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| 01 G NA _ A C RST- 309' <
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| r7 OFFICIAL TRANSCRIPT OF PROCEEDINGS L) ~
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| NUCLEAR REGULATORY COMMISSION ADVISORY COMMITTEE ON REACTOR SAFEGUARDS I
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| l
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| ==Title:==
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| MEETING: RELIABILITYAND PROBABILISTIC RfSK ASSFSSMENT AND REGULATORY POLICIES AND PRACTICES TRC4 (ACRS; RETURN CRIGINALNiy TO BJWHITE 1
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| m Docket No.: ws T- 2E2e
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| * A
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| < 1
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| ) - 415-713: )
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| THANKS! - It t rti,1 l l' l , 1 Work Order No.: ASB-300-928 LOCATION: Rockville, MD D 1
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| DATE: Friday, September 24,1999 PAGES: 107 - 309 9910010037 990W4 PDP ACHG T PDW
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| ...-3091 ANN RILEY & ASSOCIATES, LTD.
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| ,/ x . 1025 Connecticut Ave.,NW, Suite 1014
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| ! ) ,
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| W40.lfp ,11 0s-29036, -
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| $$3280E030lls.E aaw map- 1
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| i l
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| P'
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| ['T l
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| \ ,) l l
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| DISCLAIMER UNITED STATES NUCLEAR REGULATORY COMMISSION'S ADVISORY COMMITTEE ON REACTOR SAFEGUARDS SEPTEMBER 24, 1999 The contents of this transcript of the proceeding of the United States Nuclear Regulatory Commission Advisory )
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| /~T
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| () Committee on Reactor Safeguards, taken on September 24, 1999, as reported herein,'is a record of the discussions )
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| recorded at the meeting held on the above date.
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| This transcript had not been reviewed, corrected and edited and it may contain inaccuracies. l gg V
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| 107 l
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| 1 UNITED STATES OF AMERICA
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| () 2 3
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| NUCLEAR REGULATORY COMMISSION ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 4 ***
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| l 5
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| * MEETlNG: RELIABILITY AND PROBABILISTIC RISK l
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| 6 ASSESSMENT AND REGULATORY POLICIES AND PRACTICES 7
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| 1 8 U..S. Nuclear Regulatory Commission l
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| l 9 11545 Rockville Pike
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| ! 10 Room T-2B3 11 White Flint Building 2 A
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| 12 Rockville, Maryland l
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| 13 Friday, September 24, 1999 14 -;" The subcommittees met, pursuant to notice, at 1:00 15 p. .
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| l 16 MEMBERS PRESENT 17 GEORGE APOSTOLAKIS, Chairman, Subcommittee on l
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| 18 Reliability and Probabilistic Risk Assessment l 19 THOMAS S. KRESS, Chairman, Subcommittee on 1
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| i 20 Regulatory Policies and procedures 21 MARIO BONACA, ACRS Member l 22 JOHN J. BARTON, ACRS Member l
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| l 23 ROBERT E. UHRIG, ACRS Member 24 WILLIAM J. SHACK, ACRS Member 25 JOHN D. SIEBER, ACRS Member O
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| \>
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| ANN RILEY & ASSOCIATES, LTD.
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| Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
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| {
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| c >
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| p 108 I 1 g PROCEEDINGS 2 -
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| [8:30 a.m.]
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| 3 DR. APOSTOLAKIS: The meeting will now come to 4 order. This is the second day of the Joint Meeting of the
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| ! 5 ACRS Subcommittees on Reliability and Probabilistic Risk I
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| 6 Assessment and on Regulatory Policies and Practices. I am 7 George Apostolakis, Chairman on the Subcommittee on 8 Reliability and PRA. Dr. Thomas Kress, on my left, is the i 9 Chairman of the Subcommittee on Regulatory Policies and i
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| 10 Practices.
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| l 11 ACRS members in attendance are John Barton, Mario 12 Bonaca, William Shack, Jack Sieber, and Robert Uhrig.
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| 13 The purpose of this meeting is to review the 14 proposed rulemaking plan and study for development of risk l
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| l 15 informed revisions to 10 CFR, Part 50, domestic licensing of l 16 production and utilization facilities. The subcommittees !
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| 17 will gather information, analyze the relevant issues and
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| ! 18 facts, and formulate proposed positions and actions as :
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| 19 appropriate for deliberation by the full Committee.
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| l 20 Michael T. Markley is the Cognizant ACRS Staff l 21 Engineer for this meeting.
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| 22 The rules for participation in today's meeting 23 have been announced as part of the notice of this meeting --
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| l 24 previously published in the Federal Register on September 25 3rd, 1999.
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| O
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| \
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| ANN RILEY & ASSOCIATES, LTD.
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| Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 J
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| 109 1 A transcript of the meeting is being kept and will
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| [G\ 2 be made available, as stated in the Federal Register notice.
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| 3 It is requested that speakers first identify themselves and 4 speak with sufficient clarity and volume so that they can be 5 readily heard.
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| 6 We have received a request from Mr. Jim Riccio, 7 public citizen, for time to make oral statements to the 8 subcommittees regarding matters discussed during this
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| )
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| 9 meeting. The ACRS has reviewed SECY-98-300 in December '98 10 and issued a report to the Commission dated December 14, 11 1998, 12 In a Staff Requirements Memorandum dated June 8th, 13 1999, the Commission directed the Staff to pursue the 14 proposed Option 2 and Option 3 approach. The joint
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| () 15 subcommittees previously met on July 13, 1999 to discuss i
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| 16 Staff plans on this matter. l 17 The Staff has met with the Nuclear Energy 18 Institute and licensee representatives several times to 19 discuss options for revising 10 CFR, Part 50 and possible 20 pilot participation. The Staff also held a public workshop 21 on September 15, 1999 to discuss possible changes under j 22 Option 3.
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| 23 Before we start with the Staff, I have a couple of 24 comments to make. A lot of the risk informed approaches 25 that we have discussed in the last two, three years rely on
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| (~S ANN RILEY & ASSOCIATES, LTD.
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| \ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
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| 110 1 importance. measures, and I am not sure that we all
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| () -2 understand what these measures mean and the implication of 3 their use. In fact, I was doing some calculations yesterday 4 and I found some things that are interesting I would say, so 5 I know this comes as a surprise to everyone, so I don't 6 expect answers but I think it would be useful to at least 7 discuss some of these issues maybe at some later time to try 8 to come up with some answers.
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| 9 I believe you are getting copies of this --
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| 10 somebody is bringing them, okay.
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| 11 Let's take a very simple case. There is only one 12 accident sequence. You can't get simpler than that -- one 13 initiating event and one protection system. The core damage 14 frequency or-the unavailability is simply the product Fq: F
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| () 15 is the Frequency of the initiating events and q is the 16 unavailability of the protection system. Right? It's the
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| : 17. simplest possible case.
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| 18 Now I can calculate the two common measures, like 19 Fussell-Vesely and the Risk Achievement Worth. Fussell- l 20 Vesely tells me that I should take the minimal cutsets that 21 involve t he unavailability of this protection system, and 22 there is only one, Fq, and divide it by the total, so Fq 23 divided by the total is one, so this is the Fussell-Vesely 24 of the system. It is also the Fussell-Vesely measure for 25 the initiating event. l l
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| O ANN RILEY & ASSOCIATES, LTD.
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| Court Reporters 1025. Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 ;
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| I i
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| 111 l
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| 1 To get the Risk Achievement Worth I am supposed to I r~
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| ( }j 2 find the new CDF that would result with Q equal to one, in 3 other words assuming that the protection system is always 4 down, what is the new CDF? Well, it is just F, and divided 5 by the total CDF of the base case and the result is 1 over 6 q. Right? So this is a very simple calculation.
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| 7 Now I decide to spend money and add protection 8 systems, so I add a number N of them, so the new CDF now is 9 Fq -- the Frequency of the initiator -- times the 10 unavailability of my original system times the product of 11 the unavailabilities of all the other systems that I added, 12 and for simplicity I am assuming independency. That's a 13 seven-day issue.
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| 14 I calculate now the new Fussell-Vesely and the new
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| () 15 Risk Achievement Worth of the original system. Well, 16 Fussell-Vesely is again the ratio of the minimum cutset over l 17 the total, so it is still one, and RAW set q equal to one, l
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| 18 so you have got F times the product of the gj, divide by the i 19 total. It is still 1 over q.
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| 20 So the two importance measures of the new system 21 have not changed, even though I added a number of additional 22 protection systems.
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| 23 The question is really is the system as important l
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| l 24 as before? According to these two measures, yes. The two 25 measures have not changed. Now intuitively, though, you l
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| l 112 1 would say no, I don't care. If I add a hundred more
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| () 2 3
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| systems, even if this one fails, who cares?
