Joint Subcommittees on Materials & Metallurgy, Thermal-Hydraulic Phenomena, and Reliability & Probabilistic Risk Assessment - July 9, 2001


                                         UNITED STATES OF AMERICA
                   July 9, 2001
                Rockville, Maryland
                 The Subcommittee met at the Nuclear Regulatory
           Commission, Two White Flint North, Room T2B3, 11545
           Rockville Pile, at 1:30 p.m., William J. Shack, Joint
           Meeting Chairman, presiding.
                 WILLIAM J. SHACK           Subcommittee Chairman
                 GEORGE APOSTOLAKIS         ACRS Chairman
                 MARIO V. BONACA          
                 F. PETER FORD
                 THOMAS S. KRESS
                 GRAHAM M. LEITCH
                 STEPHEN ROSEN
                 JOHN D. SIEBER
                 ROBERT E. UHRIG
                 GRAHAM B. WALLIS
                 B. Shack . . . . . . . . . . . . . . . . . . 3
                 Mary Drouin and Alan Kuritsky. . . . . . . . 3
                 Adrian Heymer, Terry Reick . . . . . . . . 124
           ACRS GENERAL DISCUSSION AND ADJOURNMENT. . . . . 147                           P-R-O-C-E-E-D-I-N-G-S
                                                      1:33 p.m.
                       DR. SHACK:  This is the Advisor Committee,
           an ACRS Joint Committee on the ACRS Subcommittees on
           Materials and Metallurgy, Thermal-Hydraulic Phenomena,
           and Reliability and Probabilistic Risk Assessment.
                       The meeting will now to come order.  I am
           William Shack, Chairman of the Subcommittee on
           Materials and Metallurgy.  Graham Wallis is Chairman
           of the Subcommittee on Thermal-Hydraulic Phenomena,
           and George Apostolakis is Chairman of the Subcommittee
           on Reliability and PRA.
                       Subcommittee members in attendance are
           Mario Bonaca, Peter Ford, Thomas Kress, Graham Leitch,
           Steve Rosen, Jack Sieber and Bob Uhrig.
                       The purpose of this meeting is to discuss
           the status of risk-informed revisions to the technical
           requirements of 10 CFR 50.46 for emergency core
           cooling systems.  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 meeting.
                       The rules for participation in today's
           meeting have been announced as part of the notice of
           this meeting previously published in the Federal
           Register on June 27, 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 may be readily heard.
                       We have received no written comments from
           members of the public regarding today's meeting.
                       I don't really have any comments.  We've
           sort of discussed some proposed revised of 50.46
           before, and I think we'll be going into a little more
           detail on some of these options today.  And I assume
           that Mark or Mary will do the honors.  
                       So now we'll proceed with the meeting, and
           I'd like to introduce Mike Johnson of NRR who'll
           introduce the topic and the presenters.
                       MS. DROUIN:  My name is Mary Drouin with
           Office of Research, the probabilistic risk analysis
           branch.  At the table also with me is Alan Kuritsky,
           also from Office of Research, and the PI branch.
                       Today we're here to give you a status of
           where we are in 50.46, and we're going to concentrate
           primarily on the paper that is on its way to the
           Commission. I will remind the committee the paper has
           not been signed out at this point, so it's still
           sensitive.  Hopefully, it will be to the Commission
           within the week.
                       For today's briefing, we are going to
           concentrate on 50.46. We'll quickly go over, you know,
           the purpose and what we would like to see out of
           today's discussion, the feedback we'd like from ACRS.
                       Quickly to remind a little bit about
           option 3 in the background and what we're supposed to
           be accomplishing.  And then hone in on the particular
           activities that are associated with 50.46.  
                       There are three primary things that we're
           going to touch on:  The feasibility of changing the
           actual 50.46, going in and tentatively we have some
           considerations to change the actual rule; also looking
           at additional changes to 50.46, things that are more
           in the long term; other Option 3 activities.  And then
           wrap up with what our tentative recommendations and
           our schedule is for 50.46.
                       In regard to today's meeting, again, we're
           focus in on 50.46 and the paper that is making its way
           up to the Commission.  And for today, as we go through
           the different options that we're considering, we would
           like to get feedback from the ACRS on these options,
           any implementation issues that you feel that we may
           overlooked or not addressed adequately enough and
           whether or not was really have come to the conclusion
           that this is feasible or not feasible.  And, of
           course, at this point we are looking for a letter from
           the ACRS to accompany our paper to the Commission.
                       Just briefly on the background, we go back
           to SECY-264, which was the original plan for the
           Option 3 work.  And we also had a framework.  And the
           two important things to remember was a big lesson on
           50.44 is that part of Option 3 has two phases to it.
           And this first phase is strictly a feasibility study. 
           Is it feasible to do the things that we would
           ultimately recommend to the Commission.  That does
           mean that we have done all the technical work that
           would be needed to support a rulemaking, because that
           technical work is part of Phase 2 when we get into the
           implementation once we have received approval from the
           Commission to proceed forward. And there seems to have
           been some confusion there.  So, I just wanted to
           quickly highlight that again that the Phase I when we
           complete it and we make our recommendation to the
           Commission, that does mean that all the technical work
           is done.  
                       We've done enough work to have a good
           comfortable feeling that this is feasible, that it
           will work out, but there's no guarantee that it would.
                       DR. WALLIS:  Besides feasibility, are you
           looking at desirability as some sort of criterion for-
                       MS. DROUIN:  To me desirability is part of
                       DR. WALLIS:  You can do all kinds of
           feasible things, but they may not be desirable.
                       MS. DROUIN:  That's right.  So part of
           that feasibility is that it's desirable.
                       DR. WALLIS:  Okay.  
                       MS. DROUIN:  I mean, you might be able to
           do something, but if nobody wants it --
                       DR. WALLIS:  That's right.
                       MS. DROUIN:  Right.  So absolutely, that's
           part of the feasibility.
                       DR. SHACK:  Well, that was in your
           prioritized bullet, right, that you've already decided
           this particular one is a high priority candidate for
           Option 3?
                       MS. DROUIN:  Yes.  Yes.  And that looks at
           the resources and the cost, and the benefits.  I
           wasn't going to spend time going through each of
           these, I just wanted to really focus on the difference
           between Phase I and Phase II.  Okay.  
                       Now, getting into 50.46.  We talk about
           50.46 and, and they used that number 50.46 rather
           loosely.  But when you go and you look at Part 50 and
           you talk about the ECCS performance, which is really
           more what we're talking about, then you're really
           talking about 50.46, you're talking about Appendix K
           and you're talking about GDC 35.  These you have to
           handle together.  You can't just deal with 50.46 and
           exclude Appendix K and GDC 35.  They work together as
           one entity.
                       And when you look at these and what are
           the ECCS requirement, they break down into these four
           what I would call topical areas in terms of what the
           requirements are trying to achieve.
                       One is the ECCS reliability.  The
           acceptance criteria for the ECCS, it's evaluation 
           model and then ultimately the LOCA size definition.
                       And as you come out of these boxes to the
           right, then you start seeing -- and we tried to mimic
           the words right from the regulation so what exactly
           what is the technical requirement.
                       When you look at the ECCS reliability, and
           this is where I come back to, it's not just 50.46,
           because that reliability, this row here is showing up
           in GDC 35.  And that ultimately gets to the single
           failure criteria and the requirement for your
           simultaneous LOCA and LOOP requirement.
                       We come down into the next one, which is
           the ECCS acceptance criteria and you ultimately get to
           -- this one is in 50.46, the five criteria that they
           have to meet from their performance.  And you hear
           about, you know, your peak cladding temperature, 2200
           degrees, your long term cooling, your coolable core
           geometry, etcetera.
                       Your next one, your evaluation model, now
           this is a coupling here of both 50.46 and Appendix K,
           which gets into what the analysis you have to do and
           what model that you're going to have to use.
                       And then your last topic then gets into
           the LOCA size definition, and this is showing up in
           several places.  It does show up exactly in 50.46.  It
           shows up in Appendix K, which actually defines, and
           you'll see these same words in those three places of
           what is defined as a loss of cooling accident in terms
           of the pipe break size and location.  
                       So in risk-informing this, these are the
           things that we're dealing with, trying to look the
           reliability, looking at the acceptance criteria or get
           the evaluation model and look at the LOCA size.  So
           those are going to be the four things that we're going
           to touch on.
                       So, at this point, I'm going to turn it
           over to Alan, and he will start walking us through
           each of these four areas.
                       MR. KURITSKY:  Okay.  As Mary said, I'm
           Alan Kuritsky, I'm in the PI Branch in the Office of
                       Based on the staff's feasibility
           assessment of 50.46 and GDC 35 and Appendix K we feel
           that changes to the reliability and acceptable
           criteria and evaluation models may be justified.  
                       More specifically what we're looking at is
           ECCS reliabilities resulting from the technical
           requirements may not always be commensurate with the
           risk significance of the various LOCA sizes.  
                       DR. WALLIS:  How do you make a measure of
           this commensurate?  What do you balance against what
           to decide whether its commensurate or not?
                       MR. KURITSKY:  Right now we've been using
           as our metric core damage frequency.
                       DR. WALLIS:  Balance versus?
                       MR. KURITSKY:  In other words --
                       DR. WALLIS:  When it gets below a certain
           amount, it's not worth bothering, its a go/no go kind
           of thing?
                       MR. KURITSKY:  Yes.  For instance, if you
           had a 10-5 frequency of initiating event and you had
           10-3 ECCS reliability and it required some additional
           failures in your calculation that would make it even
           lower, you may say okay that's not commensurate.  It's
           either CDF or just a total frequency of the sequence
           of events you consider.
                       DR. APOSTOLAKIS:  I don't understand the
           second bullet anyway.  Can you explain it?
                       MR. KURITSKY:  The one that we're just
                       DR. APOSTOLAKIS:  Yes.  What does it mean?
                       MR. KURITSKY:  Well, just pretty much what
           I was just saying.  If you have a frequency of, let's
           say, a class of LOCA that may be 10-5, okay. And then
           the technical requirements may require -- let me use
           this example first.
                       Technical requirements may require you
           also consider for that class of LOCAs a simultaneous
           loss of off-site power and a single worst additional
           failure.  If you have a 10-5 frequency of this
           initiator and it's another 10-4 or 10-2 for something
           as loss of off-site power, an additional maybe 10-2
           for another single worst additional failure and you
           end up with a frequency of that series of -- you know,
           sequence of events which is already down to the 10-8/9
           level and you're having that in the core damage, it's
           just that sequence, that's the events.  So to us that
           means that, you know, you rely on what you require of
           these, yes.  You would not need to have as high
                       When I go to the loss of off-site power
           assumption and that single failure, that all feeds
           into the ECCS reliability.  In other words, when
           you're assuming that it has to operate with off-site
           power failure, you're assuming it has to operate given
           the failure of some piece of equipment, final has to
           go to how reliability that system has to be.  In that
           case you may be requiring a greater reliability than
           is really called for by the frequency of that
                       DR. APOSTOLAKIS:  Now, if I look at the
           first bullet and what you just said, and compare it
           with the -- what is left out is the LOCA size
                       MR. KURITSKY:  Yes, and that's going to
           show up when we discuss the longer term, the
           additional --
                       DR. APOSTOLAKIS:  So the message you're
           sending with this is that change as to the LOCA
           definition model may not be just --
                       MR. KURITSKY:  Right now we don't -- we
           haven't established the feasibility level right now.
                       DR. APOSTOLAKIS:  Okay.  
                       MR. KURITSKY:  And some we're still going
           to look into.
                       DR. WALLIS:  This is really focused on the
           LOCA LOOP simultaneous requirement, isn't it?
                       DR. BONACA:  One of those.
                       DR. SHACK:  
                       Mary, you wanted to say something.
                       MS. DROUIN:  Also the thing that I wanted
           to add is that we say it may be justified.  The words
           that are missing here are "in the short term."  These
           are things that can be done immediately.
                       DR. APOSTOLAKIS:  Okay.
                       DR. SHACK:  We're going to discuss the
           solution of the large break LOCA in more detail,
                       MS. DROUIN:  We're going to get into that
           also here.
                       In answer to Dr. Wallis, if we go back and
           we look at, you know, the flow chart.  Remember the
           liability, that's being set.  So when we talk about
           reliability, we're talking about the single failure
           criteria, we're talking about the simultaneous LOCA
           LOOP assumptions.
                       DR. SHACK:  Although in your second bullet
           you certainly are leaning on the frequency of the
           breaks as a function of break size as far as the ECCS
                       MS. DROUIN:  Yes, that comes into play.
                       DR. SHACK:  You're certainly arguing that
           certain frequencies are much more likely than others.
                       MS. DROUIN:  Correct.
                       MR. KURITSKY:  Okay.  And then the last
           bullet there also is that based on feasibility study
           we recognize that there may be some unnecessary
           conservatisms in the existing requirements we want to
                       DR. APOSTOLAKIS:  Maybe you said?
                       DR. WALLIS:  Are these just conservative?
                       MR. KURITSKY:  Well, we say maybe because
           EDO hasn't signed off on those yet.
                       DR. BONACA:  Well, isn't bullet 2 and 3
           the same?  I mean, really what you're saying there is
           excessive conservatism --
                       MR. KURITSKY:  Yes, it is --
                       DR. BONACA: -- being imposed right now
           because of the requirements?
                       MR. KURITSKY:  Right.  The third bullet
           also is trying to capture things that aren't -- just
           dealing with ECCS reliability.  As Mary showed you in
           that previous slide there's some other things.
                       DR. BONACA:  I understand.
                       MS. DROUIN:  And when you get into the
           acceptance criteria, you know, that's separate from
           the reliability that there's conservatisms in the
           evaluation model.
                       DR. WALLIS:  It's only unnecessary
           conservatisms, and when NEI were here they were saying
           that the accuracy on some of these -- the focus on
           some of these very unlikely events was diverting the
           design into channels which were actually harmful when
           it came to dealing with likely events.  It's not just
           conservative, it's that you're doing the wrong thing.
                       MR. KURITSKY:  Yes, there are a couple of
           examples that indicate --
                       DR. WALLIS:  So you're going to bring that
           sort of thing up, too.  It's not just conservatism
           that's the problem, it's doing the wrong thing because
           you're responding to the wrong kind of -- the less
           likely one and then you're impairing your ability to
           deal the more likely.
                       MR. KURITSKY:  There may be a more optimum
                       DR. WALLIS:  Right. That's right.
                       MR. KURITSKY:  It doesn't mean that the
           current way is a safety concern, but there may be a
           more optimum way.
                       DR. WALLIS:  The optimum, and that's a
           very good one if that can be made.  The optimization
           is a very clear one to me if you can make it.
                       MR. KURITSKY:  Okay.  Some of the
           technical observations and conclusions that we've
           arrived at during the feasibility study conducted by
           the staff is that, as we've been mentioning, current
           evaluation models of ECCS performance may be overly
           conservative for large-break LOCAs.  And that goes
           right back to what we just discussed.  That could be
           because of the additional assumptions that you put on
           in the models.  And it also could be due to specific
           features of Appendix K which we may feel a little
           overly conservative.
                       Current estimates of the frequency of
           large-break LOCAs are uncertain and are not low
           enough, at least the current estimates that we have
           are not low enough to eliminate all large-break LOCAs
           as design based accidents.
                       DR. APOSTOLAKIS:  How long should they be?
                       MR. KURITSKY:  Well, we haven't put our
           finger on the exact number.  Certainly it'd be below
           10-6 confidently.
                       DR. APOSTOLAKIS:  Mean value?
                       MR. KURITSKY:  I say confidently, so I'll
           leave that up to whether we see it as a percentile or
           whether we would be comfortable with a mean.  But if
           we could be comfortable with them being below 10-6,
           that may be somewhere in that ball park.  But we're
           not anywhere near that right now, so we don't really
           have to establish that threshold because we just know
           we're not actually there.
                       DR. SHACK:  Well, you know, when you said
           that the current estimates are not low enough to allow
           elimination, that's the current estimates based on
           data and observations which will, in fact, will be
           limited by the fact that you just -- you know, to get
           those kind of times, you need a lot of observations
           and a lot of hours.
                       MR. KURITSKY:  Exactly.
                       DR. SHACK:  Certainly the estimates from
           probabilistic fracture mechanisms would certainly
           suggest that they're low enough to meet your 10-6
                       MR. KURITSKY:  Right, except that again --
           I don't want to tread to that area because I'm not an
           expert.  That's your expertise.  But our fracture
           mechanics experts actually have some -- are not
           necessarily as comfortable with the operational data,
           the numbers coming from the operational data because
           they don't necessarily address certain failure
           mechanisms like primary wire first corrosion cracking
           which has been showing up recently, and so there's
           some concern on their part that the operational, the
           numbers coming up from operational data are not, say,
           maybe not conservative or they're not properly --
                       DR. SHACK:  They haven't been updated
           sufficiently to take into account new phenomena.
                       MR. KURITSKY:  Right.  Exactly.
                       DR. APOSTOLAKIS:  Has probabilistic
           fracture mechanics ever produced numbers that are 10-3
           or 5 for anything?  It's always 10-x, and X goes -- is
           that an inherent property --
                       DR. SHACK:  Well if you look at a 2 inch
           pipe and a 28 inch pipe, you get very different
                       DR. APOSTOLAKIS:  But never high numbers?
                       DR. SHACK:  Well, the ones for the 2 inch
           pipe would be high.
                       DR. APOSTOLAKIS:  They would be?
                       DR. SHACK:  Yes.
                       DR. APOSTOLAKIS:  Then we would believe
                       DR. WALLIS:  Can I go back to the first
           bullet, I'm sorry.
                       When you say evaluation model, do you mean
           the criteria in Appendix K or do you mean something in
           the codes, which is what I think of as an evaluation
                       MR. KURITSKY:  Well, I guess what I'm
           thinking of is two things.  One may be the assumptions
           used in the model, which goes back to the single
           failure criteria --
                       DR. WALLIS:  Those are sort of criteria,
           they're not technical assumptions in the code of some
                       MR. KURITSKY:  Right.  That's just --
                       DR. WALLIS:  So regulatory assumptions?
                       MR. KURITSKY:  Right.  Right.
                       DR. BONACA:  I understood, for example,
           that your multiplier under the code, it's one of those
           things, is it?
                       MR. KURITSKY:  Okay.  What I just
           mentioned was the first type.  And the second time is
           what Mario just mentioned; it's multiple -- you know,
           anything in Appendix K, some of the actual features,
           required features in Appendix K we may feel are
           actually conservative.  Like, for instance, 1.2
           multiplier on decay heat or, as we're going to mention
           later, the few that we're going to look at.
                       DR. WALLIS:  This might even get down into
           the actual calculation model for a large break.  I
           mean, requiring something like a Moody model in
           Appendix K may not be appropriate if you know how to
           do something better.
                       MR. KURITSKY:  Yes.  
                       DR. WALLIS:  Well, you seem to be thinking
           more in terms of regulatory part rather than the
           technical --
                       MR. KURITSKY:  Right.
                       DR. WALLIS:  -- code modeling part.
                       MR. KURITSKY:  Right.
                       DR. WALLIS:  Okay.  
                       DR. KRESS:  Those models and those
           conservatisms were put there on purpose --
                       MR. KURITSKY:  Right.
                       DR. KRESS:  -- because of the
           uncertainties, probably.
                       MR. KURITSKY:  And the idea being that
           more recent information may allow us to be in a better
           position to --
                       DR. KRESS:  If you think you know better
           what the large-break LOCA frequency might be, so that
           you --
                       MR. KURITSKY:  Well, that's a whole
           another issue.  In the Appendix K part we may know
           more about, you know, heat transfer or we may know
           more about downcomer boiling or something.  There's
           different things that we know more about now then we
           did back in, say, 1974 time frame.
                       DR. KRESS:  So that's sort of somewhat
           separate from actually making a risk-based move.  It's
           just the fine tuning Appendix K as it is now.
