.
                       CHAIRMAN KRESS:  To tell you the truth, I
           prefer this.  I'm used to seeing them like that.
                       DOCTOR ORECHWA:  All right.  Let me say
           then what's TRACG in the context of what we're going
           to do.  We can write down in operator notation the
           neutronics model and the thermal-hydraulic model. 
           Those are coupled through the thermal-hydraulic
           conditions and the power of that.  Both operators are
           dependent on parameters.  Those parameters, like in
           the neutronic model, the reactivity coefficients of
           course are important.  In the thermal-hydraulic model
           it would be from correlations and things like that. 
           In my notion, the theta and phi set are the things
           that are the beginning and are at issue at the
           starting point.
                       TRACG is deterministic.  You put in your
           input, you specify theta and phi.  You will get a
           number when you do your computation.  If you put the
           same input, the same phi and the same theta, you're
           going to get the same number.  Whether that number is
           right or wrong, Tony discussed.  We're assuming that
           that's done.  Now the question is what are the theta
           and phi going to do?  We have also initial conditions
           where there are also some parameters usually and stuff
           like that.
                       So at issue is the determination of the
           distribution of those parameters.  In order to do
           anything statistically, you've got to have sample from
           somewhere and you have to characterize that sample. 
           To determine the model uncertainties, we need to
           always estimate some distribution and the parameters
           for that distribution.  That represents then, it
           summarizes the state of knowledge.  And GE has
           presented in my view, an enormous amount of data from
           tests, from qualifications and all that.  
                       Now, suppose we get our distribution of
           those parameters of theta and phi.  Then we know that
           the solution, the TRAC solution -- that is the
           parameters that are the output of the TRAC -- will be
           dependent on the theta and phi.  Because those come
           from the distribution, will give us a distribution of
           TRAC solutions.  So in the TRAC solution which I kind
           of write like a vector.  It's not really a vector in
           the mathematical sense but the set parameters.  Each
           parameter will be distributed.  Given that
           distribution, you can them make some kind of
           determination of the confidence you can put into a
           design limit.  So that's the issue.  How do I get then
           to the design limit?  
                       MEMBER SCHROCK:  Yuri, could I ask, how
           does the selection of the node size enter into what
           you're describing, or does it, for a specific --
                       DOCTOR ORECHWA:  Because it was
           considered, but I don't think it's big.  I don't
           consider it here.  It's not a statistical issue.  
                       CHAIRMAN KRESS:  It seems like the only
           way you could incorporate it is to change it and see
           what effect  it has on the distribution you get out.
                       DOCTOR ORECHWA:  That's a question of
           algorithm.  It's not a statistical issue. 
                       DOCTOR ANDERSEN:  This is Jens Andersen. 
           We did do a fair amount of nodalization sensitivity
           studies that are documented in the qualification
           reports.  We did it both for simple tests as well as
           for full scale plant cases.  What we did was that we
           basically looked at the simpler test to determine what
           was an adequate nodalization.  We then ran a plant
           case and we did nodalization studies around what was
           considered an adequate nodalization and we basically
           quantified how large the sensitivity were on the
           critical safety parameters, and we were able to show
           -- and this is actually documented in the
           qualification report -- that with the nodalization we
           had chosen, doing further refinement to the
           nodalization had very little impact on the calculated
           results.  
                       DOCTOR ORECHWA:  Nodalization is a
           convergence issue.  It's not a statistical issue.
                       MEMBER SCHROCK:  Well, I'll have to think
           about that a little more.  I think the distributions
           are influenced by the nodalization.
                       DOCTOR ORECHWA:  The distribution of the
           basic parameters has nothing to do.  Once you do a
           solution to the TRAC equation, it will be. 
           Nodalization will enter a bias, you might say, but
           that should come out given some parameter.  If I pick
           a theta and a phi, then I can compare a TRAC for
           different nodalizations and see if I'm going to a
           solution.  I converge to this level.  Now this level
           will vary because I choose different parameters for my
           models.  So it's a convergence issue.
                       CHAIRMAN KRESS:  There may be a question
           about when you use nodalization to determine the input
           as to whether or not that might affect the
           distribution.
                       DOCTOR ORECHWA:  I think, at least in my
           experience, any code that's been nodalized is in a
           fine mess.  Once you get it, somewhere there has to be
           in the manual documented what the effect of
           nodalization is.  That's a verification and validation
           issue.  The models that enter for the specific
           versions is a different issue.  Just say with respect
           to thermal-hydraulics.
                       CHAIRMAN KRESS:  So so far you're saying
           that there are specific inputs to the code that have
           to have a distribution.
                       DOCTOR ORECHWA:  That's right.
                       CHAIRMAN KRESS:  And that distribution has
           to be determined.
                       DOCTOR ORECHWA:  That has to be
           determined.
                       CHAIRMAN KRESS:  And it's generally
           determined as much as possible by data and GE has a
           lot of data.
                       DOCTOR ORECHWA:  Right.  I will go through
           each of these points again.
                       CHAIRMAN KRESS:  And the input has to be
           propagated through the system to get these outcome
           design limits.
                       DOCTOR ORECHWA:  That's what I want to
           step through afterwards.
                       CHAIRMAN KRESS:  Okay.
                       DOCTOR ORECHWA:  I was just going to say
           with regard to nodalization and convergence, one of
           the millennial problems in mathematics is the
           uniqueness of the Navier-Stokes equation.  So we don't
           even know if the solution exists.
                       MEMBER SCHROCK:  We don't solve Navier-
           Stokes equations here so that's not a problem.  
                       CHAIRMAN KRESS:  We bypass that.
                       DOCTOR ORECHWA:  We can all run out and
           solve the how the existence and come home with a quick
           million dollars.  But those are the issues.
