Joint Subcommittees on Materials & Metallurgy, Thermal-Hydraulic Phenomena, and Reliability & Probabilistic Risk Assessment - November 15, 2001

                Official Transcript of Proceedings


Title:                    Advisory Committee on Reactor Safeguards
                               Joint Meeting of the Materials and Metallurgy,
                               Thermal-Hydraulic Phenomena and Reliability
                               and Probabilistic Risk Assessment

Docket Number:  (not applicable)

Location:                 Rockville, Maryland

Date:                     Thursday, November 15, 2001

Work Order No.: NRC-112                               Pages 1-156

                   NEAL R. GROSS AND CO., INC.
                 Court Reporters and Transcribers
                  1323 Rhode Island Avenue, N.W.
                     Washington, D.C.  20005
                          (202) 234-4433                         UNITED STATES OF AMERICA
                                 + + + + +
                           JOINT MEETING OF THE
                                 + + + + +
                             NOVEMBER 15, 2001
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                            ROCKVILLE, MARYLAND
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                       The ACRS/ACNW Joint Subcommittee met at
           Nuclear Regulatory Commission, Two White Flint North,
           T2B3, 11545 Rockville Pike, at 8:30 a.m., William J.
           Shack, presiding.
           WILLIAM J. SHACK           Chairman, ACRS
           DR. THOMAS S. KRESS        Co-Chair, ACRS
           DR. DANA POWERS            Member, ACRS
           MR. MARIO V. BONACA        Member, ACRS
                 Mr. Michael T. Markley,      ACRS
           ALSO PRESENT:
                 Mr. Ralph Meyer
                 Mr. Steve Bajorek
                 Mr. Norm Lauben
                 Ms. Carolyn Fairbanks
                 Mr. Alan Kuritzky
                 Ms. Mary Drouin 
                 Mr. Tom King
                                            I N D E X
                     AGENDA ITEM                           PAGE
           Opening Remarks by Chairman Shack. . . . . . . . . 4
                 Update on Rulemaking Changes - Tom King. . . 6
                 Background - Risk-informing 10 CFR 50.46
                 Presented by Mary Drouin . . . . . . . . . . 9
                 Acceptance Criteria Overview - Steve 
                   Bajorek. . . . . . . . . . . . . . . . . .15
                   Revisions to Decay Heat Standard - Norm 
                         Lauben . . . . . . . . . . . . . . .16
                   Risk Informed Regulation Consideration on 
                   Appendix K
                   Analysis Requirements - Steve Bajorek. . .34
                   Acceptance Criteria - Ralph Meyer. . . . .93
                 Recess at 10:48 a.m., until 11:09 a.m. . . 107
                 Status of technical work on 10 CDF 50.46
                 Presented by Mary Drouin . . . . . . . . . 108
                   Reliability Evaluation - Alan Kuritzky . 109
                   Large-Break LOCA Analyses - Carolyn 
                   Fairbanks. . . . . . . . . . . . . . . . 133
           Adjournment. . . . . . . . . . . . . . . . . . . 161
                                                      8:31 a.m.
                       CHAIRMAN SHACK:  The meeting will now come
           to order, the Joint Meeting of the Subcommittees on
           Human Factors and Safety Research Program, previously
           scheduled for today, has been postponed.  This is a
           joint meeting of the Advisory Committee on Reactor
           Safeguards, Subcommittees on Materials and Metallurgy,
           Thermal-Hydraulic Phenomena and Reliability and
           Probabilistic Risk Assessment.
                       I am William Shack, Chairman of the
           Subcommittee on Materials and Metallurgy.  Graham
           Wallis, Chairman of the Subcommittee on Thermal-
           Hydraulic Phenomena and George Apostolakis, Chairman
           of the Subcommittee on Reliability and PRA were unable
           to attend this meeting, and we are proceeding with
           this meeting on their behalf.
                       The Subcommittee members in attendance are
           Mario Bonaca, Thomas Kress and Dana Powers.  The
           purpose of this meeting is to discuss the status of
           NRC staff and industry initiatives to risk-inform the
           technical requirements of 10 CFR 50.46 for emergency
           core cooling systems for light water nuclear power
                       The subcommittees will gather information,
           analyze relevant issues and facts and formulate
           proposed positions and actions as appropriate for
           deliberation by the full Committee.  Michael T.
           Markley is the cognizant ACRS staff engineer for this
                       The rules for participation in today's
           meetings have been announced as part of the notice of
           this meeting previously published in the Federal
           Register on November 6th, 2001.  A transcript of the
           meeting is being kept and will be made available as
           stated in the Federal Register Notice.
                       It is requested that speakers first
           identify themselves and speak with sufficient clarity
           and volume so that they can be readily heard.  We have
           received no written comments or requests for time to
           make oral statements from members of the public
           regarding today's meeting.
                       I guess we're going to hear an update from
           the staff on some of the technical work they've been
           doing to support the rulemaking for changes, and I see
           Tom King is in attendance here, and I'd like to note
           this is probably one of the last times we're going to
           get to see Tom at a subcommittee meeting, since he's
           going on to retirement.
                       We certainly enjoyed having you for many
           extended discussions.
                       MR. KING:  Thank you, but you know, you
           may see me again.  So don't be too optimistic over
                       DR. POWERS:  Well, in light of his
           advancing years, should we get him a bottle of Geritol
           or something like that?
                       CHAIRMAN SHACK:  Well, that's one of the
           politer bottles that you buy.
                       MR. KING:  I'll take a bottle.  It doesn't
           have to be Geritol, though.
                       CHAIRMAN SHACK:  Since I don't see Mark
           Cunningham, we'll assume that Tom King is going to
           speak to --
                       MR. KING:  Yes.  We were going to provide
           the status report on where we stand at this point. 
           You know, the SECY paper was out.  We've not received
           an SRM yet from the Commission, but we're proceeding
           as if we're going to go forward with the rulemaking,
           that the Commission's going to approve proceeding.
                       We're doing the technical work to see what
           would that rulemaking look like.  Today's meeting is
           to provide you a status report on the options and
           issues that we're dealing with in doing that technical
           work and try and solicit some at least informal
           feedback from the subcommittee on questions, views,
           concerns you may have.
                       So with that, I'll turn it over to Mary
           and the others who are going to give the presentation.
                       DR. POWERS:  Tom, is there anything going
           on that you might call Option 4, which would be the
           complete reexamination of the regulations?
                       MR. KING:  The short answer is, yes, there
           is.  There's a meeting this afternoon where NEI is
           going to come in and give us their views on this clean
           sheet of paper approach for -- particularly directed
           toward future plants.
                       DR. POWERS:  Yes.
                       MR. KING:  We owe the Commission a paper
           in June of '02 with our recommendations on whether or
           not to proceed to do that, and if so, what are the
           options.  And if we can, what's our recommended option
           for doing that.
                       So there is some work underway.  This is
           clearly as a policy question.  The Commission's going
           to have to make a decision and our target date is June
           to get them something.
                       DR. POWERS:  I think we might want to
           alert the Planning and Procedures Committee that it
           sounds like in the April, May, June time frame that we
           ought to try to help staff where we can on the
           development of that paper.
                       MR. KING:  Yes.  I think I -- in fact, I
           ran into Med in the elevator and I said we need to sit
           down and schedule several meetings with subcommittees
           and the full committee, PBMR, GTMHR.
                       DR. POWERS:  Is it the type of thing, Tom,
           where we ought to have sort of an ad hoc committee? 
           I mean, it doesn't really fit within any of the
           existing subcommittee structures.  What I'm fishing
           around for is how to be most helpful to you and not a
           pain in the neck on this, because this is not a lot of
           time to prepare that paper.
                       MR. KING:  Yes.  The idea of the paper is
           to look at the pros and cons, look at the options,
           give the Commission a recommendation.  But assuming
           the recommendation is to go forward, we also want to
           give them at least a conceptual idea of what this new
           clean sheet of paper approach would look like, so at
           least they know what they're being asked to approve.
                       DR. POWERS:  Yes.
                       MR. KING:  So there is some technical work
           that goes along with this.
                       DR. POWERS:  Sure; sure.  And we may want
           to pursue that a little bit in December just to line
           out schedules and things like that, from our own part.
                       MR. KING:  Okay.
                       MS. DROUIN:  We ready?
                       CHAIRMAN SHACK:  Yes.
                       MS. DROUIN:  My name's Mary Drouin, with
           the Office of Research.
                       MR. KING:  Who?
                       MS. DROUIN:  Cute, Tom.
                       DR. POWERS:  Are you related to the
           outstanding individual that produced the ITE Insights
           Report that has had such a tremendous impact?
                       MS. DROUIN:  Yes.
                       DR. POWERS:  Okay.
                       MR. KURITZKY:  We'd just like to get you
           off to a good start.
                       MS. DROUIN:  And I greatly appreciate
           that; really, I do.  Before we get started we'll go
           around and let everyone at the table introduce
                       MR. MEYER:  I'm Ralph Meyer, from
                       DR. POWERS:  Are you new in this?
                       MR. MEYER:  What?
                       DR. POWERS:  Are you new in this
                       MR. MEYER:  Lots of jokes this morning.
                       MR. KURITZKY:  I'm Al Kuritzky.  Work with
           Area Branch.
                       MR. BAJOREK:  Steve Bajorek, Research.
                       MS. FAIRBANKS:  Carolyn Fairbanks,
           Research with the Materials Engineering Branch.
                       MR. LAUBEN:  Norm Lauben.  I'm very new,
           about 30, 40 years.
                       CHAIRMAN SHACK:  Yeah, I know; I know.
                       DR. POWERS:  Well, you know, as a rookie
           trainee, maybe you'll listen to these experienced
           hands and, you know, get some insights here.
                       MS. DROUIN:  Okay.  I think the last time
           that we were in front of the subcommittee on 50.46,
           the Option 3 part, was back in the summer as we were
           writing our SECY paper.
                       And at that time, you know, we made the
           commitment to maintain contact throughout the program
           and solicit input and feedback from the committee as
           we move forward.  There are a lot of issues associated
           with risk-informing 50.46.
                       So we did want to come in at this point,
           since we have been proceeding with the technical work. 
           We had said in the SECY to the Commission that we
           would not wait on the SRM to continue with the
           technical work.  We were going to move forward.
                       The rulemaking aspect, though, is
           contingent upon when the SRM comes out.  So we've had
           about four months behind us in proceeding forward, and
           we thought it was very timely at this point to give
           you, you know, our status, what our -- kind of our
           early thinkings are and issues we may have come
                       So I'm not going to spend a lot of time
           going through the background.  We'll just quickly, you
           know, refresh your memory of what our changes were,
           what our recommended changes were to the Commission on
                       We primarily are going to focus on the
           technical work that we've been doing in support of the
           recommended changes we made to the Commission and then
           quickly go over what our schedule is at this point.
                       Again, primary purpose for being here is
           to solicit feedback from the committee and comment,
           one, on our overall approach because we're still --
           have not quite solidified our approach.  We are
           converging on it and we thought, again, this would be
           a good time.
                       We are encountering some, you know,
           technical and implementation issues that we wanted to
           bring to your attention and still, on some of our
           recommended changes, whether we still feel that
           they're feasible or not.
                       At this point, of course, we're not
           requesting any letter from the committee.  On the
           background, you know, starting way back with SECY-300,
           which instigated the program, 264-R Plan, 86 and 198
           were two different updates of the framework.
                       198 gave our recommendations for 50.44,
           and then our most recent SECY 133, which provided our
           recommendations for risk-informing 50.46.  Now, I'll
           personally use the term "50.46," and when I use it, I
           use it loosely.
                       It encompasses Appendix K and also GDC 35. 
           This here shows in a figure, an overview of 50.46,
           plus Appendix K and GDC 35.  I think it's a good
           breakdown of the regulation in terms of how the
           different requirements are grouped.
                       When you come over from the right -- or
           from the left to the right, sorry.  I still haven't
           learned my left from my right yet.  And you look at
           the requirements, they tend to be divided up into what
           we call these four functional groups.
                       The first one we're looking at the ECCS
           reliability.  Now, of course, when you look at the
           50.46 and Appendix K, you're not going to see the word
           "reliability" there, but for example, when you look at
           GDC 35 and you look at the single failure criteria
           requirement and the LOCA/LOOP, what that in essence
           does in an indirect way of sitting with the
           reliability of the ECCS as is.
                       So we have those requirements and this box
           actually says what the technical requirements are. 
           The next LOOP tend to deal with the acceptance
           criteria of the emergency core cooling system.  The
           next group is the evaluation model.
                       And finally, the last one is dealing with
           the LOCA break size.  And it's those different groups
           that in 133 that we made recommendations to.  Now,
           when we go back to 133 we had two sets of
                       We had some that we called short-term
           considerations and we had those that we considered
           long-term.  The short-term considerations dealt with
           those first three boxes, looking at the ECCS
           reliability, looking at the acceptance criteria and
           the evaluation model.
                       In terms of the acceptance criteria in the
           evaluation model, those we were going in and making a
           recommendation to put a permanent change right into
           the rule.  That change would, though, be voluntary. 
           So it would be entered in through like an "or" gate.
                       Then an alternative to that would be an
           alternative on the reliability side, and that is
           dealing with GDC 35.  We thought we could do those in
           the short-term, and the technical work that we had
           proposed on the short-term would be finished in the
           April and July time frame of 2002.
                       On the long-term considerations we felt
           there was still a lot more work done even to determine
           if the feasibility was doable.  And so we were looking
           at the outside, two to three years to just finish the
           feasibility study.
                       And again, in doing anything that -- in
           terms of looking at Option 3, part 50, we have our
           framework document which sets the guidelines and rules
           of how we make the decisions that we make.
                       So at this point we're going to get right
           into the technical work we were at, and we're going to
           start first with the acceptance criteria in the
           evaluation model, and so I'm going to turn it over to
           Steve Bajorek.
                       MR. BAJOREK:  Okay.  Thank you, Mary. 
           Want to just slide over?
                       MS. DROUIN:  Want us just to change it for
                       MR. BAJOREK:  Well, no.  Let me --
                       MS. DROUIN:  Okay.
                       MR. BAJOREK:  -- let me just kind of
           introduce what we're going to do next.  The next
           segment should be in a package that we just handed
           out.  We have three presentations in this.  We're
           going to start off with Norm Lauben.
                       He's going to talk about revisions to the
           decay heat standard, how we deal with the
           uncertainties.  I'm going to talk about the use of the
           evaluation models and the impact that may have on how
           we do those analyses.
                       And Ralph Mayer is going to talk about the
           50.46 performance-based criteria, and I think also
           deal with a couple of cladding-type of issues that
           have been brought up before.  But Norm.
                       MR. LAUBEN:  Yes.  Let's see.
                       MR. BAJOREK:  How's the --
                       MR. LAUBEN:  I was happy to sit here, if
           you want to change the slides for me.
                       MR. BAJOREK:  Give me your --
                       THE REPORTER:  Mr. Lauben, can you use the
           microphone there?
                       MR. LAUBEN:  Yes.  I'll tell you what. 
           Why don't you move over a chair.  Then I can just use
           this microphone.  And as long as I don't hit anyone in
           the eye, I can use my laser beam.
                       MS. DROUIN:  High tech.  You might set a
                       MR. LAUBEN:  Yes, right.
                       Carolyn, you may want to get out of the
                       MR. LAUBEN:  Okay.  Let's see.  Yes,
           that's -- let's see.  This is what we're talking
           about.  That's who you are and that's who I am.  So we
           can go to the next slide.  The real context for this
           is going to be in Steve's presentation.
                       So mostly what I'm going to talk about are
           the decay heat standards and their uncertainties and
           some of the issues that we have uncovered with respect
           to them, and how that all fits.  But the context in
           terms of conservatism and so forth is really, really
           in Steve's presentation.
                       But so the hard part is to come after my
           presentation, I hope, unless you all have questions
           that I'm not expecting.  Okay.  This is just kind of
           a review, first of all.
                       10 CFR 50.46 and Appendix K was
           promulgated in '74, required the use as a draft, '71
           ANS decay heat standard with a multiplier of 1.2 and
           the assumption of infinite operating time for use in
           ECCS evaluation models.
                       It's very simple.  The '71 standard did
           virtually have a curve with a table of uncertainties
           that we chose 1.2 out of, and the assumption of -- you
           could have finite operating time if you wanted to do
           summation calculations, but we chose infinite
           operation, which made the '71 standard very simple to
                       It was not -- there was no difficulty at
           all in that.  Anyway, number one, the research and
           analysis since 1973 has shown that the most
           significant conservatism in Appendix K is the decay
           heat requirement.
                       The 1988 ECCS rule change allowed use of
           a realistic evaluation model analysis option with an
           uncertainty evaluation.  In other words, instead of
           using the conservative Appendix K, now you can use the
           best estimate option.
                       So there's always two choices.  One is the
           best estimate option that was allowed since 1988.  The
           other was the Appendix K conservative option which was
           the only option from 1974 to '88.  But then after '88
           it was still grandfathered.  So licensees still have
           a choice today of whether they want to use the best
           estimate option or the Appendix K option.
                       Regulatory Guide 1.157, which accompanied
           the '88 rule change, declared the acceptability of
           using the '79 ANS decay heat standard for a realistic
                       It said there's a few more physical things
           that you need to consider, such as neutron absorption
           efficient products and things of that sort.  So it
           says it's now become a little bit more complicated.
                       The '79 option now has three isotopes --
           fissionable isotopes that you have to worry about, not
           just one.  So it's now more complicated.  It has three
           different ways of applying the standard.  You can use
           summation calculations -- excuse me.
                       Yes.  You can use a summation calculation
           for groups of decay products and you can also use some
           integrated values for post-fissions, or you can use
           integrated values for infinite decay heat and a
           summation methodology where you can change that
           infinite irradiation into finite irradiation.
                       So there's lots more choices that you have
           to use when you start to use the '79 or then
           eventually the '94 option.  But okay.  Regulatory
           Guide 1.157 only applies to the best estimate option.
                       That Regulatory Guide does not apply to
           Appendix K.  Appendix K is self-standing.  There's no
           regulatory guides associated with it today or in the
           past.  It's just -- it's self-standing.  You abide by
           those rules and that's it.  So 1.157 applies to the
           best estimate option.
                       There's nothing to prevent a licensee or
           an applicant from using all or part of an even newer
           standard, the 1994 decay heat standard today, if you
           want to, because there's no -- there are -- there's
           really no requirements to -- as it says in the second
                       The only technical requirement in the
           realistic option has to do with the things that Mary
           has addressed, i.e., the break spectrum in GDC 35. 
           Otherwise -- and those things apply to both the best
           estimate and the realistic option.  Okay.  Back to --
                       CHAIRMAN SHACK:  The current best estimate
           models have been improved and they're really based on
           the '74 guide or --
                       MR. LAUBEN:  No.  No.  No.  No.  No.  No. 
           No.  No.  No.  No.  Oh, excuse me.  No.  No.  No. 
           What I said was that Reg. Guide 1.157, that's the
           guidance as to what's acceptable to the staff with
           respect to the best estimate option.
                       The best estimate option in 50.46 doesn't
           say very much.  It says, do a best estimate with a
           high degree of certainty that your peak clad
           temperatures won't exceed the limit.  That's really
           what it says, or that the criteria won't be exceeded
           with a high probability.  That's really all it says.