                       MR. KURITSKY:  Right.  And, in fact, we're
           going to actually mention when we get a little further
           along how we are actually kind of separating off our
           purposed changes in two groups.  One, which we're
           really changing the Appendix K or 50.46, which would
           then apply to everybody and then the other would be,
           you know, coming from a risk-informed alternative to
           Appendix K  or a 50.46 and then that would be
           something that would be voluntary.
                       So you're right, some of these things are
           just fine tuning what's there already.
                       DR. SHACK:  Where did we leave off?
                       MR. KURITSKY:  Okay.  The third bullet
           just kind of follows on from the second bullet.  The
           current estimates of the LOCA frequencies aren't
           sufficiently low that we can rule them out from the
           design bases, but they are low enough that when we
           combine them with the reliability of the ECCS we don't
           see them as being risk significant.
                       DR. WALLIS:  But if you made the large-
           break LOCA no longer a part of this rule, then the
           reliability might get lost because it no longer has to
           confront the break.  So these aren't independent
                       MR. KURITSKY:  Right.  That's right. 
           That's right.  Okay.
                       And lastly, we note from our plant
           equipment that has been there and designed for the
           LOCA design or large LOCA and LOCA design-basis
           accidents. However, it actually gets a lot of use in
           the defense against a spectrum of beyond-design-basis
           accidents.  So we have to be very conscious that if we
           do make some changes to what's covered in the design
           basis, that we don't allow for something to be  --
           change, removed that we are currently taking credit
           for that has good significance.
                       DR. APOSTOLAKIS:  Can you give an example?
                       MR. KURITSKY:  Well, I'm just trying to
           think.  Almost any equipment that's used in design of
           a large-break LOCA, whether it be a low pressure
           injection pump or whatever that's used to meet the
           success criteria, the current ECCS acceptance criteria
           for large-break LOCA and, you know, that's also used
           for, let's say, in a seismic event beyond design basis
           seismic event that could result in a loss of coolant
           greater than a small LOCA, so therefore you would need
           to have low pressure injection --
                       DR. APOSTOLAKIS:  Well, then you're back
           to a large LOCA, just that the cause changed.
                       MR. KURITSKY:  Right.  The idea being that
           it was in the design basis because of a large-break
           LOCA, but yet it's used for a response to something
           that may be beyond the design basis, in an issue
           that's not considered within the design basis.
                       DR. BONACA:  But actually the report
           identifies the view on design basis, but also in
           transients, for example, certain transients that will
           lead you to the need for some injection, right?  You
           mean, your knowledge, at least in the report, shows
           pretty big spectrum of applications of ECCS injection
           for some issues.
                       MR. KURITSKY:  Right.  Right. Yes, to
           require further initiation.
                       DR. BONACA:  I mean ultimately they end up
           in a LOCA of some type, or maybe, you know, examples
           of station blackout issues and things that drive need
           for -- any requirements for ECCS.
                       MR. KURITSKY:  Right.
                       DR. SHACK:  I mean this notion that the
           large-break LOCA is also the surrogate for all the
           other LOCAs, whether it's man ways or seismically
           induced equipment failures and supports and things is,
           again, even if you could show that the large pipe
           break was infrequent, you'd also have to show that all
           other sources of large LOCAs would be equivalently
                       MR. KURITSKY:  Actually, that's very good. 
           The -- that's one of the one main things he's getting
           at too, things like that.
                       DR. SHACK:  Well, I think -- and, again,
           you know, we're talking about ancient history here. 
           But I mean the Livermore studies had the indirect
           failures essentially as contributing more to the
           large-break LOCA, you know, back when the did those
           things in the '80s than the pipe failures themselves.
                       MR. KURITSKY:  Right.
                       DR. WALLIS:  Back to number three, not
           only is the large-break LOCA less likely, but it may
           be easier to handle than small-break LOCAs.  This is
           one reason that the AP600 opens up a valve, because
           you depressurize and it's easier then to refill. It
           may well be that, although it appears in the big pipe
           break is a worse thing to happen, in fact it's easier
           to handle with your ECCS.  Is that a true statement?
                       MR. KURITSKY:  And that's also why you've
           seen a lot of PRAs, you see the contribution to core 
           -- in small breaks is greater than for large breaks.
                       DR. WALLIS:  Not just because they're less
                       MR. KURITSKY:  They're more likely, in
                       DR. WALLIS:  They're more likely and
           they're more difficult to handle.
                       MR. KURITSKY:  And they can be, because
           you have to depressurize, right.
                       DR. WALLIS:  Right.
                       DR. KRESS:  And that's why I think the
           rule calls for looking at a spectrum of breaks, too,
           because it doesn't limit it to the large.
                       DR. APOSTOLAKIS:  Again, going to the last
           bullet, are we regulating now beyond design basis
                       MR. KURITSKY:  No, we're not regulating
           beyond there, but it just --
                       DR. APOSTOLAKIS:  Then where do we go?
                       MR. KURITSKY:  Because this equipment
           helps reduce the --
                       MS. DROUIN:  This is more of a cautionary
           type statement in consideration of our defensive tab,
           which is going to come out on the next slide.
                       DR. APOSTOLAKIS:  Okay.  
                       DR. KRESS:  Well, but we've always
           regulated beyond design basis.
                       DR. APOSTOLAKIS:  We have?
                       DR. KRESS:  We always have.
                       DR. APOSTOLAKIS:  Like when?
                       DR. KRESS:  The design basis regulates
           beyond design basis.
                       DR. APOSTOLAKIS:  It's meant to be a
           surrogate --
                       DR. BONACA:  I think for the regulation
           the ELPs are very much beyond design basis, too.  I
           mean, they have considerations and multiple -- sort of
           support where directions are given to the operator on
           what he has to put up and how -- and so there is a use
           for whatever equipment you have.
                       DR. APOSTOLAKIS:  Yes, but you're not
           asking for new equipment or new design.  
                       DR. BONACA:  No.
                       DR. APOSTOLAKIS:  Yes, that's my point.
                       DR. BONACA:  But you're asking for
           mitigation on whatever you got.  I mean, we've been
           banking on this system for what it is.  And so by the
           time --
                       DR. APOSTOLAKIS:  Is an earthquake part of
           the design basis?  But the stuff you're talking about
           is really beyond the -- earthquake right?
                       MR. KURITSKY:  Yes, and PRAs, yes.  
                       DR. APOSTOLAKIS:  Well, not in PRAs.  I
           mean reality.  You're not going to have a large-break
           LOCA with an earthquake that's safe shutdown.
                       MR. KURITSKY:  Right.  Right.
                       DR. APOSTOLAKIS:  And so that's something
           legitimate to worry about what's going to happen
           beyond the SSE?
                       DR. KRESS:  You always worry about that.
                       DR. APOSTOLAKIS:  Well, we should worry
           about it.  We make it part of the regulations.  I
           thought the whole idea of the design basis accidents
           was we defined an envelop beyond which we don't go.
                       DR. KRESS:  That's exactly right. 
                       DR. BONACA:  Yes, but after TMI, we
           discovered that we needed some -- I think many of the
           things right now we have really conquered whatever we
           got, and I think the U.S. regulatory system has not
           imposed additional requirements, in other countries
           they have.  
                       DR. APOSTOLAKIS:  I think what Mary said
           makes more sense to me, that this is a cautionary.
           Yes.  But strictly speaking if I start worrying about
           beyond design basis accidents, I would deny 99 percent
           of the industry.  It's like defense-in-depth and risk-
           informed regulation.  In the name of defense-in-depth,
           no. In the name of protecting me from accidents that
           go beyond design basis, I deny.  Because I'll find
           some weird occurrence --
                       DR. KRESS:  It depends on your criteria
           for what you mean by protection.
                       DR. APOSTOLAKIS:  We don't have criteria
           how to handle these, do we?
                       DR. KRESS:  No, that's the problem.
                       DR. SHACK:  But if they contribute enough
           to CDF  you certainly --
                       DR. KRESS:  Yes, I understand, George, but
           CDF itself is beyond design basis.  Core damage is
           beyond design basis.
                       DR. APOSTOLAKIS:  And we are not
           regulating on the basis of CDF.  We are not.
                       DR. BONACA:  And the program, severe
           accident management guidelines are based on utilizing
           whatever we got for events that go beyond design
           basis.  And, so, I mean there has been a commitment of
           the industry to use, the OPs use it and in some cases
           PWRs, APGs are intertwined between design basis and
                       DR. KRESS:  The whole idea, though, is to
           see if we can change the regulation.
                       DR. APOSTOLAKIS:  Sure.
                       DR. KRESS:  And in a risk-informed manner,
           and then you're automatically going beyond design
           basis whether you like it or not.  You're not
           regulating to it, you're using it as a tool to see how
           to change the regulation. The regulation is always
           addressed beyond design basis.
                       The way it does it, is like you said, they
           generally use the frequency of the currents and the
           cut off for the design basis.  So if you dream up a
           design basis accident which has a frequency of the
           currents less than 10-6 per year, you usually don't
           worry about it.  That wasn't a strict rule.  Some of
           them do go beyond 10-6, but for example, the design
           basis that includes a LOOP for the large-break LOCA.
                       DR. APOSTOLAKIS:  I think the 10-6 applies
           to the initiator, not the sequence.
                       DR. KRESS:  No, it's the initiator, but
           you know, you can forget about it at that point.
                       DR. APOSTOLAKIS:  Not the sequence.
                       DR. KRESS:  Well, no, I think it applies
           to the whole sequence when it comes to design basis.
                       DR. BONACA:  I would agree that the
           statement that Mary made is the correct one, because--
                       DR. APOSTOLAKIS:  But Alan said their view
           that it's not low enough.  The frequency of the large-
           break LOCA is not low enough to forget about it, not
           the sequence.
                       DR. KRESS:  Maybe not low enough.
                       DR. APOSTOLAKIS:  Maybe.
                       DR. KRESS:  Your assessment might not be.
                       DR. APOSTOLAKIS:  Well, I'm just trying to
           understand the rules of the game.  Are we really
           regulating -- I mean, we're attempting to regulate
           using risk information, are we attempting to do things
           in a traditional --
                       DR. WALLIS:  That's the whole idea. It's
           the whole idea.
                       DR. KRESS:  Yes, that's the whole idea.
                       DR. APOSTOLAKIS:  Yes.
                       DR. BONACA:  But, for example, if they go
           into the notice that has been used for a certain
           scenario beyond design basis and the probability of
           that scenario combined with blah, blah, blah is
           extremely low, then surely you would exclude the
           importance of the ECCS for that scenario.
                       DR. APOSTOLAKIS:  Okay.  
                       DR. BONACA:  And you may just consider the
                       MS. DROUIN:  Correct.
                       DR. BONACA:  So you're just looking at
                       DR. APOSTOLAKIS:  Again, okay, this is
           Option 3 risk-informed.  So why then do we care about
           the frequency of the initiator itself?  Shouldn't the
           frequency of sequences --
                       DR. WALLIS:  But if the initiator is small
           enough, you don't care about the sequence, do you?
                       DR. APOSTOLAKIS:  But not the other way.
                       DR. WALLIS:  Because the sequence isn't
           going to be large.
                       DR. APOSTOLAKIS:  But it can be large,
           large and they're small enough, and I would still not
           care on the basis of other things.
                       DR. WALLIS:  That's why you look at --
                       DR. KRESS:  You could go that step, too.
                       DR. APOSTOLAKIS:  Yes.  But we're not
           going that way?
                       DR. KRESS:  Well, I think the first step
           is to --
                       DR. WALLIS:  We're doing both.
                       DR. KRESS:  Yes, we're doing both.  I
           think if we listen to them, they'll tell us they're
           doing -- 
                       MS. DROUIN:  If you go back to -- I didn't
           bring a copy of it with us, but if you go back to our
           framework document --
                       DR. KRESS:  Yes, it's in there.
                       MS. DROUIN:  It's in there. And, I mean,
           I'm going to just bring it down for a second because
           our second bullet on the next slide says it follows
           the guidelines and the framework.  And so if you go
           back to the framework to that figure that shows the
           quantitative guidelines, we deal with initiated
           frequency, we deal with the CDF.
                       DR. KRESS:  We had three ranges of
                       MS. DROUIN:  That's right.
                       DR. KRESS:  And they had to -
                       DR. APOSTOLAKIS:  All right.  I remember
                       DR. KRESS:  Yes.  Okay.  And then they had
           the CDF, and then they had the LERP.
                       DR. APOSTOLAKIS:  Okay.
                       MS. DROUIN:  So we deal with all of those.
                       MR. KURITSKY:  Okay.  Now we're on this
                       DR. APOSTOLAKIS:  And we're done with it.
                       MS. DROUIN:  Want me to go back to the
                       DR. KRESS:  No, please don't.
                       MR. KURITSKY:  Okay.  And we mentioned in
           the previous discussions -- we're looking at two
           different types of changes to make.  The first set of
           changes --
                       MS. DROUIN:  In the near term.  These are
           the near term ones.
                       MR. KURITSKY:  The near term.  Near term.
                       DR. APOSTOLAKIS:  Within a year, or
           something like that?  Right now?
                       MS. DROUIN:  We're going to get to the
           schedule.  Bear with us.
                       MR. KURITSKY:  That's the last side, so it
           keeps your attention.
                       In any case, we're looking at two types of
           changes.  The first set of changes would be to the
           actual technical requirements of the current 50.46 and
           Appendix K.  Again, like Mary said, we use 50.46 very
           loosely but it can mean that 50.46 and one or more of
           these accompanying regulations.  And particularly
           terms of the acceptance criteria and the evaluation
           model, we'd be looking to make changes to the existing
                       And then a second set of changes would be
           part of a voluntary risk-informed alternative to 50.46
           and GDE 35 and/or GDE 35, and that would deal with the
           reliability requirements.  That goes to the assumption
           about the simultaneous loss of off-site power and the
           single failure criteria.
                       DR. KRESS:  Can we view what's going under
           A as allowing utilization of what margins already
           exist?  Cutting down on those margins?
                       MR. KURITSKY:  Using new information to
           help us, you know.  Going back to what you had said
           before about how new information -- back then there
           was, say, certain margins --
                       DR. KRESS:  Yes, but regardless of what
           information you use, you're cutting down the margins. 
           Because you maybe have a better appreciation of what
           the margins are.  You can ease up on them, because you
           have a better idea of what the margins are?
                       MR. KURITSKY:  Right.  Where there were
           margins that were applied on the past based on not
           knowing certain things.
                       DR. KRESS:  Yes.
                       MR. KURITSKY:  Now we have the knowledge,
           we don't need as much --
                       DR. KRESS:  Yes, you have a better idea of
           what the margins are, you can ease up on them a
                       DR. WALLIS:  But the result will be that
           the reactors are less safe?
                       MR. KURITSKY:  No, I wouldn't say that. 
           That's a requirement.
                       DR. WALLIS:  If they make changes in their
           operating procedures or design as a result of
           regulations, it will be in the direction of cutting
           down on safety margin?  It may be to establish a
           safety margin which was reasonable all the time,
           because it was too conservative before.
                       MR. KURITSKY:  Right.
                       DR. WALLIS:  But the effect will be to
           reduce safety margin.
                       MR. KURITSKY:  Except that where margin
           was applied based on not understanding a certain
           process, and now better understanding that process
           tells us that we can now model that process better.
                       DR. WALLIS:  It means that you were too
           conservative before?
                       MR. KURITSKY:  Right.
                       DR. KRESS:  That they were unsure about
           what the uncertainty was.
                       DR. WALLIS:  That's right.
                       DR. KRESS:  Now they have a better idea,
           they say well we were too conservative.  We can use
           some of that.
                       DR. SHACK:  But, again, it's not simply a
           matter of conservatism.  You know, your steam
           generators -- I mean, your diesel generators may work
           ore reliability now for small breaks --
                       DR. WALLIS:  Then something has changed
           which is better.
                       DR. SHACK:  I think that you actually can
           argue that there is a safety benefit to changing this
           rule as well as a --
                       DR. WALLIS:  It would help if we could do
           that.  It really would help.
                       DR. BONACA:  No, the question is how do
           you do that.  I mean --
                       DR. WALLIS:  Now, B you start with a fresh
           sheet of paper?
                       MR. KURITSKY:  Well, not really.  B is the
           more risk-informed piece.  We're actually using risk--
                       DR. WALLIS:  B sounds very interesting.
                       MR. KURITSKY:  B is using the risk -- A
           really isn't, as I think Dr. Kress pointed out, isn't
           really looking at risk-information.  It's just kind of
           cleaning up what's there.
                       DR. WALLIS:  A you can see achieving.  A
           is something achievable.  How much is doubt, but A is
                       B is much more iffy and much more
                       MR. KURITSKY:  What have a schedule for
           this, which if you believe it is 12 months.  
                       DR. WALLIS:  You're just looking at the
           record then, so maybe I went too far.  There is no C,
           which is development of a fully risk-informed --
                       MR. KURITSKY:  No.  We're just focusing in
           the near term.
                       DR. WALLIS:  Okay.  I understand.
                       DR. APOSTOLAKIS:  But he's talking only
           about the reliability requirement.
                       DR. WALLIS:  That's right.
                       MS. DROUIN:  We talk about the reliability
           again --
                       MR. KURITSKY:  Any rule change in 12
                       MS. DROUIN:  When we talk about
           reliability requirements, again we're talking about
           the single failure criteria and the LOCA LOOP.
                       DR. BONACA:  Right.  And I think your
           report already makes a convincing case that for a
           large-break LOCA you assume also a LOOP.  It's an
                       MS. DROUIN:  Yes.
                       DR. BONACA:  And so, I mean, that's a
           pretty clear cut.  
                       DR. APOSTOLAKIS:  Now I'm confused myself. 
           So A deals with acceptance criteria in the evaluation
                       MR. KURITSKY:  Yes.
                       DR. APOSTOLAKIS:  But if you develop a
           risk-informed alternative, you're not going to deal
           with acceptance criteria and evaluation.
                       DR. KRESS:  Well, you might.
                       MR. KURITSKY:  In the long term you may. 
           right now in the short term we don't have a change
           proposed dealing with the evaluation model.  We had
           thought about some of them, but we couldn't establish
           their feasibility in the short term.
                       DR. APOSTOLAKIS:  And why can't you change
           the reliability requirements in the short term for the
           current 50.46?
                       MR. KURITSKY:  Well, we are going -- you
           mean, as opposed to making a risk-informed
                       DR. APOSTOLAKIS:  Yes.  I mean, you
           mention explicitly acceptance criteria and evaluation. 
           Why don't you say and the reliability requirements? 
           I mean, they're very explicitly stated on slide 5: 
           "On site power operation and assuming a single
           failure," and so on.  I mean these would easily change
           in the current rule, right?
                       MR. KURITSKY:  Right.  But we want to
           allow people, the licensees, to choose to keep the
           current requirements if they want to.  If they want to
           do their analysis assuming a lost of off-site power,
           simultaneous loss of off-site power and a single worse
           failure, they may do so.  This is going to be an
           alternative if they want to use either of the two
           methods that we're going to discuss shortly.
                       DR. APOSTOLAKIS:  The question is in A.
                       MS. DROUIN:  It wouldn't be mandatory.
                       DR. APOSTOLAKIS:  Huh?
                       MS. DROUIN:  It wouldn't be mandatory.  B
           is not a mandatory.  It's a voluntary.
                       DR. APOSTOLAKIS:  No, but in A you're
           explicitly talking about acceptance criteria and
           evaluation.  And I'm wondering why you don't also
           mention reliability requirements.  They're very
           explicit.  I mean, you can say don't do this anymore. 
           You don't have to have a risk-informed alternative to
           do that.  You can easily say as part of the current
           50.46 we're changing this.  No?