                       Okay.  Now, suppose we have the
           distribution of the TRAC output.  Then the third basic
           figure of merit which is used by GE is based on
           critical power ratio.  And that's defined as the GEXL
           correlation as a function of what the thermal-
           hydraulic conditions are that TRACG gives over the
           power given by TRACG. 
                       Because our TRACG solution has a
           distribution, the critical power ratio will have a
           distribution and there again then we can talk about
           what is the confidence level with which we pick some
           limit or operating limit?
                       CHAIRMAN KRESS:  Is there a distribution
           on the GEXL part of that?
                       DOCTOR ORECHWA:  No, because the input --
           this is the thing that has a distribution.  It has its
           own uncertainties.
                       CHAIRMAN KRESS:  I know.  There are
           parameters in it.
                       DOCTOR ORECHWA:  Right, but that's a
           separate issue.
                       CHAIRMAN KRESS:  That's a separate issue.
                       DOCTOR ORECHWA:  I don't want to touch
           that one.  But the point is that we start with
           parameters in the TRACG. Varying those, we get a
           distribution of the output, the thermal-hydraulic
           conditions and the power distribution.  Putting that
           into this correlation, we can get a distribution of
           the CPR and we can then make statistical statements
           about it.  So that's the basic name of the game.
                       So the first thing is model uncertainties. 
           That's in my notation theta and beta.  GE follows the
           CSAU methodology for that and begins with what I would
           call the delphi method.  People see what phenomena are
           important in the TRACG calculation, the relative
           importance, and identifies those.  Those are then the
           phenomena that are associated with parameters that
           will have the highest impact on the solution and,
           therefore, we need to go out and get them.
                       The next step then is, having identified
           what phenomenon there are and what parameters are
           associated with those, you establish the nominal
           values and uncertainties for these parameters.  There
           is an enormous amount of data that is presented from
           separate effects test facility data, integral test
           facility data, components qualifications, BWR plant
           data, and these are all analyzed and the statistical
           analysis for each is presented in the report.  
                       For some parameters for which there is no
           data, code comparisons are made.  In particular, for
           the void coefficient, for example, which Tony
           discussed, code comparisons need to be made.  And also
           everywhere there always lurks engineering judgment, no
           matter what you do.  
                       Now, let me just comment with regard to
           the void coefficient, the analysis there.  Overall,
           the evaluation of the experimental plant, etcetera,
           data is done by standard techniques.  Look at the
           distribution.  You assess whether it's normal.  They
           use a test which I had never heard of before, the
           Anderson-Darling test, but that's neither here nor
           there.  And goes through, presents the data, shows
           everything in regular fashion so it can be assessed. 
           And it looks proper.  
                       In the void coefficient analysis, the main
           variation comes with the variation across assemblies
           or fuel types, whatever they call it.  There is an
           enormous number of them in the GE stable.  There's 11,
           Charlie, or nine?  Eleven.  Eleven are chosen as
           representative of variation.  These aren't chosen by
           random.  These are chosen to be representative because
           there are so many.  If you get down to the nitty-
           gritty, you should have chosen them by random but that
           would have been an extremely small sample.  Probably
           would have had a big bias.  So the natural tendency is
           we would like to choose something which is
           representative.  I don't have a problem with that, but
           it is not according to the rules of sampling
           statistics, and I don't think -- with small samples,
           you will always have a problem of bias and I think by
           trying to be representative you're probably moving in
           the right direction.  I just want to comment on that
           issue.  So the spirit is there.
                       CHAIRMAN KRESS:  When an application comes
           in to use this, the variation in fuel types across the
           core won't be random.
                       DOCTOR ORECHWA:  There are a lot of
           different fuel types in the core.
                       CHAIRMAN KRESS:  Yes, but they'll know
           what they are.
                       DOCTOR ORECHWA:  Oh yes, but you're
           putting in one number to say the uncertainty is.  The
           uncertainty is not being associated with each lattice,
           type of lattice.  Okay.  It's across lattices.
                       MEMBER FORD:  Would you mind going back to
           your previous slide, please.  Maybe I missed the
           discussion of the very first bullet.  Have an impact
           on what?
                       CHAIRMAN KRESS:  On the important outputs.
                       DOCTOR ORECHWA:  Looking at anticipated
           operational occurrences, these are measured with
           what's happening to the power pressure and things like
           that in a transient.  What will affect those the most? 
           You have a huge equation.  Some parameters will be
           more important than others.
                       MEMBER FORD:  So if I was worried about a
           materials problem -- just for instance -- for
           instance, what is a fast neutron flux of the core
           shroud?  Outside this --
                       DOCTOR ORECHWA:  No, it's not a transient
           issue of materials.
                       MEMBER FORD:  I'm still learning here.
                       DOCTOR ORECHWA:  Okay.  Then, of course,
           as I said, for all of these different phenomena that
           have been rated, the normality of the distribution is
           assessed, which is nice, and then there's an estimate
           made.  
                       Do you have a question?
                       CHAIRMAN KRESS:  Yes, on the "evaluate the
           normality."  That's based on the assumption that the
           distribution will be normal and you'll want to check
           to see if your assumption is correct.
                       DOCTOR ORECHWA:  Yes, there are
           statistical tests.
                       CHAIRMAN KRESS:  Yes, I understand the
           test.
                       DOCTOR ORECHWA:  You look at the data and
           it gives you a statistic for various --
                       CHAIRMAN KRESS:  And suppose that
           statistic makes you question your assumption of
           normality.  What do you do then?
                       DOCTOR ORECHWA:  Statistic tells you at
           what confidence you can say and those chose at the 95
           confidence level that it is normal.  You never have
           100 percent.