                       DR. KRESS:  Does it explicitly call out
                       MR. LAUBEN:  No, it does not.  That's
           called out -- the 95 percent probability is called out
           in the Regulatory Guide.
                       DR. KRESS:  Yes, okay.
                       MR. LAUBEN:  Not in the rule.  The rule
           doesn't say anything about that.  The rule just says,
           high probability that the criteria won't be exceeded. 
           You have to go to the Reg. Guide before you first see
           the words, "95 percent" used.
                       DR. KRESS:  So if somebody wanted to, they
           could come in with less confidence level if they could
           justify it?
                       MR. LAUBEN:  If they could justify it.
                       DR. KRESS:  Had a reason for it?
                       MR. LAUBEN:  That's true of any regulatory
           guide.  You don't have to abide by a regulatory guide. 
           You can -- it's something that's acceptable to the
           staff, but if you want to do something else, risk the
           prolonged review that would be required for something
           that's not in a regulatory guide, you can do it. 
           That's the rules.
                       DR. KRESS:  Okay.
                       MR. LAUBEN:  So at any rate, the
           Regulatory Guide's been in place since '88 for best
           estimate option.  And it did say that the '79 standard
           was acceptable.  That's because the Regulatory Guide
           came out in '88.
                       The '94 standard wasn't available at the
           time, obviously.  Okay.  The last bullet.  The '94
           ANS-5 standard is potentially more accurate and less
           conservative than the '71 draft standard, but requires
           more choices to be specified by the user, as I
                       Instead of three fissionable isotopes, the
           '94 standard has four fissionable isotopes.  Still a
           lot more than the one that was implied by the curve
           that was in the '71 standard.  So there's much more to
           be -- choices that you have to make when you're using
           the more modern standards.
                       More choices in '94 than there was in '79,
           and certainly, many, many more choices than you had to
           make from '71 standard.  In fact, the '71 standard had
           so few choices that the options could be contained in
           two or three sentences in Appendix K.
                       Okay.  If NRX makes it -- okay.  Here's
           the problem.  You have a lot of choices now that you
           have to make with the '94 standard, if you want to use
           that.  So the question is, who's going to make the
                       If NRC makes the choices ahead of time,
           that may make life easier, but it also means that we
           would have to make choices that would conservatively
           bound any number of things that you have to consider
           when you're applying the decay heat standard.
                       So let's see.  What is -- let's see.  If
           NRC makes a choice -- yes, right.  Okay.  Anyway, if
           NRC makes the choices, however, it's likely to make
           the process more predictable and stable.
                       That is, if the choices are made at a time
           by the NRC, no one argues with them, then there's no
           -- there's very little potential for review, now, when
           somebody comes in and says, I'm applying the '94
           standard and here are the things that I choose to
           implement out of that standard.
                       If each applicant or licensee selects the
           options, then obviously, there's a lengthy review
           process involved.  Okay.  Now, here are --
                       CHAIRMAN SHACK:  Is there really a lengthy
           review process?  I mean, is it --
                       MR. LAUBEN:  Yes, there could be.  It
           depends on -- it would depend on how the licensee or
           applicant came in and decided to implement the
           standard.  He may be very -- he may want to get a lot
           out of this, so he may be very tight in how he defines
           his operating cycles, because that's one of the things
           that you have to choose in here.
                       Or he may want to do a bounding histogram
           that he could have, in which case it might not be.  It
           just depends on how much margin he's trying to shave
           by using it, and that's the point of us making some of
           these choices first.
                       And I can go through -- these are the six
           that I identified as being the most important choices
           that you have to make.  Operating time.  Well, in the
           old standard infinite operating time is easy.
                       That's conservative.  It's easy to use. 
           It actually reduces -- it reduces the complexity of
           your uncertainty analysis.  It makes life very easy
           and it's obviously a conservative assumption, too. 
           But like I say, if you wanted to use a bounding
           histogram of operating cycles, you could do that.
                       But if it was tightly bound then you may
           run the risk of it doesn't apply to the next cycle of
           operation or something like that.  And that's part of
           the problem, how tightly do you want to do this?
                       You going to leave it up to the individual
           licensees or are you going to leave it up to -- or
           should the NRC decide ahead of time?  Part of the
           reason I'm bringing this up is that -- and we didn't
           mention this, but there was a petition by NEI to use
           the '94 standard, just use it.
                       Well, they didn't say how they would use
           it.  They just said use it.  So that -- the
           implication is not clear.  Do you mean for the NRC to
           make choices ahead of time, or do you choose to come
           in and make your own choices?
                       And if you're going to make your own
           choices and each licensee makes a different choice,
           then it does increase the potential for review.
                       CHAIRMAN SHACK:  Let me put the question
           a different way.  You know, suppose you're just using
           this to determine that decay heat --
                       MR. LAUBEN:  That's all --
                       CHAIRMAN SHACK:  -- that seems to me one
           question.  Well, is in fact -- I mean, do you feel
           that your calculation of decay heat is now covering
           some other non-conservatism somewhere else?  I mean,
           that would seem to me --
                       MR. LAUBEN:  Yes.
                       CHAIRMAN SHACK:  -- the difficult thing to
           assess when you're trying --
                       MR. LAUBEN:  Indeed
                       CHAIRMAN SHACK:  -- to trade these off.
                       MR. LAUBEN:  Indeed.
                       CHAIRMAN SHACK:  Just looking at the decay
           heat --
                       MR. LAUBEN:  Yes.
                       CHAIRMAN SHACK:  -- by itself I would
           think --
                       MR. LAUBEN:  Yes.  Yes.
                       CHAIRMAN SHACK:  -- looking at these would
           be a relatively straightforward thing.
                       MR. LAUBEN:  Relatively straightforward
           thing.  I agree.  And Steve's going to address the
           other part.
                       CHAIRMAN SHACK:  Right.  Okay.
                       MR. LAUBEN:  I left the hard stuff for
           him.  But indeed, you're right.  It should be
           relatively straightforward, but the point is, even --
           there are still some issues that need to be addressed,
           just to do the straightforward part.
                       And that's what I'm attempting to address
           here, that in the petition there was no mention of how
           you even deal with the straightforward part.  So I
           bring these issues up here.  I've brought them up in
           a couple public meetings in the past, but there didn't
           seem to be as much interest then, however.  Okay.
                       Okay.  Second one, fission fractions per
           isotope.  Well, this requires some -- okay.  Well,
           like I said, the '71 standard assumed 235U only.  Three
           additional isotopes in the '94 standard; fission
           fractions vary with time and space.
                       You need a physics calculation to
           determine what those fission fractions are for each
           isotope.  They vary with time.  They vary with space. 
           They're burnup dependent and enrichment dependent.
                       So it's not -- you know -- it's not a
           straightforward thing.  You can make simple choices,
           simple bonding choices like all 235U.  That's a simple
           bonding choice.  Okay.
                       Neutron capture.  This effect was added in
           '79 and '94.  The effect is burnup dependent and adds
           to the decay heat.  There's also some uncertainty in
           it, although the amount is low until you get up to
           beyond the times of interest that I think we're
           interested in, like 10,000 seconds or so.
                       However, it's still something that needs
           to be considered and addressed, and you can choose
           times that are very high and then, you know, you're
           conservative, because it's a T to the fourth effect in
           the equation.  It's there for neutron capture.
                       Okay.  Fission energy.  Each fissionable
           isotope has different recoverable fission energies. 
           The standard in the past has always been to shoot 200
           MEV per fission, because that's conservative.  You can
           actually reduce conservatism by using higher values
           because that number appears in the denominator.
                       So you can, if you can justify it, choose
           other numbers for other fissionable isotopes.  So
           that's another choice you have to make, or somebody
           has to make, either the NRC ahead of time or the
           licensees or whoever.
                       Okay.  Actinide heavy element decay.  The
           same basic equations are in all three standards for
           actinide decay.  However, required 235U fission yield
           is not specified and is burnup dependent.  It was not
           even specified in the '71 standard -- excuse me -- it
           wasn't even specified there.
                       It was assumed I think that the value was
           .7, but I don't -- you can -- I can't find the
           documentation of it anywhere.  In the examples in the
           '79 and '94 standard I think it was like .7.  There
           are codes that use a default value of one.  But the
           point is, it's another choice to be made.
                       Okay.  Tabular data.  As I think I
           mentioned earlier, there are three tables now for each
           fissionable isotope, four fissionable isotopes.  That
           means you have 12 tables.  You have 12 tables you can
           go to and that depends on your method that you choose
           to evaluate the decay heat.
                       That's quite different than just one table
           that you had in the previous '71 standard.  Okay.  So
           those are the key choices you have to make.  At least
           -- like you say, they're not -- they don't have to be
           that difficult.
                       They can be chosen in a bounding way, but
           if you want to reduce your conservatism you may not
           want to make them quite as bounding as somebody else
           might want to make them.  Okay.  So that's it.  I
           guess we can go to the next slide, then.
                       Okay.  The issue here is uncertainty and
           conservatism.  Well, as we all know, now that we have
           a decay heat standard that has many more variables in
           it, your uncertainty analysis becomes a different
           issue than it did before.
                       There are RMS equations or something like
           that, that you have to go through and use to determine
           your overall uncertainty in this.  There are
           uncertainties with two of the table types, the post-
           fission type and the infinite irradiation tables, that
           could be used.
                       They're different because they come out
           with different values when you do this.  But in
           addition to the uncertainties in those tables for
           those methods, you now have to look at other
           uncertainties like uncertainties in power, or any of
           the other variables that we're talking about,
           uncertainties in fractions of fissionable isotopes.
                       So all these things now have
           uncertainties, uncertainties in neutron absorption. 
           What if -- although the standard says, don't bother
           doing that because we've picked conservative values
           for you.  So but the point is how to deal with
           uncertainties now becomes an issue.
                       It wasn't an issue before, but how to
           combine them and deal with them does become an issue. 
           There are equations in the standard, however.  Let's
           see.  Let me see.  I don't want to get ahead of myself
                       Okay.  Oh, yes, okay.  Let me not get
           ahead of myself then.  Okay.  Bullet number 3 here. 
           Use of the '94 standard with nominal inputs and
           uncertainties could result in a substantial reduction
           of overall conservatism in the Appendix K analysis.
                       And number 4, thus the magnitude of one or
           more non-conservatisms is too large.  If it is, the
           appropriate overall conservatism may be in jeopardy. 
           I think this is Steve's presentation.  I'm jumping the
           gun a little bit.
                       But the point is here, is that if you now
           reserve the conservatism in your analysis you now have
           to worry about those other things that create
           uncertainties in your analysis that you didn't have to
           worry about before, because you don't have a bounding,
           conservative -- it may be in jeopardy.
                       Let me just say that.  It may be in
           jeopardy.  Okay.  The current version of Appendix K
           makes no break size distinction concerning application
           of the decay heat requirement.  Longer transients,
           such as small breaks, would derive substantially
           larger benefit from a reduction in decay heat,
           compared to faster large breaks.
                       Large breaks, some of them, depending on
           -- depending on a particular plant that you're looking
           at, some large breaks can be over so quickly, peak
           clad temperature can turn around so quickly, that it's
           virtually a stored energy issue and not a decay heat
                       So large breaks that turn around quickly
           are going to be -- are not going to be decay heat
           dominated the way some small breaks that may be
           uncovered, albeit later, for a longer period of time
           become much more decay heat dominated.
                       Among the required features of Appendix K,
           decay heat is the only one, except for the ones that
           Mary talked about, i.e., the break size and the GDC 35
           types of things.  The only thing that really applies
           to small breaks in Appendix K specifically is decay
                       Or let me put it this way, largely.  There
           are some other things that can influence it, too, but
           I mean it's by and large virtually the entire
           predominant feature of Appendix K, is decay heat for
           small breaks.
                       Okay.  RES is evaluating -- okay.  Number
           5 -- or 6.  This may be somewhat new.  We are
           evaluating potential errors in the uncertainty methods
           in the '79 ANS and '94 standards.  Therefore, previous
           sensitivities may not be appropriate.
                       Some of our assessments before -- the
           uncertainties -- in other words, some of the
           equations, I don't want to say for certain that
           they're wrong, but I've had a number of physicists and
           statisticians tell me that they are.
                       But wrong may not be a good adjective.  It
           may be that they were -- that they used methods that
           were designed to enhance the uncertainty, and that it
           has to be looked at more carefully.  I think in fact
           we've talked with the ANS Standards Subcommittee on
           this subject and they -- those members agree also.
                       They believe that this should be fixed. 
           So our choice is either to convene a group of experts
           under ANS and work this through or make the exceptions
           ourselves.  I tend to -- would tend to prefer to work
           this through the ANS committees.
                       I think that's a better way, get a new
           standard out which everyone agrees on these
           methodologies and so forth.  So that's something, like
           you say, not necessarily that difficult to do, but
           still something that you sort of need to establish
           your baseline by doing these straightforward things
                       And I think that's what we -- so that's
           what we mean when we say, number 7, we're going to do
           some additional work.  We need to get some of these
           things straightened out.
                       And now, as I said a couple times, number
           8 there, the context of the decay heat work and the
           -- is really the basic subject of Steve's
           presentation.  So I don't know if there are any other
           questions or not.  Okay.  Thank you.
                       MR. BAJOREK:  Those go back to Norm. 
           Thank you, Norm.  Where I'm going to pick up now,
           then, is if we start to change the decay heat model,
           going from '71 or '79 to something that's technically
           better, what are the consequences that we're going to
           see in two different evaluation models that have been
           presented to the staff, the classic Appendix K model
           and how this might impact best estimate analyses, as
                       Our directive to do this comes from the
           SECY-01-133, and what I've summarized here in the
           first three or four bullets are some of the items that
           specifically discuss this.
                       What basically 01-133 asks us to do is to
           take a look at Appendix K, identify those models which
           are unnecessary conservatisms, come up with revisions
           to them, but also keep in mind that Appendix K may not
           cover everything.
                       We do have new knowledge in front of us
           and there may be issues related to Appendix K where
           there may be non-conservatisms involved.  So we've
           been asked to look for the unnecessary conservatisms,
           as well as look at features that may not be
           appropriately counted for.
                       DR. KRESS:  Is there such a thing as a
           necessary conservatism?
                       MR. BAJOREK:  I think there is, and I
           think Norm hinted on it.  We see that the '71 decay
           heat model is very overly-conservative technically,
           compared to what it should be to an accurate
                       But that excess conservatism has been used
           in evaluation models to account for other things.  It
           forgives a lot of sins, okay, uncertainties in other
           models, processes where you may have questions, but
           from a regulatory viewpoint you may feel comfortable
           with because you know there's so much conservatism in
           the Appendix K, as well as in things like the single
           failure criteria.
                       I'm going to talk about a few things that
           we would consider as non-conservatisms in a couple of
           minutes here.  Principally, the focus of the efforts
           in our branch have been by the norm to take a look at
           the decay heat standard itself, what its
           implementation should be, and then to look at options
           to deal with incorporation of a revised decay heat
           standard and how we should deal with some of these
           things that we're terming as non-conservatisms.
                       Well, I think the first question is, well,
           what is this thing that you would refer to as a non-
           conservatism?  And I would say that there are three
           potential sources.  First, there may be models in
           Appendix K that even though they're intended to be
           conservative, later information has shown them not to
                       Now, the only example that we're aware of
           is in the case of the Dougal-Rohsenow Model for post-
           critical heat flux heat transfer.  Information that
           was uncovered in the '70s and '80s showed that it was
                       And in the '88 rule change there were
           restrictions placed on the Dougal-Rohsenow Model.  It
           could only be grandfathered and if there was a change
           to the analysis, you had to justify its conservatism.
                       And to my understanding, most evaluation
           models have basically replaced that at this time.  So
           that's not really an issue anymore.  However, Appendix
           K, while it gives prescriptions for several thermal-
           hydraulic models, it doesn't account for everything.
                       And there has been the concern that these
           models, which have not been specifically discussed by
           Appendix K, may have a large uncertainty when they're
           applied in an evaluation model.  This was the focus of
           another SECY paper, 86-318, that actually looked at an
           issue very similar to what we're doing right now.
                       The premise for 86-318 was reduce the
           decay heat by changing to an updated standard.  I
           think they were looking at the '79 standard at that
           time.  And the conclusion at that time was that, no,
           that was not a good thing to do unless you accounted
           for uncertainties in the other thermal hydraulic
                       Now, it having been written in 1986, you
           can see that this was basically a formulation for the
           1988 rule change and the best estimate rule that
           required people to actually address these
                       But it still remains a concern that if we
           start to do things with Appendix K, we still have to
           do something to look at those uncertainties and assure
           ourselves that there is some conservatism remaining in
           that type of an evaluation model.
                       The third source of potential non-
           conservatism are things that have arisen out of
           thermal hydraulic test programs that were conducted in
           the late '80s and the early '90s.  These are processes
           -- we'll talk about those in the next overhead.
                       These are processes that were identified
           in the test programs that Appendix K didn't know about
           in 1971, and had basically fallen through the cracks. 
           SECY 133 is asking us to identify what some of these
           processes are and make sure that they are at least
           compensated for by any revision in the decay heat
           standard, plus some adequate multiplier.
                       A couple of examples that are considered
           non-conservatism, and these are large break models. 
           The first one to refer to is downcomer boiling, and
           this is something that was seen in the 2D/3D Program,
           CCTF, SSTF that were run in Japan and also UPTF that
           was run in Germany in the last '80s, early '90s.
                       They noted that some of the heat transfer
           that occurred in the core wasn't as good as they
           anticipated it to be.  They thought the reflood rate
           was going to be a little bit higher.  In looking at
           some of that data, part of it was attributed to things
           that had gone on in the downcomer.
                       Later in the transient the fluid begins to
           boil, takes awhile to get that energy out of the
           walls.  This voids part of the downcomer and two
           things go on.  One, you reduce your gravitational head
           that drives fluid into the core.
                       And secondly, when that downcomer fluid
           frosts up, part of it gets pushed back out the break. 
           So your result is a lower collapsed level in the
           downcomer than you would have if you had made the
           assumption it didn't boil and you were full up to the
           cold leg.
                       Now, typically Appendix K evaluation
           models don't really account for this.  There are two
           reasons.  One, the models themselves are based on
           equilibrium models that stem from work in the '60s and
           early '70s.
                       They assumed that both the vapor and the
           liquid were at the same temperature.  Boiling does not
           begin until you brought everything up to the
           saturation temperature.  Subcooled boiling, however,
           is well-recognized to begin while you still have some
           subcooling remaining in your bulk fluid.
                       So we know it will begin earlier.  This is
           also complicated by the simplified nodalization that's
           used in many of these Appendix K evaluation models. 
           They lump everything in the downcomer together, as
           opposed to allowing a thermal stratification to occur,
           which is put in most of the realistic codes like RELAP
           or TRAC or COBRA.
                       Now, the most vulnerable plants are ones
           that have relatively high power, low containment
           pressure.  The large break transient extends for a
           fairly long period of time.  So you're depending on
           your downcomer driving head during -- after your
           accumulator period, okay, when boiling may occur to
           start to recover your core.
                       So the longer this transient proceeds, the
           larger this defect is going to be.  The other one --
                       CHAIRMAN SHACK:  Would this be a problem
           even with the current best estimate models?  Would
           they account for this?