                       DR. BONACA:  Well, they have to have a
           basis determinable to that, that's what they're trying
           to do now.  They're trying to develop the basis for
           which they can tell them as part of 50.46 don't do
           that.  Don't take --
                       DR. APOSTOLAKIS:  Why are two of the four
           mentioned and not a third one?
                       DR. SHACK:  Well, hold on, maybe they'll
           get to that. I'm interested, too.
                       DR. KRESS:  The current regulation
           addresses reliability very, very indirectly.  In fact,
           by using the single failure criteria --
                       DR. APOSTOLAKIS:  Yes, and off-site power.
                       DR. KRESS:  Right.  
                       DR. APOSTOLAKIS:  Right.
                       DR. KRESS:  It doesn't specify what the
           reliability has to be.
                       DR. APOSTOLAKIS:  No.
                       DR. KRESS:  And if you're going to change
           that, I don't now what you do.  You have to have a
           basis for saying what the actual reliability is and
           from erring it and determining.  I mean, I don't think
           they ought to get into that with A.  I sort of think
           that's something that leads to D.
                       DR. BONACA:  A is more like, you know,
           they're saying for example 2100oF. Okay.  It may be
           inappropriate to measure the real objective, which is
           the coolability of the core; that's what they're
           talking about.
                       DR. KRESS:  Yes.
                       DR. BONACA:  And you may show that you can
           have higher temperature than that and still meet those
           requirements. So within the models existing right now
           they find there are ways to meet the same objectives
           with less -- so that's really much more into the
           evaluation model and 2100, which is one of the
           accepted criteria.
                       The other one, it's more of this
           reliability requirements which are really right now
           there isn't a solid basis for understanding why you're
           imposing LOOP in addition to single failure, in
           addition to the blended -- that's -- okay.  And if you
           kind of develop an understanding of extremely low
           probability, then you can eliminate that.  But you
           don't want to eliminate that blended break, so then
           you can eliminate a LOOP.
                       DR. WALLIS:  It's interesting, but we're
           still trying to infer why they might have divided  it
           into classes A and B. Maybe we should ask them why.
                       MS. DROUIN:  Going back, A is we're going
           to the acceptance criteria in the evaluation model and
           the current 50.46.  And with current knowledge we're
           doing some clean up work in the current rule.  That's
           all it is.  It's really that simple.
                       Now we get more into of what Option 3 is
           about and bringing risk-information and coming with
           our risk-informed alternative, which is supposed to be
           voluntary.  So this would be creating a separate
           regulation that a licensee could choose to implement
           or not.  It'd be like -- I mean, in 50.46 where we
           came up with a alternative, here's our risk-informed
                       DR. APOSTOLAKIS:  So the second bullet
           then really refers to B only?
                       MS. DROUIN:  In B you don't need A,
           because you've already done it.  It will be there.
                       DR. APOSTOLAKIS:  But A will not be done
           following the guidelines in Option 3
                       MS. DROUIN:  I'm sorry?
                       DR. APOSTOLAKIS:  A will not be done
           following the guidelines in Option 3?
                       MS. DROUIN:  It certainly won't contradict
                       DR. APOSTOLAKIS:  It's just in there?
                       MS. DROUIN:  As I said, it's not really
                       DR. APOSTOLAKIS:  Okay.  
                       MS. DROUIN:  It's more just clean up
                       DR. WALLIS:  Well, are you going to look
           at something like 2100o?
                       MS. DROUIN:  Yes.
                       DR. WALLIS:  Are you going to say what
           risk benefit is there from that and suppose it were
           2250 or 2300, what would be the additional risk?  And
           then you're going to make choice based on risk?  Is
           that the kind of thing you're going to do?
                       MR. KURITSKY:  Well, I think --
                       MS. DROUIN:  Well, we're going to get into
           it, so why don't we move on to the next slide.
                       DR. KRESS:  But before you leave, are we
           going to talk about in this meeting about this
           framework document and all?
                       MS. DROUIN:  No, we hadn't --
                       DR. KRESS:  Could I ask one question about
                       MS. DROUIN:  No.
                       DR. KRESS:  Why?  In your table of
           framework where you have three ranges of initiating
           event frequencies and then you have the conditional
                       MS. DROUIN:  Yes.
                       DR. KRESS:  It wasn't quite clear to me
           whether those ranges of initiating event frequencies
           referred to just one initiator or the summation of a
           set of initiators.
                       MR. KURITSKY:  The summation of the set? 
           You mean --
                       DR. KRESS:  So you're going to take all
           initiators and group them into these three sets, in
           some there are frequencies and that's the range you're
           talking about in that range of frequencies?
                       MS. DROUIN:  Yes.
                       DR. KRESS:  Okay.  I just wanted to get
           clarification of that.  Because it's something that
           bothered me when I looked at it.
                       MS. DROUIN:  We are planning on reissuing
           an updated version because we did receive comments
           from the ACRS. We did get some public comments.  And
           we've gone through and we're trying to clarify all
           this, and we hope we have a new version out in August.
           It doesn't change any of the technical basis or
           concepts, just better --
                       DR. KRESS:  Just clarifies it?
                       MS. DROUIN:  Better explanations of the
           numbers and how they're used.
                       The next set of slides that Alan's going
           to get into is going to go into detail of what we're
           doing in A and what we're doing in B.
                       MR. KURITSKY:  Okay.  First in A, which is
           the possible changes to the existing 50.46 and
           Appendix K.  One of the first things we're looking at
           is replacing the current prescriptive ECCS acceptance
           criteria with a performance-based requirement.  And
           the performance-based requirement would be that you
           would have to demonstrate adequate post-quench
           cladding ductility and adequate core-coolant flow area
           to ensure that the core remains amendable to cooling.
                       DR. KRESS:  Well, let me ask you a
           question about that.  The current version is based on
           failure to develop for zircaloy clad, I presume.  And
           it has to do with how much oxidation you had as far as
           clad embrittlement and how much bowing and swelling
           you might have as with respect to the temperature.
                       Well, if you were to write a general rule
           that says you demonstrate the coolability, well won't
           whoever makes that demonstration have to go through
           the same -- if they're using, say, a different kind of
           clad, it's got to go through the same experimental
           program and same database?  I mean, develop it all
           over again for their new clad?
                       MR. KURITSKY:  In fact, that's exactly --
           you see the last bullet.  The whole purpose -- the
           main purpose of this change to these acceptance
           requirements is to allow uses of other cladding
                       DR. KRESS:  Yes.
                       MR. KURITSKY:  What currently they have to
           do is if they want to use a different material, is
           they have to apply for a license exemption, okay.  And
           what we want to do is have that changed so that the
           rule will be more general, you know, it would be more
           performance-based nonprescriptive.  And in the rack
           out we would specify some conditions they'd have to 
           meet, and one of them would be what they would have to
           go through in order to demonstrate that adequate post-
           quench ductility, which would be that criteria.
                       DR. KRESS:  Okay.  So you'd spell that out
           in a reg guide?
                       MR. KURITSKY:  Right.  Right.
                       DR. KRESS:  Okay.  
                       MR. KURITSKY:  And as a matter of fact was
           the main purpose of this change, this clean up, so to
           speak.  So it's not limited just to zircaloy and
                       DR. WALLIS:  I like this.  I think,
           though, that you have to think very carefully about
           what the performance is to be.  
                       MS. DROUIN:  Yes.
                       DR. WALLIS:  The performance-based
           requirement.  And amenable to cooling, I challenged
           last time because you can always cool some things some
           how eventually.  
                       And then your thing about a core
           temperature and acceptably low value, well there's
           nothing magically about temperature.  It's got to be
           something other than temperature.  It's got to be some
           consequence to safety.
                       DR. KRESS:  What the temperature does to
           the geometry, yes.
                       DR. WALLIS:  To geometry or the
           coolability, or to eventually release of fission
           products.  There's got to be something here about
                       MR. KURITSKY:  Right now this is just
           taking this thing --
                       DR. WALLIS:  You've got to think very
           carefully about what these performance measures are to
                       MR. KURITSKY:  Right.  Right. Right now
           we're working on it.  That's taking an existing -- the
           five criteria that are there right now, this is the
           long term cooling criteria --
                       DR. WALLIS:  But you see hydrogen release
           isn't covered by any of this, is it?
                       MR. KURITSKY:  Right.  And the idea being
           that hydrogen is not really controlling and it's going
           to be adequately taken care of with the 50.44.
                       DR. WALLIS:  So they can release as much
           hydrogen as they like?
                       MR. KURITSKY:  Well, no.  But the control
           of hydrogen is going to be covered under 50.44.
                       DR. KRESS:  Well, they have an oxidation
           limit in this rule which could be converted into
           hydrogen, but it doesn't produce much hydrogen because
           what it has to do is embrittle of the clad. So that
           will actually control the amount of hydrogen.  It'll
           be a lot less.
                       DR. WALLIS:  But you know we can't produce
           a great deal of hydrogen.
                       DR. KRESS:  Not with that level, no.
                       DR. WALLIS:  Not with that level.  So
           something else happens first.
                       MR. LEITCH:  You overly embrittle the clad
           before you get much hydrogen.
                       DR. WALLIS:  At least with the cladding we
           know today, right?
                       DR. KRESS:  Yes, that's true.  Good point.
                       DR. SHACK:  But it would still be covered
                       DR. KRESS:  Yes, the hydrogen part will be
           covered under 50.44.
                       MR. KURITSKY:  Okay.  I think the major
           area of change under A, which is the changes to the
           existing criteria or existing 50.46 is changes with
           regards to the evaluation -- the test evaluation
           model.  And that's to make them use more realistic
                       And in the near term what we're
           specifically looking at would be changes to Appendix
           K to use more, as we mentioned before, more current,
           more realistic information.  And specifically this
           could involve taking the main pieces -- what's
           currently for the -- the '71 ANS decayed standard
           using a multiplier of 1.2 to account for uncertainty. 
           And we'd be looking to use instead something like the
           '94 ANS standard and then coming up with an NRC-
           prescribed uncertainty treatment because the '94
           standard has a lot more options and perimeter and
           uncertainty treatments.  It's a little more
           complicated than just applying factor, which is done
           for the '71 standard.  So that's one of the main
           pieces that we're looking at under changes to Appendix
                       But we also wanted to take a look at these
           other few things that are on the list.  There's a
           couple of items that we're looking.  We want to look
           at more recent data to see whether or not they want to
           delete the limitation on the PWR reflood steam cooling
           for small reflood rates.  And then also the
           possibility of deleting the prohibition on the return
           to nucleate boiling during blowdown.
                       And lastly, we're also looking at the
           Baker-Just -- what currently is used at the Baker-Just
           zirconium steam model and we'd be looking at possibly
           using the Cathcart-Pawel zirconium steam oxidation
           model just for heat generation.  Replacing that plan
           for fuel embrittlement, that would be covered on the
           other. And we're looking at demonstrating adequate
           ductility, but for the heat generation part, we would
           be looking at replacing Baker-Just with the Cathcart-
                       So those are some of the clean up items
           that we're looking under at under Appendix K.
                       And then the important thing to note at
           the bottom is that as part of this update we'd also be
           looking at recognized nonconservatisms and model
           limitations that exist right now and to make sure that
           those are accounted for and that the safety focus is
           still, you know, maintained such that the impact of
           these nonconservatisms, recognized nonconservatisms
           and model limitations wouldn't -- what's that phrase--
           significantly erode the conservatism remaining in the
           Appendix K model.
                       DR. KRESS:  Well, when you start getting
           rid of only conservatisms, replacing them with more
           realistic best estimate type, should one start
           thinking about these best estimate calculations need
           to be accompanied by uncertainties so we really know
           how close we are to limits?
                       MS. DROUIN:  Yes.
                       DR. KRESS:  Would that part of this change
           maybe then?
                       MS. DROUIN:  You're not going to be able
           to do that without thinking of the uncertainties
           associated with them.
                       MR. KURITSKY:  Okay.  As part of these
           changes that we -- these proposed changes that we're
           considering, there'd be additional technical work that
           would have to be done.  As Mary mentioned, right now
           this Phase 1 work is a feasibility study and there is
           additional work that would have to be done under Phase
           2 in order to support rulemaking.
                       And the main thing that would need to be
           done under Phase 2 for these A changes would be work
           to support the removal of the unnecessary
           conservatisms from Appendix K, which means for each of
           those items that we just listed as possible changes on
           the previous slide, we'd have to go through and look
           at data or look at different calculations and
           sensitivity analysis and uncertainty consideration to
           determine what we feel comfortable -- what changes
           we'd feel comfortable making.
                       Also as part of the ECCS acceptance
           criteria changes we discussed a couple of slides ago,
           and I think we mentioned, too, we'd have to go through
           and identify what would be necessary for -- what
           guidance would be necessary for demonstrating adequate
           post-quench ductility.
                       DR. WALLIS:  Again, that's a funny
           criterion.  I mean, ductility is a means to an end,
           not an end in itself.
                       MR. KURITSKY:  And this, again, not my
           area, but my understanding is that we're saying as
           long as we can hold the core in its shape --
                       DR. WALLIS:  But how much is it allowed to
           distort, and what does this do to the cooling
           capabilities and such?  It's not a simple question. 
           It can stretch into all kinds of shapes and still be
           okay, but then someone has to analyze to see what the
           consequences are of those events and so on.
                       MR. KURITSKY:  Right.  And I think that's
           what the other -- I mean, that's -- the adequate post-
           quench ductility is one of the two pieces.  The other
           piece was adequate core-coolant flow area.
                       DR. WALLIS:   You're saying the same as
           nonreleasing fission product, isn't it?
                       DR. KRESS:  But that's part of the post-
           quench ductility.
                       MR. KURITSKY:  That's the ultimate, right.
                       DR. WALLIS:  Well then why don't you put
           that in as a criterion instead of these means to an
                       MR. KURITSKY:  Well, I guess, again this
           is not my area of --
                       DR. WALLIS:  But if you can't cool it, it
           gets hot and then eventually releases product.  It is
           ductile, it splits and it releases fission products. 
           The end is releasing fission products, isn't it?  
                       MR. KURITSKY:  Yes.
                       DR. WALLIS:  So why don't you put that in
           as a criteria, otherwise you get into something which
           is too wishy-washy.
                       MR. KURITSKY:  Well, I think -- and again
           this --
                       DR. WALLIS:  It'll blow out like a great
           big balloon, and that doesn't make it okay.
                       DR. KRESS:  It's because you can't --
           because if you had limits on fission products --
                       DR. WALLIS:  Yes.
                       DR. KRESS:  -- you couldn't quantify very
           well, and you have to back off to the next level. 
           Say, well let's put the limit on ductility and if we
           got a certain level of ductility, we know we're not
           going to release fission products.  So it's one of
           those things were you back off to where you can deal
           with something you can deal with.  Because you're not
           going to be able to calculate the amount of fission
           products you get out a given ductility level.
                       DR. WALLIS:  Right.  But then if you
           can't, you get conservative about your ductility then?
                       DR. KRESS:  You get more conservative
           about your ductility, yes.  You back off to where you
           can -- to something you can deal with.
                       DR. WALLIS:  Well, I'm just saying don't
           back off until you have to.
                       DR. KRESS:  Yes, well I think it's a good
                       DR. WALLIS:  Because if you're doing
           something which is a much better measure of
           performance than -- 
                       DR. KRESS:  You should always turn to high
           level and see where you can deal with it, yes.
                       DR. WALLIS:  Right.
                       DR. BONACA:  But I thought that's why you
           need the time, right, to develop so this criteria --
                       DR. WALLIS:  
                       Yes, that's why Bill Shack's right about
           the one year.
                       DR. SHACK:  No, no.  The one year is after
           they finish the technical work.  
                       DR. KRESS:  To write the rule?   To change
           the rule?  Well, they could probably do that.
                       MR. KURITSKY:  Actually, the work for this
           actually is currently ongoing at Argonne National Lab. 
           And so we'll be able to borrow off that and use it for
                       DR. KRESS:  Well, that adds a couple of
           years to it.
                       MR. KURITSKY:  I was told it would be done
           by December.
                       DR. APOSTOLAKIS:  December 2003.
                       MR. KURITSKY:  They may have left that
           part out.
                       MR. LEITCH:  On your previous slide one of
           the bullets said deleting the prohibition on return to
           nucleate boiling during blowdown.  Why can we
           eliminate that prohibition?
                       MR. KURITSKY:  Well, we don't know if we
           can. What we're saying is --
                       MR. LEITCH:  Well, why do you suspect you
                       MR. KURITSKY:  It's just we want to look
           at more recent data on heat transfer during blowdown
           and on minimum film boiling temperature.  Actually,
           the expert is here.
                       MS. DROUIN:  Norm's going to --
                       MR. KURITSKY:  Norm is here.
                       MR. LAUBEN:  I think that there's
           certainly a lot of question as to whether you really
           could eliminate that, because minimum film boiling
           temperature of the data is quite large, although you
           could choose a low enough one and be -- might be okay. 
                       But this request was made by one of the
           industry representatives, and if they have some
           interesting science to provide us, we'll be willing to
           look at it.  But the people I've talked to thus far,
           I would have to say there's not a lot of optimism in
           this particular one.  That's why the word "could" is
           up there.  But we don't want to exclude from making a
           case for that, that's all.
                       Oh, excuse me.  I guess I'm supposed to
           say I'm Norm Lauben from the Office of Research.
                       MR. KURITSKY:  Okay.  If there are no
           other questions on this slide, we can go to the next
                       MS. DROUIN:  Just I want to add, going
           back again, all we've done now is determine it's
           feasible.  Over the next year as we do the technical
           work, we'll be coming to the ACRS, I'm sure, on
           numerous occasions as we get into the details of this
           and, hopefully, during that time period, you know, a
           lot of these questions that you're raising are very
           good and, hopefully, we're start beginning having
           answers to them.
                       DR. KRESS:  One with respect to this Part
           A, it would be interesting to know if you made these
           changes what would be the resulting changes that the
           licensees would make in the way they operate their
           plant or even plant hardware.  And then how would one
           look at those changes and perhaps give it the 1.174
           treatment that would say these changes are acceptable
           to us from a delta risk standpoint?  Is that part of
           this A activity or is it a thinking part of it?
                       MS. DROUIN:  I'm sorry, I didn't follow
           your question.
                       DR. KRESS:  Well, if you make these
           changes in the regulations, Part A, then the plants
           are going to do something.  They're going to up the
           power, they're going to maybe even relax some of the
           ACC requirements; I don't know what they're going to
           do, but they're going to do some things.  You have a
           made a list of what these possible changes might be,
           and then looked at that list of changes and give it
           the reg guide 1.174 treatment to say that list of
           changes would likely result in a delta risk of so
           much, and therefore maybe we'd better think about it
           again or something?
                       MS. DROUIN:  If you go back to the earlier
           slide where we said we're going to follow our
           guidelines, our framework guidelines, which are
                       DR. KRESS:  Yes, but for A --
                       MS. DROUIN:  Yes.
                       DR. KRESS:  For A you're going to follow
           the guidelines?
                       MS. DROUIN:  Oh, absolutely, yes.
                       DR. KRESS:  Oh, okay.
                       MS. DROUIN:  Yes.
                       DR. KRESS:  And they're sort of consistent
           with 1.174?
                       MS. DROUIN:  They're totally consistent
           with 1.174, yes.
                       DR. KRESS:  Okay. I didn't realize you
           were going to the guidelines for the A part.
                       MR. ROSEN:  Mary, as long as we're on A
           and B, could you go back to that slide for a minute
           and let me ask you a question?  Slide 9, I think it
                       From a licensee's perspective -- no, I'm
           sorry. It's slide 8 that I want to look at.  Okay.
                       From a licensee's perspective what you've
           described now seems to be we've put them in a position
           that once they did the changes to their modeling and
           processes that A would allow, they would get some
           improvement, some value from that which would then be
           the baseline for whether they would go ahead with the
           risk-informed alternative.  In other words, they might
           get so much value out of A, that going ahead with the
           risk-informed alternative might even not be necessary
           or even desirable.  Could you comment on that?