                       CHAIRMAN KRESS:  But suppose I only had 70
           percent confidence in my normality.  What do I do
           then?
                       DOCTOR ORECHWA:  Okay.  You can approach
           it in different ways with non-parametric statistics
           and stuff like that.  I think this is experimental
           data and this is traditionally normal because there
           are so many other small things that come in.  I think
           in what GE has presented invariably it is.  In a few
           cases, it looks kind of ---
                       CHAIRMAN KRESS:  So it's just kind of a
           hypothetical question.
                       DOCTOR ORECHWA:  Later on it becomes a
           little bit more of an issue.
                 
                       Let me just say that although in the
           report it's almost parenthetic that they do a
           sensitivity analysis, but I think it's very important
           in the long run that the sensitivity of CPR in the
           turbine trip event with respect to each parameter as
           to what the sensitivity to that is and it's diligently
           done for each case.
                       CHAIRMAN KRESS:  You'll already have a
           distribution.
                       DOCTOR ORECHWA:  Yes.
                       CHAIRMAN KRESS:  But you don't know what
           particularly caused that distribution or what the most
           important parameters are so you go back and do a
           sensitivity study to find out which of those
           parameters had the biggest effects.
                       DOCTOR ORECHWA:  How big the effect is if
           I vary that one parameter only.
                       CHAIRMAN KRESS:  That one only.  It gives
           you just additional information.
                       DOCTOR ORECHWA:  It gives you very
           important information later on, at least the argument
           that I will make.  So that's important.
                       Design limits.  The parameters are
           combined by random sampling from each of the
           parameters.  Now, GE just does straight random
           sampling.  There are methods where you can kind of
           tighten up by using choice of sampling.
                       CHAIRMAN KRESS:  Latin Hypercube test.
                       DOCTOR ORECHWA:  Latin Hypercube is the
           one in KSU and things like that.  Let me jump ahead a
           little bit.  I think for this application it's
           probably okay because things are kind of -- the
           transients are slow and things like that.
                       CHAIRMAN KRESS:  The only issue that
           generally comes up with strict random sampling is how
           many do you need to get the right --
                       DOCTOR ORECHWA:  How many.  For small
           samples, it's an issue because you introduce bias
           right away in a small sample.  So it's just something
           that needs to be noted but if you have rapidly
           changing functions as you would have in a severe
           transient, you might want to pay a little bit more
           attention as to your sample size and its behavior in
           that case, I think.  But it's something that has no
           definite yes or no answer again, as usual.  So I want
           to bring that up.  
                       So you sample from these parameters, you
           stick them in TRAC, you compute values.  We get those
           values and then we do our usual normal theory.  Put
           them in the frequency table and we again check
           normality.  If it's normal, we can then make a
           statement concerning at 95 percent level various
           design parameters, temperature, pressure, etcetera,
           whatever you want to do, and you can set those.  
                       Note greater than or equal to 59.  Why is
           that?  As you said, suppose it's not normal.  Then
           what do you do?  I still want to talk about setting a
           limit with this level of confidence.  And GE does the
           usual thing.  You look at order statistics.  What you
           do is you sequentially by size put your sample down,
           59 out, and then the 95th limit is the 95th one.  So
           if I random sample all those, it comes from the theory
           that 59 is -- it's not 60, it's 59.
                       Now note though.  This isn't mentioned. 
           You can't get blood out of a turnip.  Because when you
           say you have a normal distribution, that's an enormous
           amount of information so the non-parametric interval
           is going to be usually significantly larger and then
           it might be so large as being not very meaningful at
           times.  So just because you have an interval that's
           95, your data may really be somewhere else or
           something. Just because you're using order statistics,
           that's fine and you can talk about it but you still
           have to be careful as to exactly what you're doing
           underneath that.  This is just a comment on that.
                       CHAIRMAN KRESS:  The bottom line is for
           realistic code applications the rule calls for a 95/95
           -- figures of merit?
                       DOCTOR ORECHWA:  Yes, that's what people
           usually talk.  And for that you need 59 samples.
                       CHAIRMAN KRESS:  You need 59 samples and
           you reached it then.
                       DOCTOR ORECHWA:  Yes.  And even for normal
           that's my experience is it's getting to be.  Okay.  So
           using that, you can get your design limits.  But what
           we want in order to assess the transient is what GE
           does is talks about the operating minimum critical
           power ratio.  It has two components.  The safety limit
           critical power ratio, which is the value of CPR which
           is less than .1 percent of the rods and the core
           expected to experience.  That's just a definition.  
                       In the transient, delta CPR is the
           contribution from the transient itself and then the
           equation says that steady state CPR basically equals
           -- you have the absolute limit plus the contribution
           from the transient.  So that's the relationship on
           which we base.  
                       The key element in the computation is the
           computation of the probability of rod experience in
           transition or boiling.  There are two things that GE
           focuses on.  The two ingredients, I should say, that
           are in the computation that they use.  Experimental
           data from the Atlas facility which gives you a
           distribution of experimental CPR.  This is defined
           this way and because it is experimental data, it will
           give you a distribution.  
                       Now, then you have a computed by TRACG for
           a specific reactor.  Minimum critical power ratio.  I
           have an intellectual disagreement with GE on their
           computation of the probability.  Let me first, because
           this dates back, I think, 30 years.  Let me just point
           this out.  The probability is the integral over a
           distribution function of CPR.  What is done is the
           computation, if this is your experimental data, this
           value that they put on to compute the probability,
           this is determined by TRACG.  You're mixing two
           distributions.  The TRACG value is in your limit and
           you're integrating over an experimental value.  So you
           can do this only if this is true that the two
           distributions are the same.  