                       MR. BAJOREK:  They account for it.  Most
           of the realistic codes have what they will call
           mechanistic models for subcooled boiling.  And what
           this allows you to do is to boil in the downcomer well
           in advance of the time when everything is at
                       In fact, this is how this issue started to
           arise, because in the realistic calculations people
           were noticing, hey, there's not as much margin here as
           everyone had hoped, and in looking at those
           calculations the cause was this downcomer voiding that
           was going on in the calculations.
                       Let me show you an example of what goes
           on.  This figure is from the calculation using
           COBRA/TRAC for a combustion engineering system 80
           plant.  The plant in this case is at 3800 megawatts,
           sort of a standard 3800 system 80 design.
                       What's shown in the figure is the upper
           curve, the saturation temperature, and the lower,
           which is the liquid temperature in the downcomer. 
           Now, early in time at 50 seconds or so, the
           accumulators come on.
                       In this plant the accumulators are
           enormous with respect to other types of designs.  So
           you get a very high amount of subcooling early in the
           transient.  Well, eventually enough heat comes out of
           the vessel wall and core barrel, so at roughly 180,
           about 180 seconds or so into the transient the
           downcomer is effectively saturated.
                       This figure shows the collapsed level in
           the downcomer.  Now, early on at 50 seconds or so,
           that's when the accumulators are active.  They just
           fill the downcomers all the way up to the spray
           nozzles and up into the cold legs.
                       At by about 100 seconds, the level in that
           downcomer is about to the bottom of the cold light. 
           So they're effectively filled.  Liquid is still
           subcooled at that time.  If you recall from the last
           figure, saturation occurs at about 180 seconds.
                       And what you notice in the collapsed
           liquid level is now a fairly significant decrease,
           dropping from cold level to two or three meters lower
           in this calculation.  Eventually, your pressure
           decreases, the pump's safety ejection comes on and you
           recover your downcomer level and subsequently the
                       Now, on the system 80 3800 megawatt plant,
           which this calculation is for, there's not a real big
           concern.  This shows the peak cladding temperature in
           the core.  The reflood peak is reached shortly after
           the accumulators inject.
                       Turned around, the core quenches by 140,
           150 seconds.  So with regards to downcomer boiling
           it's basically no harm, no foul.  Downcomer boiling
           doesn't take place until after you've gotten the
           energy out of the core, not much of a concern.
                       Well, now let's try to uprate the unit. 
           Now, to do this I took calculations that had been
           performed for a system 80+, effectively the same
           geometry.  There is a difference in downcomer
           injection location, but if I compare the transients,
           I basically see that same accumulator effect.
                       We fill the downcomer, okay, and the
           downcomer again boils around, oh, around 150 seconds,
           a little bit earlier, because now we're looking at a
           plant 3800 to 3914 megawatt thermal.  Now, the energy
           has not been removed from the core by the time
           downcomer boiling begins.
                       And you see that rather than the peak
           cladding temperature decreasing, as it would have at
           150, 160, it starts off and reaches a second peak, in
           this case at about 400 seconds.  Quench of the core
           because of the reduced reflood rate does not occur out
           until roughly 900 seconds or so.
                       The transient is significantly prolonged
           because of the downcomer boiling process.  We'll get
           back to the net PCT effect in a second, but let me
           mention the other non-conservatism that has been
           talked about for several years, and this one's
           referred to as fuel relocation.
                       During the transient the clad will swell
           at several locations, usually just below your peak
           temperature location.  Experiments that have been run
           in this country, in France, in Germany, have found
           that upon ballooning, the pellet fragments above the
           ballooned location relocate and move into this balloon
                       Now, if you're doing a calculation and you
           don't account for fuel relocation, you have a
           situation where you have a stack of pellets with the
           balloon clad.  The clad effectively behaves like a
           fin.  Ballooning in some ways is good for the clad
           because you remove it from the heat source, push it
           off into the fluid where it gets effectively good
                       That's why you really shouldn't see your
           PCT location at the burst or the balloon location. 
           However, the concern from these experiments is that
           upon ballooning you don't maintain a concentric stack
           of pellets.
                       The pellets are fragmented due to prior
           operation.  They come down, increase the local power
           and increase the pellet to clad gap conductance, which
           would significantly increase your PCT.  Now, one of
           the things that we've been working on has been
           attempting to get estimates of what does all this
                       If we change the decay heat from '71 to
           '79 or '94, how does that impact the analysis and how
           does these non-conservatisms stack up?  Decay heat,
           we've gotten estimates from two different sources. 
           Westinghouse had a meeting with the staff about a year
           ago and they were asked their estimate of what would
           happen if they took their Appendix K model and reduced
           the decay heat to the '79 standard.
                       Their estimates were 250 to 340 degrees,
           and there had been some calculations done to
           substantiate those numbers.  We also had one of our
           contractors modify a RELAP to do a similar
           calculation.  They looked at an older vintage
           combustion engineering unit.
                       I think it was Millstone or Calvert
                       MR. LAUBEN:  Millstone.
                       MR. BAJOREK:  And they estimated that it
           was 372, so more or less consistent with the
           Westinghouse estimate, 3- to 400 degrees due to the
           decay heat relaxation.  Both also estimated what would
           be the benefit of going from Baker-Just to Cathcart-
           Powell for the metal heat reaction.
                       Smaller in effect, less than 100 degrees,
           and you can see the estimates of 50 and 75 degrees. 
           Now, for downcomer boiling and relocation we've gone
           to information that the vendors have provided us,
           information that has been obtained publicly.
                       We have three estimates for the downcomer
           boiling.  Westinghouse took a look at their
           calculations for a four-LOOP ice condenser unit and
           they estimated that the penalty by accounting for
           downcomer boiling in your calculation relative to
           ignoring it was roughly 400 degrees.
                       ISL did some RELAP calculations for us,
           again taking a look at a system 80+ unit.  This is
           similar to what I just showed you, but their interest
           there is looking at the Korean next generation, which
           is even at a higher power than the Palo Verde and the
           powers that we're looking at for a system 80+ in this
                       Now, their estimate was 700 degrees, or I
           should say that's our estimate in taking a look at the
           first reflood peak and the second reflood peak.  What
           I think you should gather from that is a few hundred
                       I don't think it's 700 degrees.  I think
           that's a RELAP problem.  The interfacial drag is too
           high.  We've seen that consistently in other RELAP
           calculations.  Once you get some bubbles it pushes up
           far too much liquid into the downcomer.
                       Okay.  So I think that number's too large. 
           The calculation that I showed you there in the last
           four figures, if I subtract away a power effect and
           look at the difference in PCTS and attribute that to
           the downcomer boiling, my estimate was slightly over
           300 degrees on that one.
                       So for at least for the downcomer boiling
           we're seeing three separate organizations using
           different relisting codes, all basically agreeing that
           downcomer, it's not a 10 or a 20-degree effect.  It's
           something larger.
                       And those values, three, four -- three or
           400 degrees are basically on the same order of the
           decay heat change that would be envisioned for
           Appendix K models that do not account for this process
                       Fuel relocation.  A technical paper was
           written by the French and they took a look at the
           experiments.  They estimated some filling fractions of
           the balloon region, did some CATHARE, which is
           considered a realistic code for relocation versus not
           accounting for relocation.
                       Their estimate -- or I should say our
           estimate comparing their numbers translates to 313
           degrees by accounting for this fuel relocation.  Those
           are the two that we see public information, we've
           heard talked about at technical meetings and the
           vendors have made us aware of.
                       They know that some of these are going on. 
           It's a question on how you should really deal with
           those.  We don't want to say that we're clairvoyant
           and we k now everything with respect to the non-
                       So I made a couple of phone calls to a
           couple of university professors; what would you
           consider a non-conservatism.  We got a few things. 
           Some fit into Appendix K.  Some really don't.  They're
           more plant condition issues.
                       An example may be, do you account for
           secondary to primary leakage during a LOCA.  We know
           that during steady-state operation there is a amount
           of leakage allowed from the primary to the secondary
                       Well, if you account for that during an
           analysis you would be increasing the amount of steam
           binding, okay, and potentially having a penalty.  I
           guess my point on the final one there is even though
           we have a list of several things that we would account
           for, we would consider non-conservatisms, we still
           feel we want to do a little bit more work, not going
           on a witch hunt, but trying to make sure that we are
           at least informed on things that are recognized as
           these major non-conservatisms.
                       DR. POWERS:  You have looked or reported
           some examinations of a comparison between Cathcart-
           Powel and Baker-Just for the parabolic reconstants. 
           Has anybody looked at what effect would happen if we
           had deviations from parabolic?
                       MR. BAJOREK:  I'm not aware of it, but
           Ralph is best to answer that one.
                       MR. MEYER:  No, I don't have that.
                       DR. POWERS:  It has always struck me that
           one of the best justifications for using Baker-Just in
           the face of several examinations that took place later
           that suggested it was quite conservative was the fact
           -- a couple of things.
                       One, you really don't know the surface
           area that you're oxidizing, and the second loophole is
           that we usually calculate these things in a fairly
           stylized fashion and don't calculate the epitaxial
           stresses that arise in cylindrical coordinates that
           might cause delamination of the oxide, locally if not
           globally, especially around things which cause
           deformations of the ballooned region around grid
           spacers and the like that would cause a deviation from
           strictly parabolic kinetics, and that because those
           things were challenging to do you just used Baker-Just
           to cover your ignorance there.
                       But I don't know that anybody has ever
           gone through and looked and said, how much ignorance
           are we covering.
                       MR. BAJOREK:  Right.  Ralph.
                       MR. MEYER:  Well, we are going to look at
           that in the work that we're doing at Argonne right
           now.  I would say that based on the early results that
           are now coming out of the program, I don't expect to
           find much here because what we have found in the last
           couple of months for the BWR high burnup rods that
           have undergone oxidation kinetics measurements, the
           oxide layer doesn't seem to have any protective effect
           in altering the rate of oxidation.
                       And our results for the high burnup
           cladding appear to be virtually identical to results
           for fresh tubing.  Now --
                       DR. POWERS:  Well, I guess the question I
           would ask is, have you ballooned that cladding around
           a grid spacer and can you come to that conclusion?
                       MR. MEYER:  Have we -- well, so far we
           haven't made measurements with balloon cladding, but
           we are going to make measurements with balloon
           cladding.  Now, you're asking about, is the location
           of a balloon close to a grid spacer and I can't tell
           you the answer.
                       What I can tell you is that we are
           discussing right now whether the upper fasting point
           for the fuel rods should be shaped like a grid so that
           we would get any grid effects on this.
                       But I think the best answer we can give,
           and I think it's an adequate answer, is that we are in
           the process of testing under conditions that are just
           as prototypical as you can imagine, and we would be
           able to detect any deviation in the oxidation kinetics
           that results from the deformation and related
           processes, like flaking off of the oxide, because we
           will have at the outset very careful measurements of
           oxidation kinetics on undeformed irradiated tubing in
           order to compare with the more integral tests that
           we're going to do.
                       DR. POWERS:  Have you tried to determine
           the conditions by say modeling or some sort that would
           optimize the conditions for delamination of the oxide? 
           I know that the French have set up what looks to me to
           be a relatively impressive model of those epitaxial
                       I have never taken their model and tried
           to say, okay, now, what kinds of things lead to high
           strains and stresses at the interface that would cause
           delamination?  But it looks like they have one that's
           sophisticated enough so that you could do that sort of
                       MR. MEYER:  Well, we don't have a model
           with that level of sophistication, but I don't see why
           you couldn't get that information more reliably from
           a test rather than a model.
                       DR. POWERS:  Well, I mean, the problem is
           -- I mean, maybe you could if you're fairly
           imaginative in the testing capabilities.  It's just
           that I worry that you can't test all -- I mean, I'm
           just not smart enough to participate.
                       MR. MEYER:  No, that's true, but the
           indications right now are that the oxide isn't going
           to affect the oxidation rate, that large amount of
           oxide that has accumulated from corrosion and is
           present at the time of this ballooning deformation.
                       Now, remember, the ballooning deformation
           occurs at a relatively low temperature.  So you
           haven't gotten into the high temperature oxidation
           region where you're going to build up 17 percent.
                       The ballooning deformation is over with
           before you ever start accumulating the large amounts
           during the high temperature portion of this transient. 
           So you're really only talking about the spallation of
           oxide that's on there from the corrosion process
           during burnup operation.
                       In that part of it there's already a
           preliminary indication it doesn't make any difference.
                       CHAIRMAN SHACK:  Well, of course, that BWR
           cladding has a relatively thin oxide --
                       MR. MEYER:  It has a relatively small
           amount of oxidation, that's absolutely true.  It has
           only seven to ten microns of oxide on it, and we have
           PWR cladding that we're going to test soon that has
           100 microns and even more than that in some locations.
                       So you know, I can't say that this is a
           general observation, but there is an expectation that
           even the heavier corrosion layer thicknesses, that
           it's cracked and it's pervious.  Is that the right
           word?  The opposite of impervious.
                       DR. POWERS:  I mean, the challenge one
           faces in this is that when we look at analog systems
           with fluoride structure oxides on metal surfaces, the
           analog systems that come immediately to mind are
           things like cerium metal, uranium metal and plutonium
                       In every one of those cases they suffer
           catastrophic delamination of the oxide at very thin
           levels, and zirconium just doesn't do that.
                       MR. MEYER:  Yes.
                       DR. POWERS:  And hafnium even more doesn't
           do that.  And you keep saying why, and what is it that
           will cause delamination of this oxide?  Is it so
           extreme that it's outside the range of things that you
           can have during a reactor upset condition?
                       And I don't know the answer to these
           things but I keep struggling with it, because I can't
           keep my oxides on plutonium, so why are you guys with
           zirconium so successful at keeping your oxides intact?
                       MR. MEYER:  Well, I haven't suggested that
           it won't spall.  What I have suggested, that it won't
           make any difference if it does spall.  And I think we
           will be able to see both, whether it flakes off during
           the deformation process and if it makes any
                       CHAIRMAN SHACK:  Steve, just --
                       MR. BAJOREK:  Sure.
                       CHAIRMAN SHACK:  -- when I look at this
           kind of one at a time thing it sort of suggests to me
           that I'm not going to get anything from a best
           estimate calculation, that everything's going to wash
           out.  That doesn't seem to jibe with experience.
                       MR. BAJOREK:  The penalties that you see
           for the realistic calculations are relative to what
           you would have gotten from that calculation without
           conservatism boiling.  For this one, the peak cladding
           temperature was probably around 1900 degrees.
                       So there was a benefit in there.  I mean,
           it came due to relaxing the decay heat, okay, but if
           you had ignored the boiling processes in the downcomer
           you would have been dealing with a peak cladding
           temperature 15 -- you know -- 1500 degrees or so.
                       So yes, there is a reduction, but the net
           reduction isn't as large as what had been anticipated. 
           These numbers, by the way, are for large break.  Now,
           I've got some numbers, some estimates here for small
           break, but the situation there is a lot more nebulous,
           quite likely because most plants are large break
           limited, or I should say, the vast majority are vast
           break limited.
                       There hasn't been a tremendous amount of
           work looking at the sensitivities with regards to
           small break.  Estimates that we have gotten from --
           basically one of our contractors looked at the issue
           and did some of their calculations, found some
           information from Combustion Engineering and
           Westinghouse that basically estimated close to 1,000
           degrees, 800 to 1,000.
                       Their calculations, based on RELAP, were
           showing another range, five to 1,000 degrees by going
           from '71 to the '79 standard.  I don't have an
           estimate for the metal water reaction.
                       If you were to do that separately, my
           guess it would be larger than what you would see for
           a large break, because it occurs over a much longer
           period of time, but we're not aware of any unique
           sensitivity studies at a high enough temperature
           whether it would an effect.
                       MR. LAUBEN:  It is about the same.  I did
           some with -- for the 2700 megawatt CE plant and it was
           about the same.
                       MR. BAJOREK:  Okay.
                       MR. LAUBEN:  The same 50 to 75 degrees.
                       MR. BAJOREK:  Okay.
                       MR. LAUBEN:  Because intransient's usually
           a little bit slower.
                       MR. BAJOREK:  Well, you have lower decay
           heat at the time.
                       MR. LAUBEN:  Right.
                       MR. BAJOREK:  So it's --
                       MR. LAUBEN:  Right.
                       MR. BAJOREK:  Okay.  Let's go.  Now, some
           of the things that we might want to consider as non-
           conservative issues, we've seen some cases with
           nodalization, where whether you uniquely look at
           cross-flow into the hot assembly.
                       I think, Norm, you have these RELAP
           calculations that show you get a 600-degree effect. 
           And this kind of goes back to the idea that these
           codes were written '60s, '70s.  You were -- had them
           on CRAYS, 7600s, and you tended to want to simplify
           your nodalization compared to what you could do so.
                       So by incorporating more complexity into
           your model you start to see more variations, simply
           because of the number of processes that lie cross-flow
           that you would take into account.
                       Now, one that has been recognized in the
           past has been the consequences of operator action
           during a small break.  Right now, you don't have to
           worry about it as much in small break if you have the
           loss of off-site power, the pumps trip on reactor
                       If you have off-site power available,
           which is another one of the avenues that is being
           pursued under risk-informed regulation, now you have
           to depend on the operators to trip the pumps according
           to their EOPs.
                       This usually calls for them to recognize
           that the rods are on the bottom, you've got a safety
           injection pump and that you've lost, by looking at
           your monitors, lost some cooling into your hot leg. 
           Once you recognize that the reactor pumps are tripped.
                       Now, this is going to depend on how
           quickly they go through the EOPs, their recognition of
           these various signals while there's a lot of confusion
           going on.  Calculations that had been performed in the
           mid-80s looking at this, found that there were periods
           of time where the operator could trip them while you
           had a plant at an elevated pressure and lost
                       Then if you tripped the pumps you
           collapsed the froth over core -- over the core, you're
           still at high pressure, meaning you weren't getting as
           much safety injection into the system, and could get
           a very high peak cladding temperature.
                       So it's one of the things that may need to
           be considered.  The other two have more to do with
           model and correlation uncertainty.  In taking a look
           at the decay heat sensitivity, the contractor noted
           that, hey, being off just a couple of inches in your
           level swell, where your froth level is in the small
           break, can result in several hundred degree increase
           or decrease in what your peak cladding temperature is.
                       LOOP seal clearance refers to the effect
           out in a small break when steam starts to slip through
           one or more of the LOOP seals of a plant.  This
           redistributes the fluid.  Some goes out the break.
                       Some goes to the vessel; some stays in the
           LOOP seal.  And what happens then is you get a
           different two-phase hydraulic loss through the LOOPs. 
           If that loss is high you tend to suppress the core
           level much more than if you had a nice, clean blow in
           that LOOP.
                       People who have tried to model this in
           codes have had a fairly difficult time doing this.  I
           don't put a basis down on this because I'm talking a
           little bit more from personal experience in developing
           a small break evaluation model.
                       This was a very complex issue when we saw
           hundreds of degrees of variation.  We have also seen
           some experimental tests that have raised it as a
           concern, mainly due to LOOP seal replug.  Some of the
           ROSA tests said that you've got very good heat
           transfer in your steam generator.