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| So it seems to me that there is a problem there, 4 that the measures are insensitive or appear to be 5 insensitive to such drastic changes in the design. Now the l 6 question is so what? What are you going to do? Well, I i
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| l 7 don't know. I mean this is just something that I realized 8 yesterday, but it bothers me and if we are to -- and one can 9 have other things that are not as impressive as this one by l 10 adding failure modes and so on, but the question really is l
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| 11 do we understand what these importance measures mean to the 12 degree that we can comfortably use them in regulations, l 13 routinely, because now we are talking about changing, l
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| l 14 revising the scope of systems, structures and components and
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| ( 15 I believe the major tsols to make that process risk-informed 16 are the importance measures, and this is a trivial case 17 obviously, but sometimes trivial cases give you some t
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| 18 insights. I don't know what happens if you have a complete l
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| 19 PRA with thousands of minimal cuts sets and so on. I 20 haven't looked into it, but it just doesn't make sense that j 21 the importance measures are so insensitive.
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| 22 So for example I was reading a paper from Duke l
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| 23 Power some time ago, how they implement -- how they use PRA 24 to evaluate online maintenance configurations, and they have 25 a very nice table there where they say we will put the I
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| > 113 1 components into categories depending on the value of the (f 2 Risk' Achievement Worth and in one group they have the 3 components whose RAW is 100 or more, so if EDQ is 10 to the 4 minus 2, which.is a reasonable unavailability, this RAW will 5 be 100, and then they impose on themselves a requirement 6 that between refueling outages these systems that-have a RAW 7 of 100 or more should have no failures. They are so l
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| 8 important they should have no failures, okay? j I
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| 9 Now that presumably means that you have to be very l 10 careful with your maintenance and quality assurance and all l
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| .11 that. It implies there is an expense there, so now if that 12 same utility said, well, hell with it, we don't want to do I i
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| 13 that all the time -- it's a pain in the neck -- we are going 14 to spend -- this is crazy of course, but we are going to )
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| .15 spend a few hundred thousand dollars to add systems, so I -
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| 1 16 don't have to worry about quality assurance. I 17 The NRC comes back and says sorry, your RAW is 18 still'100, so the money.you spend there is irrelevant. Your
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| )
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| I 19 RAW is still 100. You still have to do these things, 20 okay? -- so this is the thing. Yes, Mary?
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| 21 MS. DROUIN: George, I am not going to argue with 22 your mathematics there because they aren't incorrect, but 23 the --
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| 24 DR. APOSTOLAKIS: Are incorrect?
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| 25 MS. DROUIN: Not incorrect -- but what is 1
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| 114 l 1 misleading here is that you have only looked at the ratio of 2 looking at the' Risk Achievement.
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| (
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| 3 -It-is improper when you are looking at these 4 important measures just to look at the ratio calculation.
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| 5 If you took the same thing on the Risk Achievement and l 6 didn't do it in the ratio, you would see a different result.
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| : 7. If you jupt' looked at what the delta CDF is --
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| 8 DR. APOSTOLAKIS; Wait, wait, wait. That was my l 9 next comment, that using these measures may not be 10 appropriate precisely'because they are ratios --
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| 11 MS. DROUIN: That is exactly right.
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| 12 DR. APOSTOLAKIS: The possible solution is to 13 actually look at the delta CDF, but that is not what is 14 done. That is not what is done. If you go back to the risk
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| () 15 'nformed i graded. quality assurance guide --
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| 16 MS. DROUIN: Well,.let me say it's not -- I mean I 17 don't look at just the ratio.
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| 18 DR. APOSTOLAKIS: But let's go back to the graded 19 quality assurance regulatory guide. They don't talk about 20 delta CDF at all because we all agree that there are no 21 tools for estimating delta CDF when it comes to quality 22 assurance so the only thing that happens is we use 23 importance measures to --
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| 24 MS. DROUIN: But the important measure calculates 25 it has a ratio. It also calculates it has an interval which O, ANN RILEY & ASSOCIATES, LTD.
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| 115 1 is the delta.
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| () 2 DR. APOSTOLAKIS: And I agree with you.
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| 3 MS. DROUIN: And hopefully people use both of 4 them.
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| 5 DR. APOSTOLAKIS: And that comes naturally from 6 this, the last sentence here -- which I deleted at the last 7 moment was that the absolute value of CDF or delta CDF if 8 you want should play a role in these decisions, and you 9 agree with me. My point is that right now it does not play 10 a role because many times we give up. We say we can't 11 calculate delta CDF. Maybe we shouldn't look at delta CDF 12 but we have CDF itself, okay, because in other cases for a 13 plant where the core damage frequency is 10 to the minus 6 14 and another one is 10 to the minus 4, Fussell-Vesely and RAW
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| () 15 still are still the same so presumably the licensee would 16 have to take the same action in both cases.
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| 17 MS. DROUIN: I guess I am confused by when you 18 said we can't do it. I am not aware of any of the computer 19 codes that don't do. I mean they all calculate the delta, 20 interval.
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| 21 DR. SHACK: She is saying the delta for the RAW 22 calculation, not the delta that the graded QA makes the 2'3 difference. See, you're only looking at --
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| 24 DR. APOSTOLAKIS: No, delta CDF she is saying.
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| 25 DR. SHACK: The delta CDF in terms of the RAW.
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| 116 3
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| 1 MS. DROUIN: -- of the RAW. Right.
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| () 3 2 If you go and use your same example but calculate your RAW asLthe interval, not the ratio --
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| 1 4 DR. APOSTOLAKIS:
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| . That's fine and I agree that 5 that is the way it should be done. What I am saying is the 6 regulatory guides as.they are today I don't think they do 7 that.
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| 8 MS. DROUIN: I don't,think the guides 9 differentiate whether it is a. ratio and interval. They just 10 say use the Risk Achievement Worth, which could be either 11 measure.
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| 12 DR. APOSTOLAKIS: No. We just put the components 13 into categories and then take action based on that without 14 looking at the absolute value or delta CDF and so on. I 15 mean if we did that, then this problem would not be there, I 1 16 agree. I fully agree. So you just gave me the answer in 17 other words -- yes, I agree.
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| 18 I didn't -- I think the only message here is that 19 we cannot make decisions using these measures only, I think, 20 okay? Now there may be other implications but it's probably l l
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| 21 too soon to tell. j 22 Now we can proceed with Mr. Matthews --
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| 23 MR. NEWBERRY: Mr. Newberry.
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| 24 DR. APOSTOLAKIS: Okay -- Mr. Newberry. Please 25 identify yourselves.
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| 117 1 MR. NEWBERRY: I am pinch-hitting for Mr.
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| 2 Matthews.
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| 3 DR. APOSTOLAKIS: Okay.
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| 4 MR. NEWBERRY: Good morning, Mr. Chairmen and 5 committees. We are glad to be here. I am Scott Newberry --
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| 6 I am Dave Matthews' Deputy -- and we'll open our 7 presentation here. For such an overwhelming project there 8 is no way I could do this alone. We have a team of folks 9 working on this and I am going to introduce them in a 10 minute.
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| 11 Dr. Apostolakis talked about importance measures.
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| 12 Mike Check will be getting into that aspect of 13 categorization a bit in the presentation. I just jotted 14 down some reactions. One -- I think it is critical that we
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| () .15 have an understanding of importance measures because it's 16 one aspect of what we're trying to do here certainly. Mike 17 will talk about that but I know in the NEI proposal, which 18 Adrian may talk about later, they talk about a blended 19 approach and I think perhaps there's an appreciation of some j 20 of the difficulties here, but in Option 2, which we are ;
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| 21 going to be talking about today, the design basis will stay 22 the same. The Option 3 approach, which Tom King will talk 23 about later today, I think will look at the possibility of 24 changing the design of the plant, the design basis of the 25 plant. Here we are talking about grading the treatment on ANN RILEY & ASSOCIATES, LTD.
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| 118 1 systems, structures and components.
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| () 2 3
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| But I think most' importantly we have to have that understanding if we are going to have an effective rule.
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| 4 DR. APOSTOLAKIS: Again, and please don't 5 misunderstand the purpose of my little talk there. It's 6 really to look at -- I mean there is a wonderful paper that 7 is out there written by I believe Mike, Rick, Sherry, but 8 this is kind of different here.
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| 9 I think we need to explore a little bit better the 10 significance of these measures and make sure that we and the 11 expert panel know some of the implications.
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| 12 For example, I don't know if the expert panel can 13 say, yes, on the basis of the risk measures we should do 14 this to this component but because the core damage frequency
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| () 15 is so low already we are not going to do it.
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| 16 MR.-NEWBERRY: Right.
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| 17 DR. APOSTOLAKIS: I don't know. Maybe they should 18- be able to say that, so don't misunderstand what I just 19 said. I didn't present it as a fatal flow in what we're 20 doing. It's just that we need to get more into it.
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| 21 MR. NEWBERRY: Thank you. I am going to do the i
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| 22 first viewgraphs, which basically are to touch on items in i 23 the agenda and then get into some of the objectives of the 24 rulemaking.