                       Let me give an analogy that's extreme. 
           Let's take the price of bananas, 1.25 per pound or
           something.  I can put it on here and calculate a
           number, a probability.  You say you're crazy, price of
           bananas has nothing to do with CPR, which is true, and
           to a more limited extent, the computation of TRACG and
           the experiment, there is a difference.  This is the
           heart of the matter that we're getting at and you
           can't just slough over this intellectually.
                       CHAIRMAN KRESS:  Experimentally.  Can you
           extract a CPR out of that?
                       DOCTOR ORECHWA:  Let me go on.
                       CHAIRMAN KRESS:  Okay.
                       DOCTOR ORECHWA:  Fundamentally, this is
           strictly verboten to mix.
                       CHAIRMAN KRESS:  I can see that.
                       DOCTOR ORECHWA:  You can do it in the
           context of Bayesian statistics but then you're going
           to have to find a loss function in order to get your
           point estimate of the probability.  That would be the
           correct way to go, blah-blah-blah.  But you still have
           to then-- you can mix the distributions and then say
           I have --
                       CHAIRMAN KRESS:  The problem I have is
           experiments don't actually measure the critical power
           ratio.  You have to derive it somehow.
                       DOCTOR ORECHWA:  Excuse me.
                       CHAIRMAN KRESS:  I'm trying to figure out
           how you would overcome your objection.
                       DOCTOR ORECHWA:  Let me go on.  I will
           overcome my objection.
                       CHAIRMAN KRESS:  I'll let you go on.
                       DOCTOR ORECHWA:  Let me say we apply
           statistics and there are certain assumptions for all
           these things.  We will never meet the assumptions
           exactly.  So you got to have a little bit of judgment. 
           So given that in principle, what we're doing is
           strictly verboten.  GE doesn't do this but let me try
           to argue the following.  This will be my argument and
           you can give me a grade on it.  With classical
           statistics you come through the back door and you
           bring engineering judgment.  
                       Point one is if we take the experimental
           value and we just expand it -- I mean we live by that. 
           Here is all the sensitivity.  Now they've computed all
           the sensitivities.  I can use just chain rule and get
           all the sensitivities through there.  The
           sensitivities are all very, very small if you look at
           them down the line.  The qualification examples that
           they give and I think what Tony showed, that this is
           pretty good.  So the correction that differentiates
           these from what we know of the real world and TRACG
           and all that is probably okay.
                       My other argument would be we're talking
           about .1 percent probability and less.  So we're way
           out in the tail end of the distribution.  The
           contribution to the probability of a difference in the
           CPRs out there will be almost negligible.  So either
           one or both will, I think, support that what they are
           doing is, I think, within our engineering judgment.
                       MEMBER SCHROCK:  The experimental CPR from
           Atlas is for one bundle.
                       DOCTOR ORECHWA:  Is it for one?  I thought
           it was for many bundles.
                       MEMBER SCHROCK: A small number, in any
           case.
                       DOCTOR ORECHWA: There are thousands, I
           thought.
                       DOCTOR ANDERSEN:  This is Jens Andersen
           from GNF.  We have measured the critical power for
           each single fuel design that we have developed in the
           Atlas test facility, 7 X 7, 8 X 8, 9 X 9, 10 X 10
           fuel.  For each fuel design, we run a large number of
           tests, typically anywhere from 500 to 1,000 tests in
           order to characterize the critical power as it depends
           -- pressure inlets, up-cooling.  So we have typically
           a database of 500 to 1,000 data points in order to
           determine the experimental uncertainty or the
           uncertainty in the jet fuel correlation in predicting
           the critical power.  That's an ECPR distribution.
                       MEMBER SCHROCK:  So you've put together
           many tests to build up a core characterization of CPR. 
           Is that the picture?
                       DOCTOR ORECHWA:  Yes.  Right.
                       MEMBER SCHROCK:  The reason I ask the
           question is that you're defining minimum critical
           power in terms of one-tenth of one percent of rods in
           core.  I didn't think that you had that kind of
           capability in the experimental determination, but I
           see that you do.
                       DOCTOR ORECHWA:  There's a tree you're
           barking up on that I'd like to address that should
           really be looked at.  And I think it's mentioned in
           CSAU methodology, which is when you have a lot of
           parameters, which you do in this case, in order to
           really represent the response surface for that, you
           quickly need a lot of data because it goes by the
           number of values on each axis to the power of the
           dimension that you run out of data very quickly in
           order to give a characterization and, here again, I
           think what saves this case, at least my view of
           looking at the data, is the transients are mild,
           response is smooth.  
                       Once you get into something else where you
           may be getting into instabilities or something like
           that, you're not going to have smooth functions, and
           I think there you're going to have to very carefully
           look at that issue.  So this case, yes.  Another case,
           it's not going to be so smooth.
                       Any other questions?  What grade do I get?
                       CHAIRMAN KRESS:  On your proposed fixed,
           you get an A.
                       DOCTOR ORECHWA:  Thank you.
                       CHAIRMAN KRESS:  That's a good fix. 
           Expect I really don't think you need a fix.
                       DOCTOR ORECHWA:  All right.  Since I got
           an A, we can now determine the operating limit
           critical power ratio.  Let me just make a comment
           here, one comment concerning the submittal.  This is
           probably one of the most critical parts and it gets
           one page in the write-up and it's pretty
           undecipherable.  Things should be written up a little
           bit better, I think, for us even to review.  So I made
           my best stab at it.  