                       What that means is later in the transient
           you can put enough condensate into the LOOP seal to
           replug it, force it to blow again.  So in terms of the
           non-conservatism, it's something that we feel would at
           least have to be looked at in terms of the consequence
           of reducing decay heat if we're going to be relaxing
           the amount of conservatism that we see now.
                       The next thing that I want to move into
           are options that we're currently looking at.  And I
           want to emphasize that we have not reached a staff
           consensus on which option should be pursued.
                       MR. BONACA:  I have a question on one of
           the thoughts just --
                       MR. BAJOREK:  Sure.
                       MR. BONACA:  You just made a pretty strong
           case for some of the conservatisms that you have in
           Appendix K, I mean, in the tradeoffs.  And in the best
           estimate, when you do best estimate calculations, do
           you have -- there is no modeling of downcomer boiling
           in best estimate testing.
                       MR. BAJOREK:  In best estimate you do.
                       MR. BONACA:  You do?
                       MR. BAJOREK:  Yes.
                       MR. BONACA:  Okay.  That's one of the --
           what I --
                       MR. BAJOREK:  The two fluid codes would
           take a look at non-equilibrium.
                       MR. BONACA:  Okay.  So yes, all right.
                       MR. BAJOREK:  Phases that allow voids to
           develop.  The RELAP, as we noted --
                       MR. BONACA:  Yes, that's right.
                       MR. BAJOREK:  -- in the calculations we
           think isn't doing it very well, but it's doing it very
           conservatively, which gave that 700 number.  We think
           that the COBRA formation is maybe doing that in a more
           kinder, gentler fashion, but it's still significant,
           three to 400 degrees.
                       MR. BONACA:  I guess the point I'm making,
           it would be interesting to have a comparison of these
           effects also for the best estimate so we could have an
           understanding of what tradeoffs have already occurred.
                       And now in the best estimate modeling do
           you still -- are most -- what's happening to the decay
           heat curve?  Which one is being used?
                       MR. BAJOREK:  Usually, the '79.
                       MR. BONACA:  Seventy-nine.
                       MR. BAJOREK:  Yes.
                       MR. BONACA:  Not '94 effect.
                       MR. BAJOREK:  No.  In fact, what I wanted
           to point out with this overhead -- this is not in your
           package -- but to point out the work that we need to
           do in coming up with an option for Appendix K and a
           revision to the decay heat, just to make sure that
           that revision satisfies a new option for the Appendix
           K, but also addresses some of the issues in a best
           estimate model.
                       And I think as you noted and as Norm
           noted, for a best estimate evaluation model, Reg.
           Guide 1.157 simply says for decay heat, calculate in
           a best estimate manner.  It considers by way of a
           reference that the '79 decay heat is acceptable.
                       Now, you could take that Reg. Guide at
           this time and use the '94, but it's certainly not
           clear to anyone that goes through when we're
           developing a model.  Perhaps even a little bit more
           cloudy is the metal water reaction.
                       Again, the Reg. Guide says to calculate it
           in a best estimate manner and it cites Cathcart, et
           al., Cathcart, Powel and who else may have been on
           that, their data is acceptable and doesn't even cite
           the correlation.
                       It just says "that data is acceptable,"
           and leaves it go at that point for the licensee and
           the review process to sort out what is truly a best
           estimate model.
                       CHAIRMAN SHACK:  What have people actually
           done in the best estimate models today for the metal
           water action?  Do they use Cathcart-Powel?
                       MR. BAJOREK:  Yes.  Yes.  They've been
           using Cathcart-Powel.  There is an uncertainty in the
           application that I'm aware of in how it's applied.  So
           they're -- Westinghouse is using Cathcart-Powel. 
           There is an uncertainty about that calculation.
                       CHAIRMAN SHACK:  In my simple-minded view
           of this thing, you know, the thing I'm normally
           looking at when I have a conservative calculation, you
           know, when I decide how conservative it is I go out
           and I get a better calculation and I compare the two.
                       Well, you know, now I've got a better
           calculation.  It would seem to me that, you know, I
           look at all my best estimate calculations and I go off
           and I do my simple Appendix K calculation, it would
           seem to be relatively straightforward to do.
                       You know, suppose I change my Appendix K
           calculation with the decay heat and I look at my best
           estimate calculations, you know, and --
                       MR. BAJOREK:  We have that.  That was
           discussed in the meeting last year.  There's a figure. 
           I'm not sure if it's proprietary or not.  That's why
           I didn't -- that's why I wanted to stay with stuff
           that I knew was public.
                       Those calculations showed that the
           Appendix K evaluation model, okay, with '71 decay
           heat, gave a peak cladding temperature that was just
           larger than best estimate plus uncertainties.  Okay.
                       When they reduced the decay heat, the
           Appendix K calculation gave values that were closer to
           the best estimate, but without the uncertainties. 
           It's somewhere in the middle.  Now, you have to take
           it a bit with a grain of salt, because I think the
           plant types were slightly different and there were --
           it was more of a apple versus a different type of
                       CHAIRMAN SHACK:  Pear.
                       MR. BAJOREK:  Yes.  So it wasn't
           straightforward, but the calculations suggested that
           if you reduced the decay heat in that -- for that
           plant in that Appendix K evaluation model, the PCT
           would not -- would be more favorable than what you
           would be getting out of a best estimate methodology.
                       And that raises some concerns going back
           to the SECY paper 86-318, which says, hey, there are
           models which can result in a fairly large uncertainty
           and you should account for those in your overall peak
           cladding temperature and your analysis methodology.
                       MR. LAUBEN:  But you're right about -- as
           long as you have the standard of a best estimate
           calculation to compare with the Appendix K
           calculation, you can do it.  But if you don't have
           that standard, what do you do?
                       And for some plants, some vendors, some
           plants, you have the standard with which you can
           compare, and the calculation Steve has was actually
           done by the same vendor, that he was able to compare
           one to the other.
                       So that was an apple -- as close as you
           can get to an apple and an apple.  But it's not as
           easy to do if you don't have a best estimate standard
           by which you can compare to the existing Appendix K
           calculation.  That's --
                       CHAIRMAN SHACK:  Well, I guess I just
           don't have a feel whether we have enough best estimate
           results --
                       MR. LAUBEN:  Yes.
                       CHAIRMAN SHACK:  -- available now to be
           able --
                       MR. LAUBEN:  Good.
                       CHAIRMAN SHACK:  -- to make the benchmark.
                       MR. LAUBEN:  Yes.
                       MR. BAJOREK:  One of the problems that
           occurs --
                       MR. LAUBEN:  Good question.
                       MR. BAJOREK:  -- is because they are
           complex analyses to perform, you know you're getting
           margin.  So immediately what you want to do is to use

           that margin, okay, for an operating enhancing the core
           peaking factors.
                       So if you do the work you don't want to do
           it at the levels that you already have the Appendix K
           calculation.  And because of that you always wind up
           in this apples versus oranges type of comparison.
                       Three options that we are looking at right
           now, and as I mentioned in this previous figure, we
           feel that in coming up with an alternative option to
           Appendix K we have work that needs to be done.
                       We also need to do work on what I'll call
           the realistic option, to clarify the use of the '94
           standard for decay heat.  How you would use Cathcart-
           Powel, if that's to be recommended for metal water
                       What is the difference and how should we
           deal with uncertainties and conservatism in either of
           these analyses?  Option A, as I'll refer to it.  In
           the realistic option -- and this is going to be true
           in the two or three options that we'll discuss -- we
           would revise Reg. Guide 1.157, clarify that you can,
           perhaps should use the '94 decay heat standard, take
           the work that Norm is doing to recommend how it should
           be implemented into those decay heat questions, which
           we have work ongoing.
                       Recommend a specific metal water reaction
           that should be used, and clean up.  Perhaps, the more
           nebulous part of that Reg. Guide is how you deal with
           these uncertainties.  This is why you need to quantify
           the accuracy.
                       You need to deal with the uncertainties,
           and then you were sort of left to the winds on how to
           do that.  And part of the difficulty in the
           application is coming up with an appropriate
           statistical method to account for those uncertainties.
                       And it's been one of the things that has
           driven up the difficulty in that analysis.  Now, in
           this particular option the Appendix K revision would
           involve replacing the ANS '71 standard with '94, plus
           some uncertainty, okay, that would account for the
           experimental uncertainty in the decay heat.
                       Okay.  One, two, three sigma, something
           along those order.  It would address solely the decay
           heat model uncertainty.  We would ask licensees to
           take a list that we would propose and they could
           augment to address recognized non-conservatisms,
           things like the downcomer boiling, fuel relocation,
           other things that we may identify.
                       We think that the approach is consistent
           with what was requested in the 0-133.  That relax
           where it is clearly non-conservatism -- overly
           conservative decay heat would account for
                       DR. KRESS:  When you say "consider non-
           conservatisms" what does that actually mean?
                       MR. BAJOREK:  They would be required to
           account for those in their Appendix K evaluation
                       DR. KRESS:  Okay.
                       MR. BAJOREK:  Okay.  We would envision
           -- and this would depend on NRR, on how they wanted to
           deal with this -- the licensee coming in with
           basically an alternative approach to Appendix K, a new
           evaluation model, which would have reduced decay heat,
           but those Appendix K evaluation models would have to
           have features to account for downcomer boiling, fuel
           relocation and in the case of small break, the issues
           that we would have to identify for that.
                       MR. BONACA:  More and more that would look
           like the best estimate.
                       MR. BAJOREK:  Well, we're -- you're
           jumping ahead just a little bit, but I want to let
           -- what I want to say.  I want to lay this out because
           as a staff we have not reached a consensus on this. 
           I want to summarize what we're looking at and lay out
           the pros and cons of each one.
                       And you raise a good point and we're going
           to point that out.  Now, one of the obstacles we see,
           that this approach would result in a new methodology
           and we think that it would be very likely that it
           would require a review.
                       NRR would have to expend resources for
           vendors.  The licensees would have to deal with these
           issues.  They aren't straightforward and simple to
           deal with.  They would have to come up with new models
           for those.
                       In some cases, experimental information to
           address those may not be entirely satisfactory right
           now.  There's some 2D/3D data, UPTF, CCTF, that points
           out the effect.  I think it's questionable right now
           whether it has the right range of conditions by which
           you might want to develop a new model for.
                       So I think there are some questions there
           that need to be answered and we are going to take a
           look at that.  We have to come up with a list of all
           recognized non-conservatisms.  We have a few.
                       I guess our fear is once we get this list,
           if something else crops up or is recognized, there's
           a difficulty in getting it in, okay, without violating
           some type of a back-fit rule that we might want to
           keep on ourself.
                       Because of the difficulty in coming up
           with new models, licensing those and dealing with the
           potential uncertainties in the remaining models, we
           start to think that this may not be that attractive to
           vendors and licensees.
                       Our fear is that when you start to look at
           expenses to come up with this, make Appendix K look
           more realistic, but still be conservative, deal with
           modeling uncertainties, you start to tip the balance
           close enough to best estimate, there may not be an
           advantage to going this way right now.
                       On a philosophical point, one of the
           stones that we would throw at this option is that this
           would effectively delay the transition from codes that
           were developed in the '60s and early '70s to more
           modern thermal-hydraulics codes.
                       Okay.  We would be instituting codes that
           people have objected to because of their ad hoc models
           and implications in the past.  The second option is
           one that has been suggested by NRR.
                       It retains many of the features of
           Appendix K -- excuse me -- of Option A that we talked
           about.  We would still deal with Reg. Guide 1.157 as
           we had in the previous overhead.
                       The idea here is to replace Appendix K,
           take out the '71 model, replace it with '94, and apply
           a conservative multiplier, not one that just accounts
           for uncertainties in decay heat, but now has
           additional conservatism built in, but sufficient to
           cover the uncertainties that are observed in the
           realistic calculations.
                       DR. KRESS:  That sounds just like the
           current Appendix K, only with a little better
                       MR. LAUBEN:  Right.
                       MR. BAJOREK:  That's pretty much it.
                       CHAIRMAN SHACK:  Well, and to come up with
           the right multiplier you still have --
                       DR. KRESS:  Yes.
                       CHAIRMAN SHACK:  -- to do everything they
                       DR. KRESS:  You really have to do the --
                       CHAIRMAN SHACK:  I mean, it's magic when
           you're done, but --
                       MR. BONACA:  It's one added superficiality
                 (All talking at once)
                       MR. LAUBEN:  A lot of print.
                       MR. BAJOREK:  It's a tough row to hoe.
                       CHAIRMAN SHACK:  Yes.
                       MR. BAJOREK:  Jump ahead on here.  If we
           were to do this, our estimate is that this would take
           the staff something on the order of ten man years,
           because we would need to, one, make sure that we get
           realistic codes behaving the way we want to.
                       We're fairly close on that.  We still have
           work to do.  But we need to satisfy ourselves that
           they're handling fuel relocation, downcomer boiling
           appropriately.  Okay.  That's an issue in itself.
                       In the past, we haven't developed
           evaluation models here at the staff.  So we would have
           to take our realistic code, revise it, change the
           decay heat, put Baker-Just back in, prevent rewet
           during blowdown, change the steam cooling models,
           change this and the other thing to make it mimic an
           evaluation model.
                       DR. KRESS:  Let me ask you another
           question about that.  If you did that, including the
           uncertainties, and then you ended up with your answer
           at the end, and you took the 95 percentile and used
           that to get your multiplier on your decay heat curve,
           how is that any different at all than just the best
           estimate approach?
                       MR. BAJOREK:  You would not know what the
           uncertainties are here.  You would be basing your
           conclusions based on another set of calculations and
           hoping those are mimicked by the Appendix K evaluation
           model.  Where things --
                       DR. KRESS:  But you would have to make
           Appendix K conservatism enough to cover all plants is
           what --
                       MR. BAJOREK:  That's right.
                       DR. KRESS:   -- I think you're saying.
                       MR. BAJOREK:  We jumped ahead.
                       DR. KRESS:  Yes.
                       MR. BAJOREK:  Where we say it may not be
           technically achievable is that if we do this strictly
           as it was proposed, come up with a multiplier.  Well,
           we could look at the worst plant.
                       DR. KRESS:  Yes.
                       MR. BAJOREK:  Like that one I showed you
           earlier that has a very long transient.
                       DR. KRESS:  Yes.
                       MR. BAJOREK:  Treat it as an evaluation
           model, put a multiplier on it; look at some other
           issues, things that we might want.  Well, I don't
           think it takes a big stretch of the imagination to see
           that you can wind up with a multiplier based on that
           plant that when you apply it to lower power units
           you're going to have something that's even more
           restrictive than the Appendix K as it is today.
                       DR. KRESS:  Yes.  I am --
                       MR. BAJOREK:  I'm aware of one attempt,
           not in this country, to do something like that.  Their
           approach was to take a realistic code, say we want to
           stay away from all this uncertainty calculation, but
           let's make our heat transfer conservative.
                       Let's make our plant initially
           conservative and do it for a range of plants.  Well,
           they want through the exercise and they eventually
           went back to a realistic methodology, because the
           answers they were getting when they applied them for
           all of the units were now even worse than what they
           had been getting in Appendix K.
                       That's where the work comes in, because to
           make this any benefit, we think, to industry we would
           have to break this down into a plant-specific type of
                       And when you start looking at the
           different types of BWRs, PWRs, BNWs, CE units, large
           break and small break, the magnitude of number of
           calculations that you have to do and get right becomes
           very large, and that's what propagates into this.
                       I estimated a ten-year effort.  I've been
           told that I was too low.  It's substantial.  Go to the
           last bullet.  One of the reasons we've noticed
           downcomer boiling as a potential issue has been due to
           plants being uprated.
                       In that first figure I showed you, the no
           harm, no foul, that was primarily due to the
           relatively low power of that unit.  It quenched before
           the downcomer boiled.  As we start to uprate the
           units, the transient link must get larger because you
           have more decay heat, okay, to remain.
                       So as we start to uprate units beyond what
           they are now, the multiplier, even if it captured the
           downcomer boiling in today's power levels, may not
           necessarily capture that effect if that plant is
           uprated by another five or ten percent.
                       The margin is not going to go unused.  It
           will likely be absorbed in another power uprating.  So
           our fear is that even if we came up with multipliers,
           they would be invalidated once the plants start to
           deviate from the present-day operation.
                       Also been notified by some of the staff at
           NRR, they said, well, even if you come up with
           multipliers using TRAC or RELAP in our versions of
           evaluation models, we've recognized over the years
           that the sensitivity of evaluation models that we see
           from Combustion, from Westinghouse, from GE and BNW
           aren't necessarily the same from one to the other,
           much less how the staff's models would behalf.
                       They approximate things, but the power
           sensitivity could be different.  Nodalization can have
           effect, as well.  So as a result they said, well, even
           if you spend your ten staff years coming up with a set
           of multipliers, we're still going to have to go back
           to the vendors to either verify or come up with
           equivalent multipliers for their codes, because they
           may behave significantly different.
                       Okay.  Third option, and this is one where
           we see it as perhaps an opportunity to move ahead
           technically.  And we see this as an option that says,
           rather than continue to sink more resources into
           Appendix K, maybe this is a point to say, let's put
           the best technology into the best estimate rule.
                       Let's put those resources into revising
           1.157, clarify how we would use the decay heat; what's
           an appropriate way to apply it; what's an appropriate
           model for the metal water reaction?
                       Pursue the other 50.46 risk informed
           criteria, because there's a tremendous amount of true
           margin that can be gained by relaxing plant boundary
           condition assumptions, break size, loss of off-site
                       But retain in the realistic option of a
           way of analyzing it to at least a conservative fashion
           or at least to a fashion by which we know what the
           true margin is.
                       So in Option C, by focusing our attention
           on the best estimate rule, making it easier to use,
           easier to apply, we feel that we'll at least maintain
           the present-day margin in Appendix K, okay, and if we
           go to a realistic type of calculation we'll know what
           that margin is.
                       I think it's been said in some of the ACRS
           meetings that safety is better served by having to
           quantify measure of the margin, rather than some
           nebulous amount of conservatism that we don't know the
           extent of.
                       We already have clear guidelines for the
           review.  We would have to clarify those further in the
           Reg. Guide 1.157.  NRR wouldn't be able to apply their
           reviews as they currently perform those.  In the long
           run, we feel that this would encourage vendors to
           continue to develop and use realistic models and more
           advanced thermal-hydraulic tools.
                       Westinghouse currently has an approval for
           best estimate.  Siemens-Framatome has submitted one
           several weeks ago.  NRR says that in about a year they
           think they can get approval for that.  We've been told
           that General Electric would be coming in, in a
           realistic local methodology early next year.
                       We're seeing most of the vendors already
           going down this path.
                       MR. BONACA:  They already had Safer-
           Gester, right, so.
                       MR. BAJOREK:  Safer-Gester, my
           understanding is that it's more consistent with an
           inter-methodology.  There are some -- it's not a true
           best estimate and now they're ready to go the rest of
           the way.
                       MR. LAUBEN:  It has a 600 degree penalty
           associated with its use, too.  So it's not truly best
           estimate.  So it's TRAC-G that they're coming in with
           to get approval.
                       MR. BAJOREK:  Now, the cons of doing this. 
           Reduction in regulatory burden is probably minimal. 