                       MS. DROUIN:  I think that --
                       MR. KURITSKY:  That possibility exists. 
           I mean, I --
                       MS. DROUIN:  Yes, but I don't think it's
           very probable.  Because I think these are two very
           separate distinct entities when you look at the
           acceptance criteria and the evaluation model versus
           what gets imposed because of GDC 35.  I mean, I think
           they're two separate benefits.
                       A licensee could certainly come along and
           say "You know, I've gotten these benefits from A and
           I don't care for anymore benefits."  But I think both
           of them offer independent benefits.
                       MR. ROSEN:  Okay.  Thank you.
                       MS. DROUIN:  Were we on 12.
                       MR. KURITSKY:  I think we're on 12, yes. 
                       The type B changes that we're considering,
           which are the ones that involve developing a voluntary
           risk-informed alternative to 50.46 and/or GDC 35 would
           involve -- the technical requirements that are used to
           ensure or that -- well, the changes that we would be
           recommending would include technical requirements to
           ensure an ECCS reliability that's commensurate with
           the frequency of the challenge.  And that goes back to
           the discussion we had early on in the presentation
           where we would be trying to match up the ECCS
           reliability with the frequency of the LOCA initiators
           or whatever.
                       DR. WALLIS:  Now reliability includes
           functionality?  I mean reliability per se to me just
           means does the pump work or not.  But, I mean, does it
           perform?  Does the whole thing work, it's
           functionality.  That's got to work.  That's got to be
           there, too.  It's got be functional and reliable.
                       MR. KURITSKY:  Yes, again --
                       DR. WALLIS:  Conceivably if you said don't
           worry about this size break and that size break,
           people would change the size of the accumulator or the
           size of the pumps or something, so they couldn't
           handle a big break.  It wouldn't even function.
                       MR. KURITSKY:  Right.  In my mind
           reliability means it has to be reliable to accomplish
           its function.  So to me I see functionality being part
           of it.  But I'm sure that, you know, people are going
           to have to defend wording interpreting, so that point
           is definitely true, I mean that has to be accounted
                       DR. KRESS:  When you say commensurate with
           the frequency of challenge, the only reason that seems
           to me like it's a useable concept is because you
           somehow know the next step, and that's the conditional
           core damage frequency.  So you could back off from
           some criteria like 10-4 to take conditional and then
           say now what is the frequency that I can live with.
                       MR. KURITSKY:  That's exactly right. 
           Based on the options in the framework guidelines we
           come up with some, say, GDF limit and then we can back
           off of that.  Looking at different -- the frequency of
           different groups of initiators, whether it be a
           spectrum of LOCA sizes or whatever, and then come up
           with what should be the commensurate reliability that
           we're looking for.
                       DR. APOSTOLAKIS:  Well, at the same time,
           though, we are not trying to bring all the plants up
           to the 10-4 goal, are we?
                       MR. KURITSKY:  This is voluntary.
                       DR. KRESS:  It's voluntary.
                       DR. APOSTOLAKIS:  Yes, I know.  But, I
           mean, you're giving now -- I mean, is that a good idea
           to say here you keep the goal and as long as you're
           under the goal, it's fine?  I thought the idea was not
           to push everybody toward the goal.
                       DR. KRESS:  Well, you know, this is a
           question about the framework document.  The framework
           document really starts from 10-4.
                       DR. APOSTOLAKIS:  Yes.
                       DR. KRESS:  And works -- well, it actually
           starts from LERC and even works its way backwards, but
           it has 10-4 built into it as a defense-in-depth
                       DR. APOSTOLAKIS:  But that's at the high
                       DR. KRESS:  Yes, but they back off to a
           frequency that's consistent with that based on the
           success criteria of ECCS  and the conditional core
           damage frequency that you get when the ECCS fails. 
           And that's another question I was going to have, do
           you factor success criteria into that some way? 
           Because, you know, they may discover they can do away
           with one of the trains, but success criteria has that
           built into it sometimes, how many trains are
           operational of ECCS.
                       MR. KURITSKY:  Well, in fact, the way this
           will work, let me just jump to the second book,
           because we're looking at two different options.
                       MS. DROUIN:  Why don't we just get right
           into them. 
                       MR. KURITSKY:  Okay.  We're looking at two
           different options for how we would accomplish this
           ECCS system liability requirement.  And the first
           option, and it says a deterministic system reliability
           requirement based on risk information.  And as an
           example we put up there an ECCS requirement that only
           one train of ECCS would be required for some set of --
                       DR. KRESS:  That is a success criteria.
                       MR. KURITSKY:  Right, sum set of LOCAs. 
           And that actually is what you'll be using to establish
           maybe a less stringent reliability requirement for
           initiators that are much lower frequency.  And those
           various LOCA frequency intervals and the associated
           ECCS reliability requirements would be something that
           the NRC would be establish based on generic
           information.  And so once we would come out and
           specify what you would need.  For this LOCA interval
           you would need to have this reliability requirement,
           you know, one train or two trains.  Well, you need to
           consider loss of power, you would not.
                       DR. KRESS:  But would you specify that in
           terms of some confidence level in order to factor a
           defense-in-depth concept in?
                       MR. KURITSKY:  Well, certainly -- I'd
           certainly --
                       DR. KRESS:  I mean you're not going to
           stick to means, are you?
                       MR. KURITSKY:  The framework you
           definitely need to consider uncertainty.  To get a
           mean you, obviously, have to consider uncertainty.
                       DR. KRESS:  Yes.  You have to have the
           uncertainty to get to mean.
                       MR. KURITSKY:  And the framework document
           does talk of means.  I mean, the values that are
           provided in the framework document are based on mean
                       DR. KRESS:  See, that bothers me because
           you could have a given mean, large uncertainty or
           small uncertainty, you ought to treat the two
                       MR. KURITSKY:  Right. But that's why this
           is something the staff has to -- on this particular
           one it will not be up to the licensee to come up with
           that value.  We'll be doing that evaluation ourselves. 
           So if we run into a situation where you can have a
           very wide uncertainty that could give you a -- mean or
           whatever, and we are well aware of that.
                       DR. APOSTOLAKIS:  Or they could specify an
           appropriate threshold.
                       DR. KRESS:  Or a confidence level.
                       DR. APOSTOLAKIS:  Yes.  They say they're
           going to specify a threshold.  So, the earlier comment
           that it's going to be based on 10-4 is not really
           valid.  I mean, it's got to be the location issue. It
           has to be a large LOCA contribution of some kind, and
           they will specify that.  And, presumably, they work
           with mean values.  The value that they will choose
           will allow for the uncertainty also.  It'll be low
           enough to allow for the uncertainty.
                       And you want it more explicit, that is
           what you're saying?
                       DR. KRESS:  Yes.
                       DR. APOSTOLAKIS:  They might give you
           reason why --
                       DR. KRESS:  Because I think people would
           treat it differently if --
                       DR. APOSTOLAKIS:  They might then give you
           a reason why they selected this mean value and do some
           sensitivity studies to show what the 96 percentile
           does, for example.  Because in these cases it's the
           high tail that drive the mean, really.
                       DR. KRESS:  Yes.
                       DR. APOSTOLAKIS:  So it's -- but I think
           the appropriate NRC specified threshold should address
           this question.  That's going to be a challenge to do
                       DR. KRESS:  Yes.
                       MR. KURITSKY:  Okay.  And just to jump
           down.  So for number 1, the NRC would establish those
           requirements and they would be, I guess, maybe in a
           reg guide or whatever, but once we establish then --
                       DR. APOSTOLAKIS:  Now, all this is with
           the current definition of large-break LOCA, right?
                       MR. KURITSKY:  Well, right now we're not--
                       DR. APOSTOLAKIS:  You're not touching
                       MR. KURITSKY:  Yes.  And this is not just
           relegated to large-break LOCA.
                       DR. APOSTOLAKIS:  All LOCAs?
                       MR. KURITSKY:  This would be all LOCAs.
                       DR. APOSTOLAKIS:  Well, the interest is
           really in the large-break, isn't it?
                       MR. KURITSKY:  Right, that's obviously 
           where you would find --
                       DR. APOSTOLAKIS:  So this is the current--
                       MR. KURITSKY:  It's the current
                       DR. APOSTOLAKIS:  The current definition,
           current frequencies?
                       MR. KURITSKY:  Yes.
                       Okay.  And so, like I said, in the first
           case  --
                       DR. APOSTOLAKIS:  And now you don't expect
           -- I mean, you said there earlier that the issue of
           the frequency or the size will be visited later?
                       MR. KURITSKY:  Yes.
                       DR. APOSTOLAKIS:  And if you reach certain
           conclusions, then you don't expect these things to
           change much?
                       MR. KURITSKY:  No.  As you'll see when we
           discuss that later, that of course --
                       DR. APOSTOLAKIS:  But it's frequency,
                       MR. KURITSKY:  -- had a large synergistic
           beneficial impact with these.
                       DR. APOSTOLAKIS:  Yes. Yes.  
                       DR. WALLIS:  I don't quite understand why. 
           If you've got two trains of ECCS  for LOCAs of a
           smaller size, you don't know what kind of LOCA you're
           going to get anyway, so saying you're only going to
           have one for a large LOCA, I don't quite know what you
           mean, unless you mean in a probabilistic sense, in
           which case you're putting in an improbable LOCA with
           a improbability of failure of a train, say you're
           going to sort of beating a dead horse, really.  I
           mean, you're putting in a weaker requirement for a
           LOCA which isn't required anyway.  I don't think you
           gain anything for that.
                       If you have to have two trains for some
           other kind of LOCA, you need the two trains.
                       MR. KURITSKY:  Right.  Like, as an
           example, look at accumulators.  You only need them for
           large LOCAs.  So if you could show that for large
           LOCAs you only need one train step, then you would
           only need to have one accumulator, let's say, or you
           know, something along those lines.
                       So, you're right.  If it's a high pressure
           injection pump that's used for small LOCAs and large
           LOCAs and transients, just the fact that you only need
           one for this case but you need two or more for other
           cases, you're right. It doesn't buy anything.  But if
           there's specific equipment that is associated with us
           a particular subset of LOCAs or subset of initiators
           that you can then demonstrate --
                       DR. WALLIS:  You might get rid of those
                       MR. KURITSKY:  Well, what we're saying is
           that you would say, for instance, especially you only
           need to have one train for LOCAs above size X and if
           accumulators are only needed in your plant for LOCAs
           above size X, you would only need to have one train of
                       DR. WALLIS:  Why?
                       MR. KURITSKY:  If you only had one
           accumulator, and now whether or not --
                       DR. WALLIS:  Because one accumulator is
           able to handle the large LOCA and the second one's
           just a backup?
                       MR. KURITSKY:  Right.
                       DR. WALLIS:  Okay.  
                       MR. KURITSKY:  And if there's four, you
           need two then it means that, you know, two need two,
           you wouldn't need the other two.
                       DR. APOSTOLAKIS:  How would you
           accommodate in this risk-informed approach or allow
           for the statement you made earlier the plant equipment
           that is designed to the requirements of design basis
           LOCA also provide defense-in-depth against a spectrum
           of beyond design-basis accidents?  It seems that this
           is strictly based on LOCA.
                       MR. KURITSKY:  Well, actually, it's not
           here on the slide, but in the description on
           attachment 2 we mention that  -- and it applies both
           to 1 and 2 here -- is that changes that are made at
           the plant based on these things need to consider the
           impact not just on LOCAs but on all initiators because
           ECCS, of course, is used for a wide swath of
           initiators, it's not just LOCAs.  So, obviously, no
           change is going to be made without considering the
           risk impact and the risk significance of those changes
           across all initiators.
                       So, it can impact what you have to assume
           for your thermal-hydraulic ECCS performance
           calculations.  It may -- if you can find things like
           an accumulator only applies to a subset of LOCAs, you
           can change those requirements, then you can get some
           benefit from that.  But you need to consider the
           impact across all initiators.
                       MR. ROSEN:  But it might also impact
           allowed outage times?
                       MR. KURITSKY:  Well, that's what one of
           the benefits may be.  In other words, I wouldn't say
           necessarily that if you had three accumulators in your
           plant and now this thing says you only one, you may
           not take get rid of one, but you could certainly have
           the case for a greatly relaxed allowed outage time on
           one accumulator.
                       DR. WALLIS:  You wouldn't go from green to
           white --
                       MR. KURITSKY:  Yes.  I don't exact with
           that oversight program what's what, but -- okay.
                       So anyway, so getting back, under option
           1 it's something the NRC will specify.  We'll
           establish it and it will be specified.  And so a
           licensee who chooses this option will go ahead, they
           will not require any NRC review and approval, because
           it would already be there, they can pick it.  
                       And I make that point because in under
           option 2 what you're doing is actually allowing the
           plant to use plant specific LOCA frequency information
           and plant specific ECCS reliability information to
           come up with -- you know, to do the same type of thing
           but do it on a plant specific basis.  So they'll come
           up with commensurate ECCS reliabilities based on the
           frequency of LOCAs or challenges that they have at
           their plant, and that can allow them more relaxation
           than what would be obtained through the generic
           application the NRC would do.
                       DR. WALLIS:  So people are going to be
           exercising these thermal-hydraulic codes a lot to look
           and see if they can gain anything by saying well, you
           know, if we didn't have this functional, then this
           would happen and maybe we could tolerate that, and
           maybe something else could happen.  There's be a lot
           of exploring to see what would happen if you backed
           off on all sorts of requirements.
                       MR. KURITSKY:  Right.  But I think for the
           most part the way it would probably work out is you're
           talking about relaxation of allowed outage times. And
           you already know from your calculations that you need
           this one train or this two trains.  And so anything
           more than that --
                       DR. WALLIS:  But that you need a train,
           who is going to decide whether you need the train? Is
           that the calculation of the licensee or the NRC?  The
           NRC is going to run in some codes to decide that one
           train's okay.
                       MR. KURITSKY:  No.  I think that the ECCS
           performance calculations that are already done
           determine how many trains you need.
                       DR. WALLIS:  Oh, they've already been
                       MR. KURITSKY:  I think everybody has to
           have those done.
                       DR. WALLIS:  And they have explored all
           these --
                       MR. KURITSKY:  Well, they know what the
           minimum -- they know the minimum number of trains that
           they need or the amount of equipment they need.
                       DR. WALLIS:  Okay.  So much of the
           technical work has already been done?
                       MR. KURITSKY:  In that regard, yes.
                       DR. WALLIS:  Okay.  
                       DR. KRESS:  Based on the current Appendix
                       MR. ROSEN:  Or best estimate.
                       DR. KRESS:  Best estimate.
                       DR. WALLIS:  When you start changing some
           of these things, you may need to run those again,
           though, when you change these --
                       MR. KURITSKY:  That's right.
                       MR. LAUBEN:  This is Norm Lauben again.
                       I think in general because of the single
           failure requirement currently, and it's the state of
           the single active failure, usually it turns out that
           the whole thing is designed so one train will do the
           trick in terms of pump ECCS.  But I think in terms of
           accumulator outage times, there may be a dearth of
           information about how many accumulators you'd need
           under various circumstances.  Because you do require
           some accumulators even for large small breaks or
           certain evaluation models show that.  
                       DR. WALLIS:  Small large breaks, too.
                       MR. LAUBEN:  Excuse me?
                       DR. WALLIS:  And small large breaks.
                       MR. LAUBEN:  And small large breaks,
                       So I think there might be studies that the
           vendors would -- and utilities would need to do also
           with respect to their accumulator outage.
                       DR. WALLIS:  And the, of course, when
           you've changed the decay heat curve and the decay heat
           multiplier and all these other things, you have to run
           them again and again.
                       MR. ROSEN:  Well, where the margins would
           show up, would be in the margin to the peak clad
           temperature requirements that utilities have to keep
           track of all the time anyway.  And with these changes,
           my first take on it is that they'd show up with much
           larger margins than they now show.  Is that correct?
                       MR. KURITSKY:  I think with the A changes,
           yes.  That's basically would be in, you know, getting
           increased peak clad temperature.
                       MR. ROSEN:  And some plants are now quite
           restricted --
                       MR. KURITSKY:  Yes.
                       MR. ROSEN:  -- by the conservatisms in the
           existing model requirements.
                       DR. WALLIS:  It's going to be very
           interesting for the codes.  Because up to now, the
           codes have been accepted based on the way things have
           always been done.  When we start changing these decay
           heats and these zirconium steam models, and all those
           things, it's going to change everything, isn't it? 
           So, there's got to be then a careful evaluation of
           whether the codes are now adequate for this new
           environment and what the uncertainties are and so.
                       DR. SHACK:  Now, bullet 2 would let me get
           rid of the simultaneous LOOP and large-break?
                       MR. KURITSKY:  You mean the second option?
                       DR. SHACK:  Yes.
                       MR. KURITSKY:  Yes.  It's essentially the
           same thing, only it's more of a plant specific type of
           calculation.  So the NRC would establish some CDF
           threshold and they would do their calculation
           underneath that threshold.
                       The first one is meant to do something
           where we wouldn't require any reviews.  We'd go
           through and establish it ahead of time and licensees
           who wanted to choose it could just go do it without
           having to get review and approval.  One allows them to
           do that in order to be comfortable, we can do that
           across the board, we have to be more conservative. 
           The second one allows them to be a little more plant
           specific if they want to sharpen their pencil and use
           their PRA models or do reliability analyses.  And,
           again, that goes to -- coming with the LOCA
           frequencies, it goes to the issue we mentioned before
           where it may be some kind of updating of operational
           data to come up with the new LOCA frequencies, or it
           may involve some PFM analysis and more detailed things
           along the lines of large-break LOCA redefinition.  So
           that would be something they could consider. Maybe it
           would take a little longer, but that's something that
           they could use their --
                       DR. WALLIS:  And that would be consistent
           with the loss of their performance-based regulation
           would you just had some -- at a high level a
           requirement and then it has to be met somehow.
                       MR. ROSEN:  The first one's more
           prescriptive and the second one will be more
           performance based.
                       MR. ROSEN:  Plants with more robust
           designs, like three safety trains, would particular be
           able to take good advantage of that second bullet.
                       MR. KURITSKY:  And the first bullet, too,
           for that matter.  Because they may show that maybe two
           of their trains can have relaxed aspects or something.
                       MR. ROSEN:  Conversely, plants with less
           robust designs might not get any improvement out of
           this because they're bumping up against the limits now
           and even with the changes, they might not get more
           margin, much more margin?
                       MR. KURITSKY:  And the same thing with the
           A changes.  I know it's very plant specific.  Some
           plants, you know, may get a lot of benefits, some may
           not get that much benefit depending on how close you
           are to bumping up to the margins right now.
                       DR. WALLIS:  Well, 2 ought to be more
           acceptable to the public if you could say that these
           plants -- we are now assuring that these plants have
           a certain NRC specified CDF threshold.
                       MR. KURITSKY:  The first one --
                       DR. WALLIS:  That's much more direct than
           saying that it's got to have all these prescriptive
           requirements, but we don't know what the consequences
                       MR. KURITSKY:  Right.  Only -- yes.  Maybe
           as far as when the public sees it.  But for us to go
           ahead and come up with those prescriptive requirements
           under 1, we're going to be using a CDF threshold as
           our metric, too.  You're right, it's not as much in
           the public in that sense, but it's the same thought
           process, the same procedures can be used in 1.
                       DR. WALLIS:  Well, at least it's clear
           what your measure of safety is.  Your measure of
           safety now is analysis specified CDF threshold.  It's
           not some statement that if they follow our
           requirements, that's adequate for the safety.  I mean,
           this is a definite statement that you have an NRC
           specified threshold.
                       DR. SHACK:  Progress, right?
                       DR. WALLIS:  That's progress.