                       I think the spirit of the thing is that we
           can't track any of these large codes which take a half
           a year to set up.  You're not going to run random
           sampling on them.  It will take an enormous amount of
           runs.  You'll be there forever.  So how do you divide
           and conquer?  How do you compartmentalize some of the
           calculations to maximize your information so you can
           make a statement with a little bit less effort by
           emphasizing certain things? 
                       GE's approach, the way I read it, is that
           you first look at the generic behavior of transients
           for classes. You have a transient class, you have this
           type of BWR, you have this type of fuel, etcetera, and
           you can develop a distribution of the CPR for that. 
           So the ingredients are first by class a distribution. 
           The other one then is for a specific case you run a
           specific transient all the way through.  Then you can
           also for the specific case just in steady state, your
           initial condition because it's not a transient, it's
           an easier calculation, you can do sampling on that and
           run them through.  
                       You can then combine them via this
           equation by sampling the two distributions that you
           have and you get a distribution of MCPRs for which you
           can then compute the value which is the criteria for
           setting your operating limit minimum critical power
           ratio.  To my mind, that looks legitimate.  I think it
           accomplishes the purpose.  You do capture the

           uncertainties present both in transient, both in the
           initial state and you kind of bridge them with a
           calculation which is specific to the case under
           consideration.  I don't think that that's an
           unreasonable approach.
                       Now, I think now having gone through the
           methodology and  it looks okay, GE does present a lot
           of qualifying data where they look at actual
           transients, the uncertainty band which is generated
           using this methodology and I believe that there is
           sufficient agreement to be able to use it for analysis
           of AAOs given the background of all the back when we
           started with the uncertainties that today we associate
           with the input parameters to the TRAC calculation.
                       CHAIRMAN KRESS:  So your bottom line is
           that uncertainty methodology is pretty good with the
           possible exception of the philosophical difference
           which probably doesn't make much difference.
                       DOCTOR ORECHWA:  Yes.  I wanted to bring
           that up because it can make a difference in some
           situations.
                       CHAIRMAN KRESS:  Could later.
                       DOCTOR ORECHWA:  I think in that case it
           has to be -- because for 30 years that calculation has
           been done as if those two distributions are identical. 
           And I just want to put a flag out there not in
           principle because if they're not in principle, then
           you have to make an argument for why you think you can
           get away with it and I passed the argument by you guys
           why I think they can get away with it.
                       CHAIRMAN KRESS:  Are there any other
           questions?  You're getting hungry?  Well, thank you
           very much for a tutorial on how to do uncertainties, 
           Staff us not through yet.  
                       MR. BOEHNERT:  It should be short.
                       CHAIRMAN KRESS:  Why don't we go ahead and
           hear it then and that won't give such a gap in
           between.  Sorry, I thought that was it.  
                       DOCTOR LANDRY:  I'd like to cover just a
           couple more items before we break and go on after
           lunch to the applicant's presentation.  You've heard
           a great deal of the experience that Tony has had
           running the code and some of the work that he has
           done.  We've also been running the code on plant decks
           and to look at the overall experience of a user in
           applying the code to an analysis of an AOO transient.
                       That experience has shown us that TRACG
           uses input decks that are very closely related to the
           decks that are from the original TRACB code which
           really means that if you have a knowledgeable TRAC
           user, that person can come in and pick up work with
           TRACG with a minimal level of additional education or
           retraining.  
                       Major changes from TRACB to TRACG are
           well-described in the model description report
           appendix.  We're pleased with that.  We did note that
           the execution structure of control blocks though has
           been retained from the TRACB.  In other words, the
           control box must be executed in numerical order and if
           you want to go back and use the same control block,
           you have to put it in again.  There's no ability to
           select control blocks according to the use within the
           input stream.  You have to continue in a numerical
           sequence.  
                       We did feel that additional guidance could
           be provided to the user on time step size.  The time
           step size selection.  But on the other side of that
           issue, the applicant has developed a set of standard
           input decks for all of their plants which takes the
           user effect out very much, that the user doesn't have
           too much option and doesn't have too much effect on
           the calculation with TRACG.
                       We also noticed that TRACG determines the
           correct flow regimes during the steady state
           initializations, unlike some other codes where the
           user can select flow regimes randomly or for different
           stages, different components.  The user doesn't have
           that option with TRACG so we're pleased that this
           removes the user effect from the code.
                       CHAIRMAN KRESS:  Is the time step checked
           internally in the code to see that it meets stability
           criteria?
                       DOCTOR LANDRY:  There are time step checks
           but we thought that in looking at the material it
           would be useful if the user had a better definition of
           proper selection of time step.  
                       CHAIRMAN KRESS:  I was trying to figure
           out what you thought was needed as additional guidance
           there.
                       DOCTOR LANDRY:  There are checks and
           balances there but we thought that the user would
           benefit by having it better defined.  But then again,
           as has been said a couple of times already, the code
           is used internally within the General Electric
           corporation where they have the ability to educate the
           user beyond what the documentation would say.  They
           have an ability that if the documentation is not
           adequate for the general public, they can cover for
           that by making it part of their training program.
                       MEMBER SIEBER:  Is that institutionalized?
                       DOCTOR LANDRY:  Yes.  They have a training
           program within the corporation.
                       MEMBER SIEBER:  It has a QA program
           attached to that so that you can carry on?
                       DOCTOR LANDRY:  Right.  That all comes
           under the QA program also.  The use of the code, the
           ability of the user, all gets checked and balanced
           through the QA program.  
                       MEMBER SCHROCK:  Does this imply the
           utility user is less skillful?
                       DOCTOR LANDRY:  Well, the utility doesn't
           use the code.
                       MEMBER SCHROCK:  Not at all?
                       DOCTOR LANDRY:  Unless General Electric is
           licensing the code to their utilities, all the
           calculations are done by General Electric.