           There would be benefit in clarification of the best
           estimate rule and how you do this, but it's not a
           tremendous leap.  There's still a lot of work involved
                       The expectations of SECY-01-133 may not be
           met in going this approach.  I think you go through
           there, there was an expectation that we would make a
           definite revision to the Appendix K.  So that -- we
           would need to make I think a very strong argument on
           why we wouldn't think that the Appendix K revision is
           necessarily the right way to go as part of supporting
           this option.
                       Where we plan to go from here, we feel
           that we need to get a -- agree on a list of non-
           conservatisms, lay that out in a little bit better
           fashion.  We've talked about a few.  Let's try to make
           that list complete.
                       We want to go back and look at the
           experimental data, because if we have to start asking
           people to look at these non-conservatisms, we should
           be well aware of whether the current database supports
           development of those models.
                       The reason I suspected we may have a
           problem in doing that, I did a kind of a quick scaling
           evaluation CCTF.  In taking a look at a parameter that
           relates the energy that would be available in the
           downcomer and core barrel walls, versus the energy
           that would be required to raise the entire downcomer
           to saturation.
                       In kind of a very crude fashion, looking
           at energy available versus energy that would be
           necessary.  For the PWR, if you'll look at the energy
           that's available in the core barrel in the vessel
           wall, it's about seven and a half times the amount of
           energy that would be required to raise this bulk of
           fluid in the downcomer to saturation.
                       That's a lot of stored heat.  CCTF where
           we did see evidence of downcomer boiling -- you don't
           have to get the whole thing up to saturation, just
           part of it -- we're looking at something closer to
                       So this is why I said, well, when we look
           at the experimental data, we need to take a look at
           the tests versus what we were expecting in the PWR,
           because when we go down this path now of treating
           these non-conservatisms for Options A or B, the folks
           who want to go down that are going to have to
           demonstrate that the experimental data is adequate to
           come up with models for that.  That may require them
           to participate in new test programs.
                       Third, once we lay this out it's probably
           advisable for us to hold a public meeting to discuss
           what this alternative approach to Appendix K would
           look like, and I think as someone pointed out, well,
           are you getting so close to best estimate now that
           you're going to throw a party and no one's going to
           show up.
                       And if we get that word from the vendor
           then maybe what's recommended in 0133 should be
           revised somewhat.  That's all I have, but we're
           interested in your comments.
                       MR. BONACA:  You made a case again for the
           fact that in Appendix K you have tradeoffs that you
           car calling for.
                       MR. BAJOREK:  I couldn't hear you.  I'm
                       MR. BONACA:  Yes.  I'm saying that you
           made a case for the fact that there are tradeoffs in
           Appendix K right now that are an impediment to simply
           moving on to 1994 ANS standard.
                       MR. BAJOREK:  Right.
                       MR. BONACA:  But the industry has
           requested it and the way it came out was almost as if
           in fact those issues were not there.  Is there
           consensus on the part of the industry, the technical
           community, regarding these tradeoffs, these issues? 
           Or do you have to go to this public meeting before
           that will be surfacing?
                       MR. BAJOREK:  I think we have to go to the
           public meeting to really surface that.
                       Norm, it was the vendors that came to you
           last year and pointed some of this out.
                       MR. LAUBEN:  Well, we have -- let's see. 
           We have the questions that we've -- you know -- they
           came with the request for rulemaking.  We have
           proposed some questions to them about their proposal.
                       But as Steve said, it isn't clear what
           venue it's -- addressing those questions would take. 
           Would it be a public meeting?  Would it be publishing
           the questions and then having them respond to it, or
           what I think -- I think eventually it has to be some
           kind of a public meeting so that all interested
           parties get a chance to address their concerns about
                       So I don't know.  Last -- let's see.  A
           couple of years ago we did ask -- informally now. 
           This was not formally at all.  At some public meetings
           we asked questions about, you know, similar to the
           ones that I had on decay heat.
                       How would you -- you know -- this is not
           as simple as it was, but we -- at that time there was
           no apparent interest in the decay heat change.  And so
                       MR. KURITZKY:  Yes.  I think in all
           fairness to the industry and that --
                       MR. LAUBEN:  Yes.
                       MR. KURITZKY:  -- those public meetings
           were focused on --
                       MR. LAUBEN:  Right.
                       MR. KURITZKY:  -- on all the different
                       MR. LAUBEN:  Yes, right.  Right.  Right.
                       MR. KURITZKY:  And industry was really
           interested in the larger picture, local redefinitions
                       MR. LAUBEN:  Right.
                       MR. KURITZKY:  So they really didn't want
           to spend time looking at other types of changes.  So.
                       MR. LAUBEN:  Right.  So they're interest
           in decay heat is relatively -- is subsequent to those
           meetings.  And I think we have to somehow get, you
           know, stakeholder involvement in this, right.
                       MR. BONACA:  The other question I had was,
           you made a statement that typically, best estimate
           results plus uncertainty, comes quite close to the
           Appendix K, and that's the experience I've had, too,
           I mean, in looking at that.
                       And that's -- and of course, the point of
           comparison you used was PCT, peak core temperature,
           okay.  I'm trying to understand if there are other
           measures of merit that you're using in these
           comparisons to see what is appropriate to make
           reductions in what is not.
                       Or rather than appropriately, what is
           convenient or not convenient.  Is PCT the only
           criteria you use in there to compare the two
           approaches and --
                       MR. BAJOREK:  We should probably look at
           clad reaction.  I think in the shorter transients
           usually that the equivalent clad reaction is not as
           limiting as PCT.  That may not be the case as we get
           out to fairly long duration transients.  It probably
           should get looked at, because we haven't done that
                       MR. BONACA:  And one last question I have
           is, again, I mean, if I have the best estimate, which
           typically, I mean, it has certainly conservatism built
           in plus uncertainty, and I come up with the results
           very close to the Appendix K and typically pretty
           close to 2200 degrees fahrenheit, I mean, typically,
           these plants don't have a lot of margin there, really,
           what is the opportunity for margin reductions or for
           reducing regulatory burden?
                       MR. BAJOREK:  It would probably be in --
           I think reduction in break size would certainly amount
           to --
                       MR. BONACA:  Well, that -- yes, that was
           something we didn't want to -- I mean, that's a
           different issue, talking about purely that we walk
           down this path with the belief that there were
           opportunities purely in the artificiality of Appendix
           K, but then, you know, this comparison you're
           referring to, it's a solid one.
                       I mean, I've seen it many times for
           different plants and it's there.
                       MR. BAJOREK:  Well, I guess, you know,
           some of that -- they wouldn't necessarily wind up in
           the Reg. Guide -- well, they could wind up in the Reg.
           Guide.  And when we developed the best estimate for
           Westinghouse, in a number of cases the range over
           which you addressed the uncertainty bounded all of the
                       Appendix K doesn't have to do that.  You
           just have to be conservative relative to the mean.  So
           what happens when you go to best estimate under that
           type of a regulatory requirement, Appendix K really
           gets an advantage.
                       If the Reg. Guide were revised relative to
           treatment of the experimental data that you have to
           bound 95 percent or within two sigma, and made your
           uncertainties smaller, first, you would make it clear
           for people developing new pools what they had to come
           up with.
                       And secondly, I think there would be a
           fair amount of margin gained by, you know, getting
           away from the wings of some of this experimental data. 
           I can think of several models where you would get a
           lot of benefit in taking that approach, but that's
           something that would have to come from probably a Reg.
           Guide as opposed to a regulation.
                       That, again, goes back to -- as I
           mentioned on that one slide, the problem with 157 is
           the discussion and treatment of the uncertainties.  It
           kind of leaves it too wide open, and if that were
           clarified there would probably be a fair amount of
           benefit in that.
                       CHAIRMAN SHACK:  I'm not sure I understand
           that last argument.  Are you just saying you just cut
           the uncertainty analysis at the 95th percentile?  That
           would certainly help.
                       MR. BAJOREK:  I don't have a pen.
                       MR. BONACA:  What you seem to say, that
           you have more opportunities in the best estimate than
           you have in Appendix K, of course.
                       MR. LAUBEN:  Here's one that works on
                       DR. KRESS:  Just do it on the screen.
                       MR. BAJOREK:  Are you telling me to?
                       DR. POWERS:  He's hoping somebody else
           will to --
                       DR. KRESS:  Yes.
                       MR. BONACA:  To be the second.
                       DR. KRESS:  I hate to be the only idiot in
           the crowd.
                       MR. BAJOREK:  If we take a look at an
           uncertainty distribution in some model, we may see
           some bias away from perfection.  We've got everything
           on here.  But we also see a scatter in how well you
           get a prediction to the experimental measurement.  It
           may take some distribution.
                       Well, if you want to range the uncertainty
           for that model, well, you have to make a decision, do
           I range it over best to worst, or do I say, hey, I
           don't necessarily have to address the wings out in
                       Most specifically, can I get away from
           some of these worst situations?  And in the
           calculations that I see, what drives your 95th
           percentile PCT frequently comes from this part of the
           distribution, then an experimentalist may say it's a
           bit of an outlier and isn't representative of the bulk
           of the data.
                       But right now, the Reg. Guide is not very
           clear on where you draw that limit.
                       DR. KRESS:  Well, it looks to me like
           there's not a very lot to be gained by changing the
           Appendix K part of the rule.  It looks like what we
           didn't know before was that the non-conservatisms were
           pretty much balanced out by the conservatisms.
                       And you know, that's -- you maybe don't
           have them all quantified exactly right, but it's a
           good guess that it's getting close.
                       MR. BAJOREK:  Whoever picked out the
           1.2 --
                       DR. KRESS:  Yes, did a pretty good job.
                       MR. BAJOREK:  -- did a pretty good job.
                       DR. KRESS:  Yes.  So since it would be a
           big deal to change it and you have to worry about
           back-fits, I guess, because it could require some
           plants to redo their analysis and do things over, my
           leaning right now is for your Option C.
                       But I would encourage you to continue on
           with this action plan, because it does two things for
           you.  One, it bolsters your case because it does give
           you a better look at what these non-conservatisms are
           compared to conservatism, and it gives you information
           that could be very insightful when you go into
           evaluating the best estimate models.
                       MR. BAJOREK:  Right.
                       DR. KRESS:  So that's kind of my
           inclination right now.  I don't know how these other
           guys feel about it.
                       MR. BONACA:  Absolutely.  I totally agree
           with that.  It seems to me Option C is the one that
           has some opportunities.
                       CHAIRMAN SHACK:  Well, clearly, there's a
           difference of opinion, because somebody submitted a
           petition to change it.  So --
                       MR. BAJOREK:  Yes.
                       DR. KRESS:  Yes, but weren't they mostly
           interested in changing the large break LOCA definition
           in that?  Or did they want --
                       MR. LAUBEN:  No.  No.  I mean, this
           petition is strictly for the decay heat.
                       MR. BAJOREK:  Strictly decay heat.
                       MR. BONACA:  Well, that's why I asked the
           question about the technical community, because I
           mean, the case you made today would discourage a
           change without your investigation of this -- and you
           have data that says that in fact you have -- you may
           not be able to support the intention of that
           multiplier literally.
                       DR. KRESS:  And anyway, you have the best
           estimate option which --
                       MR. LAUBEN:  Right.
                       DR. KRESS:  -- let's them do what --
                       MR. BAJOREK:  It's there, now.
                       DR. KRESS:  It's there now.
                       MR. BAJOREK:  It's there now.  It's not
           clear and there are things that could be done to make
           it perhaps less onerous.
                       DR. KRESS:  Yes.  You have -- yes.  That
           might be the place to focus your attention, I think.
                       MR. BONACA:  I mean, any use of these
           changes would require a new analysis, anyway.
                       MR. BAJOREK:  Yes.
                       MR. BONACA:  And you know, Appendix K may
           be less expensive one.  I don't know.
                       MR. BAJOREK:  Generally, it is.
                       CHAIRMAN SHACK:  Well, I guess just to
           follow along here.
                       MR. BAJOREK:  Okay.
                       CHAIRMAN SHACK:  I guess it seems to me we
           have realistic analyses, you know.  People can make
           comparisons, you know.  Your case is reasonably
           convincing in terms of discussion, you know, but I
           just have to see more of these comparisons.
                       Now, Mario says he's looked at them and,
           you know, they're there, but it seems to me that
           really is the thing.  You have best estimate
           estimates.  You have other estimate you can really get
           a much more concrete comparison of what the effect
           would be.
                       MS. DROUIN:  I was going to say, Steve
           covered the evaluation model.  We now have the
           acceptance criteria.  I did notice, though, that on
           the agenda you had a break at this point, whether you
           want us to go ahead and get into the acceptance
           criteria, or do you want to take a break now?
                       CHAIRMAN SHACK:  Ralph's discussion looks
           reasonably short.  I think I'd just as soon keep on
           going and then take the break.
                       MR. MEYER:  Looks short, but the
           discussion may be -- looks short, but may be
           deceptive.  All of the discussion so far has been on
           analytical methods for calculating the peak cladding
           temperature which are laid out in Appendix K.
                       There are in fact five acceptance criteria
           specified in 50.46, not just peak cladding
           temperature.  These are the speed limits, so to speak,
           and they are listed here on this slide.
                       The objective in examining the acceptance
           criteria in 50.46 for possible modification is to see
           if we can remove some or all of the prescriptive
           nature of these criteria, which are related
           specifically to zircaloy cladding and to ZIRLO, which
           are written into the present rule, and take them out
           so that the rule could apply generally to any
           zirconium-based alloy that's used for fuel rod
                       I think that this can be done simply by
           removing number 2 on this list, the maximum cladding
           oxidation, which is specified at 17 percent, and I
           want to discuss that.  So I have in fact just one
           option here.
                       It's either do it or don't do it.  You
           could, I guess, make some variations on this, but this
           seems like a logical approach, relatively simple in
           procedure, that would solve the problem.
                       DR. KRESS:  What does it change, Ralph?
                       MR. MEYER:  What?
                       DR. KRESS:  It just changes the -- it's a
           perceptions change.
                       MR. MEYER:  What you would do here is to
           take the 17 percent equivalent cladding reactive limit
           out of 50.46 and replace it with a performance-based
           requirement that says simply that you should retain
           some post-quench ductility in the cladding.
                       DR. KRESS:  Yes, but isn't the 17 percent
           a surrogate for that?
                       MR. MEYER:  That's -- well, 17 percent was
           a measure of that for zircaloy.
                       DR. KRESS:  I see.  It may not be the same
           surrogate for other things.
                       MR. MEYER:  That's correct.  It may not be
           the same, for example, for M-5.  Even ZIRLO wasn't
           tested carefully against this limit, although the rule
           was changed to include it.
                       DR. KRESS:  And if you made the change,
           the licensee would have to come in, if you had a
           different clad, and show you the database.
                       MR. MEYER:  That's correct; that's
                       DR. KRESS:  I think that'd be a good
           change.  That would clarify a lot of things.
                       MR. MEYER:  Yes.  Most of this is on the
           next slide, but before you move to the next slide,
           let's --
                       DR. POWERS:  Before we get too excited
           about making this change.
                       MR. MEYER:  Yes.
                       DR. POWERS:  What you want to do is to
           preserve some ductility so that you can cool this core
           and keep it cool and not have it fall apart on you.
                       MR. MEYER:  Right.
                       DR. POWERS:  We test for ductility in a
           variety of fashions and we get different results when
           we test in different ways.
                       MR. MEYER:  Yes.
                       DR. POWERS:  How do we know that the test
           that we propose to use for ductility is the one that's
           applicable for the core and the post-quench
                       MR. MEYER:  Could you say a little more so
           I understand what's in your mind a little better?
                       DR. POWERS:  Okay.  What I know is if you
           test it one way it says there's lots of ductility. 
           Test it a different way there's not so much ductility,
           okay.  That's laboratory tests of remaining ductility.
                       Okay.  Now, what we want to have is the
           core not fall apart after we have gone through the ECS
           injection or something like that and we've got
           -- everything's cooled down, and it doesn't because
           there's some ductility there.
                       How do we know that the ductility we
           derive from whatever test we endorse is ductility that
           actually exists in the clad under the conditions of
           the post-quench environment?
                       MR. MEYER:  Well, the -- first of all, the
           testing that was done back in the early '70s and late
           '60s was in fact done under a post-quench environment. 
           That is, the cladding pieces were taken through a
           high-temperature steam oxidation.
                       They were cooled down.  They were quenched
           and then they were tested at a relatively low
           temperature.  And there -- while it's true that you
           could use other methods than the ring compression
           method that was used back in the '70s, and there would
           be some scatter in the result, from reviewing what had
           been done earlier, it still appears to be a reasonable
                       And in fact, we are at the present time in
           an ad hoc expert group that has participation from a
           number of international groups.  We are exploring
           several different test methods for determining
                       All you're trying to do here is to have a
           screening test where you can differentiate between
           fully brittle material and material that has some
           residual ductility.  From what I've seen so far, I
           think the ring compression test will continue to be a
           good way of doing this.
                       You can do it with a hardness indentation. 
           You could do it with some sort of plastic extrusion
           method of providing the loading on the rings.  But
           it's materials property, and basically, any way you
           test it except for some variations introduced by the
           testing method, you're going to get about the same
                       So I guess the answer to your question is,
           we are aware of the concern about the appropriateness
           of the test.  We have an effort underway to see if
           some other procedure would be better than the one that
           was used in the early '70s.
                       At the present time the general
           configuration of ring compression test still appears
           to be a good approach, and the details of the test
           method that would be used for this would be laid out
           in a regulatory guide.
                       And I guess we can just -- you're jumping
           to the bottom line here and going --
                       CHAIRMAN SHACK:  Going at it a different
           way because I think Dana's coming from -- there's two
           problems here.  One, given a given temperature strain
           history I end up with a certain condition of cladding,
           and to determine the ductility --
                       MR. MEYER:  Yes.
                       CHAIRMAN SHACK:  -- then it really is an
           experimental problem of what is the right test.
                       MR. MEYER:  Right.  Right.
                       CHAIRMAN SHACK:  And that's one we can
                       MR. MEYER:  Yes.
                       CHAIRMAN SHACK:  I think in a fairly
           straightforward way.  I think Dana's concern is with
           temperature strain history you put the clad through --
                       MR. MEYER:  Oh.  Oh.  Oh.  Okay.
                       CHAIRMAN SHACK:  -- before you get to the
                       MR. MEYER:  Okay.  Okay.  Well, we're also
           poking into that and the way -- we haven't completed
           this, and you'll see that the last column on this
           second slide here is that we will not have done enough
           work to actually put this thing through a -- its paces
           for one or two more years because we haven't finished
           the work yet.
                       But we know pretty much now how this would
           play out.  You would use a temperature -- you would
           simulate the several of the high-temperature LOCA
           transients.  You would have a slow temperature rise up
           to some temperature at which you would soak it for a
           period of time to accumulate the oxidation.
                       You would cool it at some steam cooling
           rate.  I forget the number, but I think it's on the
           order of five or ten degrees a second, down to 800
           degrees centigrade, at which point you would then
           flood it and quench it.
                       And we are exploring the effect of
           different heating and cooling rates and the effect of
           different temperatures at which you hold the specimen. 
           And it's likely that one would want to prescribe tests
           at a series of temperatures, not just at a single
           temperature, up to and including the peak cladding
           temperature of 2200 fahrenheit, which is 1200, 1204
           degrees centigrade.