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| 25 To my right is Tom Bergman, and Tom is really the I
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| x l' lead Project Manager on the effort. He will do most of the 2 briefing. Tim Reed, to his right, will be keeping him out 3 of trouble with flipping viewgraphs and answering questions, 4 and Mike' Check will get into the importance and 5 categorization aspects as we get into the presentation.
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| l 6 Just to give you a feel for where we are on this,
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| ! 7 we sent you a big package to help on this meeting. The 8 package, frankly, is still a bit fluid. It is just going 9 into the office concurrence process here, but I did feel 10 comfortable sending it to you. I think it lays out the 11 issues, challenges and the concepts that we feel that we 12 need to get to the Commission so we can get out and get 13 comment on those things. That is where we are in the 14 process right now is the need for comment including the 15 input from the committee, so we do have a plan and that is 16 what we will be talking about today.
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| 17 I think we're certainly well enough along to talk 18 about what the major tasks and issues are and we will go 19 through some of those, and also the timing -- the timing 20 here is important. When do you grant an exemption? You may 21 have gaestions on the exemption process or the pilot 22 process, how they fit together with proceeding to proposed 23 and final rule.
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| 24 We can talk about that largely based on the last 25 meeting, where we got comment from the committee on how you O ANN RILEY & ASSOCIATES, LTD.
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| r 120 ,
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| i 1 select rules, and Tom will get into which rules we think can l
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| <~\ j
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| ( 2 be affected here, those that might not be affected, and we, s
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| 3 like I said, based on some comments from the committee, we 4 worked hard to come up with criteria to apply to our review 5 of the rules and we will talk about that a little bit.
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| 6 It is a complicated project. When you see the 7 list of rules that we are talking about touching upon, you 8 start worrying about the relationships and unintended i
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| 9 consequences of changes you could make. We are struggling 10 with some of those issues. When you start talking about 11 50.59, you start talking about 50.36 -- the tech spec l I
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| 12 rule -- and you really start struggling when you look at the l 1
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| 13 relationships of a deterministic regulation and risk 14 informed regulation and the roles of those rules, and we
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| ) 15 will talk about that today a little bit.
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| 16 I think somewhere out there in the audience we i
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| 17 have an attorney. Janice is in the back. If we get into 18 process issues, OGC is here to keep us honest, but I think 19 before we get going the objective today I think is to impart l 20 understanding to the committee. We don't have answers to 21 all the questions ourselves -- I will tell you that right 22 upfront -- but maybe we can at least figure out what the 23 questions are. I think in this project that's the objective 24 and we look forward to the input from the committee so we 25 can move on. Tom? Oh , wait -- I've got the next viewgraph, i l
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| l I
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| [~)
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| 121 1 don't I? I (n) 2 ;I insisted we put this in here to talk about what 1
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| 3 we are trying to do. When we got ready for the brief, I 4 didn't think we were really doing that, so we are trying to 5 set.up an alternative approach that a licensee could 6 voluntarily select to categorize or risk inform the 7 treatment requirements. " Treatment" is a term that we 8- do attempt to define in the rulemaking plan, and we'll talk 9 a bit about it today, but it is really the investment that a 10 utility makes to grant the highest level of assurance in the 1
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| )
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| 11 regulatory process to equipment.
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| 12 It is derived largely today by the term " safety-13 related"'-- that is the highest treatment, the special 14 treatment, and the intent here would be to relax treatment
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| () 15 in areas where the equipment is of low importance -- low 16 importance, lower significance, 17 The second bullet there is a listing of our 18 primary performance measures in all of our projects -- I 19 mean they are found in the strategic plan and we're working 20 to define them, but here we are really, as I said, we're not 21 changing the design of the plant, but we need to maintain 22 safety as we look to see what programs or what equipment we I
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| 23 will focus on and retain the special treatment that reduce l 24 burden on equipment, _a large set of equipment where we think l
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| 25 the.importance is lower, and I think, as was proposed in 98-l .
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| F 122 1 300, the process would include a testing of the process
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| () 2 3
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| through pilot plants -- we will talk about that a little bit and as we have gotten into the projects we see that as a l
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| I 4 necessary step before the agency would proceed with the 5- final rulemaking, and we will talk about the pilot plant '
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| l 6 project 7 So with that --
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| 8 DR. APOSTOLAKIS: Scott --
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| 9 MR. NEWBERRY: Yes.
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| 10 DR. APOSTOLAKIS: -- the second bullet there I 11 think needs rewording because if you reduce unnecessary 12 burden and you improve staff efficiency and effectiveness it i l
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| 1 13 is quite likely you are actually increasing, enhancing 4 14 safety, because you are freeing resources that may be used.
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| O(, 15 I think what you mean is maintained just at what you are 16 doing, but then these other things will actually have a 17 positive impact.
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| 18 MR. NEWBERRY: I share that view. I think as a 19 standard or a minimum, a minimum standard would be to 20 maintain safety, but as we proceed here, I think that will 21 certainly be a hope, if we could improve efficiency and 22 reduce burden and focus our resources and attention on the 23 higher significance equipment I think we would be enhancing 24 safety.
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| 25- Is it your comment that that should be the ANN RILEY & ASSOCIATES, LTD. I Court Reporters I 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 l
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| 123 1 objective, to enhance safety?
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| ] ) 2 DR. APOSTOLAKIS: .I think it is more of a 3 statement of fact. It is not an objective. If you make it 4 risk informed --
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| 5 MR. NEWBERRY: No - -
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| : 6. DR. APOSTOLAKIS: -- yes, it should be the 7 objective.
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| 8 You start out with the objective of maintaining 9 safety but then because of these other benefits you may end 10 up-actually enhancing it. Somehow that has to come across.
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| 11 It's just a comment.
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| 12 MR. NEWBERRY: Thank you for the comment. I share I
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| 13 the view and we'll see if we can do that. Tom.
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| 14 MR REED: Good morning. Just quickly, you are
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| ) 15 pretty familiar with the background.
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| 16 This effort was initiated in SECY 98-300, 17 described as Option 2. The Staff Requirements Memorandum l
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| l 18 dated June 8th approved the approach and gave us a due date 19 on the.rulemaking plan of October 31st. As you have been l- 20 provided,. we do have a draft paper and all the attachments l
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| L 21 and we are currently on schedule to meet that due date.
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| l 22 This next slide is done to show how the difference 23 from what we are proposing to do from what is traditionally 24 been done. The traditional approach has divided the 25 components into safety-related and non-safety-related. Now
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| 124 1 we will'also do it on the basis of safety significance, by
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| () 2 3
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| segregating those of high safety significance and those of low safety significance. The result of that is you get four 4 regions of components, those that are safety-related and 5 high safety significant, those that are non-seiety-related 6 and high safety significant, and those that are safety-7 related of low safety significance and non-safety-related of 8 low safety significance, 9 DR. APOSTOLAKIS: So this new system then will 10 preserve the definitions of safety-related and so on? You 11 are not replacing them?
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| 12 MR. REED: Right, we are not replacing them.
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| 13 First, from a rulemaking standpoint we thought that would be 14 too difficult to do within the current rules both in terms
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| () 15 of since we are expecting voluntary implementation it would 16 become very confusing to have safety-related mean different 17 things depending on the licensee and the specific rule, and 18 second, simply replacing the term " safety-related" with 19 "high safety significant" would not work alone in changing 20 some of the rules, because they say the scope of this rule 21 is safety-related and other things, so we felt it was best 22 to bring in new terminology.
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| 23 This also helps us maintain the current design 24 basis because you can still refer to safety-related which 25 links you to that design basis.
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| 125 1 DR. KRESS: Now when you say " safety significant" j 2 you have something in mind other than just effect on risk?
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| 3 You have other things --
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| '4 MR. REED': .That is correct. It would be a risk-5 informed process but-it is not a risk based process.
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| 6 DR.'APOSTOLAKIS: Now --
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| 7 MR. NEWBERRY: I think it would be good to leave 8 this up here awhile so the committee is at least comfortable 9 with these regions as we proceed, so if you have any 10- questions we can talk about them now.
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| 11 DR. KRESS: . Well, any time you have a sharp 12 boundary --
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| 13 MR. BERGMAN: We are not implying a sharp 14 boundary.
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| () 15 DR. KRESS: Well, if you did have a sharp boundary 16 ~ you would want it set at a level that you felt was 17 conservative.
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| 18 MR. BERGMAN: Yes.
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| 19 DR. KRESS: Or you could have a gray boundary 20 which would be -- amount to the same thing.
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| 21 DR. APOSTOLAKIS: That's different.
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| 22 MR. BERGMAN: Well, what we are doing within this 23 approach iF within Regions one, two and three will all get 24 treatment. They'll still'be within. scope of the 25- regulations, okay? Region one currently gets a lot of ANN RILEY & ASSOCIATES, L1D.