                       MEMBER SCHROCK:  Okay.  I didn't
           understand that.
                       DOCTOR LANDRY:  Some of the conditions and
           limitations that we identified in the SER.  We have
           already discussed the GEXL 14 correlation and the
           issues surrounding GEXL 14.  Again, to emphasize that
           once resolution of those issues is arrived at, that we
           expect that to be applied within the use of TRACG.  
                       We've also pointed out in the
           presentations already this morning and in the SER that
           TRACG, if it is to be applied to stability analysis,
           will have to be submitted for staff review for that
           application.  We are not approving the code for a
           stability analysis.  They haven't asked for that
           either.  It has not been reviewed for Atlas.  They
           have not asked for that, but we want to call out. 
           Since Atlas is considered a transient, we want to
           identify that if it is applied to Atlas, we want to
           re-review it.
                       The discussion that Tony presented, the
           PIRT 18 model needs further justification before
           application to reactivity insertion or control rod
           ejection accidents.  Tony raised that question.  How
           can Monte Carlo model reliably predict point kinetic
           answers?  Of course, the code is not being applied for
           that at this point anyway, but if it should be, these
           are issues that are going to have to be addressed.
                       We also identified in the review that for
           isolation condensers further justification or review
           may be necessary.
                       MR. BOEHNERT:  What's the deal there,
           Ralph?  What's the problem?
                       DOCTOR LANDRY:  This was identified back
           when the in-depth thermal-hydraulic review was
           performed.  There was a feeling that the modeling of
           isolation condensers was not adequate and needed
           further review.  So again, we did not see where that
           had changed and we felt that we needed to point out to
           future reviewers, as has been said a couple of times
           this morning, this is a flag to reviewers of
           applications of the code that if it is applied to a
           plant with an isolation condenser, they need to look
           carefully at this condenser to see if it is critical
           to the transient progression.  Then they need to look
           at it more carefully.  If it's irrelevant or low
           meaning for the transient, we're not so concerned.
                       MEMBER SCHROCK:  You had another proviso
           in the SER which says that if the level tracking model
           is invoked where there is significant void, it will
           have to be re-evaluated.
                       DOCTOR LANDRY:  Right.  That's an
           identification to the staff also when this code is
           submitted for LOCA, which we anticipate in the not too
           distant future, that we want to look at that level
           tracking model.  There is not significant voiding for
           the transients for which it is being applied, but when
           they get into LOCA space, then we want to look
           carefully and we want the staff involved to look
           carefully at the level tracking model.
                       MEMBER FORD:  On the staff evaluation and
           conditions limitations, there's a whole series of
           questions arising out of the earlier subcommittee
           meeting here.  Are these conditions/limitations you
           have there, would they be changed if you took into
           account these questions?
                       DOCTOR LANDRY:  We could put in more but
           we have looked at and discussed with the applicant
           those concerns that were brought out and identified on
           the agenda and this afternoon General Electric is
           going to present information dealing with those
           specifically.  We have been discussing with General
           Electric what they're going to present and we do not
           have problems.  We are not in conflict with them at
           this point.  
                       MEMBER FORD:  So these are merely points
           of detail which get washed out.
                       DOCTOR LANDRY:  Well, they're points of
           detail that may not affect the application to AOO
           transients, but they are some points which we will be
           looking at carefully when we see the code for LOCA
           analysis.  Some of those are not important for AOOs
           and will be important for LOCA.
                       MEMBER FORD:  But that will be discussed
           this afternoon.
                       DOCTOR LANDRY:  Yes.
                       MEMBER FORD:  The justification for that
           statement will be discussed this afternoon.
                       DOCTOR LANDRY:  General Electric is going
           to present information on those this afternoon.  
                       Staff conclusions.  Again, GEXL 14 will be
           acceptable when it is handled in accordance with
           agreement with the staff.  The kinetic solver is
           adequate to support the conclusion that the models are
           correctly derived and account for phenomena involved
           in AOO transients.  Kinetic solver benchmarking
           demonstrates that TRACG adequately predicts results
           for AOO transients.  Staff analyses provide confidence
           that TRACG is acceptable for AOO transients.  
                       Uncertainty analysis follows accepted CSAU
           analysis methodology.  Uncertainties and biases have
           been identified and all highly ranked phenomena based
           on experimental data have been validated.  The process
           is acceptable and the quantities are reasonable.  
                       MEMBER FORD:  I guess my frustration with
           all these conclusions. If you are reading those
           conclusions from a paper, certainly there's been no
           support from any of those conclusions given today.
                       DOCTOR LANDRY:  No support?
                       MEMBER FORD:  Well, the last one, the
           process is acceptable and the quantities are
           reasonable.  We haven't seen any detailed
           documentation to support those conclusions.  I'm
           assuming that the back-up for those conclusions are
           given in other documents.
                       DOCTOR LANDRY: In the documentation on the
           code, but that's what Yuri was going through, that
           yes, the process that they went through in their
           analysis, he had some philosophical differences, but
           for the application the conclusion was it's
           acceptable.  
                       MEMBER FORD:  I guess I'm learning about
           this process as to what we're signing up to approve. 
           That's where I'm -- if I was a reviewer of a paper or
           of a report, I wouldn't sign off on it based on what
           has been presented today.
                       CHAIRMAN KRESS:  No, you have to do it in
           connection with all of the documentation we've been
           supplied which is a lot of stuff to go through.
                       DOCTOR LANDRY:  We don't reiterate all of
           the submittal.  What we're doing is saying what our
           findings are based on a review of the submittal
           without going through a reiteration of everything that
           was submitted to us.  