                       MR. ROSEN:  Okay.  And, again, going back
           to the fact that this is a feasibility study right
           now, page 1, you know we got to work on feasibility,
           establish the feasibility, now under Phase 2 we will
           continue with additional technical work to support the
           rulemaking.  And just as under the A changes, under
           the B changes we have a number of items that we have
           to pursue.
                       Specifically, as we've all been
           discussing, when it comes to this risk-informed
           alternative, we need to determine acceptable methods
           and assumptions for performing those LOCA CDF and
           system reliability analyses.  And that does mean that
           we have to take a lot of consideration of
           uncertainties, because that becomes a very big part of
           determining how we're going to come up with threshold
           and what types of analyses will be acceptable for
           meeting those thresholds.
                       Again, the --
                       DR. APOSTOLAKIS:  Excuse me.  Option 3 is
           separate from 1.174?
                       MS. DROUIN:  Yes.
                       DR. APOSTOLAKIS:  So there in Option 3 you
           can actually increase the CDF more than what the
           regulatory guide says?  Because I mean if you
           establish a threshold value that's high enough, then
           for a particular plant the result may be a change in
           CDF that's more than regulatory guideline 1.174.
                       MR. KURITSKY:  The Option 3 doesn't
           specify a limit on like reg guide 1.174 is on
           increase.  Just like you say, if there's a threshold,
           theoretically someone may move up more than what would
           be in reg guide 1.174 theoretically.  But we do, I
           believe, and the framework does say that any changes
           that would tend to increase risk would have to be
           limited.  It's qualitative wording, but I think there
           is some wording in the framework that limits -- says
           that increased numbers have to be limited and they
           must still remain below the framework guideline values
           and also may have to be limited.  But it's not as
           clearly specified as reg guide 1.174, which has actual
           quantitative limits.
                       MS. DROUIN:  I mean, our goal is to stay
           consistent with reg guide 1.174.  The difference is
           that between them is you have to remember is that reg
           guide 1.174 is applied on a plant specific basis.  Our
           framework is applied on a generic basis.
                       Now, if because of some circumstance the
           numbers are going to have to differ, then there will
           have to be a real good basis for it.  Because our goal
           is to stay consistent.  It doesn't mean that we can't
           deviate, but there'd have to be a good technical basis
           for it.
                       MR. ROSEN:  But, Mary, after you're done
           with this, 1.174 still stays in play, right?
                       MS. DROUIN:  Absolutely.
                       MR. ROSEN:  So then a utility could then
           still make small changes to that based on 1.174?
                       MS. DROUIN:  Absolutely.  Absolutely true.
                       DR. WALLIS:  I think you're going to have
           to face the question of the risk that ECCS wouldn't
           work based on uncertainties in the codes.  Fit that
           somehow into your risk analysis and in a formal way as
           soon as you move away from conservatism.
                       DR. APOSTOLAKIS:  It seems to me when you
           talk about codes here, the issue of model uncertainty
           would be that important, would it not, Graham?
                       DR. WALLIS:  That's the issue, yes.
                       DR. APOSTOLAKIS:  That's the issue.
                       Now, are you guys having an approach?  I
           mean we keep hearing now for two years at least that
           the University of Maryland is developing something on
           model uncertainties. Is that done?  Now you have an
           approach to this?  How are you going to handle it.
                       MR. CUNNINGHAM:  There's, I guess, two
           issues of this.
                       This is Mark Cunningham from the staff.
                       DR. APOSTOLAKIS:  That's one issue.
                       MR. CUNNINGHAM:  That's one issue, who I
           am, yes, sir.
                       And the second issue is where I'd rather
           be, but that's -- the University of Maryland work on
           model uncertainty is being feed into the PTS work that
           we've talked to the Committee about on several
                       DR. APOSTOLAKIS:  Yes.
                       MR. CUNNINGHAM:  And how you deal with
           model uncertainty there.  Probably some of that same
           thinking will go into play as we do the greater -- the
           next phase of the technical work for the ECCS modeling
           as well.  So I think it's going to spell over into
                       What we've learned so far, if you will,
           the PTS work we'll feed into this work the next time
           around or over the next year or so.
                       DR. APOSTOLAKIS:  But we haven't seen any
           report, have we?  Have we seen anything yet?
                       MR. CUNNINGHAM:  I think that's right,
           yes.  It'll come in at least in the context of the PTS
           documentation that you see.
                       MR. KURITSKY:  Okay.  As you mentioned,
           there's a lot of work to be done in Phase 2 for
           determining the methods to use between the LOCA CDF
           and ECCS system reliability.  We have to determine the
           appropriate thresholds concerning many of the things
           and the comments that the ACRS has just brought out,
           and also the items that we already have considered.
                       Another thing that we have to do is
           identify features that tend to decrease the likelihood
           of loss of off-site power after a LOCA and determine
           acceptable methods and assumptions for estimating the
           plant-specific probability of loss of off-site power
           given a LOCA.  And the reason we have those two kind
           of separate, because the first one really kind of
           applies to Option 1 from the previous slide where
           we're going to specify some generic requirements and
           it may be that in order for a plant to take advantage
           of certain requirement where they do not have to
           consider loss of off-site power for a certain set of
           LOCAs, they have to meet features.  
                       Like, for instance, they'd have to have
           the capability -- or they may have to have the
           capability for communication with -- you know,
           communication with the transmission system operator or
           something like that.  There may be some features that
           plants would have to meet, and if they meet those,
           then they can have the relaxation on the LOOP
                       And the second --
                       DR. WALLIS:  Does the LOOP always follow
           a LOCA and not precede it?
                       MR. KURITSKY:  It can go either way.  
           Preceding the LOCA, there isn't as much -- at least to
           date there hasn't been shown to be as much of a tie. 
           There's been shown more of a tie where when you have
           a LOCA, you have a big inrush of loads when big pumps
           start and so you can precipitate a LOCA.
                 Q     So it's of common cause then?
                       MR. KURITSKY:  Yes, right.  And the other
           way around, you don't tend to really have that much of
           a --
                       DR. WALLIS:  So the loss of off-site power
           doesn't set off a transient which lead to a LOCA?
                       MR. KURITSKY:  Right.  I mean, is there a
           possibility they could have a greater chance of
           popping open a valve or leaving it open or something? 
           I mean, there is some connection-- there's some
           connection, but it's not as strong, nearly as strong
           as -- at least to date from --
                       DR. WALLIS:  Not perhaps the broken pipe,
           but the stuck open valve or something might be more
           likely if you lost off-site power?
                       MR. ROSEN:  Right.  Right.
                       MR. ROSEN:  But what you're talking about
           are all hypotheticals.  I mean, we're not talking
           about experience of losses of off-site power causing
           LOCAs or LOCAs -- or LOCAs causing losses of off-site
           power.  You don't have much data on that.
                       MR. ROSEN:  Yes, we don't.  There's very
           little data.
                       MS. DROUIN:  That's correct.
                       DR. APOSTOLAKIS:  You don't have much data
           on LOCAs, period.
                       MR. ROSEN:  That's right.  I mean, we're
           talking about this hypothetical space and trying to
           think about -- what you were talking about here is
           trying to think about mechanisms where losses of off-
           site power, for example, can cause a LOCA.  And you
           have to go pretty far to figure that -- to think about
           that.  And there's no operating experience that shows
                       There's been lots of losses of off-site
           power and no LOCA's as a result of it, or very few.
                       MR. KURITSKY:  Right.
                       MR. ROSEN:  I mean these are not causally
           linked subjects in my mind.  We can think about
           possible ways to link them causally, but in fact
           experience says they're not.
                       MR. KURITSKY:  And going from LOCA --
           going from LOOP to LOCA we don't have anything. Going
           from LOCA to LOOP we don't have -- we don't have data
           to show it because we don't have that many, because as
           we said we don't have many LOCAs.  We have some ECCS
                       DR. BONACA:  Yes, because then it would be
           ECCS acutations and sequencing that --
                       MR. ROSEN:  You have lots of scrams,
                       MR. KURITSKY:  Right.
                       MR. ROSEN:  And how many LOOPs are caused
           by a scram?
                       MR. KURITSKY:  Right.
                       MR. ROSEN:  When the plants scrams, how
           many times has the LOOP gone done?  And the answer is
           very, very infrequently.
                       MR. KURITSKY:  Right.  But the issue is
           not from just a regular scram, but from an ECCS 
           actuation.  The drawdown on the voltage from all of
           the safety injection pumps coming on line.  There is
           limited data as far as ECCS actuations, but again --
           I don't say it's conjecture, but I mean --
                       DR. BONACA:  The numbers they use here,
           you know, are pretty low in frequencies.
                       MR. KURITSKY:  Right.
                       DR. BONACA:  I mean projected frequencies. 
           So it's not that it's very high.  
                       MR. KURITSKY:  Right.
                       DR. BONACA:  But it justifies the thought
           that for certain break sizes, you know, those
           estimates tell you you don't overkill to assume loss
           of of-site power.  And an interesting thing is that,
           of course, as you go to a smaller size break size,
           then LOOP seems to be less of a necessity because the
           loading is differently, probably you're not going to
           have as much demand on the electrical system as you
           will have in a large-break LOCA.
                       So, for both of them really it seems to me
           when I read the report, it becomes questionable
           whether we're using a loss of power assumption, except
           it's a conservative assumption.
                       MR. ROSEN:  One of the other features of
           using a loss of off-site power assumption is a
           regulatory principle.  It neglects the fact that a
           off-site power systems at all the different sites are
           different, some more robust than others.
                       MR. ROSEN:  Yes, that's very true. And
           that's why we talk about in this last bullet
           determinable acceptable methods for us being plant
           specific for us being plant specific probability of
           loss of off-site power because it can be very plant
                       MR. LEITCH:  I thought some of the work
           related to this had to do with the elimination of
           single failure criteria.  In other words, what we're
           talking about here is simultaneous LOCA LOOP and be
           able to do this with a single failure.  And I thought
           in some of the reading it was thought that perhaps the
           single failure could be eliminated.
                       MR. KURITSKY:  Well, in this -- what we're
           doing with these reliability thresholds or CDF
           thresholds is accounting for simultaneous LOOP -- LOCA
           LOOP assumption and single failures, kind of all round
           up into one.
                       MR. LEITCH:  Yes.
                       MR. KURITSKY:  So if you can demonstrate
           that, you know, you're below some threshold and only
           let's say, for instance, with just one train of
           equipment --
                       MR. LEITCH:  Right.
                       MR. KURITSKY:  You know, that you're below
           this threshold, then you don't need to have like a
           second train.  So in other words, you don't have to
           have to have that single failure criteria, you don't
           have to have that extra redundancy built in.  So it's
           addressing that single failure criterion through
           reliability framework.
                       MR. LEITCH:  Liability, yes.  Okay.
                       MR. ROSEN:  And that's perfectly
           appropriate, because the single failure criterion was
           a surrogate for a real reliability framework when we
           weren't able to put one together and analyze it
           because we didn't have the PRAs and because we didn't
           have the data to support the reliability analysis that
           we now have based on real experience at operating
                       DR. KRESS:  And this is where I keep
           harping on uncertainties.  You've got two trains that
           have a mean reliability of this level for that, and
           then you are going to replace it with one train that
           has reliability down here.  Then you have to worry
           more about the uncertainties in this train down here
           because as the reliability gets lower and the
           uncertainties does get bigger.  So you can't just swap
           out means.
                       MS. DROUIN:  I mean, one of the biggest
           challenges, you know, over the next year we're going
           to be faced with is how to deal with the
                       DR. APOSTOLAKIS:  Absolutely.
                       MS. DROUIN:  And how to incorporate that
           in, without a doubt.
                       DR. KRESS:  And I know I keep harping on
           that, and you keep giving me the same answer.  So, I
           appreciate it.
                       MS. DROUIN:  I may not have the answer to
           you today, but we don't.  We have lots of ideas, but--
                       DR. WALLIS:  Well, I think it would be
           good to try to implement some of those ideas in a
           preliminary way to see if they work.
                       MS. DROUIN:  Yes.
                       MR. KURITSKY:  That's kind of what Phase
           2 does.
                       DR. WALLIS:  Rather than sort of promising
           to do it.  I mean, I think you need to start trying
           some of them out and seeing if they work or not, since
           not too much of this is work to be done, but some of
           it gets done and then you can say "Yes, we know.  We
           know we can do that."  
                       MR. KURITSKY:  And that's exactly what the
           Phase 2 work is going to do.
                       DR. WALLIS:  I was looking at this slide
           here. I was wondering if eventually we're going to
           see, or you're going to have to develop a work scope
           for all this stuff.
                       MR. KURITSKY:  Yes.
                       MS. DROUIN:  Yes.
                       DR. WALLIS:  It'll be interesting to see
           how comprehensive and long it is.
                       MR. KURITSKY:  We have a little bit in
           attachment 2, the paper, there's a little more detail
           on it.
                       MS. DROUIN:  But that's still a high level
                       MR. KURITSKY:  Yes, it's still high level.
                       MS. DROUIN:  No, you're right. We're going
           to have to sit down and work out all the things that
           are going to be needed to be done.  And once we get
           the go ahead, yes.  Okay.
                       DR. WALLIS:  Consequently it becomes a
           real thing and not a dream.
                       MS. DROUIN:  That's right.
                       Now the long term changes. You heard about
           the short term and now we will get into the long term.
                       MR. KURITSKY:  Right.  Based on our
           feasibility study we also feel that additional changes
           to 50.46 may also have merit, particularly possibly in
           the definition of the spectrum of breaks and
                       The extent of potential change to 50.46 --
                       DR. KRESS:  What do you mean by
                       MR. KURITSKY:  The specificity of the
                       DR. KRESS:  The speculation, rather.
                       MR. KURITSKY:  The spectrum, specified
           rate spectrum.
                       The extent of potential change to 50.46 is
           dependent on our state of knowledge regarding the LOCA
           frequencies for different break sizes.  And as an
           example, you know, if we could confidently demonstrate
           that a set of LOCAs has a collective mean frequency,
           again that means, of course, we take into account
           uncertainties, but --
                       DR. KRESS:  But you're adding them up? 
           That's what collective means.
                       MR. KURITSKY:  Right, collectively means,
           right.  In other words, all breaks above 16 inches.
                       DR. KRESS:  Well, let me ask you a
           question about that.  I would have thought that the
           conditional core damage frequency would be a function
           of the LOCA frequency, they're not independent.
                       For example, small-breaks have higher
           frequency and small-breaks have a different
           conditional core damage frequency.  Therefore, there's
           a link between CDF and frequency, but the numbers you
           have, 10-4, 10-5, 10-6, seems to me to assume a
           constant conditional core damage frequency.
                       DR. WALLIS:  This is just initiation
           frequency shown here.
                       DR. KRESS:  Yes, but in order to arrive at
           those numbers, you've assumed the constant core
           damage, conditional core damage frequency, I think.
           And it seemed to me like a little bit a issue that you
           ought to think about.
                       MR. KURITSKY:  Right.  Well, I think --
           the way something like this would work, and this is
           just an example to illustrate how we would --
                       DR. KRESS:  Yes.
                       MR. KURITSKY:  If we had such data, what
           we could work with.  If, for instance, we could that
           a set of LOCAs had a collective frequency of 10-4, you
           know, lower than 10-4, then we may say that some
           regulatory relief is appropriate.  It may be reducing
           it to one train of ECCS.  Now, regardless of whether
           that's a small or large-break, what we're saying is if
           you had one train, you're going to get, let's say,
           another 10-2, but your 10-4, so that may be
                       DR. KRESS:  Yes.  I would prefer it, I
           think, more high level specification.  Say, if a set
           of frequencies can be determined such that the
           convoluted frequency and the conditional core damage
           frequency is less than 1/10th of the core damage
           frequency, then you could do some of these things.
                       Let's ignore high level.  You know, you
           may be able to plant specifically back it off to some
           numbers like this, but I think for that particular one
           I would look for more of that kind of statement.
                       DR. BONACA:  Yes.  He had already give you
           some kind of blanket credit to your ECCS system.
                       DR. KRESS:  Yes.  Right.
                       DR. WALLIS:  Yes, sort of in the low
                       DR. KRESS:  Yes.  Yes.
                       DR. WALLIS:  And so --
                       DR. KRESS:  This is too -- I'm looking for
           more of a performance one rather than a prescriptive
           one idea.
                       DR. WALLIS:  But 10-6 you might go for
           anyway no matter what the conditional core damage
                       DR. KRESS:  Yes, 10-6.  You might get the
           one level like that or you just forget it.
                       DR. BONACA:  Well, then I think the
           implication there is that, you know -- I mean, even if
           you just give 10-1 as credit for the ECCS system, you
           would -- your sequence would be successful enough.  I
           mean, a likelihood, I mean it's so low, I guess.  But
           that makes it more clear, you're right.
                       MR. ROSEN:  Yes.  The point is we've
           already done that.  The NRC has already done that for
           vessels.  The vessel failure is so low we don't
           consider it.
                       DR. WALLIS:  Or our estimate with current
           knowledge is so low, yes.
                       DR. BONACA:  On the other hand, I mean if
           you take that last case, 10-6, I assume that these
           would be double and can break.  And you're saying that
           -- if -- in the case there will be no credit or very
           little credit given for the ECCS effectiveness because
           if you step down the capability, not to be designed to
           meet this kind of criteria for the LOCA, then you're
           really hanging your hat on 10-6 for reactor here,
           right?  Assume that you said I don't need an ECCS
           system for a large-break LOCA because the frequency of
           that is so low, so therefore I step down --
                       DR. KRESS:  Therefore it doesn't
           contribute to CDF anyway?
                       DR. BONACA:  That's right.  
                       DR. KRESS:  Because it's more than a
           certain percent to --
                       DR. BONACA:  So for that particular case
           you're taking no credit for the ECCS system at all. 
           You're saying 10-6 is good enough and then live with
                       MR. KURITSKY:  Don't need it.
                       DR. BONACA:  That's right.
                       DR. WALLIS:  This is long term work
           anyway, isn't it?
                       MR. KURITSKY:  Yes.  Yes.
                       DR. WALLIS:  So I think you understand
           what we're saying how can it do it tomorrow.
                       MR. KURITSKY:  Yes.
                       DR. BONACA:  In other words, how can you
           get that kind of constant.
                       MR. KURITSKY:  Assuming we have a
           schedule, that's longer term.
                       DR. KRESS:  Yes, but my problem is how are
           you going to demonstrate these set of LOCAs, how they
           collective mean frequency?  That seems like a pretty
           tough problem.
                       MR. KURITSKY:  That is --
                       DR. KRESS:  I guess we'll leave that to
           Bill Shack.
                       DR. BONACA:  And to Peter.
                       DR. SHACK:  Without Mayfield here to argue
           this out, I mean you know we calculate these things
           all the time for leak before break, for pipe wipe
           restraints, we deal with environmental fatigue by
           calculating things.  And now all of a sudden it's --
                       DR. BONACA:  Too hard.
                       DR. SHACK:  -- too hard to do, you know.
                       I think to my mind somehow I just sort of
           get the feeling that we're making this more difficult
           than it has to be.  You know, I look through some of
           this work and, you know, you're not trying to
           calculate the leak rate through every crack and every
           pipe.  You're trying to sort of block off the
           feasibility of a very large pipe break, a double under
           guillotine pipe break.  And we've done an awful lot of
           leak before break and pipe probabilistic fracture
           mechanics.  You know, we've studied in connection with
           PTS initial flaw sizes.
                       I get a little worried, you know, you're
           going to get bogged down on your short term, which
           will turn out to be longer term than you think it is
           and more difficult than you think it is and the pay
           off there is really a whole lot less than it is here. 
           And to just go for it and concentrate the resources on
           the thing that has the pay off.
                       DR. BONACA:  Yes, I totally agree with
           that that there's a great pay off.  To some degree
           it's a little bit like, you know, a little bit
           different but like, say, okay we're going to remove a
           container.  What I'm trying to say is that ECCS when
           it comes down to makeup water and so, you know,
           everything you think about --
                       DR. SHACK:  Not a safer cow, right?