                       And so we are doing those kind of tests in
           the near future on a high burnup cladding and the
           archive under-radiated fresh material that corresponds
           to that to try and map out what these effects are and
           what would be the best rates and temperatures to
           conduct this temperature history for the ductility
                       So that would all be set out in the
           Regulatory Guide.  Now, in the relatively near term we
           could set out in a draft guide the conditions that we
           in fact are planning to use in the laboratory.
                       But if you rush this through before we're
           able to actually do those tests in the laboratory and
           see if the result appears satisfactory, then you run
           the risk that we might have to change something.
                       MR. MEYER:  Now, there is -- may I move to
           another point?  There is one thing that I wanted to
           emphasize here, and that is that the peak cladding
           temperature of 2200 degrees and the cladding oxidation
           limit of 17 percent really arose as a pair of numbers
           originally, and these both came from these ductility
           tests, the ring compression tests.
                       The 17 percent -- okay.  So you have some
           flexibility if you want to move away from these
           precise numbers you could say, well, let's work with
           2300 degrees fahrenheit and maybe we would get 15
           percent for zircaloy.
                       So there would be some flexibility in
           working with both of those numbers, but you'll notice
           that I've suggested that we keep the 2200 degree
           fahrenheit number, and I've suggested that for what I
           think is a good reason.
                       And that is during the ECCS hearing this
           was the most contentious part of the debate about the
           acceptance criteria.  And in fact, a second line of
           concern was raised about the peak cladding
           temperature, and that had to do with rapid oxidation
           at higher temperatures.
                       And so the Commission reached a decision
           to limit the temperature a relatively low value so
           that you didn't have the concern of rapid oxidation. 
           And at the same time it fit in with the -- with
           Hobson's ring compression test data on the ductility.
                       And so I think that if you were to alter
           that temperature that you would probably open this up
           to a lot of contention.  And I don't believe there's
           a need to change that because we can work with that as
           a fixed number, and then let the maximum cladding
           oxidation figure vary in order to capture the effects
           of both cladding alloy variations and burnup effects.
                       And so it might go up or it might go down. 
           And it might be different for high burnup, low burnup,
           different cladding alloys.  And so you pull that out. 
           You put it into a Regulatory Guide.  Everything else
           can stay fixed and then the -- in 50.46.
                       And the 50.46 would not be pegged to
           zircaloy or ZIRLO and could be used for all zirconium
           based alloys.
                       CHAIRMAN SHACK:  Why not just pull them
           out to the Reg. Guide?
                       MR. MEYER:  Well, you could --
                       CHAIRMAN SHACK:  Use the coolable geometry
           and the long-term cooling as the fundamental
           requirements, which they really are.
                       MR. MEYER:  Yes.
                       CHAIRMAN SHACK:  And then how you assure
           that, put that in the Reg. Guide because if you get
           new data some day --
                       MR. MEYER:  Well, you could do that.  I
           think that you would also need to address the question
           of rapid oxidation at higher temperatures.  And to me
           this would open up the possibility of litigation
                       There's no reason that we couldn't work
           with that 2200 figure on the embrittlement criteria. 
           Leave it fixed.  It was, you know, a hard fought
           number in the beginning and it does not cause, as far
           as I can see, any problems with the technical adequacy
           of an embrittlement criterion that you would derive
           with that as a fixed number, because you've got two
           parameters to work with.  So we can do it all with the
           other one.
                       CHAIRMAN SHACK:  It's just that, you know,
           you don't really have the database on M-5 or even
           ZIRLO.  I'm not sure that people were worried about it
           as much.
                       MR. MEYER:  No.  It hasn't been worried
           about too much in the past, but we're worrying about
           it now.  And in fact, just for your interest, I could
           say that we've made excellent progress in our
           discussions with Framatome about an agreement to begin
           testing their M-5 cladding.
                       And we're now down to the point of some
           legal language in a memorandum of understanding with
           all the basic issues having been agreed upon between
           us and Framatome.  So I think the time is coming soon
           that we will begin to test, first, the Framatome M-5
           cladding on irradiated material at first, and then
           hopefully, Westinghouse, their low cladding, although
           those negotiations are simply on hold waiting the
           outcome of the negotiations with Framatome.
                       DR. KRESS:  You're fairly confident,
           though, that the 2200 will keep you below a runaway
                       MR. MEYER:  Yes.
                       DR. KRESS:  That's well enough below it
           that it's safe.
                       MR. MEYER:  Yes.  I'm not aware of
           anything that would be significantly altered by making
           these small alloy changes.  I mean, it's still based
                       DR. KRESS:  Just not enough that has
                       MR. MEYER:  -- and zirconium and zirconium
                       CHAIRMAN SHACK:  I mean, 2200 is more than
           runaway oxidation.  It really is sort of oxygen pickup
           that --
                       MR. MEYER:  Sure.  2200 first of all is
           part of the embrittlement criteria.
                       CHAIRMAN SHACK:  Yes.
                       MR. MEYER:  And how it came about -- put
           my backup slide.  I've got my backup slide to make me
           look smart here.  When you ran a piece of zircaloy
           cladding through a high temperature transient and
           brought it back down, if you -- you're looking at the
           outer surface on the left and the inner surface on the
           right, it went through a phase change.
                       It was hexagonal close-packed in its alpha
           phase at normal temperatures.  And some of it changed
           to a body center cubic structure at high temperatures,
           and then you quenched it and brought it back down.
                       And you could tell what had been body
           center cubic and it turns out that the body center
           cubic phase is the one that provides your strength and
           ductility.  And so what you really are interested in
           is maintaining a ductile prior beta region in the
                       And the gross amount of oxidation
           correlated pretty well with the thickness of a ductile
           prior beta layer.  Above 1200 degrees centigrade, 2200
           degrees fahrenheit, you've got additional oxygen
           diffusion into this prior beta region that pretty much
           upset that handy little correlation.
                       And so that was the reason that you didn't
           go above 1200 degrees centigrade, because your use of
           gross oxidation as a surrogate for this one layer fell
           apart.  Now, you could deal with that by backing down
           the total amount of oxidation in say 15 percent or 14
           percent, and let the temperature go up.
                       But the Commission did not do that.  They
           stuck with that number and then they said, and by the
           way, we don't want to make it any higher because there
           is this consideration of rapid oxidation at higher
           temperatures and we don't have much information on
                       And it was a huge -- that was a huge part
           of the hearing.  It was a huge part of the Commission
           opinion, and it seems like the sensible thing to do is
           to leave it alone and to work with the oxidation
           thickness for the embrittlement criteria.
                       CHAIRMAN SHACK:  Any additional questions
           for Ralph?  If there are none, this seems like a good
           place for a break and I suggest we come back at 11:05.
                                                       (Whereupon, a recess was taken
                                 at 10:48 a.m. until 11:09 a.m.)
                       CHAIRMAN SHACK:  So in that quandary, we
           can start again.
                       MS. DROUIN:  Okay.  He has it on.  It's
           not working.

                       CHAIRMAN SHACK:  Time to change bulbs.
                       MS. DROUIN:  Okay.  We just have one slide
           here to bring in the status of what's happening on the
           rulemaking side with NRR.  Unfortunately, Sam Lee
           couldn't be here today.  There was a petition that was
           sent in, in September by NEI.
                       The primary purpose was, as we saw with
           50.44, if there's a part that can be -- that appears
           to be -- that can -- that appears -- man, I just can't
           get these words out of my mouth -- that can be
           separated out and move on a faster track, they like to
           see that be done that way.
                       And so they have submitted a petition to
           separate out the decay heat part and put that on a
           faster track and make a separate rulemaking activity
           out of that.  We had noted in our SECY that all of
           these things could be one rulemaking or several
           rulemakings, and that would be decided as we move
                       But in their particular petition, you
           know, it would allow the licensees optional adoption
           of the latest standard and allow adoption by the
           licensees of any subsequent revisions to the standards
           that are endorsed by the NRC as we go forward in time.
                       Right now, the staff is currently
           evaluating the petition.  It's in the normal process. 
           Okay.  Now, today so far we have talked about the
           status on the evaluation criteria and the evaluation
                       Those were two very important parts
           because we are right now deviating on the
           recommendations that we had made on the evaluation
           criteria and the evaluation model.  We had made one
           set of recommendations, and now, as we move forward in
           the technical work we are now proposing somewhat
           different things.
                       On the reliability part, we've still got
           a lot more work to do here, and as we've seen in the
           criteria in the evaluation, we're coming up against
           some technical issues that we had not anticipated.  So
           with that, I'll turn it over to Alan.
                       MR. KURITZKY:  Okay.  As Mary said, the
           previous discussion dealt with the proposed changes in
           SECY 133 dealing with the ECCS evaluation model and
           the acceptance criteria.
                       We also proposed changes in the near-term
           to the reliability requirements, particularly those
           that are included in, you know, GDC 35, dealing with
           the loss of off-site power requirement and also the
           single failure criterion.
                       In the SECY what we recommended was a
           risk-informed alternative to those ECCS reliability
           requirements.  The idea was that we would replace the
           existing requirements of GDC 35 with requirements that
           were more risk-informed and more realistic.
                       Particularly, we would be deleting the --
           oh, we'll call it the requirements or the assumption
           that you have a loss of off-site power when you have
           a LOCA, and also the need to model the single worst
           additional failure.
                       Instead, we would be offering two
           performance-based options that would get at -- that
           would help assure ECCS reliability.  A first option
           would be a generic -- would be something that was done
           in a generic fashion by plant type that the NRC staff
           would do ahead of the game.
                       We would put together, we would define by
           plant group or plant type what minimum ECCS equipment
           would be required for that group or type, and we would
           -- that would also include whether or not you need to
           consider the loss of off-site power for -- to prevent
                       And the equipment requirements themselves
           would be tied to different groups of accidents.  You
           may have one set for large LOCA ones and for small
           LOCA, et cetera.  The idea under Option 1 is that's
           something that the NRC staff would do ahead of time so
           that if a licensee wanted to implement it they would
           not have to do any technical analysis.
                       It would be pretty much cut and dried. 
           They can choose to go with it.  They don't have to do
           any analysis and nor does -- do any review, and it's
           -- it'll go quickly.
                       However, if a licensee decides that they
           feel they are not getting as much unnecessary burden
           reduction as they feel they could get, you know, doing
           a more detailed analysis, a more plant-specific
           analysis, they don't like the group they're in, they
           feel some bad actor was dragging their group down,
           they will have the option to go ahead and do a plant-
           specific analysis and that will be based on guidance
           that we would include in a Regulatory Guide.
                       We would give them an ECCS function
           reliability threshold that would be derived from,
           well, what we're envisioning is probably something
           derived from the core damage frequency threshold
           that's in our framework, our Option 3 framework, the
           qualitative guidelines we have there.
                       And then the licensee would go through and
           do analysis using their own data, you know, whatever
           analysis they want to do analysis mix they want, their
           own PRA, and try and justify some -- they would have
           to meet some reliability threshold for the ECCS
           function, and it could be with whatever equipment they
           have at their plant, whatever set they feel is
                       And again, that would also cover whether
           or not they would need to consider the simultaneous
           loss of off-site power assumption for different acts
           and classes.  To kind of explain that a little bit
           better I have -- this just shows you the --
                       CHAIRMAN SHACK:  Now, your own Reg. Guide
           would also give them some way to calculate LOCA
           frequencies, right?
                       MR. KURITZKY:  Well, what the Reg. Guide
           wold do would give them guidance on LOCA frequencies,
           exactly.  That's going to be one of the main things. 
           You'll see as we get to the technical issues, that's
           one of the main things we are still wrestling with. 
           But that's -- yes, you're right.  It would give them
           guidance or --
                       CHAIRMAN SHACK:  Or a set of numbers or
                       MR. KURITZKY:  Yes.  It could give them a
           set of numbers or it could --
                       THE REPORTER:  Excuse me.  Would you pull
           your microphone up.
                       MR. KURITZKY:  It can give you -- it would
           give you a set of numbers or it could tell you things
           you have to consider when you want to calculate your
           own numbers.  They say that latter part about things
           you have to consider, some of that stuff may have to,
           you know, I don't know whether it's something we'll do
           now in the short-term, whether it's something that
           would have to wait till we get to the long-term thing
           of looking at the spectrum of LOCAs.
                       Just to kind of clarify a little bit about
           what we're looking at from coming from these two
           options, for Option 1 we're envisioning that we would
           have matrices that we have produced, and the matrices
           would have plan group or plan type along one side.
                       You know, it'd have different acts and
           classes along the other side.  And it would delineate
           what minimum system requirements you would have or
           equipment requirements you would have for the ECCS
                       And these -- the purpose of specifying
           that equipment is if a plant finds out that they have
           more equipment than the minimum required, it would
           give them fuel or additional justification for making
           some kind of operational relaxation, whether it be in
           technical specifications or whether or not it would
           allow some kind of design change.
                       That would be up to us to decide, you
           know, the NRR to decide in the implementation phase. 
           But in addition, there would be a second matrix that
           would identify the actual sections that are used in
           the ECCS thermal-hydraulic performance calculations.
                       And specifically, it's the GDC-35
           requirements of the single additional -- single worst
           additional failure, and considering both with or
           without off-site power available.
                       This matrix would again be the same thing,
           plant type and accident type on the other side, and it
           would specify whether or not you do need to consider
           a loss of -- a conditional or a current loss of off-
           site power with that particular accident class, and
           also whether or not -- what failures you'd need to
                       It could be a single failure.  It could be
           multiple failures.  It would also allow you to address
           passive failures.  It would give us the opportunity to
           finally try and resolve the footnote that's been in
           Appendix A to Part 50 for -- since I was a small boy,
           because all that would fall into this reliability
           threshold.  And so --
                       DR. POWERS:  It seems to me that the
           assumption is the ECCS requirements right now were
           installed in response to the possibility of some
           stochastic event during normal operations, and you're
           trying to address that.  That doesn't seem to me,
           then, to span the entire spectrum of reasons for
           having an ECCS.
                       MR. KURITZKY:  Well, as far as I
           understand, the ECCS -- we're looking at all the
           different types of acts and issues that you could have
           at the plant.
                       DR. POWERS:  No, you're not.  You're not
           looking at all of them.  You're not looking at any
           kind of sabotage.  You're not looking at any kind of
           external threat whatsoever here.
                       MR. KURITZKY:  External threat.  You're
           referring to a sabotage threat or external events like
           seismic activity?
                       DR. POWERS:  Clearly, I'm talking about
                       MR. KURITZKY:  Sabotage, yes.  Yes. 
           Sabotage isn't --
                       DR. POWERS:  Well, doesn't that -- I mean,
           doesn't that make you -- I mean, why can you exclude
                       MR. KURITZKY:  That's an interesting
           question.  I mean, as I understand it -- I'm not privy
           to all that's going on in the Agency on that topic. 
           There's a lot of work going on there and that's going
           to impact -- I assume that's going to impact a lot of
           the work that the Agency does.
                       It can impact a lot of the regulations. 
           I don't know how that's all going to fall out.  I
           would say I wouldn't want to hold up everything else
           waiting to see how that falls out.  So what we're
           going to do is based on current risk insights.
                       And unfortunately, as we all know, they do
           include sabotage as an initiator.  I mean, it does not
           include sabotage is -- that's my answer.
                       DR. POWERS:  I mean, it seems to me that
           until you can establish that the only reason we have
           any CTS in each plant is for stochastic events that
           are covered by the PRA kinds of analyses, you can't go
           around doing this.
                       MR. KURITZKY:  Well, I don't know.  I
           guess my opinion is that I don't necessarily agree
           with that.  I feel that we have enough knowledge that
           we can propose some changes based on what we feel are
           reasonable events.
                       I think you make a good point and that's
           one thing that just has been kind of overlooked by
           PRAs, and it's not a question of something that's
           overlooked because of the frequency is so low, which
           we can make some probabilistic argument why we don't
           need to worry about it, but it's one that obviously we
           can't make that argument about.  I guess that may be,
           you know, policy --
                       MS. DROUIN:  I'm confused by your -- I
           wasn't even sure what your question was in all of that
           data.  But what I'm more confused by is your concern
           doesn't seem to be addressed by the current set of the
           way the regulation is written right now anyway.
                       DR. POWERS:  Why not?
                       MS. FAIRBANKS:  I guess if I can
           interrupt, I was going to say that later when I had a
           slide come up that we were going to be providing from
           our branch some support to PRAB.  And one of the
           things that we were trying to look at, too, was some
           of these indirect causes.
                       And we had actually considered potentially
           sabotage or maybe that would be the subset of
           something like an indirect crane hit to piping, which
           could cause a large break LOCA.  But to fully risk
           inform --
                       DR. POWERS:  Well, I think you -- I mean,
           I don't think there's an analogy, a good analogy
           there, because one of the reasons for saying -- you
           got a large break LOCA and a simultaneous loss of
           power, it is clearly a, gee, this is a deliberate
           sabotage event and I want to be able to respond to
           that with my system.
                       And I don't think you can do both of them
           with a stochastic event.  I mean, that's why he's
           interested in dropping out the simultaneity, because
           it's hard to come up with a finite, nonvanishing
           probability, is to have both at the same time.  But
           you can when you come to sabotage.
                       MS. FAIRBANKS:  Yes, you're right.
                       MS. DROUIN:  If you give the sabotage a
           probability of 1.0 -- the frequency --
                       DR. POWERS:  No, I don't think I have to
           do that.  I have to say that in any event even those
           of a vanishingly small probability can in fact occur,
           and if they do occur I want something to protect me.
                       MS. DROUIN:  So regardless of how small
           the occurrence is, I mean, to me that's not being
           risk-informed, and that's where we are right now.  We
           have two events there that are extremely low
                       MR. KURITZKY:  And I think also in the
           off-site thought, Mary's point is that -- or to
           address more your question, Dr. Powers, is that the
           -- if we do make some of these changes, it does not
           mean that -- you mentioned you'd like to have
           something to protect you in case that event does
                       And it's not that these changes that we're
           going to make here are necessarily going to strip away
           all that protection.  Your reliability may be somewhat
           reduced, but it doesn't strip that away.
                       So then it's the question of that
           reliability times the probability or the frequency of
           a sabotage event that results in the loss of off-site
           power and large break LOCA, plus your residual
           mitigated capability, is that frequency -- previously
           something that gives us heartburn in that -- without
           a quantification of sabotage frequency, I can't say
           one way or the other.
                       DR. POWERS:  I guess I'm wondering if
           suppose somebody even figured out how to calculate the
           sabotage frequency, would I want to give up that
                       MR. KURITZKY:  Well, what protection
           specifically are you giving up?
                       DR. POWERS:  Be able to cool the core.
                       MR. KURITZKY:  Well, what I'm saying, I
           don't envision that what we would be changing would
           necessarily give up your ability to cool the core.
                       DR. POWERS:  I am --
                       MR. KURITZKY:  You still have low pressure
           injection pumps that are most likely going to be on
           the -- so it's not -- you know -- there is a
           mitigative capability remaining in the plant.
                       MR. BONACA:  I think this is somewhat of
           a broader issue of how the -- you know -- the issue of
           security has always been dealt with.  I think that the
           fact that there is a security has always been
           eliminating consideration of sabotage as initiator for
                       I mean, it's an issue but it's broader
           than this specific one, I think.
                       MR. MARKLEY:  I think the point here that
           you're driving toward is that it was built on internal
                       MR. BONACA:  Right.