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| E 126 1 special treatment.
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| h
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| [O 2 It may need different treatment because the l 3 reasons those components are of high safety significance may i
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| 4 not be quite the same reasons they are safety-related. That '
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| 5 is this Issue 4 we address in the paper, part of it.
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| 6 In Region two those SSCs are currently non-safety- i 7 related. They will likely need to have some special 8 treatment added to address the reasons they are of high 9 safety significance.
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| 10 Region three is where the burden reduction comes 11 into play. That.would be components that are currently 12 safety-related and thus have a great deal of special 13 treatment but are of low-safety significance and we expect 14 that we shall be able to reduce the amount of treatment,
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| (
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| O) 15 however we'll still need some assurance that the components 16 are capable of performing their functions in response to 17 design basis events, because that is what is required in 18 Part 50. We-are not changing those design basis 19 requirements.
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| 20 DR. APOSTOLAKIS: Are you done? I was intrigued 21 by something in the report that cited several regulations 22 where these things are defined, so went there. In Part 23 50.2, safety-related SSCs are defined as those that must 24 remain functional during and following design basis to 25 assure the integrity of the reactor coolant pressure
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| ! ) ANN RILEY & ASSOCIATES, LTD.
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| 127 1 boundary, capability to shut down the reactor, and
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| () 2 3
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| capability to prevent or mitigate the consequences of accidents - and that is repeated in several other 4 regulations.
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| 5 .Then, as you' point out in the report, there is
| |
| -6 also this concept of " basic component," which is I guess 7 different. Is it -- because in all cases " basic 8 component" -- this is now from 21.3 -- " includes safety-9 related design, analysis, inspection, testing, fabrication, 10 replacement of parts or consulting services."
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| 11 So a consulting service is a basic component?
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| 12 MR. BERGMAN: Yes.
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| 13 MR. REED: Yes.
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| 14 DR. APOSTOLAKIS: And this is different from
| |
| () 15 safety-related stuff or is it the same thing?
| |
| 16 MR. BERGMAN: That is the principal difference. )
| |
| 17 MR. REED: Yes'. I think basic component goes in a 18 sense, at least in my view, goes beyond what you think in 19 terms of safety-related.
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| 20 If you read the safety-related definition, that is 21 a structure, system, component definition --
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| 22 DR. APOSTOLAKIS: Okay.
| |
| 23 MR. REED: -- whereas basic component is any 24 activity involving those things including calculaticas, 25 analyses -- anything you do that meets the basic components.
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| ANN RILEY & ASSOCIATES, LTD. !
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| 1025 Connecticut Avenue, NW, Suite 1014 4 Washington, D.C. 20036 )
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| l 128 1 If_you are doing an' accident analysis calculation on an SSC
| |
| () 2-3 that is-safety-related, that is a basic component, that calculation. ,
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| }
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| 4 DR. APOSTOLAKIS: And there is consistency in fact 5 if you go to 50.49 -- there is again safety-related and so 6 on, except when you hit Appendix A. Now we have something 7 new -- components, structures and systems "important to 8- safety" now. That is SSCs that provide reasonable assurance 9 that.the facility can be operated without undue risk to the 10 health and safety of the public.
| |
| 11 So where does that fit in here? This not safety-12 related, right? These are not safety-related, are they?
| |
| 13 MR. BERGMAN: Right. The traditional view has 14 been that important to safety is a broader set of SSCs that
| |
| () 15 safety-related, and that the equipment that is important to 16- safety varies somewhat with each regulation.
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| I 17 DR. APOSTOLAKIS: Now why in Appendix A do they j 18 feel the need to refer to those and in the other parts they 19 didn't? .Because it is more recent?
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| 20 MR. BERGMAN: Is that it?
| |
| 21 DR. APOSTOLAKIS: That is what it is? It's more 22 recent?
| |
| 23 MS. MOORE: No. Appendix A is not more recent.
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| 24 DR. APOSTOLAKIS: You have to come to the 25 microphone.
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| o 129 1 MS. MOORE: Appendix A is not more recent than
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| 50.19.
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| DR. APOSTOLAKIS: Would you identify yourself, 4 please.
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| 5 MS. MOORE: Yes. My name is Janice Moore, with 6 the Office of General Counsel.
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| 7 DR. APOSTOLAKIS: Okay.
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| 8 MS. MOORE: But 50.59 is more recent regulation.
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| 9 DR. APOSTOLAKIS: So I mean is this concept of 10- "important to safety" similar to the safety significant?
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| 11 MR. REED: No.
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| 12 DR. APOSTOLAKIS: No?
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| -13 MR. REED: Janice will correct me if I am wrong 14 but if you read through Appendix A, the whole appendix, all
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| () 15 those GDCs, by the time you get to the end you will be 16 completely ccnvinced that "important to safety" means 17 exactly safety-related.
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| 1 18 I mean they thought in terms of design basis, 19 redundancy, diversity, separation -- you meet all the GDCs, 20 the mentalities, built throughout that appendix, and in fact 21 if' you start looking at other regula' ions like take GDC-1, 22 which is quality control, and then go to Appendix B, you 1
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| 23 will see that they in a sense equate safety-related to 24 important to safety, so in a sense the regulations almost 25 equate the two terms.
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| 130 1 1 There is obviously a lot of argument and, you I
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| 2 know,_ through'the years on'what the terms mean.
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| ()' That was 3 one of the reasons why we didn't want to touch either term
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| _4 and leave them go and start with.something new, some-l 5 different terminology, if in fact we use new terminology at 6 all.
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| 7 As you will see, we are suggesting a new rule 1
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| ;8 without any defined terminology, so we are staying out of 9 the terminology battles completely but when I look at that 10 discussion there in the introduction to Appendix A, the 10 11 CFR 50, which you just read, there is a very broad 12 definition. It is almost a perfect definition of what we l
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| 13 would like to say. You know, this is the stuff that is 14 really important, but when you look at it from a legal. 1
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| () 15 standpoint, regulatory standpoint, it starts to unravel.
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| 16 DR. APOSTOLAKIS: Well, couldn't this thing be I 17- used to define those high safety significant and say, well,
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| : 18. if important to safety means without undue risk to the 19 health and safety of the public we have the PRA. We are 20 defining here what is important to safety, instead of saying 21 we are ignoring it. ;
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| .22 Why wouldn't that work?
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| 23 DR. BONACA: But isn't safety-related really the 24 original classification -- 1 l
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| 25 DR. APOSTOLAKIS: Yes. I l
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| 131 l 1 DR. BONACA: It came from the FSAR.
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| 2 DR. APOSTOLAKIS: Yes.
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| 3 DR. 1BONACA: And that is why there's many FSARs 4 originally that have GDCs applicable to them, for example, 5 some plants, okay?
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| 6 MR. REED: That's correct.
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| 7 DR. BONACA: So it is a way to provide a j 1
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| 8 definition that is broader and captures things and that is 9 why we saw for example in the Oconee application --
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| i 10 DR. APOSTOLAKIS: So what happens now? I'< are 11 ignaring what Appendix A says?
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| 12 MR. REED: No. Oh, no.
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| 13 MR. BARTON: I don't think we can, George.
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| I 14 MR. REED: Unfortunately we can't. 1
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| () 15 DR. APOSTOLAKIS: So tell me what we are doing.
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| 16 How is the safety significant categorization there related 17 to the important to safety?
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| 18 MR. NEWBERRY: I think we are going to get to l
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| 19 another viewgraph about how we would approach that.
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| 20 DR. APOSTOLAKIS: One last point -- ;
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| I 21 MR. NEWBERRY: That is a good question and part of j 22 the struggle we have --
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| 23 DR. APOSTOLAKIS: One last point. Mike here 24 showed me the SRM, the SRM dated June 8th, 1999 says Option !
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| 1 25 2 --
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| "The Commission has approved implementation of Option 2 l O ANN RILEY & ASSOCIATES, LTD.
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| 132 1 to develop risk informed definitions for safety-related and
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| ( 2 important to safety SSCs."
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| 3 MR. REED: Right.
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| 4 DR. APOSTOLAKIS: You are not developing risk 5 informed definitions. You are offering something new.
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| 6 MR. REED: Absolutely correct.
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| 7 MR. NEWBERRY: The rulemaking plan talks about 8 alternative approaches to do what the SRM is asking and the 9 guys will get into this a little bit.
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| 10 As we struggled with that, we identified another 11 way to do this which we think is more effective.
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| 12 DR. APOSTOLAKIS: Another way? You mean this way?
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| 13 MR. NEWBERRY: No. He will talk to you about that 14 in a couple more viewgraphs.
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| (h 15 MR. REED: Yes. We can hit that basically a 16 little later here if you want, but if you look in the l
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| 17 rulemaking plan we had three basic approaches.