                       We also have concluded that the standard
           input has been developed for the classes of BWR
           systems for which TRACG is to be applied, BWRs 2
           through 6, and that the staff finds TRACG 02A code --
           again, that's designation of which version this is --
           is acceptable for application to the AOO transients
           presented in the submittal that's dated in January of
           2000.  
                       So those are the conclusions that the
           staff has arrived at.  Based on our review, we feel
           that the code is acceptable for application to the AOO
           transients.  We've identified areas of concern and
           we've identified items that we would call out as flags
           for future applications, that if it goes outside the
           scope of AOO transients, other things need to be
           looked at.
                       CHAIRMAN KRESS:  Thank you.  Are there any
           other additional comments from either members or from
           GE before we break for lunch?  I propose we come back
           at 1:00 and hear the rest of the story.  Recess.
                       (Whereupon, off the record at 11:55 a.m.
           to reconvene at 1:00 p.m.)                     A-F-T-E-R-N-O-O-N  S-E-S-S-I-O-N
                                                    (1:00 p.m.)
                       CHAIRMAN KRESS:  Okay.  We are now back in
           session again and you guys may proceed.  Here's the
           part where you're going to answer all of our previous
           questions.  Right?
                       DOCTOR ANDERSEN:  My name is Jens Andersen
           and I'm going to give a brief presentation on the TRAC
           application for anticipated operational occurrences
           for transient analysis.  If you'll go to the second
           slide, Charlie.
                       Let me just introduce the people that are
           here for General Electric.  Over there we have Jim
           Kapproth who is the manage of engineering and
           technology.  This is myself.  We have Fran Bolger
           who's sitting here who's team leader for the transient
           analysis.  Charlie Heck is helping me who's the
           responsible engineer for TRAC.  Brian Moore who's team
           leader for technology and development who is our
           nuclear expert and we have Antonio Possolo from
           corporate research and development who is a
           statistician that has helped us out.  And then finally
           we have Bharat SHiralkar who is the project manager
           for the application of TRAC to LOCA which is the
           submittal that we are planning.
                       What I'm going to talk about is the
           submittal of TRAC.  We submitted fairly extensive
           documentation of TRAC to the NRC.  We have had a long
           review of TRAC.  We have had numerous meetings and
           communications with the NRC, phone conversations,
           emails, meetings.  There were a number of requests for
           additional information, and GE Has provided responses
           to these questions and I'll get into details on that.
                       We've also had review with the ACRS
           Thermal-Hydraulic Subcommittee.  We had a meeting on
           November 13 last year.  I'm going to address some of
           the comments that we have received from the ACRS and
           I'm also going to comment on some of the issues that
           came up at the end of the SBW review.  And finally,
           I'm going to go into some concluding remarks.
                       Just to reiterate.  The scope of the
           application was to apply to operating boiling water
           reactor in United States and that would be BWR 2 to
           BWR 6.  The events that we applied for are the
           anticipated operational occurrences, also called
           transients, which are basically operational events
           that deals with either increase or decrease in reactor
           pressure, increase or decrease in core flow, increase
           or decrease in reactor coolant inventory and decrease
           in core coolant temperature.  These are the so-called
           Chapter 15 events.  
                       The documentation that has been submitted
           for TRAC is that we first had a document that was
           called the TRAC licensing application framework for
           AOO transient analysis.  That was actually submitted
           to the NRC in 1999 and that was basically a document
           that laid out the entire plan for how we would apply
           TRAC to transient events.  And then later towards the
           end of 1999, we submitted the model description.  In
           early 2000 in January, we submitted the qualification
           document and the application methodology.  
                       In addition, we submitted the TRAC user's
           manual and we made the TRACG 02A source code available
           to NRC and, together with the source code, we made a
           number of sample problems and test cases available.  
                       The scope of the review has been to review
           the application of TRAC to transient and the objective
           was to get a safety evaluation report for the
           application and evaluation of the TRAC's capability
           for AOO transients and evaluation of the qualification
           we have supplied to support that application and
           finally, an evaluation of the application
           methodologies which is how we apply TRAC for transient
           events.
                       The time line.  As I said, we submitted
           the road map, the plan for the whole process in May of
           1999.  All the LTRs were submitted to the NRC by
           February of 2000 and we had a kick-off meeting that
           involved a meeting both with the NRC and the ACRS
           Thermal-Hydraulic Subcommittee on March 16 of the year
           2000.  In April of 2000 the NRC issued the acceptance
           review which is basically that the documentation that
           was provided was sufficient to allow the review to go
           on.
                       We had first a major meeting with NRC on
           NRC review concerns in September of the year 2000. 
           The ACRS Thermal-Hydraulic Subcommittee was in
           November of 2000.  And then we had numerous other
           communications.  During this period, we have received
           23 requests for additional information and we have
           provided responses to all these requests and all
           issues have been resolved.  The draft safety
           evaluation report, we received that in July 2001 and
           we're having this meeting today on August 27, 2001
           and, of course, what we are hoping to get out of it is
           closure by September and get the safety evaluation
           report by September.
                       As I said, we had submitted extensive
           documentation on TRAC and the previous slide listed
           the number of documents we have submitted.  We have
           relied on prior NRC reviews and acceptance of TRACG
           application.  There has been numerous application of
           TRAC where it has been applied for LOCA, transient,
           ATWS and stability applications that have been
           accepted by the NRC and the thermal-hydraulic model of
           TRAC was substantially reviewed during the SBWR
           project.  That project was canceled in 1996 and that
           review was then subsequently stopped.  However, NRC
           issued a letter documenting the status of the review
           when the SBWR program was stopped.