                       DR. BONACA:  And you want to have water. 
           And to step it back, it's a little bit of a holy
                       DR. SHACK:  Well, yes.  And I suppose it
           comes down to how feasible you really think the first
           set of changes are.  You know, if they could be
           implemented quickly.
                       DR. WALLIS:  Speaking of pay off, the pay
           off is mostly to industry, isn't it, rather than to
           NRC.  So then maybe industry should be the ones to
           demonstrate all these things with an optimism that
           they can succeed.
                       DR. SHACK:  Well, I think industry is sort
           of they think they can do this.  The NRC has to do
           enough work to be able to judge what the industry
                       DR. BONACA:  That's right.  No, they don't
           have to lead the way.  They only have to sort of drag
           industry into it by showing it can be done.
                       DR. SHACK:  Right.  But they certainly
           have their own set of work to do in order to be able
           to evaluate and to assess what industry proposes.
                       MR. ROSEN:  Let me give the other side of
           the argument, Bill, to your statement about jumping to
           Part B forgetting about Part A.
                       I think what you need to do is demonstrate
           some early success.  And so that's what Part A is for.
                       DR. SHACK:  Yes, we've been picking low
           hanging fruit here for the 8 years I've been on the
                       DR. KRESS:  The higher up the tree, the
           sweeter grows the lemon, right?
                       DR. BONACA:  Out of a lot of low hanging
                       DR. SHACK:  Yes, a lot of low hanging
                       DR. WALLIS:  When I pick the apples, I
           usually forget the low hanging ones because they're
           not worth eating.  You go for the ones that are really
           good at the top, right.
                       DR. KRESS:  The ones at the top are
           better, yes.
                       DR. BONACA:  Still there is the holy grail
           thing.  I mean, once you say that I don't have to
           design any more of my system.  Because somewhere
           you're going to capture the benefit of that for a
           double ended break.  You're making a trust issue.  I
           mean, and the consequences in case you could have a
           low ended double ended break and not a capability to
           deal with it, would be very significant.  It would be
           so -- I mean there is a -- you know, there is a real
           issue of public acceptance in stepping back on that
           kind of commitment.  It has to be really looked hard
           and tough, and you have to have a very high confidence
           in the fact that you won't have that break. 
                       Again, we depend on our colleagues with
           the metallurgical background to give us that
                       DR. KRESS:  Well, I think you can have
           probably a large confidence on a break -- the largest
           pack with the double ended guillotine.  My problem is
           you're going to back off to something else.
                       DR. BONACA:  Absolutely.
                       DR. KRESS:  And somewhere down there you
           don't have that confidence, and I don't know where
           that level is.
                       DR. SHACK:  I see what you mean, yes. 
           Yes, and you know I think getting to industry 6 inch
           break might be difficult, but I think you could
           certainly back off from the double ended guillotine
           break of the largest pipe down quite a ways with a
           reasonable degree of confidence.
                       MR. ROSEN:  And certainly back off from a
           double ended guillotine break at the same time that
           you get a LOOP and take a single failure rate.
                       DR. SHACK:  That's easy.  
                       MR. KURITSKY:  But I mean they're going to
           deal with that one, absolutely, because that's in the
           sort term.  And there you can do very conservative
           estimates of those large break frequencies and still
           get a lot of benefit.
                       MS. DROUIN:  I believe so.  Shall we go to
           the --
                       MR. KURITSKY:  Okay.  Just to -- off this
           conversation that we were just having, the staff is
           going to continue to meet with industry,
           representatives of the industry in public meetings to
           discuss the set of issues to resolve or a set of
           issues that would be necessary to be able to come up
           or satisfy the NRC they could come up with pipe
           frequencies for different sizes.
                       Like was mentioned, yes, we know that the
           double ended guillotine break of the largest pipe is
           a low frequency event and we shouldn't not to drive
           for it, but you can't take that away until you set
           what's the limit you're going to stick with.  And that
           one, it takes a little more work, and that's the one
           that both the staff and industry I think are going to
           have to pursue.
                       As I think Dr. Shack may have mentioned
           that industry will have to go ahead and do a lot of
           work, but the NRC has to do enough work to satisfy
           ourselves that what they're doing is reasonable and
           it's possible.
                       DR. WALLIS:  Do you resolve anything in a
           public meeting?
                       MR. KURITSKY:  Excuse me?
                       DR. WALLIS:  Do you resolve anything in a
           public meeting?
                       MR. KURITSKY:  Well, the --
                       DR. WALLIS:  You bring up subjects and you
           state what your positions are, but I think you resolve
           things in a different way than in a public meeting.
                       MS. DROUIN:  This is not meant to say
           we're going to resolve these in public meetings.
                       DR. WALLIS:  That's what it says.  We'll
           meet "to address and resolve the technical issues" in
           public meetings.
                       MR. KURITSKY:  Right. Yes, that may be in
           this thing.  But also the fact what this is is it's
           going to be, hopefully, a working level meeting.  It's
           going to involve -- the next one we have planned that
           we're trying to set up right now, in fact, is going to
           involve, hopefully --
                       DR. WALLIS:  It may spell out what has to
           be done to resolve the issue?
                       MR. KURITSKY:  Right. Right.  And it's
           going to, hopefully, get the experts from industry and
           NRC in this field to really hammer out what needs to
           be done.
                       DR. WALLIS:  Right.
                       MR. KURITSKY:  And some of the example
           issues are listed right here, the initial flaw
           distributions, crack propagation, material response
           and metallurgical properties, that kind of stuff. And,
           of course, uncertainly analysis are things that have
           to be dealt with.
                       And if this large-break LOCA redefinition
           is found feasible, then the staff would recommend
           additional changes to 50.46 including possibly wording
           changes to Part 50 to reestablish what the limiting
           break size is --
                       DR. WALLIS:  Are there no thermal-
           hydraulic issues that are for example in the second
           bullet?  It's all materials problems?
                       MR. KURITSKY:  No, they're not only
           material problems. But this -- at least the means that
           we've talking issue set up is to address the
           materials, metallurgical ones.  It's not to say that
           the other issues don't also have to be addressed, but
           the first stepping stone that we're trying to get a
           handle on is the materials.
                       MR. LEITCH:  It seems to me that there's
           a number of issues where double ended guillotine
           breaks are as a bounding thing for all sorts of
           things.  I mean, just all kinds of analysis and so
           forth have been done.  I'm not sure that I can come up
           with any real specific -- 
                       DR. BONACA:  The containment ropes.
                       MR. LEITCH:  We read on our reading for
           tomorrow's meeting about the CRDM failure.  Well, it
           doesn't matter because it's bounded by doubled end
           guillotine break.
                       Is there a way to -- I mean, it seemed to
           me you'd have to go back and replow those fields every
           place where that was used as a --
                       MR. KURITSKY:  Surrogate.
                       MR. LEITCH:  -- surrogate for some other
           event or issue that is, perhaps, even totally
           unrelated to it but it turned to be a bounding
           situation.  I mean, that seemed to me would be a major
           piece of work to go back and try to assure ourself
           that we hadn't missed anything along the way.
                       MR. KURITSKY:  That point's well taken, it
           is something we have to do.  I think in the big
           attachment, attachment 1, we have somewhere in there
           a list, a table of a whole bunch of LOCA initiators
           that we feel -- you know, the large-break LOCA may
           bound or be a surrogate for.  You have to go through
           them one by one to assure ourselves that either
           because of the frequency of these other events or the
           consequence of them that we're still bounding and 
           that we feel as important, and that's a very important
                       MR. ROSEN:  I think that addresses Dr.
           Wallis' point earlier.  When we do that, pay some real
           particular attention to what pops up when we take the
           double ended guillotine break away, that we may find
           the things that are really important that have fairly
           significant consequences and relatively higher
           frequencies and be able to address those as a
           regulatory and the industry.  And so that seems to me
           to begins to get to the question of how do we -- what
           are the -- 
                       MR. LEITCH:  What is in it for NRC?
                       MR. ROSEN:  What are the regulatory
           benefits of this?  And the answer is a sharpened focus
           on the accidents and the consequences that are more
           likely to happen in a double ended guillotine break.
                       DR. KRESS:  And maybe deal with them in a
           better way than just a double ended surrogate or
           something else.
                       MR. ROSEN:  Exactly.
                       DR. WALLIS:  So it's better defense of
           public safety because the folks doing the right
                       MR. ROSEN:  That's exactly right.
                       DR. WALLIS:  So there's actually a
           positive side.  It's not just backing off on a
           conservative requirements. We're actually doing a
           better job of preserving public safety.  If you can
           make that case, I think you've got a very good one.
                       DR. APOSTOLAKIS:  Well, I think that's the
           general theme of initially reforming the regulations. 
           We're focusing on what's appropriate --
                       DR. WALLIS:  But it's always sort of at a
           philosophical level.  If you can show you've actually
           done it, you have improved safety because of being
           risk-informed, then you become much more credible. 
           It's not just a promise that it ought to happen.
                       DR. APOSTOLAKIS:  You are opening up a
           whole new subject now.  That's what we've been doing
           for the last 20 years; adding things.
                       DR. SHACK:  Right.
                       DR. WALLIS:  Mr. Chairman, is this the
           presentation or is there another one? I notice there's
           a break.  Is there another presentation after the
           break or is this one?
                       DR. SHACK:  Are we going to have a
           discussion of the attachment 2, the technical work?
                       MS. DROUIN:  That's what we've been going
                       DR. WALLIS:  Yes, and so there's no second
                       DR. APOSTOLAKIS:  So what's going on now? 
           Where are we?
                       MS. DROUIN:  We only have three more
           viewgraphs to our presentation.  We're almost done.
                       DR. SHACK:  Then we can break and come
           back and we have some -- I assume you'll have
           something to say.
                       DR. WALLIS:  We might just have some
           comments.  This is the first time we're hearing it.
                       DR. APOSTOLAKIS:  Never stopped you
                       DR. SHACK:  Okay.  Why don't we finish
           your presentation and then we'll take a break.  You'll
           have 15 minutes to think about it.
                       MS. DROUIN:  Before we move on to the
           other Option 3 activities, just to wrap up on this
           long term one, different than the short term.  And the
           short term, again, we want to move forward immediately
           with the technical work because we feel it's feasible. 
           Here we're trying to establish the feasibility.  But
           once we feel that it's feasible, then we would go in
           and, as it shows here, potentially go through a
           rulemaking to change the wording to allow a licensee
           to come in and offer up a different pipe size break
           over the large double ended guillotine.
                       DR. APOSTOLAKIS:  That's just for Appendix
                       MS. DROUIN:  Yes.
                       DR. APOSTOLAKIS:  Because if you're going
           to be risk-informed, you really ought to look at all
           possible break sizes and evaluate the risk.
                       MR. KURITSKY:  But let me just say, just
           for the break size change would be -- Appendix K are
           for all of them.
                       MS. DROUIN:  Well, it goes with the 50.46
           and Appendix K.
                       MR. KURITSKY:  Right, 50.46 and Appendix
                       MS. DROUIN:  Okay.  I'll just quickly try
           and go through the next two slides just to give you a
           brief idea of where we are on the other Option 3
                       We talked about the single failure
           criterion.  The option that we're going forward in the
           short term on the single failure only relates to ECCS. 
           But if you go into Appendix A, the single failure is
           broader than ECCS.  You'll see there I have listed on
           the third bullet there's GDC 17, 34, 38 -- I can't
           remember which all of these are. I know one of them is
           containment heat removal, one's electric power --
                       MR. KURITSKY:  Electric power, residual
           heat removal, cooling systems.
                       MS. DROUIN:  But the single failure
           applies beyond ECCS, so one of the things that we were
           planning hopefully to continue doing is looking at a
           generic change to the single failure criterion that
           would apply across the board and not just to ECCS.
                       DR. BONACA:  Outside the LOCA analysis? 
           I mean --
                       MS. DROUIN:  Correct.
                       DR. BONACA:  -- for every accident that is
           written there.
                       DR. APOSTOLAKIS:  I think that's a big
           change, is it not?
                       MR. KURITSKY:  Yes, that is a big change. 
           That would be a big change.
                       DR. APOSTOLAKIS:  A huge change.  
                       DR. BONACA:  But wouldn't you use then PRA
           to identify the most likely failure that you should
           design for?  I mean, wouldn't you exchange it for a
           criteria on that is based on PRA insights?
                       MS. DROUIN:  We would still bring risk
           information into the formulation of it.
                       DR. BONACA:  Yes, because I know the
           single thing about a single failure already you have
           to take the most penalizing single failure that you
           can find, so you have to do it -- irrespective of high
           likely is the failure.  It may be impossible to have
           it, but you have to assume it.  Not that far, but
                       MS. DROUIN:  Not again, this would be --
                       DR. BONACA:  But still you would have --
                       MS. DROUIN:  -- to establish the
           feasibility of doing this.  We had not gone beyond
           just thinking -- we do it's feasible to do it for
           ECCS.  Now we want to look at a whole global generic
           change to see if that's feasible. And so that would be
           the next -- 
                       MR. ROSEN:  And here again, Graham's
           already said it, but this question of desirability
           comes back onto the table.  Would you really want to
           do it for all of the application of single failure
           criterion across the whole plant safety systems? 
           You've got to think about the desirability as well.
                       MS. DROUIN:  That's part of the
           feasibility.  Absolutely.
                       DR. KRESS:  The problem I see you're going
           to have is whether or not you can make this go away
           with this single failure criteria, you'll have to ask
           yourself if we did away with it for these GDCs that
           are listed up there, what changes will take place in
           the way the plant's operating or the way it's built
           and then what effect will those changes have on risk
           in a generic basis?  That's the kind of questions
           you're going to have to ask.
                       MR. ROSEN:  Yes.
                       DR. KRESS:  And I think that's a tough
                       MS. DROUIN:  Absolutely.
                       DR. KRESS:  Especially the first part;
           what changes are going to result.
                       MS. DROUIN:  But it's not doing away with
           it, it would be replacing it.
                       DR. KRESS:  With the reliability
                       MS. DROUIN:  Yes.
                       MR. ROSEN:  Yes, but which is in effect a
           multiple failure criteria.  But the failures will be
           at the probabilities or the reliabilities encountered
           at the plant, which is much more realistic.  Yes.
                       DR. WALLIS:  But you'd replaced it with a
           performance based criterion, wouldn't you?
                       DR. BONACA:  Remember, however, there is
           another --
                       MS. DROUIN:  Perhaps.
                       DR. BONACA:  All the analysis that you
           have with single failures, particularly what you have
           on analysis on a single failure, your reality behind
           that you have tons of analysis assuming the worst
           single -- well, until you find the single failure. And
           those analysis had also as significant deterministic
           design value in that you understood the behavior of
           the plant; if you assumed this failure versus this
           failure, versus failure and then finally you found the
           bounding one, you put in the ECCS, or behind that you
           have all the design basis of the plant.
                       So, this is a significant change.  I mean,
           clearly it would go in the direction of being more
           risk-informed.  You would identify a combination of
           probable and combination of consequences, etcetera,
           but you have to think about what you're going to lose,
           and maybe you don't lose anything.  You have to
           perform -- you know, but it's a complex change.
                       DR. APOSTOLAKIS:  I just don't know how
           you can attack just a single failure criteria in
           isolation.  That is part of a bigger -- 
                       DR. BONACA:  It's a big -- a big change.
                       DR. APOSTOLAKIS:  That's fine.  You can go
           ahead and we'll see what comes out of it.  Because I
           don't -- I mean, a first reaction is that you can't
           just do it to the single failure criterion.  You are
           really talking about risk-informing the whole thing. 
           So you have to look at the -- you have to look at a
           lot of things.
                       DR. BONACA:  Very ambitious.  Yes, it's a
           very big change.
                       MS. DROUIN:  The other thing is that, you
           know, we have started to look at the special treatment
           requirement under Option 3.  Now, under both of these
           looking at the single failure criterion and the
           broader aspect, the special treatment requirements,
           both of these have right now been deferred because
           right now over the next couple of years we're going to
           focus our resources in supporting 50.44 and 50.46.
                       DR. APOSTOLAKIS:  Oh so -- oh.  So that,
           what is it, Appendix D, was it?
                       MS. DROUIN:  Yes.
                       DR. APOSTOLAKIS:  50.69?
                       MR. CUNNINGHAM:  No, that's not being
           deferred.  That's the Option 2 or --
                       MS. DROUIN:  Option 3 aspect.
                       DR. APOSTOLAKIS:  I don't know what the
           difference is.
                       MR. CUNNINGHAM:  The work that Mary is
           talking about would be a step beyond what's in Option
           2 today.  It would be to change the -- Option 2 looks
           at what's the scope of equipment that has to be
           subject to --
                       DR. APOSTOLAKIS:  Right.
                       MR. CUNNINGHAM:  -- EQ and that sort of
           thing.  This would be what should the EQ be that would
           go with it.  What would be the environmental
           qualification standards and that sort of thing.  So
           it's revisiting that aspect of it, not the scope.
                       DR. APOSTOLAKIS:  And that's it?
                       MS. DROUIN:  Okay.  Schedule.
                       So in terms of the schedule those two
           things have been deferred because we're going to focus
           our resources into supporting.  You know, right now
           we're doing the technical work to support 50.44. 
           We're starting on the technical work to support 50.46
           and completing the feasibility on the definition.
                       So in looking at the change which is was
           our A -- I think it was our A.  Now I'm getting all
           this confused.  But where we're going to go in and
           modify the existing regulation.
                       In developing the proposed rule, the
           schedule that we have tentatively set is 12 months
           from the date of the SRM or two months after the
           completion of the technical work. And that's the
           development of the proposed rule.
                       DR. APOSTOLAKIS:  Is that a magic number
           or did someone look at all the things you have to do
           and the people available and figure out how long it
           would take to do the job?
                       MS. DROUIN:  Yes.
                       DR. APOSTOLAKIS:  Someone didn't just say
           let's do it in a year.  What's the magic about July 2,
           2002 since everything is -- 
                       DR. WALLIS:  No.  By saying they can do
           the job in 12 months, it looks like somebody's guess,
           you know.
                       MS. DROUIN:  We are continuing to do the
           technical work. We are not waiting on the -- it was --
           we are not waiting on the SRM to start our technical
           work. We're going to continue to do the technical
                       We feel that in terms of the changes to
           the acceptance criteria and the evaluation model we
           can have that work done by July 2002.
                       DR. KRESS:  Twelve months is a lot more
           believable to me than 13.62 months.  Because 12 months
           is one of those round numbers --
                       DR. WALLIS:  What's the uncertainty on the
           12 months.
                       DR. KRESS:  You can do it one year rather
           than --
                       DR. APOSTOLAKIS:  What's the risk of not
           completing the job?  You don't like the 12 months?
                       DR. SHACK:  No, I don't mind 12 months. 
           It's just, you know, trying to think of other rule
           changes that we've done in 12 months.
                       DR. APOSTOLAKIS:  And you fail.
                       DR. WALLIS:  By the time you have public
           meetings and responses to comments and all that kind
           of stuff --
                       DR. SHACK:  And you have to come to the
           ACRS and which we talk about -- and that'll last for--
                       MS. DROUIN:  No, no.  This is development
           of proposed rule.
                       DR. BONACA:  They don't say complete. 
           Yes, they don't say complete.
                       DR. WALLIS:  So you would be ready for
           public comment by then?
                       DR. BONACA:  Development.
                       DR. WALLIS:  Right.
                       MS. DROUIN:  The development.  A
           significant subtly there.
                       DR. WALLIS:  Well, we should cheer and say
           "go for it," isn't that what we should do?
                       MS. DROUIN:  Absolutely.
                       DR. WALLIS:  Okay.
                       DR. BONACA:  You agree we should cheer and
           tell you "go for it?"
                       DR. SHACK:  Short letter.