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| 18 One was the redefinition approach which is 19 suggested in the SRM. Another is a new term approach --
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| 20 " safety significant" or whatever it is -- you define that ;
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| l 21 term and use that. The third is a new rule which doesn't 22 use new terminology. It sits there in Part 50 and basically l 23 says here's all the things you can risk inform, here's the 24 ' Appendix you can use to do it, and it separates itself from 25 all these other problems.
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| , 133 1 Obv.'ously if you read'the rulemaking plan, if you
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| have, you will see that --
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| DR. APOSTOLAKIS: Yes -- this is the plan?
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| 4 MR. REED: Yes, a version of it -- a little bit 5 out of date in there but --
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| 6 DR. APOSTOLAKIS: Yes, I have read it.
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| 7 MR. REED: But we have obviously gone to a new 8 rule. We think it is the most efficient direction --
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| 9 MR. NEWBERRY: Let me try one other point. Please 10 envision -- step back -- 103 reactors here with a voluntary 11 effort, whether they could come in -- one plant could come 12 in and even on there is another issued called selective 13 implementation where you could have a plant, we think, with 14 the standard set of definitions which Mario talked about in
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| () 15 their FSAR for some systems, but then they could come in and 16 apply for some equipment the alternative regulation here and 17 you could have both sets of definitions working.
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| 18 So if you were to redefine the standard ;
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| 19 definitions here, we saw a complexity that was unnecessary 20 and the guys came up with what we think could be a more 21 efficient way to allow a plant to apply even in subsets of j l
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| 22 equipment depending on burden -- you know, costs and j l
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| 23 . benefits -- th:: new alternative approach which gets around 24 some of these complexities.
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| 25 MR. REED: George, basically vihat we were trying g ANN RILEY & ASSOCIATES, LTD.
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| l 134 1 to do was identify an approach that basically did three
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| () 2 things. One, you had to identify all the rules containing l 3 special treatment requirements somehow, okay, and then you 4 basically had to make a reference to an Appendix, okay, that 5 says here's the requirements and the methodology on how you 6 do the categorization, all right, and then there was one 7 more problem and why this third approach I think comes out 8 to be the best is we had addressed the two technical issues z...
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| ; 9 here that are depicted on the four-box figure, we call it.
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| 10 One, this issue of the safety-related, high safety 11 significance, what you thought was high safety significant 12 in the past and now you do a risk informed evaluation and 13 you determine (a) it is not really safety significant but 14 you want to maintain functionality.
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| <*T. I (G 15 That is t'ie one technical issues.
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| . How do you do 16 that without assurance, how are you maintaining 17 functionality without assurance? That is one technical 18 issue we needed to build into this somehow or address 19 somehow.
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| 20 The other issue that we needed to address is how 21 about the things that come in, the non-safety-related stuff 22 which are important for events that are beyond the design 23 basis of the facility and now you are saying, hey, these 24 things are safety significant -- I want to apply some sort 25 of regulatory treatment to them, but remember Part 50, the ANN RILEY & ASSOCIATES., LTD. !
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| V 1 l
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| 135 1 regulations, only mean things for design basis events in I
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| general, okay?
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| So when you bring it in, if you just scoped it in, 4 you would have no requirements on this equipment, so we had
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| . 5 to do something to address that situation and to address 1
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| 6 this functionality situation. As you will see in a little 7 bit, we think the new rule approach does all those things 8 better than the other two.
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| 9 DR. APOSTOLAKIS: Now --
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| 10 MR. REED: Granted we haven't completely --
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| 11 MR. BERGMAN: If it were mandatory, a mandatory 12 rule for all licensees, a lot of the complexity with 13 redefining safety-related and important to safety would go 14 away. You would still have some of these issues of how
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| () 15 would the rules work, but it is not mandatory and it just 16 becomes too complex.
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| 17 DR. APOSTOLAKIS: I went back to Scott's slide I 18 that-says that the regulatory framework that implements this 19 alternative should enhance public confidence.
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| 20 How much are we contributing to the enhancement of 21 public confidence by Box 2? Box 2 shakes public confidence, 22 in my opinion.
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| 23- You have non-safety-related equipment for decades 24 and now you decide that some of them are high safety 25 significant, so is there a reaction to that? Did we just j O ANN RILEY & ASSOCIATES, LTD.
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| l 136 1 make a mistake and we are correcting it now or what?
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| () 2 M
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| .R. BERGMAN: No. I think it reflects that we '
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| 3 have new information and where we have determined that in 4 fact those components are more important licensees need to 5 address that.importance.
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| 6 DR. APOSTOLAKIS: But the words there don't sound 7 good -- non-safety-related yet high safety.significant.
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| 8 MR. BERGMAN: We actually believe that the number l 9 of components to be quite small.
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| 10 DR. APOSTOLAKIS: These years --
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| l 11- MR. REED: And actually it is also a function of b 12 what this line really means. Wha.t is the difference between 13 lower and high?
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| 14 DR. APOSTOLAKIS: I know, but --
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| l
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| () 15 MR. REED: And I am not sure that they are really l 16 "high" the way you are thinking but they certainly aren't 17 low.
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| I 18 DR. APOSTOLAKIS: There is a seminar on risk 19 communication coming up soon --
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| 20 MR. REED: Next week --
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| 21 DR. APOSTOLAKIS: -- maybe this can be used as an 1
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| 22 example of what not to do?
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| 23 DR. SHACK: I mean South Texas had 20 out of 1500 24- that --
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| l l 25 DR. BONACA: That in a fairly small number.
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| l 137 1 DR. SHACK: That is the kind of fraction we are
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| () 2 3
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| talking about.
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| DR. APOSTOLAKIS: I know, but --
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| 4 DR. BONACA: And many of them were due to, were 5 related to recent issues, not the early issues, so there is 6 a learning process too that brings about awareness of new 7 issues and then identifies some of this, but I agree with 8 you -- communication --
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| 9 DR. APOSTOLAKIS: Look at it.
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| 10 DR. BONACA: I agree with you 100 percent.
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| I 11 DR. APOSTOLAKIS: Take it at face value, really --
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| 12 DR. BONACA: It doesn't say that at all. l 13 DR. KRESS: When you talk about enhancing public 14 confidence, you know I hate to get on such an amorphous
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| () 15 subject but what public do you mean?
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| 16 MR. BERGMAN: The general public.
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| 17 DR. KRESS: The people out there voting, living 18 around the planc?
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| 19 MR. BERGMAN: Even the ones that don't vote.
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| 20 DR. KRESS: The ones that live around the plant, 21 for example?
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| 22 DR. APOSTOLAKIS: Why do you have to say that you 23 will enhance public confidence and get into these questions?
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| 24 DR. KRESS: Yes --
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| 25 MR. NEWBERRY: Let me try that, and I am sure I am O ANN RILEY & ASSOCIATES, LTD.
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| j
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| 138 1 not going to satisfy it, but that's an effort where I think
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| () 2 3
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| we have got a lot of growing to do.
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| the, agency is struggling.
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| Le are struggling at --
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| It's a new initiative put into 4 'our strategic plan. It just went out for public comment. i 5 Mr. Riccio I'm sure will have some views on that 6 this afternoon. You might ask him about the different 7 public stakeholders, the interest groups, the general 8 public, the industry. We have many stakeholders that we are 9 trying to reach out to and plan to over the next year.
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| 10 I think we are going to be making commitments to 11 even do surveys and to reach out to get a broader range of 12 views on our programs. This might be one.
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| 13 DR. KRESS: I think my point is that we think 14 that's a laudable objective for NRC. We don't necessarily
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| /
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| (N) 15 think it is an objective of risk informing Part 50.
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| 16 MR. NEWBERRY: Okay.
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| 17 DR. KRESS: Take that as just a comment.
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| 18 MR. NEWBERRY: Okay, thank you.
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| 19 MR. BERGMAN: As we have already touched on, we 20 are proposing to create a new rule. It would have the 21 number 50.69 --
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| 22 DR. APOSTOLAKIS: So let me understand this. We 23 just have to live with Box 2? There is nothing we can do 24 about it?
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| 25 MR. BERGMAN: What do you mean, live with it?
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| 139 1 DR. APOSTOLAKIS: Non-safety-related high safety 1 2 significant -- I mean the message is very bad.
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| 3 DR. SHACK: Boxes disappear. ,
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| 1 4 DR. KRESS: If there is a box like that, you have 5 to live with it. q l
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| 6- DR. SHACK: If there is a new rule -- ]
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| l 7 DR. APOSTOLAKIS: And I have to put it up there !
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| i 8 for the world to see?
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| 9 DR. KRESS: Well, if you're going to make the 10 rule --
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| 11 MR. BERGMAN: The goal of our plan is to of course
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| -12 to explain to the Commission the issues we need to address, 13 and to the extent there are components in that Region 2 we 14 need to address that issue.
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| 15 DR. APOSTOLAKIS: Can you at least use it as an 16 argument that now you are actually enhancing safety, you are 17 not just maintaining it?