                       Anyway, we have had numerous interactions
           with the NRC.  We have supported the TRAC
           installations of the NRC computers and the
           benchmarking against the NRC codes.  We've had the
           review with the ACRS Thermal-Hydraulics Subcommittee
           in November.  We received a total of 23 requests for
           additional information including an RIA that was
           generated from ACRS comments.  Most of these RIAs
           dealt with providing additional information and
           clarification of issues and we have provided all of
           these responses and I would like to make the comment
           that I feel that we have had a very good interaction
           with the NRC reviewers.  We have had a very
           professional and open candid communication with the
           NRC and I personally have been very pleased with how
           this review has progressed.
                       Now is probably the time where we are
           getting into some of the proprietary material.
                       MR. BOEHNERT:  So we close the meeting. 
           We'll go to a closed meeting transcript.
                       (Whereupon, at 1:10 p.m., the proceedings
           went into Closed Session.)
           
           
           
           
           
           
           
           
           
           
           
           
           
           
           
           
           
                                  CHAIRMAN KRESS:  Does the staff wish to
           make any additional comments at this time?  I'll tell
           you what.  Let me go around the table here and see if
           we have comments from the consultants or the members,
           and then you might want to respond to some of those. 
           I guess I'll start with you, Virgil.  You have any
           comments in the way of wrap-up comments you'd like to
           make now or would you prefer to wait until you digest
           it?
                       MEMBER SCHROCK:  I think I'm going to have
           to write the comments.  I just don't see any way I can
           summarize them all now.  In some respects, the report
           that I submitted in November has been addressed.  In
           some respects, it's not.
                       CHAIRMAN KRESS:  Yes.  I think that was
           what I was looking for.
                       MEMBER SCHROCK:  I could try to sort those
           out for you.
                       CHAIRMAN KRESS:  I think it's a little
           premature.  Why don't you think about it and do it in
           your second report.  There's no use doing it now.
                       MEMBER SCHROCK:  My comments on the SER at
           the beginning of this meeting may have been more
           severe than they should have been, but I do think the
           SER should be written in clearer language than it is. 
           I think it needs to be more technically correct than
           it is.  I think there are still some problems that I'm
           going to comment on in my final report.
                       CHAIRMAN KRESS:  That would be helpful.  
                       I guess you're not allowed to comment at
           this stage.  Do you wish to make any more comments?
                       MEMBER SIEBER:  No, I don't think so.
                       CHAIRMAN KRESS:  I don't have any
           additional ones, so I think I'll see if the staff has
           any additional comments they want to make before we
           decide what to do for the full meeting.
                       DOCTOR LANDRY:  I think we've tried to
           make it clear that this is a draft SER.  There are
           areas in which we intend to make some revisions.  We
           had intended some revisions coming in.  There are
           areas that we felt could be bolstered and we'll, of
           course, take into consideration the comments and views
           of the subcommittee in making those revisions to the
           draft SER so that our goal is to have a complete
           product.  
                       CHAIRMAN KRESS:  Okay.
                       DOCTOR LANDRY:  We would appreciate
           getting a copy of Professor Schrock's comments.
                       CHAIRMAN KRESS:  We will.  That was an
           omission and that shouldn't have happened.  We'll be
           sure you get the next one.
                       How much time do we have on the agenda?
                       MR. BOEHNERT:  We have an hour and 40
           minutes.
                       CHAIRMAN KRESS:  On the full committee. 
           An hour.  Almost two hours.  Right?
                       MR. BOEHNERT:  10:20 to 12:00 noon on the
           6th of September.
                       CHAIRMAN KRESS:  Okay.  My suggestion
           would be, #1, that this GE presentation we just heard,
           answering the previous questions I think would be
           valuable for the whole committee to hear.  So I would
           want to see that from GE.  From the staff, I think the
           committee is pretty familiar with the way the
           uncertainty analysis was done so we don't really need
           much on that.  But I would like to see sort of a
           shortened overview of the SER because we really have
           to have that.  Not necessarily the full thing but at
           least talk about the limitations and the code
           assessment part.  Something like slide seven on or
           something in Ralph Landry's.  
                       I think we would want to hear a little
           bit, an abbreviated version of the kinetics part.  I'd
           like particularly to have a little bit of that where
           you talked about your experience with the use of the
           code itself.  I think that was helpful.  And maybe
           some abbreviated discussion of the use of MCNP and, of
           course, your final wrap-up slide of your findings.  I
           think that would be my impression.  Do any other
           committee members want to comment?
                       MEMBER SIEBER:  I'd start with slide five
           rather than seven so that people understand what the
           scope really is.  Slide five actually states that.
                       CHAIRMAN KRESS:  Let's see.  Maybe the
           staff would have about 45 minutes and GE 35.  Do you
           think you can fit it into that kind of time frame?
                       MR. BOEHNERT:  That's total time so allow
           some time for questioning.
                       CHAIRMAN KRESS:  Yes, that's total time. 
           Normally we say presentation time is 50 percent of
           total time.  So if there are no more comments or
           questions, I'd like to thank everyone.  GE, thank you,
           and thanks to staff, particularly those from Frank
           Rosenfeld for coming back and helping us out.  Hope
           you can make it to the September meeting, too.
                       MR. ULSES:  Absolutely no problem.  It's
           always a pleasure.
                       CHAIRMAN KRESS:  Okay.  Thank you very
           much.  With that, I guess this is a recess because
           tomorrow is a continuation of the same subcommittee.
                       MR. BOEHNERT:  That's right.
                       CHAIRMAN KRESS:  So tomorrow we hear about
           water --
                       MR. BOEHNERT:  That's correct. 
                       CHAIRMAN KRESS:  Okay.  I'll call this
           subcommittee meeting recessed until tomorrow.
                       (Whereupon, the meeting was recessed.)
 
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