                       MS. DROUIN:  In terms of the development
           of the voluntary risk-informed alternative, and that's
           where we're coming in and changing -- it's really
           changing GDC 35, that's going in and attacking the
           single failure criterion as it applies to ECCS, it was
           those two options.  The generic and more plant
           specific one.  
                       Again, we're going to continue, we aren't
           going to stop our technical work.  We're going to
           continue on that and we feel that can be done by April
           2002.  And the development of the proposed, again, 12
           months from the SRM or two months after the completion
           of the technical work.
                       DR. BONACA:  Yes, that second bullet seems
           to be pretty optimistic to me. Because that change in
           the GDC 35 is a very -- not GDC 35, all the other
           places where you have single failure criteria --
                       MS. DROUIN:  No, no, no.  Only for GDC 35.
                       DR. BONACA:  I understand.  Okay.  
                       MS. DROUIN:  This does not include the
           others.  Just for GDC 35.
                       And, again, we aren't going to stop, we're
           going to continue with the feasibility in looking at
           the redefinition of the large-break LOCA and the
           completing of the feasibility.  There's a lot of
           complexities and we feel that could go up to three
           years to complete feasibility.
                       DR. APOSTOLAKIS:  Now I thought we said at
           one point that maybe being a risk-informed regulatory
           system you will not need GDCs.  Didn't we say that
           once?  GDCs are remanents of the old system, so that
           a possibility that you don't need at all a GDC.
                       MR. KURITSKY:  So those would be interim
                       DR. APOSTOLAKIS:  Huh?
                       MR. KURITSKY:  These will be interim
                       MS. DROUIN:  You know, when you look at
           this what form it takes, your alternative risk-
           informed regulation, whether you characterize it as a
           GDC or as a -- I mean --
                       DR. APOSTOLAKIS:  Or something else?
                       MS. DROUIN:  It's premature to say.  But
           you are not getting rid of the current GDCs that are
           on the books.  Those are there.
                       DR. APOSTOLAKIS:  Yes.  They are, yes.
                       MS. DROUIN:  Now, whether you have a risk-
           informed alternative to it or you characterize it some
           other way, those are decisions to be made.
                       MR. KURITSKY:  And just for this specific
           point, the changes to the reliability requirements,
           even though the GDC 35 is where they're specified,
           depending on how we ultimately decide it should be
           applied, it may actually be a change in 50.46 that
           tells you whether or not you have to meet the
           requirements in GDC 35.  So that way whether or not
           the actual wording change occurs in GDC 35 or in
           50.46, we haven't decided that yet.
                       DR. WALLIS:  I don't know if we're going
           to cheer or not, but it seems to me you're much more
           positive and optimistic about the chances of success
           than you were last time we met.  Maybe that's because
           you've had the time to figure out what you need to do
           to do the job.  And it turns out that it looks
                       MS. DROUIN:  Well, I'd say that's true,
           yes.  You know, whether we come up against something
           that throws off track, but know at this point we've
           given it a lot more thought, we've done more work and
           we do feel for these first two bullets that that's
                       DR. WALLIS:  And you're going to have
           enough support from management to get this done?
                       MS. DROUIN:  Mark?
                       MR. CUNNINGHAM:  Well, of course.  Mary
           said something a little bit ago that plays into this. 
           In the context of Option 3 the focus over the next
           couple of years is going to be changes to 50.44 and
           50.46.  That was to make sure that the resources we've
           got available here are focused where we want them to
           be.  And, you know, these other things could devote
           resources away.  So from that standpoint that
           commitment is there.  
                       From a budgetary standpoint the commitment
           is there, too.  We've got money today where we can
           start each of these three efforts in parallel.  And as
           we've got money in the fiscal '02 and '03 budget to
           support these, so we've anticipated that in our budget
           preparations and we think it's there.
                       DR. WALLIS:  Now this is an RES activity?
                       MR. CUNNINGHAM:  No, it's a staff
           activity.  The technical work that you would talk
           about here, perform the technical work, that will be
           done principally in RES.  The rulemaking will be done
           in NRR.
                       DR. WALLIS:  Yes.  Is there a good tie in
           with the people who are actually going to use this
           product in the regulatory world?
                       MR. CUNNINGHAM:  Yes.  Yes.  They're the
           ones that are going to be writing the rule itself and
           the reg guides and that sort of thing.
                       DR. WALLIS:  Are we going to hear from
           them, too?
                       MR. CUNNINGHAM:  You will hear from them,
           you know, at some point we'll talk about when the next
           meeting on this subject would be.
                       DR. WALLIS:  Good to hear on that, too, to
           know that they're fully behind you and they really
           appreciate the product.
                       MR. ROSEN:  It's not going to change what
           they want --
                       MR. CUNNINGHAM:  So it's just in the next
           -- in Phase 2 Research will be behind it and all are
           supporting them.  It becomes their lead to do it.
                       And, yes, I expect that sometime in a few
           months from now the committee would want to hear from
           the staff again in terms of now -- given -- presumably
           this paper goes forward, now what's happening.
                       MR. ROSEN:  Is the risk-informed licensing
           panel in this process?
                       MS. DROUIN:  Yes.
                       MR. CUNNINGHAM:  Yes.  They basically
           concurred in these recommendations.
                       Just to be clear, some people understand
           how it works.  This is -- Mary and Alan said, this
           paper is with EDO.  NRR has concurred in this as well
           as Research.  So this is not just Research's opinion
           on this.  NRR has concurred in the paper.
                       DR. WALLIS:  Well, looking at this from a
           personal perspective at what might have been achieved
           by the time I leave the ACRS, if I can go back to talk
           to my friend and they say "Well, what have you been
           doing in Washington that made any sense that actually
           achieved something."  I can say "Well, those guys
           managed to risk-inform 50.46."
                       MR. CUNNINGHAM:  50.46, yes.
                       DR. WALLIS:  And maybe we had something to
           do with it.  That would be something that I'd like to
           be able to say.
                       MR. CUNNINGHAM:  Okay.  I think we'd like
           you to be able to say it, too.
                       MS. DROUIN:  Any other questions?
                       DR. SHACK:  No more questions?  
                       I think maybe it's time for a break and we
           can come back at 4:00 or a few minutes after and hear
           from NEI.
                       (Whereupon, at 3:44 p.m. off the record
           until 4:05 p.m.)
                       DR. SHACK:  Well, now that Adrian's had 15
           minutes to think about, I think we can get his
                       DR. APOSTOLAKIS:  Maybe you can start by
           telling us what's new in what you heard that we didn't
           know before.  I mean, I -- we -- I didn't know, at
                       MR. HEYMER:  Good afternoon.  My name is
           Adrian Heymer.  I'm a project manager with NEI on
           risk-informed regulation.
                       I have with me today Bob Osterieder from
           Westinghouse Group and Terry Reick from the BWR Group,
           Terry Reick's from Exelon in their Chicago offices. 
           And Bob's a project manager for Westinghouse looking
           after risk-informed activities for the Westinghouse
           Owners Group.
                       We are just going to give you some initial
           feedback on what we heard.  What was new, I think, was
           someone's suggestion, and it was mentioned earlier
           about climbing apple trees and picking the fruit.  And
           as we've told you before, we really think there is
           significant benefit in taking a look at redefining the
           large-break LOCA.
                       We recognize there is a significant amount
           of work to be done, and we're willing to work with the
           NRC staff in trying to develop some of that work and
           being that work to the staff.  And so, we're looking
           forward to working with them.  We've been trying to
           arrange some dates where we can start sitting down and
           get a better understanding of what we would have to
           develop or the level to which material that we would
           to develop.  And we can move forward with that.
                       We did find a little confusing in some of
           the material, and I think that was clarified briefly
           in a discussion.  But if you're going to impose new
           requirements, I think you got to be careful about how
           you word such requirements.  Because in some cases not
           everybody might want to pick up on those new
           requirements.  I'm talking about the A(1) I think it
           was of the slide.  Some people might like to stick
           with the criteria that have already been established
           and not make any changes.
                       As regards the A(1) I think it's clear
           that we can move forward.  There is an existing
           standard on the books from 1994 on decayed heat and we
           think we can move forward with a rulemaking very
           expeditiously in that area.  
                       There are some other things that are
           linked into that part associated with ECCS acceptance
           criteria. And that's where, I know it's been mentioned
           before, but we were a little surprised that that
           should be blended together along with the same time
           frame as the ECCS rulemaking.
                       Terry, did you want to comment?
                       MR. REICK:  Yes, on the Option A I had a
           couple of questions that came up when I listened to
           the presentation.
                       Decay heat clearly is something that BWR
           Owners Group has looked at and thought that we should
           move forward with.  
                       The one thing that bothered me was one of
           the bullets talked about NRC's prescribed uncertainty
           treatment.  And our understanding is we talked about
           in our committee was that the multiplier of 1.2 as
           stated in the ECCS criteria 50.46 talks about it as an
           uncertainty value.  I know we had some discussion on
           uncertainty versus margin in here.  It's an
           uncertainty value because back in 1972/71 we didn't
           know decay heat very well, and there's a lot of work
           that's been done since then that has clarified it. 
           And, in fact, the 1979 standard came out and said here
           is the decay heat as we now know it based on some
           experimentation and here is now the uncertainty that
           we attach to it.  And they said uses a two sigma value
           for uncertainty.
                       So, we see this change it should be very
           simple.  We think take the 1.2 multiplier out in the
           1971 standard and replace it with the current standard
           which has uncertainty built into it.
                       To summarize it another way --
                       DR. WALLIS:  It's not quite the same
           thing, though.  1.2 factor is a conservative treatment
           and the full treatment on uncertainty in risk-informed
           approach is not --
                       MR. REICK:  Well, I wasn't -- 
                       DR. WALLIS:  -- the conservative limit,
           but to look at the whole spectrum and make an
                       MR. REICK:  Now, I wasn't there back in
           the ECCS hearings, but if you read the ECCS rule it
           talks about the 1.2 being a factor because of the
           uncertainty in decay heat.
                       DR. WALLIS:  Yes.
                       MR. REICK:  It doesn't talk about it as
           being conservatism, it talks about uncertainty and the
           decay heat value.
                       DR. WALLIS:  But essentially it's saying
           we think the uncertainty is like this, so we'll be
           conservative and we'll step outside the uncertainty
                       MR. REICK:  But it's an uncertainty in the
           decay heat, not the uncertainty in the other 50.46
           requirements and assumptions.  And if we know decay
           heat better now and the standard has come out that
           says here is how the uncertainty should be applied to
           it, our position is let's apply that uncertainty. 
           Whereas, the words --
                       DR. WALLIS:  It would be a factor of 1.05
           or something, say 1.2.
                       MR. REICK:  Like 1.07 -- 1.08 I think they
           used the two sigma.  Whereas, this in here says NRC
           prescribed uncertainty.  So, essentially what I'm
           hearing is the NRC wants to take the margin created
           because we became more certain and then use that
           margin themselves as opposed to going to what the best
           estimate --
                       DR. WALLIS:  Well, this is the old
           business of who knows the margin?
                       MR. REICK:  Whose margin is it?
                       DR. APOSTOLAKIS:  Is that they're saying? 
           What are they saying?
                       MR. REICK:  Well, if you look on their
           page 10 --
                       DR. APOSTOLAKIS:  Page 10.
                       MR. REICK:  On the second bullet it says
           "within NRC prescribed uncertainty treatment."  So our
           position is use the uncertainty that the standard came
           up and define.  They said here's the best --
                       DR. APOSTOLAKIS:  Oh, but you yourself
           said though that the 1.08 is a two sigma?
                       MR. REICK:  Yes.
                       DR. APOSTOLAKIS:  They might three sigma?
                       MR. REICK:  Right.  They want three sigma. 
           But what I'm saying is the industry came up with a
           standard that they thought was best estimate of with
           an uncertainty, and that ought to replace was back in
           early 1970s.  But it sounds like there may be some of
           that uncertainty that staff wants to take up because
           of other unknowns or other nonconservatives that they
           have in their minds.
                       So our position is just simply replace the
           standard and that should be an easy rule change.
                       DR. WALLIS:  So whatever it is it will be
           NRC prescribed, because they make the rule?
                       MR. REICK:  Correct.
                       DR. APOSTOLAKIS:  So it might be what you
                       MR. REICK:  Right.  And our position is
           just put the new standard that talks about the
           uncertainty of decay heat.
                       DR. APOSTOLAKIS:  Have they objected to
           what you're proposing or are you speculating now?
                       MR. REICK:  We're speculating because we
           don't know what the detail is yet.
                       DR. APOSTOLAKIS:  You don't know.  Okay.
                       MR. REICK:  And that type of reasoning I
           think would apply in any other changes under A; that
           is if it was uncertainty that was in the ECCS aspects
           back in the early '70s and we've reduced that
           uncertainty and that created margin, that that's
           margin we should have rather than taking the margin
           away for something else.   That was the item on decay
                       MR. OSTERIEDER:  
                       Yes, I guess I'd like to add a little bit. 
                       I think the decay heat changes are
           certainly something we believe are going to be very
           appropriate.  The Westinghouse Owners Group has a bit
           of a concern with the rest of the changes related to
           acceptance criteria.  And I think some very
           distinguished gentlemen on this panel last time said
           that's like changing the works of Shakespeare if
           you're going to change acceptance criteria.  And we're
           very concerned that the -- owing the decay heat in
           with other changes to acceptance criteria could be a
           very lengthy process and requiring a lot of
           discussions with this Committee.  And I guess we're
           just generally concerned that the effort would be so
           big that we'd rather that effort be spent on the
           redefinition.  But I think, you know, as stated here
           we think some people feel it can be done in a year. 
           And with relatively smooth sailing, I would say to get
           there in a year, but I think this is going to be a
           much longer process to get into the acceptance
           criteria in general and try to change those.  It was
           a long process originally and we think it's going to
           be a long process now.
                       And I guess we think it would be more
           prudent to look at the decay heat independent or aside
           from and then get into the other acceptance criteria
           if we're going to go that route and we're concerned
           with spending what we think will be a sizeable amount
           of resources on that.  and maybe it won't be, but our
           experiences don't show us that.  I guess our point --
                       DR. BONACA:  You don't think about just
           the consideration of LOOP and single failure.  That
           would be a great area of opportunity for the industry,
           wouldn't it?
                       MR. OSTERIEDER:  It could be in the area
           of opportunity. Partly some of the discussion today
           has enlightened us a bit and we need to think about
           it.  We're not --
                       DR. SHACK:  That's B, right?
                       MR. OSTERIEDER:  That's B, right.  Right.
           and I guess we'll have a few more comments on that, so
           I don't know if there's any other on A.
                       MR. REICK:  I'd like the acceptance
           criteria.  Maybe Norm can help on this. Because I'm
           confused a little bit because I'm on another
           committee. I'm a committee for robust fuel with EPRI
           and in the industry and we've been working with the
           Argonne acceptance criteria.  And recently there was
           a discussion that came out and said that the current
           acceptance criteria was based on post-quench cladding
           ductility, and it was based on experiments done many
           years ago that showed 2200 and 17 percent was based on
           a post-quench ductility.  And all I read from this is
           that we're going from the current criteria to
           demonstrate adequate post-quench cladding ductility. 
           I see no change.
                       DR. WALLIS:  Part of the idea was that
           cladding wouldn't be necessarily the same in the
           future as if you had a performance based criteria.
                       MR. REICK:  That's agreed.
                       DR. WALLIS:  Then this could handle new
           cladding, which maybe could go to 2500 or something,
           whatever it is.
                       MR. REICK:  I agree.  What we've talked
           about in the industry is that new cladding would go
           through separate effects test.  And by testing new
           cladding relative to old cladding, they can see how
           the effects would change, and thus base the criteria
           on that.  And typically we would say let's live with
           the existing criteria because the new cladding is
           better than the old cladding.
                       DR. WALLIS:  Well, maybe the 2200 contains
           one of these factors, like 1.2 so that if you actually
           have more information, maybe you could get a better
                       I don't know why you'd want to go back to
           a more primitive number when a better one might be
                       MR. REICK:  Well, what I'm saying is my
           understanding is the current criteria is only 2200 and
           17 percent is already based on post-quench cladding
           ductility.  And so I don't understand what change is
           being proposed here, and we're doing some testing on
                       DR. SHACK:  Well, I think the answer is
           that suppose you had a cladding that was more
           corrosion resistent but was in fact embrittled more
           under a radiation so that in fact the true criteria
           for it was not an oxidation criterion anymore but
           essentially an irradiation criterion.
                       The true thing that you really have to end
           up with is some ductility.  So, I think it was just
           there attempt that, you know, if you were using
           zircaloy, you could still use 17 percent and 2200 F. 
           But if you had a different material, the crucial thing
           was, in fact, to maintain the ductility, not --
                       MR. REICK:  What I'm hearing you say is
           for existing claddings there is no change in criteria
           because our current criteria is already based on
           ductility.  But for new claddings, there could be a
           change in criteria.
                       DR. SHACK:  I'm not the NRC, but that
           would be my interpretation.
                       DR. BONACA:  But my understanding --
                       MR. REICK:  That's I -- that's what I
           hear.  That's what I'm hearing.
                       DR. BONACA:  -- reading the material --
                       MR. REICK:  That's the acceptance
                       DR. BONACA:  Reading the material we have. 
                       DR. WALLIS:  Is this ductility independent
           of burn up and does it change with radiation history?
                       MR. REICK:  Yes, it does.  And we're doing
           some --
                       DR. WALLIS:  So if we go into a long burn
           up should we change this criteria?
                       MR. REICK:  That's a whole separate
           discussion the industry is having with the NRC on when
           you go to higher burn ups what criteria should change. 
           This is talking about existing burn ups and we're not
           trying to lump them together.  But there's a whole
           separate committee that's working on that, extending
           burn up.
                       DR. WALLIS:  But it's not independent of
           this, surely.  I mean, if you have a performance based
           criteria and it can handle extended burn up and so on,
           it seems a much more desirable thing.
                       MR. REICK:  Yes.  There will be a whole
           separate rulemaking that'll take 3 to 5 years before
           we get extended burn up.  And this has been touted as
           shorter term, but I see no relaxation for the industry
           in changing acceptance criteria in the short term on
           that. So the only thing left today as I see it is
           decay heat.  Now, that would take some additional
           discussions with the staff and talking about.  I just
           see decay heat, and as I mentioned earlier, I think
           decay heat is a simple change.
                       DR. SHACK:  But I think the first one was
           mostly just to give you the flexibility of doing
           something like -- besides ZIRLO or zircaloy without
           another rule change.  I mean, as it is now every time
           you come up with a new cladding -- 
                       MR. HEYMER:  I'm not saying that would be
           great.  Our concern is that these discussions get
           protracted out and out and out.  And there are some
           benefits that could be added in the short term, but
           let's not lose sight of that fact and also not --
           let's not be afraid to sort of chop certain things off
           as we go down if we think we're running into some
           technical problems.
                       DR. WALLIS:  I'm not surprised to see the
           NRC going for a more ambitious way of helping you guys
           to reduce conservatism then you want to let them do.
                       MR. HEYMER:  Well, I think it's not
           necessarily a question of that.  It's a question of
           concern over timing.
                       DR. WALLIS:  So you don't think they can
           do it with the time available?
                       MR. HEYMER:  Well, judging on my past
           experience, we're probably going to struggle a little
           bit on some of those.
                       DR. BONACA:  Just before we move, and this
           is just for clarification for me, I had understood in
           reviewing this package that 22000F, the criteria as we
           have right now, may be we're over restrictive criteria
           to the term meaning what is an adequate post-quench
           cladding ductility.  Okay.
                       MR. HEYMER:  And the advantage compared
           with the rest -- because we haven't read the material,
           everything made publicly available.
                       DR. BONACA:  That would be my
           understanding.  So there would be still some benefit
           even for current licensees by exploring ways or
           criteria that would still provide adequate post-quench
           cladding ductility but less restrictive than the
           current criteria?  That's my understanding, and maybe
           I was wrong.