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| 18 MR. NEWBERRY: I think where we are going to end 19 up is when you look at the new'50.69, which doesn't really ,
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| 20 exist yet, you will see a regulatory requirement for that i
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| 21 box -- with an appropriate treatment, okay?
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| ]
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| 22 There will be a treatment for Box 1, there will be 23 a treatment for Box 2 and one for Box 3 that we will develop 24 through comment and --
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| 25 DR. APOSTOLAKIS: I am not questioning the ANN RILEY & ASSOCIATES, LTD.
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| 140 1 technical aspects. I know that you will have that. I am
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| () 2 3
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| pretty sure you will do a good job.
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| perceptions it creates --
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| It's just that the
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| .4 MR. BERGMAN: Yes.
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| l 5 DR. APOSTOLAKIS: -- what I am saying is give it a 6 positive spin, that you are not maintaining saftty you are 7 enhancing'it by doing that. Sorry -- we didn't realize this 8- but now you see? . Risk informing Part 50 we are in fact 9 enhancing safety.
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| l 10 MR. BARTON: This is a voluntary program. If I 11 don't volunteer for it, I'm not enhancing safety?
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| l 12 DR. APOSTOLAKIS: Because you don't have to. You 13 have already been found to be under adequate protection.
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| 14 MS MOORE: Excuse me, this is Janice Moore from I t 15 OGC.
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| l l 16 I think there are certain pitfalls in making that l
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| 17 kind of an argument. Remember that plants that don't comply 18 with this, there is adequate protection of the public health 19 and safety, so therefore -- '
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| 20 DR. APOSTOLAKIS: I agree.
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| 21 MS, MOORE: -- your argument would require us to 22 say that this should be mandatory and I don't believe that 23 we can go there.
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| 24 DR. APOSTOLAKIS: Can't we say it's an 25 enhancement? It wouldn't have to be mandatory. ;
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| 141 1 MS. MOORE: I'would -- I think that we would have
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| [ L 2 to think carefully about the ramifications of saying it is U.
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| 3 an enhancement but it is voluntary.
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| 4 MR. BARTON: That's right.
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| 5 MR. REED: I mean I agree, George. Box 2 clearly
| |
| '6 contributes to enhancing the safety of the facility --
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| 7 DR. APOSTOLAKIS: Everybody concedes that.
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| 8 MR. REED: --ibut Box 2 enhances the safety. You 9 can argue that Box 3 decreases safety in at least some 10 minimal aspect of safety --
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| 11 DR. APOSTOLAKIS: I think we have a problem in 12 communication with Box 2 and the problem is that most of the
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| :13 time you'are talking to engineers --
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| 14 MR. REED: Yes.
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| (%
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| () 15 DR. APOSTOLAKIS: -- or your colleagues.
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| 16 Everybody agrees with Scott -- yes, there will be a place 17 where we will discuss it and we'll take care of it. But 18 boy, it creates a bad image.
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| : 19. MR. REED: That should probably say in scope or 20 out of scope --
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| 21 DR. KRESS: You may recognize a difference in 22- opinion on this subcommittee. I believe good communication 23_ requires you to call a spade a spade. That is what this box 24 'is and I wouldn't worry about you calling it what it is and 25- to disguise it as something else I think would be a mistake.
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| [~')
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| 142 1 DR. APOSTOLAKIS: Which is related to your earlier
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| : 2. question of what is the public.
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| /~')
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| C 3 DR. KRESS: Yes.
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| 4 DR. APOSTOLAKIS: If we can't define what is a 5 subcommittee --
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| 6 [ Laughter.]
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| 7 DR. BONACA: But it calls again into question the 8 fact that this is optional. That is an issue that --
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| 9 DR. KRESS: It could. You know, it is one of 10 those probability things and I think it is a low probability 11 that that will ever happen.
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| 12 DR. APOSTOLAKIS: It's the words. Anyway, let's 13 go on.
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| 14 MR. NEWBERRY: Good comments. Thank you.
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| () 15 MR. BEPGMAN: Okay. So we are proposing this new 16 rule. Within that rule it will have two basic parts. The 17 first is it will identify the rules to which this risk 18: informed scope may be applied. It would be a simple listing 19 of rules.
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| 20 The second part is that it will provide the 21 treatment requirements for the equipment within that scope 22 with the three regions -- Regions 1, 2 and 3. In other 23 words, it may need to modify the treatment requirements that 24 exist in the rules listed in the first part. It is not a 25 simple if it is of low safety significance it's completely ANN RILEY & ASSOCIATES, LTD.,
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| 143 I 1 out of scope of the rules. We may need to specify what ;
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| 2 . treatment needs to be retained for those components.
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| (}
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| 3 The second part of the rulemaking is Appendix T, 4 which will provide the criteria for methods that allow 5 licensees to come up with an acceptable categorization of )
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| 6 SSCs.
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| 7 The goal under Appendix T is to have the criteria 8 be specific enough such that we can at least minimize the 9 amount of Staff review of licensees' implementation of the 10 risk informed alternatives.
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| 11 The schedule is in the paper. I am not going to 12 run through it. I'd just point out that as far as the South 13 Texas exemption goes, it will address many of the same 14 issues that we'll need to address in this rulemaking, so
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| () 15 there is a link between the two efforts in terms of we need 16 them to be consistent and if we can't resolve some of the 17 issues that could impact the South Texas exemption because 18 we will need to resolve them through rulemaking, or it could 19 delay the rulemaking -- depends on how it works out.
| |
| 20 The second point is that we are trying to get 21 early stakeholder input by using an advance notice of 22 proposed rulemaking. To further this, we are holding a 23 public meeting October 13th at which we will discuss the 24 draft advance notice of proposed rulemaking and the draft 25 rulemaking plan.
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| 144 1 The third point is that, as discussed in 98-300,
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| () 2 3
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| we believe that a pilot program in addition to the South
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| . Texas exemption is necessary and we should be able to issue 4 exemptions at the same time we complete the evaluation of 5 that' pilot program, so July, 2001 would be about the 6 timeframe that the pilot plants would get their exemptions.
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| 7 We do assume we will be taking the approach of 8 endorsing an NEI guideline that implements the Appendix T.
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| 9 We hope to receive a draft of that guideline later this 10 year.
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| 11- Last, implementation -- if all goes according to 12 d the schedule, implementation for the in'ustry at large would 13 begin in March of 2002.
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| 14 One of the efforts we have completed since we last
| |
| () .15 met with you in July was we developed a methodology for
| |
| .16 selecting candidate rules. If'you will remember back in 17 July the ACRS in fact suggested that we come up with a 18 methodology and criteria to provide a better means of 19 clarifying how the Staff determined which rules belonged in 20 Option 2.
| |
| 21 The first step of that was the scoping review. We 22- went through 10 CFR identifying those rules, particularly in 23 Part 50, but in some other parts as well, that use scope 24 such as safety-related, important to safety, or similar type 25 constructs. That is reflected in Table 1 in Attachment 3 to T ANN RILEY & ASSOCIATES, LTD.
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| 145 1 the paper. Then we developed five criteria and the criteria
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| () 2 3
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| aren't a simple pass / fail. There actually is a logic that you have to associate with them to determine which rules are 4 within the scope of this effort. It is pretty simple, a 5 simple diagram.
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| 6 The first criterion is does the rule include 7' special treatment requirements. If that is true, then we go 8 down to Criterion 2, which would be will risk informing the
| |
| : 9. rule improve internal efficiency and effectiveness. If that 10 is true then we said okay, this is a candidate rule. It 11 doesn't mean that we will necessarily change the rule. It's 12 just a candidate rule. We are going to look at it in the j l
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| 13 proposed rulemaking. f 14 If you answered false to Criterion 2, that it
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| ( 15 wouldn't improve internal efficiency and effectiveness, ther; 16 you go to Criterion 3, and that would be will it reduce 17 unnecessary burden, and the Staff made a judgment call. We '
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| 18 expect industry in particular to comment on what kind of 19 burden is associated with each of these rules as part of the 20 ANPR. )
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| i 21 Again, if it is true to Criterion 3 it ends up in l 22 the scope of this effort. If you got a false on Criterion i i
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| 23 1, in other words it is not a special treatment rule and 24 there is no burden reduction associated with it, you get to 25 Criterion 4 and you say will modifying the rule minimize the i
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| 146 1 need for exemptions or is it necessary to facilitate
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| () 2 3
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| rulemaking for another Option 2 rule.
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| to that is true, it is a candidate rule.
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| Again if the answer 4 An example of a rule caught by, solely caught by 5 Criterion 4 would be the introduction to Appendix A of Part 6 50. If you happen to get a false to Criterion 4, you end up 7 on the last criterion, which is that changes are necessi ry 8 to basically ensure the licensing basis is documented and 9 controlled. Rules caught by that would be 50.34, 50.71(e).