                       MR. MARKLEY:  And not external threats.
                       MR. BONACA:  Correct.
                       MR. KURITZKY:  Okay.  So as I was
           mentioning, we have these two types of matrices that
           would really -- that we're looking at, we're
           envisioning would come from this:  the one we
           specified with the minimum equipment, ECCS equipment
           that the plant -- or plant type or plant group would
           have to have for each different type of accident
           initiator category.
                       And the second matrix would specify the
           assumptions, failure assumptions to be used in doing
           the thermal-hydraulic calculations by the types of
           failures we'd have to consider, and also what
           equipment -- also whether or not you'd have loss of
           off-site power or not.
                       For Option 2 we would be producing a
           Regulatory Guide.  I guess I should have used the
           words "contain the requirements," since there are
           requirements, but I guess it would provide the
           guidance to licensees for performing a plant's
           specific analysis like I had discussed previously
           where they would essentially be going through the same
           things that we're going to be going through, trying to
           come up with the option on matrices.
                       The same issue that we are going to
           wrestle with we would have to lay out in that
           Regulatory Guide, at least to get to know how -- at
           least one way that we would approve them in doing the
                       And that would allow them, like I said
           before, to try and get additional margin or additional
           unnecessary burden reduction if they feel that the
           first option didn't give them -- or didn't get them
           where they wanted to go.
                       CHAIRMAN SHACK:  Now, what -- you know,
           when we redo this, what changes do you see the
           licensees actually making in response to this?  Is it
           tech spec requirements on the --
                       MR. KURITZKY:  I think one thing is
           probably tech spec requirements; allowed outage times,
           maybe some relaxation of allowed outage times.  I
           think the LOCA/LOOP assumption may allow them to
           extend the -- or relax the diesel generator start time
           that -- the tech spec requirements for the ten-second
           diesel start time.
                       Those are the two main things that I can
           envision, relaxation of tech specs which includes, of
           course, the diesel start time.  What's not clear is
           that if they are -- if they can do the calculation to
           show that they can extend the diesel start time,
           whether they would in fact push for a change on that
           start time or allow the diesels to start later, or
           whether or not they would just keep that margin for
           some other usage or find that margin for some other
                       But that would be up to the licensees to
           decide.  So we will just have to make sure that
           whatever that chance could entail, we're happy with
           that they would do with it.
                       MS. DROUIN:  You go back to the issues and
           when we come back if they want to hear about that.
                       MS. DROUIN:  We were going to skip the
           next slide in and get into -- because it just seems to
           go more along better with the discussion -- the issues
           that we're encountering.
                       MR. KURITZKY:  It's off the slide 13. 
           Okay.  In doing the technical work and pursuing the
           technical work since we submitted the paper, SECY 133,
           we have encountered a number of issues that we have to
           wrestle with, technical issues, implementation issues.
                       We're also looking out for policy issues. 
           Some of the issues may border or be on some fine line
           between technical and policy.  But right now we have
           a quite a long list, maybe 20, 30 issues that we've
           come up against.
                       Some of them were relatively easy to
           resolve and we've already resolved them internally, or
           have those resolutions to them internally.  Others we
           still are wrestling with.  We'll require more broad-
           based discussions and probably public stakeholder
                       And certainly, we welcome and one of the
           purposes of this meeting is to get ACRS input on some
           of these issues.  The three of them that I have listed
           on this slide are three of the more important ones
           that we're wrestling with.
                       The first one we all were just starting to
           discuss a little while ago was the LOCA scope and
           frequency.  We are planning -- or at least at this
           point the most up-to-date column, state of the art
           LOCA frequency numbers are in NUREG CR 57.50, and
           that's our starting point for getting LOCA frequencies
           for this effort.
                       However, the new NUREG CR 57.50 LOCA
           frequencies are just for pipe break LOCAs.  They don't
           consider nonpipe break failure methods, such as steam
           generator man-way, or heavy load drops.
                       So we have to determine some way to
           include those other types of LOCA initiators or LOCA
           causes into our calculations.  In addition, we need to
           address the methodology in NUREG CR 57.50.  We need to
           determine whether or not it adequately addresses aging
           effects and other unknown --  mechanisms that may show
           up sometime in the future that would serve to
           undermine the service data that is the basis for the
           NUREG 57.50 numbers.
                       We are planning to have meetings with
           contractors from the engineering folks, the
           probabilistic factual mechanics experts meeting with
           people involved with NUREG 57.50 to try and internally
           come up with something that may be acceptable to all
           parties, at which point we also want to go out to the
           public and get their input on how we're going to
           address the LOCA frequencies.
                       And obviously, it's a big driver.  It's
           going to drive both pieces that I was talking about
           previously, the LOCA/LOOP and the reliability.  Both
           -- the LOCA frequency is a parameter in the equation
           for both of them.
                       So it's obviously a very important issue
           that we need to come to some resolution on.  Another
           issue that's very important that we need to resolve
           deals with the conditional loss off-site power
           probability given a LOCA, going to that LOCA/LOOP
                       And unfortunately -- but fortunately,
           there is no data on LOCA/LOOPs.  We're happy about
           that, but as analysts it makes it a little trickier. 
           We have, instead, had to use as surrogates for an
           actual loss of off-site power conditional on LOCA,
           we've had to use just regular reactor trip events, and
           also, ECCS actuations.
                       Now, ECCS actuations more closely resemble
           the conditions you would have, at least electrically,
           electrical load-wise, from a LOCA.  However, again,
           there's very few ECCS actuation events.
                       There's more readily available data on
           reactor trips.  The problem we have with reactor trips
           is that the electrical loading conditions aren't
           nearly as severe or not as severe as you would have if
           you had a LOCA, because you don't have the ECCS loads
           coming onto the safety buses.
                       And that concern is further exacerbated by
           the fact that we have a situation now where there are
           plants sometimes operating with a degraded grade of
           voltage, and when that condition occurs, given that we
           have the degraded voltage relays or trip relays on the
           safety buses, you can run into a situation where just
           an extra load from the ECCS pump starting could be
           enough to trip those relays, and even though power may
           still be available on the grid, for all practical
           purposes the plan is experiencing a loss of off-site
           power because it's going to separate from the grid and
           have to run on the diesels.
                       So that again is one of the data
           limitations we have right now that we're working with. 
           And the third issue that we have up here involves
           giving credit for non-safety grade -- non-ECCS systems
           in the calculation.
                       The reliability threshold that we're
           basing this on is probably going to come from a CDF
           threshold from the framework.  The CDF threshold is
           based on values from a PRA.
                       PRAs and doing the core damage frequency
           calculations do credit non-ECCS equipment for serving
           a function, or a RCIC pump or in a BWR you could have
           a service -- cross-tie, or you know, a fire, a fire
           protection pump.
                       So what we have to determine is what
           credit are we going to give for non-ECCS systems in
           this -- in our calculations or in trying to come up
           with these matrices?
                       We don't want to get up in a situation
           where a licensee may try and meet the entire
           reliability threshold with non-safety grade systems
           and then say, okay, I can have a lot of relief on my
           true ECCS systems because I have all this reliability
           from my -- you know -- additionally, my other nine
           ECCS systems.
                       So we may have to come up with a -- as we
           mentioned -- a sub-threshold, which would at least
           assure a minimum reliability of the pure safety-grade
           ECCS systems.  So that's just another one of the
           issues that we're wrestling with.
                       MR. BONACA:  This is mostly on BWRs,
                       MR. KURITZKY:  Exactly.
                       MR. BONACA:  And those which rely heavily
           on the procedures that you have in place on how
           integrated those systems are in the procedures?
                       MR. KURITZKY:  Yes, that's the thing. 
           Certain systems -- like I think, I don't know, maybe
           the RCIC system, my understanding, may have a little
           better pedigree than some of the other systems.  But
           again --
                       MR. BONACA:  You know, if they're trained
           and they're used that way and there is a real hardened
           use for that, I think is different than purely if you
           have some hypothetical, you know, ideas that was
           implemented in the PRA but is not supported by
                       MS. DROUIN:  Yes, I mean, because the --
           a lot of these it's not hypothetical, but particularly
           when you look at boilers, they give a lot of credit to
           systems whose primary function, you know, is not --
                       MR. BONACA:  Not ECCS.
                       MS. DROUIN:  -- is not the core coolant.
                       MR. BONACA:  Oh.
                       MS. DROUIN:  You know, the service for the
           cross-tie, the fire water system, enhanced CRD.  And
           they do have procedures in place at the plants for
           using these systems in those, you know, extreme cases.
                       But they aren't there for ECCS -- they are
           not ECCS systems.  And with boilers in particular,
           they would have a very difficult time if we did give
           them credit for meeting any kind of CDF threshold
                       But as Alan said, on the other hand, you
           don't want them to come in and have so much credit
           that we'd back off on the ECCS.
                       MR. BONACA:  Right.
                       MS. DROUIN:  And have a reliability of --
           that's unacceptable to us.
                       MR. KURITZKY:  And I guess one of the
           other things that will come up when we -- or that we
           have to consider when we look at the non-ECCS systems
           is that right now the ECCS performance calculation is
           just to look at the safety where you need the actual
           ECCS systems.
                       And so when you make sure you meet your
           20-200 DUEF (phonetic) threshold you have, relying on
           just those ECCS systems.  If we're going to credit
           RCIC or service or cross-tie or something like that,
           you know, there are at present no calculations
           demonstrating that they can meet 20-200.
                       MR. BONACA:  Right.
                       MR. KURITZKY:  So we wouldn't want to have
           the calculations need to be run.  So we would want to
           credit systems where it would be fairly obvious that
           the function could be accomplished.  So that's
           -- those are three of the biggest issues that we're
                       MR. BONACA:  And I guess the same would be
           under the fit for PWRs.
                       MS. DROUIN:  Yes.  Yes.
                       MR. BONACA:  How credible is it that you
           complete the fit, first of all, for the given plant
           and then what credit do you give the function so that
           you don't degrade the reliability of the ECCS?
                       MR. KURITZKY:  Okay.  So
                       CHAIRMAN SHACK:  How would you -- or how
           do you propose to address the LOCA frequency for the
           non-pipe break LOCAs?  Is this a database thing again,
           you would look at experience and try to do estimates
           on that?
                       MR. KURITZKY:  That's kind of up in the
           air right now.  As I mentioned, we're going to try and
           get some meetings together with some of our -- the
           engineering folks and the PRA folks to kind of has
           some of this out.
                       It may not -- you know -- it may be some
           kind of bounding.  We may put some kind of bound on
           the numbers from 57.50 to try to account for some of
           these other mechanisms.  Some of them specifically may
           have some data on them.
                       For instance, seismic LOCAs, you know,
           seismically induced pipe breaks, okay, or at least not
           data, but the analyses show that they're very low
           contributors.  On the other hand, seismically indirect
           -- you know -- seismic indirect LOCAs where you've
           failed the supports on something and that falls and
           breaks a pipe, well, the models show that to be on the
           order of what you're getting from just the pipe break
                       So in some of them we have some kind of
           -- you know -- we don't call it data, but we have some
           kind of models that give us some feel for what kind of
           contribution they're going to make.  Other ones are
           really kind of floundering right now.
                       The shut-down conditions, drain-down
           events, we really don't have very good weight of data
           for that.  There's not very many studies that are out
           there, at least not -- and not in this country
                       So it's -- right now we don't know exactly
           how we're going to address that.  That's why that
           issue is out, you know, we're taking input from
           anybody who wants to give us input on issues like
           that.  I don't have a proposal right now.  Okay. 
           Well, let me just --
                       MS. DROUIN:  No, let's keep going, time-
                       MR. KURITZKY:  Okay.  So let me just move
           on to the other piece that we had in SECY 133 was the
           long-term piece looking at the possibility of
           redefining large-break LOCA or the spectrum of breaks
           that would be considered in the 50.46 analyses, and
           Carolyn Fairbanks.
                       MS. FAIRBANKS:  Yes.  We've just really
           initiated the work on this long-term objective out of
           risk-informing 50.46.  The objective here, which would
           be at a time line of about the end of three years
           would be to have a tech basis developed for redefining
           the large-break LOCA.
                       We've developed a program approach here. 
           The approach that we were taking was really trying to
           parallel the work that's being done to revise the PTS
           rule, pressurized thermal shock rule.  We wanted to do
           this and we've had a meeting with industry a couple
           months ago to relay that and to say that this is our
           objective in following this example, to have a level
           of rigor in our approach that's equivalent to that
           that's being pursued with PTS.
                       So far we are doing some work on tasks one
           and tasks three.  There are some existing codes on
           probabilistic break codes, probabilistic fracture
           codes.  We're adding at this point some sub-critical
           crack growth modules.
                       As Alan described, there are some issues
           as far as indirect failures that --
                       DR. POWERS:  I'm just a little confused
           when you say the word "codes."  You're not talking
           about the SME code or anything like that?
                       MS. FAIRBANKS:  No.  No.  No.  This would
           be programs.
                       DR. POWERS:  Computer programs.
                       MS. FAIRBANKS:  Programs, computer
                       DR. POWERS:  And --
                       MS. FAIRBANKS:  Modeling.
                       DR. POWERS:  -- and so which ones are
                       MS. FAIRBANKS:  We're starting off
           initially, we're just about done I think adding some
           subcritical crack growth modules to the squirt code,
           which is a probabilistic break code.  There are a
           number of other codes, P-squirt, PROLBB, and we're not
           really sure --
                       DR. POWERS:  I'm wondering --
                       MS. FAIRBANKS:  Pardon me?
                       DR. POWERS:  -- I'm wondering just which
           of these codes predicts the cracks like in plants like
           Summer and places like that.
                       MS. FAIRBANKS:  We have to add that in. 
           Jumping a little bit ahead, the --
                       DR. POWERS:  How about the cracks that we
           have not seen today but will appear next year?
                       MS. FAIRBANKS:  Jumping a little ahead
           again, those are things that are we going to consider,
           and they are difficult to do.  A year ago nobody would
           have thought we would be having to add in some BWSCC
           modules; Summer occurs, and we're going to be doing
                       We're not far along, not far enough along
           yet to have that done, and if we look back
           historically, we do see that new degradation
           mechanisms do arise, some more significant than
           others, but there is a history.
                       You know, we have a little interesting
           plot, about every seven years there's something new.
                       DR. POWERS:  Yes.
                       MS. FAIRBANKS:  And so I don't think
           anyone would feel comfortable in risk-informing this
           without accounting for some possible future
           degradation mechanism.  How we're going to approach
           that we haven't quite settled yet, but that's
           certainly one thing that's going to be incorporated
           into this work.
                       MR. KURITZKY:  And I think also the point
           that -- of course, we definitely need to focus on, but
           also, each of these clear mechanisms shows up, you
           know, I think one time Mike Mayfield showed a slide
           that showed like every seven years a new mechanism
           shows up that they hadn't thought of before.
                       But in all cases these mechanisms that
           have shown up, we don't have a LOCA so far, knock on
           wood, and we'd identify the mechanism and then we do
           some analysis of it.  We come up with some type of
           response or something that's implemented to try and
           control it.
                       And so we've managed to avoid having a
           LOCA.  So in fact, yes, we do need to consider that
           there could be other mechanisms that are going to crop
           up and get us as time goes on.
                       But we also, you know, keep in mind that
           once that mechanism -- unless that mechanism shows up
           and it acts fast enough that we end up with a LOCA
           condition right away -- we'll evaluate it and try and
           address it so that, you know, corrective actions will
           be taken to minimize its impact on the LOCA frequency. 
           That's just one other thing we need to consider.
                       MS. FAIRBANKS:  That's something that we
           really think, is considering our input, too, with LOCA
           frequency for the LOCA/LOOP.
                       DR. POWERS:  It sounds like, if I follow
           your logic, we should get rid of these things.  I
           mean, you say we got a lot of band-aids, and we don't
           really need band-aids, because nothing ever results in
           a LOCA.  So why worry about it?
                       MR. KURITZKY:  Like I say, with the band-
           aids, your band-aids is what -- the corrective actions
           that come up when we discover these things, we need
           those band-aids.  That's what keeps the LOCA frequency
                       If we didn't put these -- if primary
           -- crack and popped off and we just said, well, that's
           a new mechanism, okay, very -- that's good, let's keep
           going the way we're going, then I would expect to see
           an increase in that LOCA frequency.
                       I'm not saying we wouldn't see one now
           anyway because of this mechanism, but the idea that we
           find it, now we address it, we put in corrective
           actions to minimize it.
                       So you wouldn't expect to see, even if
           there is going to be some delta in the LOCA frequency,
           it wouldn't be of a magnitude as if you just let the
           thing go off on its own and didn't address it.  So
           there's some kind of self-correcting or self-
           modulating type of mechanism there.
                       MS. FAIRBANKS:  Also shoes that as we're
           approaching this we're looking at all of the different
           type of crack growth modules to incorporate axial,
           circumferential and surface cracks.  They will all be
           incorporated into the modeling.
                       We had a -- as I said earlier, we had a
           meeting to convey this approach to industry, and right
           now we're trying to support PRAB to the best we can
           with our knowledge and our plants, that we're using it
           in development of our break frequency and pipe size
           diagrams to support the --
                       DR. POWERS:  What is PRAB again?
                       MR. KURITZKY:  PRA -- it's probable --
                       MS. DROUIN:  That's us.  What Carolyn is
           getting there is that --
                       DR. POWERS:  I thought it was a code for
           a second.
                       MS. DROUIN:  -- our technical work on the
           reliability side, we're supposed to be finished, you
           know, early in the spring time frame.  We don't want
           to move forward with a recommendation and then say a
           month or six months later they come in on their long-
           term work and the frequency numbers that we're using
           are totally not in agreement with them.
                       So we're trying to have some kind of
           convergence here between what they're doing on the
           large pipe break size versus what we're trying to do
           on the reliability.
                       MS. FAIRBANKS:  And it is a complex issue,
           because in the approach for this we're even at the
           initial point of deciding which pipe break sizes we're
           going to look at, which lines those would be on, what
           is the -- what are the operating conditions, what are
           the environments for that size of diameter, which
           degradation mechanisms would be potentially involved
           in those.
                       And so you're not necessarily going to get
           a curve when you're looking at the break size versus
           frequency.  I think that is really just wrapping up
           where we are at this point.  We are pursuing this --
                       MR. BONACA:  Just to understand a little
           better, just to know.
                       MS. FAIRBANKS:  Okay.
                       MR. BONACA:  For example, clearly, I mean,
           you have a whole issue of crack growth and development
           in two different size breaks, depending, you know, I
           think there is a time parameter there.  I mean, you
           have a crack initiation result.
                       Now, are you looking also at how a seismic
           event could result in a certain break size, given that
           you have an identified crack?
                       MS. FAIRBANKS:  Yes.
                       MR. BONACA:  For example, there is some
           event where you have a crack or multiple cracks and
           now you do have a seismic event, and so you will be
           looking at that?
                       MS. FAIRBANKS:  Yes.  We'll be looking at
           all the modes.
                       CHAIRMAN SHACK:  It's more difficult than
           it is in the PTS case, though, where, you know, you
           sort of assume that the only flaws you have to worry
           about are due to fabrication.  You know, when you
           allow flaws to suddenly appear --
                       MR. BONACA:  Right.