                       MR. HEYMER:  Well, hopefully, the SECY 
           would be released to the public and then we can
           provide some input on the policy.
                       MR. REICK:  My reading of this it doesn't
           provide anything to current -- 
                       DR. BONACA:  Okay.
                       MR. REICK:  Cladding materials doesn't
           provide any relaxation, because the current criteria
           is based on post-quench ductility.
                       DR. BONACA:  I understand.  But the
           reading seemed to me that the implication was that
           that criterion was in amount to use to measure this,
           was over restrictive.  I don't know what else could be
                       MR. OSTERIEDER:  The other point related,
           I guess, we just have to be careful with any required
           changes to acceptance criteria.  If we're not careful,
           we may end up causing everybody to reanalyze for
           something that appears from what we heard today to be
           -- give more margin but some plants may not want to
           spend the effort.  They may be satisfied with their
           current analysis.  So, we just wanted to state the
           obvious, that we'd have to be careful that everybody
           wouldn't have to be required unless we felt we were
           doing this to -- for an issue that was not handled as
           appropriately as it should have been in the past.
                       DR. WALLIS:  This is a remarkable sort of
           seesaw issue.  I mean, when we meet sometimes you guys
           are all eager to press ahead and do stuff and NRC's
           dragging its feet.  And the next time around the NRC's
           all eager to press ahead and you guys say "Let's drag
           out feet because they can't do it."
                       MR. HEYMER:  We are happy and we're
           willing to move ahead and push on as expeditiously as
           possible.  We just want to be careful that we don't
           get ourselves bogged down into so many details that we
           don't actually make some progress on stuff that is
           relatively straight forward.
                       MR. SIEBER:  Well, it seems to me that
           there's a trade going on in squad 10.  If you look at
           the last bullet it talks about viewing with recognized
           nonconservatisms and model limitations.  And I sort of
           got the impression that there was going to be a trade
           off between the decay heat multiplier and the decay
           heat curve versus the nonconservatisms which sort of
           all in one full swoop consumes at least some of the
           margin that they built in when they built in the 1.2
           multiplier.  So you may get a thing that you might
           like and something you may not like as an output.
                       MR. HEYMER:  As I say, we were just giving
           you our first reactions.
                       DR. WALLIS:  I guess the criterion for the
           NRC to do this is not that it saves money for
           industry.  They're interested in public safety, and if
           this is the right to do it, that's the right way to do
                       MR. HEYMER:  And we fully agree with that. 
           It's just a question of if we can do it in the 12
           months, great.  We go on and do it.  But if it takes
           36 months, we'd much rather take some of the things
           that are, in fact, the low hanging fruit.
                       MR. OSTERIEDER:  I guess I just want to
           make another comment on our being gungho in some cases
           and not in others.  I think we continue to be gungho
           in large-break redefinition.  Certainly we were a lot
           more optimistic than the staff is.  And we think that
           this effort is a big effort.  And if we're going to do
           a big effort, we still think we should go for the
           risk-informed redefinition; that's why we're gungho on
           one and not the other. 
                       As we've heard already, there's limited
           resources and you can only put it in certain areas. 
           And if we're going to have a big effort, we're
           thinking that the redefinition is the more appropriate
           way to put the big effort.
                       DR. WALLIS:  Well, whose resources are you
           talking about?  Is it the effort that you folks would
           do to analyze these issues or is it the resources the
           NRC's going to put into it?
                       MR. OSTERIEDER:  Well, I thought I heard
           in here that the NRC said that their effort, you know,
           their manpower is allocated to these efforts.  So I'm
           concerned with their involvement.
                       DR. WALLIS:  Yes.
                       MR. OSTERIEDER:  Plus we've had a
           difficult time, and this isn't really a resource
           issue, I suppose, but just getting the next technical
           meeting scheduled has been a bit of a challenge.  But,
           again, I don't know that that's a resource issue. 
           It's getting the right people together.
                       DR. WALLIS:  I think the last time we met
           industry was gungho and said we're going to put the
           resources behind this to make a really case for what
           we think should be done.
                       MR. HEYMER:  And as regards the redefining
           large-break LOCA, that still is the case.
                       DR. WALLIS:  Still is the case.
                       MR. HEYMER:  But there does become an
           industry resource issue if regards to too much at
                       MR. OSTERIEDER:  Right.  And we have a
           number of resources allocated and ready to go, and
           we've kind of put the brakes on a bit if we're not
           going to have the staff looking at this to any great
           extent and we're going to be able to get the
           initiatives developed and agreed to after we do our
           work; that's what we're trying to sort out.
                       MR. HEYMER:  As regards to the other
           topics, on LOOP LOCA, yet again that's something that
           there's an awful  lot of information out there at the
           current time.  There's a lot of information out on
           loss of off-site power, and there's been a lot of
           studies done on plant centered events.  There's been
           a lot of work done as regards good reliability and
           what the impact of that could be in the last 9 months
           or so.
                       So, we are going to think that's a
           relatively quick issue to get under our belt and we
           look forward to working with the staff in that regard. 
           And in some cases, I think I'd be surprised if the
           technical work can't be done in less than 12 months. 
           So, that's good.
                       On redefining the large-break LOCA, as Bob
           said a few moments ago, that still is where we have
           most of our resources focused and we're still very
           interested in moving ahead with that.
                       One of the issues that we did have on the
           table or the suggestions that we had made previously
           was that there be an enabling rule, fairly straight
           forward, which would then provide double ended
           guillotine break or an alternative break size as
           approved by the Commission. And it's just not quite
           clear to me whether that's still in the works or
           whether or not we're trying to come up with more
           detail criteria to put into the rule.  It seems more
           like the latter, and that's something that we'll have
           to discuss internal and get back with the staff. 
           That'll probably be a comment that we make once we get
           the SECY and have had a chance to review it.
                       MR. OSTERIEDER:  Right.  And that is when
           you asked earlier on whether some of the changes,
           there was talk at the last meeting of the potential to
           put something in.  And we certainly were excited by
           that potential knowing that we still have the
           technical issues to deal with as we do in either case. 
           But now if we do move ahead and do something in the
           nearer term, then I guess we need to ask for an
           exemption or a petition or something to -- if the
           wording isn't going to be changed in the near term by
           the staff.  So, that's a bit of a change from what we
           were hoping from your last meeting and we have to
           consider what that means.
                       MR. HEYMER:  I think to sort of sum up,
           we're pleased that the process is moving forward now. 
           We would probably like to see the emphasis still be
           placed on redefining a large-break LOCA.  I think as
           somebody in this Committee mentioned, we're quite --
           you know, industry to do the work and the NRC to
           review it.  And we're more than ready to work with the
           staff to define what we need to do.  We think we know
           what that is at the moment, but before we actually
           start pulling everything together and interacting with
           the staff, we'd like to sit down with them so that we
           can get a better scope on that.  So we're really
           interested in moving forward.
                       We think there are some near term
           objectives that we can achieve, certainly within the
           12 month time frame.  And we look forward to reading
           the SECY when it's released.
                       MR. REICK:  Let me add a comment from the
           BWR perspective.
                       DR. SHACK:  Did you say B or P?
                       MR. REICK:  BWR, boiling water reactors. 
           Our committee agrees with the large-break LOCA
           redefinition of the priority, but we also looked at
           the other NRC proposed options and prioritized within
           our group other options.  And we do like some of the
           options in here, I want to make sure that comes
                       The LOOP LOCA coincidence can be a benefit
           for the BWRs.  And it was asked here what type of
           examples do you have.  And the LOOP LOCA is, I think
           a good one to illustrate how we might benefit.  For
           the large-break we require and we rely on the diesels;
           that is the LOOP in connection with the large-break
           requires the diesel to start so that you can have your
           low head pumps, your quick injecting pumps be
           available.  Because they're driven by electrical
                       For the small-break, we rely on steam
           that's still available in the small-break to drive
           some of our pumps.  And we have separate -- we have a
           separate diesel driven pump, separate from our main
           grid. So we don't have to rely on off site power.
                       So we may be able to relax our criteria,
           for example, on our fast start diesels.  That is the
           large-break we won't need them and we don't need them
           for the small-break, and so we could relax the start
           requirements and have them start at a more reasonable
           time frame and, thus, improve the reliability of the
           diesels.  And that is the diesels would not have to go
           through the fast starts and, thus, be degraded because
           of the fast starts and they could be started -- maybe
           they would start automatically, but it would be in a
           three minute time frame as opposed to 10 seconds or
           maybe they could even wait for a manual start when you
           need them for a small-break.  So there could be some
           benefit in that.  We're looking seriously at that.
                       The single failure criteria could fall
           into that, but we're still -- we still need some
           discussion on what the single failure would mean for
           us.  I think it's still a little hazy on how you might
           factor that into your analyze.
                       DR. WALLIS:  Could you put this in the
           sort of rational that optomizing the use of the
           diesels so that you have them available when you
           really need them.
                       MR. REICK:  Right.
                       DR. WALLIS:  And they're most reliable
           when you need them, so in fact safety's improved?
                       MR. REICK:  That's correct.
                       DR. WALLIS:   Could you make that case?
                       MR. REICK:  They are -- that's the case
           that we would make.  They're most beneficial when you
           need them and they're more reliable because of the way
           you would operate them.
                       So we have -- you know, those are the key
           things we've looked at, decay heat and the benefit to
           a LOOP LOCA as opposed to single failure after the
           redefining the break size.  There is some benefit in
           the proposals here and we're pleased to move forward
           on those.
                       That's all I wanted to say.
                       DR. SHACK:  If there are no other
           questions, the staff has asked for a letter, and I
           think we'll want to put one together.
                       Do I have any thoughts or comments from
           people about what we should say in a letter?
                       DR. WALLIS:  Well, about the letter, we
           don't have this document which isn't yet finished?
                       DR. SHACK:  Well, we have a preliminary
           version of it.
                       DR. WALLIS:  But it's not --
                       DR. SHACK:  It hasn't been approved by the
                       MR. CUNNINGHAM:  That's correct, it's
           still in the EDO's office.  And we would -- obviously,
           we don't anticipate changes, but as soon as we get the
           signed version, then we would get it back to the
                       DR. WALLIS:  Well, that would be before we
           have to write the letter?
                       MR. CUNNINGHAM:  I hope it's in the next
           few days.  Next week.  Again, I don't anticipate major
           changes, but we could certainly try to -- if there are
           changes, we could lay out what the changes were and
           that sort of thing to help out the Committee.
                       DR. SHACK:  But I would think that, you
           know, we could certainly talk about the options that
           are discussed in attachment 1 in the overall document
           of the options.  And, you know, it might be a matter
           of which had higher priorities.  But that's something
           we could comment on almost irrespective of what the
           staff decided the priorities with the options.
                       So, I think we could move ahead on the
           letter myself.  Well, maybe that's something we can
           discuss after people have had a chance to think about
           it a little bit.
                       DR. APOSTOLAKIS:  Well, they're coming
           back to address the full Committee, right?
                       DR. SHACK:  Right.
                       MR. LEITCH:  We're almost all here anyway.
                       DR. BONACA:  Maybe next week before,
           however, we could get a feedback.
                       DR. APOSTOLAKIS:  If we don't like the
           letter this time, it'll be in September, right?  Even
           if we slip one day, that's it.  The Commission will
           vote when?
                       MR. ROSEN:  I didn't hear any very
           negative views expressed, so I think we in general are
           in agreement with the approach.  So I think it would
           be useful.
                       DR. BONACA:  I think there is some opinion
           we have with priority for redefining the large-break.
                       DR. SHACK:  Well, I mean the staff has
           said it's going to go forward.  You know, they haven't
           stopped that work and it's, you know -- at this point
           it's just sort of a skepticism about whether -- but I
           think the short term benefits they're talking about
           are definitely benefits also.  I mean, especially the
           Appendix -- or the B one.
                       MR. SIEBER:  Well, if somebody's pressed
           on the final acceptance criteria, it would certainly
           be handy to have some of that margin that would come
           out of the short term benefits.
                       DR. WALLIS:  I would favor encouraging the
           staff, that we go ahead with what they've laid out
           here and not trying to meddle too much in redirecting
                       MR. SIEBER: Well, it's pretty early in the
           game, too. This is all feasibility study.
                       DR. SHACK:  Right.
                       MR. SIEBER:  And so the decisions as to
           what you finally will pursue and how much effort you
           put into it won't be made for another year.  So, you
           know, there isn't too much that can be said other
           than, again, encouragement.
                       DR. KRESS:  Well, I think they're on the
           right track.  I see some details --
                       MR. ROSEN:  The A&S standard has only been
           out 7 years.  I mean, it's pretty young.  It's really
           time for us -- of course, I'm kidding.
                       DR. KRESS:  Well, I think there's some
           unanswered questions on how you deal with margins in
           the deterministic end of the thing.  As we use more
           realistic calculations, we approach these limits.  But
           those limits were set knowing that you had a pretty
           good margin in the first place.  And there may be some
           question about the appropriateness of the limits as
           you approach them.
                       I think Graham raised this issue that are
           the limits independent of the margins.  And I think
           there are some questions that -- but that's for
           something later on.
                       MR. SIEBER:  The more important question
           is who owns the margin.
                       DR. KRESS:  Oh, I think definitely we
           ought to have an ACRS position on that.  And my
           position, of course, will be that the licensee owns
           the margin.
                       MR. SIEBER:  Well, provided you get the
           licensee to fix up nonconservatisms that may exist
           that the margin in the old days took care of one way
           or another.  And so to me you can't do it piecemeal,
           you have to do like a package.
                       DR. KRESS:  Well, I think I would agree
           with that.  I think as a general principle the
           licensee owns the margins.  Now there's a question
           about what margins are actually there and how do these
           limits get set, and what do the uncertainties do when
           they overlap the margins.  There's a lot of little
           questions, but I think as a general principle the ACRS
           thinks the licensee owns the margins.
                       MR. SIEBER:  I didn't see any of that
           discussion in the feasibility study.
                       DR. SHACK:  But I don't think the staff
           disagrees with that.
                       DR. KRESS:  Yes, I don't think they do
                       DR. SHACK:  They're acceptance limits and
           that's why they're called acceptance limits.  Yo know,
           there's a debate on whether you've calculated things
           properly perhaps, but that's a review process.
                       MR. SIEBER:  But the concept of defining
           what the margins are --
                       DR. KRESS:  I think there's some debate
                       MR. SIEBER:  Right.  And I think that
           ought to be dealt with as part of this project.
                       DR. KRESS:  That's part of the 8.
                       MR. SIEBER:  Yes.
                       DR. WALLIS:  Well, this would be the
           margins of the two signal or the three signal level,
           that sort of thing.
                       MR. SIEBER:  Well, that would be one
                       DR. KRESS:  Well, here once again is a
           good place for some formal decision criteria to enter
           the picture.  Right, George?
                       DR. WALLIS:  Well, this is one of the
           questions we wrestle with all the time is whether or
           not --
                       DR. APOSTOLAKIS:  Never disagree with you.
                       DR. BONACA:  Well, so much of it we have
           to see for the work they do.  For example, the issue
           of single failure or elimination of it, it's very
           significant in that it drops so many of the issues of
           LOCA; what you inject, what assumption you make, what
           is the break.  All these.  And so --
                       DR. KRESS:  But I think they're well aware
           of that.
                       DR. BONACA:  Yes, they're well aware of
           it.  So what I'm saying all we can do is to follow
           progress and I'm sure they'll ask the right questions
           before we ask them.
                       So, you know, in the broader sense of
           eliminating, that's even a bigger --
                       MR. ROSEN:  But that's long term.
                       DR. BONACA:  That's long term.
                       DR. KRESS:  But you know it's the right
           direction.  You're getting rid of some of these vague
           things that are closely related to risk somehow and
           actually getting them pinned down as to how much value
           they really are and what do they mean --
                       DR. BONACA:  For the existing plants,
           however, those decisions were integral with the design
           of the plant.  Many of the single failures were
           eliminated by designing the plant in a different way
           because that resulted in acceptable results.  So, you
           had a lot of alternations between the analysts and the
           people designing the plants and how they ended up the
           way they are.  So, you know, I think for a newer plant
           the design, I think today, with PRA you would have a
           much better approach in evaluating all the possible
           outcomes and considering also the probabilities for
           the sequences so that you know -- 
                       DR. KRESS:  And there's where I keep
           harping on  you to use your uncertainties correctly.
                       DR. BONACA:  Yes, and I agree with that. 
           But anyway, that it is along --
                       MR. ROSEN:  I think you just made a very
           important point that I hadn't heard discussed before. 
           The changes go back to 50.46 and all the other risk
           informed changes are changes that will apply to new
           plants as well.
                       DR. KRESS:  Yes.
                       MR. ROSEN:  And we're about to see I think
           -- I hope -- we hope some new plants.
                       DR. APOSTOLAKIS:  Well, I don't know. 
           50.46, I mean, everything we're discussing today is
           really water, isn't it?  Water?  ECCS and all that?
                       MR. ROSEN:  But what about changes to the
           single failure corrector?
                       DR. APOSTOLAKIS:  That, yes.
                       DR. BONACA:  But I would expect under the
           current regulatory environment, an applicant could
           come in and provide a study of single failure based on
           a PI, and that would be much more credible how you
           eliminate certain --
                       DR. APOSTOLAKIS:  It's not even a single
           failure.  It's a single failure of hardware, right? 
           And put the operator there to defeat everything.  And
           that's not the same --
                       DR. BONACA:  But the point I'm making is
           that you assume -- see -- in search almost of a design
           that was acceptable, you assume those kind of
           failures.  Now you would do it through a PRA.
                       DR. WALLIS:  If we're looking ahead to new
           plants we should encourage the staff to get
           performance-based and not sort of specific based
           entirely on the existing fleet of plants.
                       MR. UHRIG:  But what impact would this
           have on the certified plant?
                       DR. KRESS:  They have their own rule.
                       DR. WALLIS:  But this business about the
           cladding and stuff, how would it apply to a peddle bed
           reactor?  But if you had something which said that
           you've got retain fission products, then that applies
           to anything.
                       DR. KRESS:  Yes, I think that's a good
           point that you make.  I mean, why you worry about the
           ductility of the event.
                       DR. WALLIS:  Ductility of the cladding of
           a peddle bed reactor, yes.
                       What is the ductility of these ceramics?
                       DR. KRESS:  Sounds pretty good.
                       DR. SHACK:  But you put in a nice buffer
           layer to absorb all the changes.
                       Are there any particular items we want
           brought up at the full Committee, they should be
           addressing anything?
                       DR. APOSTOLAKIS:  This was a nice
           presentation for a full Committee.
                       DR. KRESS:  Yes, and it wasn't that long,
           was it?  They might have to shorten it some.
                       DR. APOSTOLAKIS:  Yes, they can shorten it
           a little bit.  But other than that --
                       DR. SHACK:  I'm sure that's not a problem
           for you.
                       DR. WALLIS:  Will NEI have a presentation
           or have you had time to think about before the full
                       MR. HEYMER:  Since we haven't seen the
           SECY and we're not really available on Wednesday
           because we have an interaction with the senior NRC
           management, we weren't planning to say anything more
           than what we've said today.
                       DR. SHACK:  Okay.  
                       DR. BONACA:  I have a question, Mr.
           Chairman, which is shall we give back this document
                       DR. APOSTOLAKIS:  No.  This pre-
           decisional, right?
                       MR. MAYFIELD:  That's right.  You just
           can't share it with anyone else.  It's for your use
                       DR. BONACA:  Then I will not share it with
                       DR. APOSTOLAKIS:  We never share anyway.
                       DR. SHACK:  Well, if there are no more
           serious items to be discussed, I think we can adjourn
           the Subcommittee meeting.
                       (Whereupon, at 4:45 the Subcommittee was

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