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| 10- If the answer is false to a Criterion 5, then you are --
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| 11 couldn't fit it all on the page -- you are not -- it is not 12 a candidate rule.
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| 13 DR. KRESS: The question I would have about this 14 is there doesn't seem to be implied in these true and false
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| () 15 c",sstions the quantity, like how much does it improve the 16 efficiency or how much does it -- is that going to be a 17 component of --
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| 18 MR. BERGMAN: Yes. That is why they are 19 candidates. In the proposed rulemaking, the regulatory 20 analysis would address that specific question -- is the 21 reduction in burden or improvement in efficiency offset by 22 the cost --
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| 23 DR. KRESS: It would be like the regulatory 24 analysis cost benefit --
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| i 25- MR. BERGMAN: Right. Yes, and the ANPR should a
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| 147 1 help us answer some of those questions, but we do need to
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| 2 address that as part of the proposed rulemaking.
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| 3 Mike Check is going to explain Appendix T.
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| 4 MR. CHEOK: Before I get started off, I guess, 5 doing Appendix T, I would like to address some of George's 6 comments at the beginning.
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| 7 I guess we have always been aware that there are 8 shortcomings to importance measures. I guess the two 9 biggest shortcomings are that, first of all, it relates only 10 to single SSCs, one at a time, and the second shortcoming is 11 that it does not relate to a change in risk. So in all our 12 documents I think we have always said that the decision 13 criteria is actually the change in risk and the use of 14 importance measures is just for an initial screening step.
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| 15 I think when you talk about importance measures we 16 always forget to say that it is actually relative risk rank, 17 relative risk importance measures. The " relative" is always 18 left out.
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| 19 If you have a flat risk profile, even as little as 20 200 cutsets in a core damage frequency equation, you will 21 always have a Fussell-Vesely of less than .005, so it 22 doesn't tell you anything. It is all relative. In your 23 case, George, you have one single cutset, so you are always 24 talking -- the cutset is always relative to itself, so no 25 mw;ter what you do to the cutset you are always comparing it
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| 148 1 to itself. 'That is why you get your 1.0.
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| ( 2 3
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| If you add a second cutset to your example, for example each contributing equal amounts, and you make 4 improvements to one of the cutsets, add components to one of 5 the cutsets, then you will see that the Fussell-Vesely of 6 the one cutset, of the components in the one cutset, now 7 becomes less because it is now relatively less important 8 than the second cutset that wasn't improved, so I guess the 9 thing we need to keep in mind here is that all importance 10 measures tells us is how important one component is compared 11 to something else in the plant.
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| 12 DR. APOSTOLAKIS: Well, no. I think you have to 13 go beyond that.
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| 14 The Risk Achievement Worth is really a very gross
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| (~ 15 measure --
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| 16 MR. CHEOK: Yes.
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| 17 DR. APOSTOLAKIS: -- of sensitivity because, you 18 know, the unavailability of the component is 10 to the minus 19 3 or 4, and say well, let me see what happens if I set it 20 equal to one. See, that is one of the messages from this, 21 because if you didn't do that, if you went with a derivative 22 for example, then even in the case of one minimal cutset you i
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| 23 would see that the absolute value of the remaining factors 24 plays a role --
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| 25 MR. CHEOK: Right.
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| 149 L 1 DR. APOSTOLAKIS: -- so I fully agree with you, I
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| 2 with everything you said. I mean you justified why these
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| 3 things happen --
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| 4 MR. CHEOK: Right.
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| 5 DR.-APOSTOLAKIS: -- but this element or this part 6 .of the problem, that the Risk Achievement Worth really 7 results by setting the unavailabilities equal to one, 8 therefore it is very drastic --
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| 9 MR. CHEOK: Yes.
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| 10 DR. APOSTOLAKIS: -- and I am not sure that all 11 the implications have been really fully understood.
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| 12 MR. CHEOK: Right, j l
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| 13 DR. APOSTOLAKIS: That is all I am saying.
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| 14 MR. CHEOK: Yes, and I think --
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| () 15 DR. APOSTOLAKIS: But I understand why these 16 things happen. I tnean --
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| 17 MR. CHEOK: The message I think you are trying to j 18 get across is that we actually will try to go by the change
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| '19 in risk as a criterion --
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| 20 DR. APOSTOLAKIS: If we can.
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| 21 MR. CHEOK: -- use your importance when we can, 22 that's right, use the importance measures as a guidance.
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| 23 I mean the Fussell-Vesely actually is a simple
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| '24 measure that tells you how much an SSC actually contributes 25 to-the risk. It is simple to use and it is additive -- you f ANN RILEY & ASSOCIATES, LTD.
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| 150 1 can add different cutsets.
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| I
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| ) 2 The Risk Achievement Worth, on the other hand, all 3 it does is gives you a margin. It tells you how much you 4 can-go before you -- when this thing fails. It doesn't tell 5 you anything else except how much margin you have. In a 6 sense you can judge -- I'm sorry?
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| 7 DR. APOSTOLAKIS: It doesn't even tell you that.
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| 8 MR. CHEOK: In the extreme, it fails, you now know 9 how much your core damage would go to -- the kind of margin 10 you have.
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| 11 DR. APOSTOLAKIS: Well, that was exactly the point 12- of my example, that the RAW is always 1 over q independently 13 of how many additional systems I have, so it doesn't tell me 14 the margin. The margin is really the conditional
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| /~N
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| (_,) 15 probability of failure.
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| 16 Anyway, again I will repeat what I told Scott. I 17 just raised this issue as something to think about and the 18 solution may be as simple as giving some guidance to the 19 expert panel that makes the decisions.
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| 20 MR. CHEOK: Okay, sure.
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| 21 DR. APOSTOLAKIS: I am not asking for a i
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| 22 mathematical resolution to this problem before you go ahead 23 with this, because that would create big problems, but I 24 think we all should be sensitized to the fact that these i
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| 25 important measures are pretty crude. They are very crude.
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| 151 1 They don't follow from the. mathematical theory of 2 sensitivity analysis of various functional forms.
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| ( They are 3 very crude and easy to calculate. Maybe it was a trade-4 off. You never know.
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| 5' But in your paper, Mike, you did a very good job 6 of addressing of the issues like the uncertainty there. You 7 have a nice Figure 7 that I like very much -- the issue of 8 if you take multiple SSCs out, how do you calculate the 9 measure, the relevant measure, so what I said is sort of as 10 a complement to that, that there are also other issues that 11 we have to understand.
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| 12 For example, people blindly take the average 13 values of the unavailabilities and calculate all the 14 measures. Now strictly speaking you shouldn't be doing '
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| ()- 15 that. You should first take the average values of the 16 aleatory part and then integrate as you show in Figure 7, 17 but it doesn't make much of a difference when the 18 urcertainties are not huge.
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| 19 Now I don't know how many people know that.
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| 20 Check, Parry, Sherry, and possibility Apostolakis. Do you 21 think many other people are aware of this? What I am saying 22 is people should become aware of the limitations and the 23 properties of these measures if they are going to be used to 24 such extent, because you don't want to have all these 25 regulatory guides and rules in place and then five years
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| I 152 1 from now a graduate student someplace says, well, gee, let
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| () 2 3
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| me see what this means and shakes up the whole system.
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| That is all I am saying. I am not asking you to
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| , 4 give -- if you can give a mathematical answer tomorrow that l 5 will be great, but I think it will probably be more along t
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| 6 the lines of advice --
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| 7 MR. CHEOK: Right.
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| 8 DR. APOSTOLAKIS: -- and, you know, here are some 9 pitfalls, be aware of them, that kind of thing.
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| 10 MR. CHEOK: Right.
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| l 11 DR. APOSTOLAKIS: That is all I am saying.
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| l 12 MR. CHEOK: Okay. Appendix T -- the intent for 13 the Appendix --
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| 14 DR. APOSTOLAKIS: Let me ask another question.
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| l (/ 15 This is a new subject now, right?
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| 16 MR. CHEOK: Right.
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| 17 -DR. APOSTOLAKIS.: And we have been at it for an 18 hour. Is it better *o take a break now? I hate to have 19 only one break in the morning. Is this a good time to take 20 a short break or do you guys have to leave and you want to 21 finish?
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| 22 MR. NEWBERRY: No , I think we have got a good bit 23 to go in terms of the categorization and then some of the 1
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| 24 key issues.
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| 25 DR. APOSTOLAKIS: Okay, so let's take 15 minutes, l i l ANN RILEY & ASSOCIATES, LTD. I v Court Reporters i 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
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| 153
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| : 1. until 9:45.
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| 2 [ Recess.]
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| 3 DR. APOSTOLAKIS: Okay. Shall we continue? Did 4 you bring your paper down, Mike?
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| 5 MR. CHEOK: I did, and they are making copies.
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| 6 DR. APOSTOLAKIS: To be reproduced, okay -- for 7 everyone or just for two or three select people?