                       CHAIRMAN SHACK:  -- and to grow, life gets
           a great deal more difficult than the --
                       MS. FAIRBANKS:  And repair welds, many
           things are going to come --
                       CHAIRMAN SHACK:  Yes.
                       MS. FAIRBANKS:  -- up to complexity.
                       CHAIRMAN SHACK:  But I guess in your case,
           though, I mean, the frequency you need to get rid of
           a large break LOCA as a design basis accident is
           really probably a whole lot lower than you need --
           although I guess you want to use the most realistic.
                       I mean, it's not as though you're going to
           just stick a sort of a conservative estimate, because
           you can move on.  But in reality, you could have a
           fairly conservative estimate for the large break LOCA
           and still be able to obtain some relief, I would
           think, in the simultaneous LOOP, wouldn't you?
                       MR. KURITZKY:  The thing -- difference
           being is that right now, since we don't have LOCA
           frequencies by pipe size, which is something that we
           idealistically hope that we can maybe get in the
           longer-term, right now we have to deal with the large-
           break LOCA category from a PRA stance, which is
           essentially something six inches per PWR, every six
           inches and above.
                       So we have to make it hold for everything
           six inches and above.  In the future we may be able to
           show that the ultimate frequency you need to get rid
           of a design based axiom, yes, we need to be lower.
                       But you may be able to do it with, say, a
           14-inch pipe or a 12-inch pipe, and that frequency may
           be much lower, while the six-inch break, you know, you
           may give up something.  So you're right.  You can
           definitely get a much lower frequency to get it out of
           the design basis.
                       But because we can't do it by a pipe size
           right now, we have to do it for everything that's,
           say, six inches and above that we can't afford to have
           too many layers of, you know, conservatism piled on
           there to, you know, address various
           uncertainties before we would start to run into a
           -- we lose our flexibility also.
                       MR. BONACA:  Although you mentioned before
           you are going to include consideration of heavy loads,
           for example, in heavy loads then the frequencies
           associated with a procedural violation of some type is
           a measured one, perceive that, you know, it's -- I
           think it's more likely that you have that happening
           than certainly you have just a mechanistic double-
           ending break.  So that may drive up your frequency
           quite a bit.
                       MR. KURITZKY:  Well, except that it's not
           just a question of having heavy load drop.  It has to
           be -- the operations have to be taking place during
           power.  You have to be doing something that's inside
           the containment where you're over --
                       MR. BONACA:  I'm talking about maybe
           you're -- you know -- you're in shutdown conditions.
                       MR. KURITZKY:  Yes, for the -- oh, for a
                       MR. BONACA:  You haven't removed the head
           yet.  You have the fuel there and whatever.  You're
           moving some heavy load and, you know, a heavy load
           have enough to do damage.
                       MR. KURITZKY:  Yes.  In fact, at shutdown,
           that's one of the -- like I mentioned before -- that's
           one of the things we're really struggling with right
           now because of all types of -- the drained elements or
           LOCA initiates that could have occur at shutdown.
                       MR. BONACA:  You know, that could drive
           your frequency there, because I mean, that's a
           procedural violation of some type.
                       MR. KURITZKY:  Something we have to
                       MS. FAIRBANKS:  I think we can move along.
                       MS. DROUIN:  Move along?
                       MS. FAIRBANKS:  No other questions.
                       MS. DROUIN:  Okay.  Well, at this point
           we've gone through the four different areas covered by
           50.46 and tried to give you an update and status of
           where we are at.  Just going back to what we had said
           in the SECY in terms of our schedule, we had for the
           evaluation model and the acceptance criteria that that
           technical work would be done, you know, on or before
           July 2002.
                       That work right now is still on schedule,
           and as you've seen, you know, we're deviating a little
           bit from what we said in the SECY in terms of what we
           would do there.  On the risk-informed alternatives to
           the reliability requirements, our work there is due in
                       It's going to be very tight to us trying
           to meet that schedule, a lot of issues there we're
           still trying to --
                       MR. KURITZKY:  Oh, that's 2002?  I thought
           it was 2003.
                       MS. DROUIN:  On the definition of the
           break size.
                       DR. POWERS:  I just have to interject. 
           One of the commissioners has bet me that he will not
           have to vote on this during his term of office.
                       MR. KURITZKY:  How many years do they have
                       DR. POWERS:  If I told you that I'd reveal
           which commissioner it was, but several.
                       MS. DROUIN:  You mean, for the break size?
                       DR. POWERS:  He said he would not have to
           vote on any revision to 50.46 in his term of office.
                       MS. DROUIN:  Well, if he doesn't vote,
           then he, you know, we can't go forward with that break
           size.  I mean, he's kind of set the -- he's stacked
           the deck -- yes.
                       CHAIRMAN SHACK:  He said it would never
           come to him to vote.  Looks like -- I mean, we're
           still working on the SECY.  The vote is a long way
           down the road.
                       MS. DROUIN:  Yes.
                       DR. POWERS:  I think I'm going to owe him
           some money here.
                       CHAIRMAN SHACK:  But the most substantive
           thing that's changed since 133 is the skepticism about
           the possibility of relief for the K curve.
                       MS. DROUIN:  Yes.
                       CHAIRMAN SHACK:  I mean, you were more
           optimistic in 133 than you are --
                       MR. KURITZKY:  Right.
                       MS. DROUIN:  Correct.
                       CHAIRMAN SHACK:  -- from today's
                       MS. DROUIN:  Correct.
                       CHAIRMAN SHACK:  But everything else is
           more or less following, which you laid out --
                       MR. KURITZKY:  Right.
                       CHAIRMAN SHACK:  -- in 133.
                       MS. DROUIN:  That's correct.  But you
           know, our technical work on 50.46 is not tied to any
           commissioner's vote.  It's the rulemaking.  So -- but
           we plan to have all of our technical work done as we
           laid out in 133.  The public has been very interested
           in this program, followed it closely.
                       We have had a lot of meetings with the
           various stakeholders.  We can -- we plan to continue
           having a lot of meetings with the stakeholders.  We
           just have listed a couple there that's happened back
           in August on the LOCA frequencies.
                       We had another one on the LOCA and new
           frequencies.  We just had a second one in October.  We
           plan to have another one at the end of November.  So
           I mean, almost on a monthly basis you can see we're
           meeting with the stakeholders on this program.
                       They've been following it very closely,
           giving us a lot of good data, also working with us. 
           So on that note, that kind of sums up where we're at
           on the status for 50.46.
                       CHAIRMAN SHACK:  You want to make any
           comments?  Okay.  
                       MS. FAIRBANKS:  No comments.
                       SECRETARY HORN:  We were scheduled to have
           a presentation from NEI, Tony -- Mr. Angelo, but he's
           had other commitments and so can't make it today.  And
           I think we're done with the formal presentations. 
           Final comments from members of the 
                       MR. BONACA:  I think it was an informative
           presentation, particularly when it came down to the
           Appendix K tradeoffs that are really in the Appendix
           K model, and then for which we need the credit,
           really, from the K-8 curve.
                       I mean, that was quite a bit of
           information.  I think that that was quite valuable. 
           I don't have any other specific comments, except it
           may be a long time before we have that relief, and
           this work seems to be --
                       CHAIRMAN SHACK:  Where's that low-hanging
                       MR. BONACA:  Yes.
                       MR. KURITZKY:  Drying up.
                       MR. BONACA:  And I thought it was in
           general a very good presentation.
                       DR. KRESS:  I thought so, too, and RP --
           it looks like Option C on that Appendix K is probably
           the best one, plus continuing with the action plan to
           get that additional information.  I worry about using
           frequencies to eliminate the LOCA/LOOP combination,
           because I've been considering this a defense in depth
           type of approach.
                       For sabotage and other things, I think
           there are other ways you can get LOCA/LOOPS at the
           same time, but I haven't thought enough about it to
           get a firm position on that.
                       MS. DROUIN:  One of the things I didn't
           say and we tend to forget about our framework
           document, but we do follow the framework very closely. 
           And the framework does not allow us, regardless of
           what the numbers say, to violate those six elements of
                       DR. KRESS:  That's true, yes.
                       MS. DROUIN:  So you know, we tend to talk
           a lot about the numbers and we tend to, you know, not
           verbalize so much the framework, but everything does
           pass through that framework and you cannot violate one
           of those defense-in-depth elements, regardless of what
           the numbers tell us.
                       DR. KRESS:  I guess we're supposed to
           decide on what to do about the full committee?
                       CHAIRMAN SHACK:  No.  I don't think we had
                       DR. KRESS:  We don't.
                       CHAIRMAN SHACK:  -- planned to have a
           presentation to the full committee.
                       MR. MARKLEY:  Just a Subcommittee report.
                       CHAIRMAN SHACK:  Just a subcommittee
                       DR. KRESS:  Okay.  Good.
                       MR. BONACA:  You know, just to interject
           on the issue of LOOP.  I mean, I agree that's an issue
           of defense-in-depth that makes you uneasy when you
           think about eliminating it if you really want to cover
           all the bases.
                       But one of the big challenges of the
           licensees is really the frequent start of the diesels,
           you know, cold and the wear of the diesels, and also
           the very strict and demanding requirements imposed on
           a lot of systems like, you know, HVAC and so on and so
                       I mean, does it mean that you -- I mean,
           could we possibly have still a design capability for
           LOCA and LOOP with less demanding requirements imposed
           on the equipment from a perspective of testing?
                       Couldn't you look at the risk significance
           of reducing some of the tests imposed on the equipment
           that really are the driving force right now for the
           licensees on requesting some relief?
                       MR. KURITZKY:  Well, I think in regards to
           that, I mean, most plants' technical specifications
           have already been changed so that that fast start of
           the diesel --
                       MR. BONACA:  Yes.
                       MR. KURITZKY:  -- only has to be done --
           used to be done once a month, but it's down to, I
           think, once every six months.
                       MR. BONACA:  That's true.
                       MR. KURITZKY:  Assuming you pass it.  So
           there has been some relief in that regard already. 
           What it comes down to is do you still have to have
           your diesel designed and your equipment designed to
           come up at a certain time.
                       And that's governed by what kind of flow
           rates -- you know -- what kind of flow rates have to
           break and how quickly you have to get water back in
           the core cylinder.  And how big a break you're going
           to consider and what the frequency of that event is,
           you know, determines the time when that diesel has to
           come on board.
                       But as far as the testing, I think most
           plants I think already have managed to reduce that,
           you know.
                       MR. BONACA:  I've not seen, but some of
           the systems like the HVAC system and the time you need
           to draw a vacuum in the enclosure buildings, I mean,
           that's stuff that is tremendously demanding on the
           plants and on the equipment.
                       And so anyway, but that's just a thought
           that one could also determine the risk increase
           associated with the relaxation of some of the
           requirements, and they may find that you can still
           have a high expectation of success of a LOCA and LOOP,
           you know, coping with both of them by imposing less
           restrictive requirements.
                       I agree with the -- on the start of the
           diesel.  That's one thing that has been done.  But
           again, many of the other systems have not been relaxed
           at all, their testing.
                       MR. KURITZKY:  That's something we can
           look into.
                       CHAIRMAN SHACK:  Well, I guess, you know,
           when I -- I'm not as concerned as Tom is about the
           defense-in-depth, because when I looked at the
           proposed changes I don't see that those really affect
           your defense-in-depth very much.
                       You know, if you were proposing to remove
           some equipment, but the kind of changes I foresee, at
           least from this part, I think eliminating the large
           break LOCA as a design basis accident could have a
           more substantive impact than what one would consider
           defense-in-depth.  But this part doesn't seem to me to
           impact it as much.
                       MS. DROUIN:  Well, you may have some PWRs
           out there who would like to get rid of their
           accumulators, and they could.
                       CHAIRMAN SHACK:  Under this.
                       MS. DROUIN:  Under this.
                       MR. KURITZKY:  Well, so far we have to
           wait and see, but it doesn't even look like they're
           going to get too much in that regard, because most of
           the IPEs or the PRAs are going to correct the
           accumulators for the smaller breaks, also, what's
           called medium breaks.
                       And so therefore, you may not -- from a
           reliability point you still may not make the grade. 
           But it's possible that maybe for A, if you have a
           spare accumulator, you know, that you may be able to
           relax the allowed out of time on it.
                       But again, whether or not somebody takes
           something out of a plant or whether this gets
           relaxation in their technical specifications, I think
           we're going to have to decide, the staff will have to
           decide whether or not -- you know -- even if the
           numbers come out that show that you could do that, we
           have to decide whether or not that meets the defense-
           in-depth filter or whether or not we're just
           comfortable with that.
                       And we may want to put some kind of
           limitations on that, some kind of restraints.
                       CHAIRMAN SHACK:  Dana?
                       DR. POWERS:  I guess I opened the Pandora
           with the sabotage concern, the defense-in-depth, and
           I think I still wrestle with defense-in-depth and what
           we're -- where it is and how it is in the regulations
           and how far it goes.
                       I come back to the earlier presentation,
           I look forward to seeing what comes out of these
           studies on the oxidation of clads and your
           circumstances.  And it looks to me like what -- after
           a lot of complications of phenomenological discussions
           -- that the basis idea that you will only go after the
           17 percent oxidation and replace it with an
           embrittlement criterion seems like a pretty good idea
           to me.
                       I mean, I feel sorry for those that have
           to demonstrate that they have retained ductility,
           because I think that's a much harder analytic tool
           than just showing that you don't hit 17 percent
           oxidation using Baker-Just kinetics than in a fairly
           simple temperature transient.
                       But I think it's a much more defensible
           thing and the challenge that the industry would face
           in showing that the oxidation kinetics of every type
           of clad that came along was bounded by Baker-Just
           might prove as much of a challenge as the calculation
           of ductility.
                       But I guess it's -- I mean, I think before
           you finalize on this we just have to wait for the
           experimentalists to get their act together and get
           some data, and it takes a lot of data.
                       CHAIRMAN SHACK:  Other comments?
                       MS. DROUIN:  I have a question.  You know,
           we were asked last time, you know, to keep the ACRS
           informed, you know, of the status.  I look down the
           road to the future of, you know, where our next
           milestones are and, you know, the technical work on
           the reliability parts to be done at the end of April,
           the acceptance criteria and evaluation model in July.
                       My question is to, when would you all be
           interested in seeing us again, and would it be at the
           Subcommittee level, the full committee level?
                       DR. POWERS:  You know, my initial
           reaction, of course, Mary, is the committee is always
           delighted when you want to come talk to us because you
           always have something interesting to tell us, but I
           think that really it's up to you.
                       And I think you've got a good strategy
           here that you're trying to pursue and I think it's
           when you think you have enough substance in there to
           get some opinions instead of some speculations and
           questions --
                       MS. DROUIN:  Okay.
                       DR. POWERS:  -- that we want to hear.  And
           I would suggest this is before the full committee
           because everybody has a stake in this.  And so you
           want to ask not only for a time, but enough time so
           that you can -- you're not rushed in getting your
           points across.
                       So don't let them short-change you on
           time, in other words.  But I think it's really up to
           you because you know your schedule and the various
           challenges.  It's when you think you've got enough to
           -- this to mark some point on it, rather than any
           -- rather than judging on the calendar list, judge
           based on the progress of the work.
                       MS. DROUIN:  No.  No.  I agree and I
           didn't know if there was --
                       DR. POWERS:  Sure.
                       MS. DROUIN:  -- something here in
           particular that you wanted to hear back again on, but
           absolutely, when we feel we've got --
                       DR. POWERS:  Your current milestones sort
           of suggest something like April or May --
                       MS. DROUIN:  Yes.
                       DR. POWERS:  -- when you've finished the
           reliability.  But obviously, if you're not there,
           you're not there.
                       MR. BONACA:  And the other thing, the
           other criteria I would use is if you feel there is
           some surprise for us.  For example, today I think was
           a very valuable presentation because at least for me
           I thought that the decay heat curve was a low-hanging
           fruit, and now I've been, you know, educated on that.
                       And I think that was an important time to
           hear about that.  Otherwise, we would be still
           proceeding in our mind with the thought that, here it
           comes, you know.
                       MS. DROUIN:  And that's why we felt it was
           important to come now.
                       MR. BONACA:  Yes.
                       MS. DROUIN:  Because we were deviating
           from what we had in the SECY, and what we had told you
           guys in our letter.
                       DR. POWERS:  I guess one of the real
           problems that the NRC will face, Mario, is just that
           lots of people think that decay heat curve is a
           "gimmee."  I mean, I've even characterized it as the
                       MR. BONACA:  Yes.
                       DR. POWERS:  And there's going to be --
           they're not going to have had the benefit of the
           discussions that we went through and so they're going
           to persist in taking that.
                       I'm wondering if maybe you shouldn't think
           seriously about formulating that into a paper that you
           could give to -- before the ANS or some body like that
           and try to socialize the opinion to at least in some
           sense take the weight off your back, because you're
           going to have a lot of people says, ah, NRC, they'll
           never change this.
                       I mean, you're just -- it's going to be
           conventional wisdom and maybe you ought to reach out
           a little bit to the -- at least the technical
           community and advertise that position.
                       MR. BONACA:  I think that's an excellent
           recommendation because I thought that the presentation
           that you provided, Steve, it was outstanding in that
           sense.  I think it was very pointed.
                       It showed some of the effects and really
           was a good -- you know -- I mean, you come out of it,
           you can ask some pointed questions to that, but then
           you come up with an understanding of what the issues
                       And I think that that would be valuable
           because I think there is -- in my judgment there is a
           widespread belief that that's an easy tradeoff and how
           come the NRC's not moving on this.
                       MR. BAJOREK:  By the way, a lot of those
           figures that I did show, we're intending to put that
           in a OCONEE paper, submitting that at the end of the
                       DR. POWERS:  You know, that's not -- I
           mean, that's the kind of forum where you need to
           socialize these ideas and what-not and put it before
           the technical community.  If they find fault with it,
           of course, you learn something.
                       But if you're of sound position, then they
           learn something.  So I mean, there's no loss here.
                       MR. KING:  We'll take a commitment to do
           that, figure out the right forum and the right
                       DR. POWERS:  Yes, you know, because
           otherwise, you get this very unfair accusation because
           people just haven't seen that sort of stuff.
                       MR. KING:  Right.
                       DR. POWERS:  They haven't thought about it
           as much as you have.
                       CHAIRMAN SHACK:  Yes.  I mean, in July you
           just sort of had a general statement that, you know,
           you have to consider the compensation non-
           conservatisms, but now you have actually something
           fairly specific, and you know, I think it makes it a
           much more substantive case than saying, there may be
           non-conservatisms that won't be bounded.
                       DR. POWERS:  And it gives the model
           builders some grist to think about, too.  They may
           find that, well, you're talking about RELAP having
           some less than desirable features perhaps in the code. 
           So maybe people developing models can think about it. 
           We'll see.
                       MR. BONACA:  The other thing which is
           significant here is that so many of the comparisons
           were based on calculations performed by licensees.
                       DR. POWERS:  Sure.
                       MR. BONACA:  And so those are facts,
           really, and not speculation on the part of the staff,
           really.  It's coming out of presentation and some
           meters provided by the licensees.
                       CHAIRMAN SHACK:  If there are no
           additional comments we can adjourn the Subcommittee
                       (Whereupon, this ACRS/ACNW Joint
           Subcommittee meeting was concluded at 12:09 p.m.)


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