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| 8 MR. CHEOK: They made 10 copies.
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| 9 DR. SHACK: They distributed that paper before.
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| 1 10 DR. APOSTOLAKIS: Yes. I made sure we had it.
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| 11 Okay. Appendix T.
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| 12 MR. CHEOK: The intent of Appendix T was to 13 establish minimum requirements for the categorization 14 process and to set some decision criteria for use when you 15 categorize SSCs as high safety significant or low safety 16 significant.
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| 17 The intent'here is that if a licensee uses this 18 process, then there will be minimal NRC review. The process 19 in Appendix T is consistent with Reg Guide 1.174 and SRP 20 Chapter 19 --
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| 21 DR. APOSTOLAKIS: Let me ask about this NRC 22 review. I want to understand it a little better. It says 23 here in Attachment 1 that the burden is less for both the 24 Staff and industry following a no prior approval appendix 25 approach. Now can you tell us a little about that? What h.
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| 1 154 1 does it mean, no prior approval?
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| () 2 3
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| MR. REED: It's judgment now. What we were looking at is whether in fact you should have a regulatory 4 process that involves prior NRC review and approval --
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| 5 DR. APOSTOLAKIS: Of each licensee?
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| 6 MR. REED: Right. You know, look at their 7 categorization method and the like, okay, or whether you 8 should try to build a framework that doesn't need the prior 9 NRC review and approval. In fact, in other words have I'll 10 call it an appendix with a box and you stay in that box and 11 that appendix -- you can go do it and I'll inspect it in 12 accordance with the new oversight process.
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| 13 DR. APOSTOLAKIS: So the licensee can come back 14 and say we have now high safety significant, low safety
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| () 15 significant; we followed your Appendix T?
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| 16 MR. REED: Yes.
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| 17 DR. APOSTOLAKIS: So then you will say, okay, then 18 his categorization has value.
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| 19 MR. REED: Yes. Right.
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| 20 DR. APOSTOLAKIS: Without going back and checking 21 each component.
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| I 22 MR. REED: By the prior NRC review and approval j 23 basis -- that's right. We would be inspecting later on, as 24 called for in the oversight process. That approach, the l
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| 25 appendix approach with no prior review, is assuming we can !
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| 155 1 construct that appendix first of all, that an appendix that
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| ('i 2 maintains safety, an appendix that also is clear and O'
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| 3 unambiguous and can be consistently implemented and that the 4 Staff can be confident that it can be implemented such that 5 we don't need to review it -- okay, if we can construct 6 that, then the judgment was that framework would actually be 7 the least burdensome for all parties and ultimately then 8 everybody benefits.
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| 9 DR. APOSTOLAKIS: Yes.
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| 10 MR. REED: But that remains to be seen, whether we 11 can do that or not, and so we are kind of hedging on it, as 12 you can tell, if we can actually accomplish that.
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| 13 MR. CHEOK: So this process is consistent with Reg 14 Guide 1.174 and SRP Chapter 19 and it is also consistent
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| () 15 with the new NRC Oversight Program and the use of the 16 cornerstones. I guess the Reg Guide 1.174 requirements, the 17 principles there are to maintain consistency in a defense-18 in-depth philosophy, maintain sufficient margins and in this 19 case, I guess maintain sufficient margins in the performance 20 characteristics of SSCs such that there is allowance for I
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| 21 uncertainty in SSC performance.
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| 22 We need to maintain adequate public health and 1
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| 23 safety by limiting risk increases, if any, to small 24 increments. There will also be a requirement for 25 performance monitoring measures to ensure the inputs that we O ANN RILEY & ASSOCIATES, LTD.
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| 156 i l' used to justify less requirements for some SSCs remain valid i e 2 for the plant life.
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| -3 The safety significance of SSCs shall be i
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| l 4 determined as part of an integrated decision-making process 5 which uses an expert panel and, as George said earlier, the 6- input from the PRA would then be used as one input. The 7 expert panel will use engineering and deterministic 8 information to blend all the information to come up with the 9 final list of what is high safety significant and what is 10 low safety'significant, and again the PRA will then be used 11 again to try to quantify the change in risk, given this set 12 of high and low safety significant components.
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| 13 DR. APOSTOLAKIS: Now if there is an expert panel 14 and there will be involved in this, it seems to me that
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| ( 15 going to a no prior approval mode of operatic. Jould be a 16 little bit difficult, because it is not mathematics anymore.
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| 17 Somehow you have to check whether the decisions the panel 18 made made sense, right?
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| 19 MR. CHEOK: And the arguments we actually make is, 20 you know, we are requiring a lot of PRA sta'ndards and 21 everything else, what now do we require of the expert panel.
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| 22 I think it should be detailed documentation, basis for the 23 decisions to be kept in the plant site that could be 24 inspectable.
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| 25 DR, APOSTOLAKIS: Now I remember some time ago the l
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| 157 1 . Staff told us that eventually there would be a document with 2 guidance to the expert panels in general. Did such a 3 document ever get produced or they're still thinking about 4 it?
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| 5 MR. Ch20K: As far as I know, such a document has 6 not been produced yet.
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| 7 DR. APOSTOLAKIS: Right.
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| 8 . bE . CHEOK: So the Appendix does get into some 9 requirements for the use of the PRA.
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| 10 For example, for risk metrics we require that you 11 use CDF and LERF and that when you risk ranking you do it at 12 the component level.
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| 13 We do suggest screening criteria for Fussell-14 Vesely and RAW -- one of .005 for Fussell-Vesely and 2 for
| |
| () 15 RAW and we suggest that initially any SSCs that exceed these 16 criteria be ranked as HSSC and then delivered to the expert 17' panel for more considerations.
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| 18 I' guess we discussed why we asked for risk 19 importance measures a little earlier -- basically to give 20 the expert panel more information on the relative worth of 21 these SSCs and what margin they have if they decide to make 22 changes to these SSCs.
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| 23 DR.'APOSTOLAKIS: So it is -- the process as it is 24 now relies on the importance measures, not on the absolute 25 value of the CDF and LERF?
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| i' ' ANN RILEY &_ ASSOCIATES, LTD.
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| l 158 1 MR. CHEOK: It depends on the importance measures
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| ~T
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| [d 2 to identify the SSCs to the expert panel. Once the expert 3 panel comes up with the list of components to be put in the 4 high safety significant bin -- in Bin 1 as opposed to Bin 3 5 for example -- then we do use the PRA to quantify the change 6 in risk from moving components to Bin 3.
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| 7 We do run into a problem here in the fact that how 1 l
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| 8 do we credit, how much credit do we give to SSCs in Bin 3 l 9 and how much credit do we give to commercial grade i 10 components when we say that something has to retain its 11 functionality -- what does that mean in terms of reliability 12 and unavailability.
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| 13 One part right now is that we do let the -- maybe 14 we can let the licensees determine a level of assurance, a
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| () 15 level of unavailability and reliability for these SSCs and 16 then they have to assure this level somehow, either through 17 testing, maintenance or however they feel that they can do 18 it.
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| d 19 DR. APOSTOLAKIS: Yes. I think there are two 20 pages in Appendix T that are critical -- 33 and 34. Indeed, 21 on page 34 you say an assessment of the potential impact of 22 removing SSCs from special treatment shall be evaluated.
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| 23 Now it seems to me that that evaluation will have to be more 24 or less qualitative, won't it?
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| 25 Ideally if we could do this, then the problem I l
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| i 159 1 mentioned earlier today wouldn't be there.
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| [T
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| %/
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| 2 MR. CHEOK: That's right.
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| 3 DR. APOSTOLAKIS: It goes away.
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| 4 MR. CHEOK: Right )
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| 5 DR. APOSTOLAKIS: But we do recognize that 6 recategorizing components -- I mean is something the PRA is 7 not sensitive to these things.
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| 8 MR. CHEOK: That's right.
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| 9 IHR. APOSTOLAKIS: And then you go on to say the !
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| 10 potential changes in CDF and LERF shall be estimated by a 11 calculation in which the failure likelihood'of all low 12 safety significant SSCS modelled in the PRA is increased to 13 levels corresponding to the failure likelihood for 14 commercial' grade equipment.
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| () .15 The problem is we don't have data for this kind of 16 thing,.so --
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| 17 MR. CHEOK: That's correct.
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| 18 DR. APOSTOLAKIS: -- so are you asking them to do 19 the impossible?
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| 20 MR. CHEOK: No. Like I said earlier, we will be 21- putting this out for public comment and we will get some 22 comments'back on it, but one possibility --
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| 23 DR. APOSTOLAKIS: We just got one.
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| 12 4 MR. CHEOK: One possibility is for the licensees 25 themselves to determine what level they think they can keep
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| v 1 160 1 these SSCs at and then they have to basically maintain this 2 level. In other words, if they want to choose a very high
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| }
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| unavailability. for example, .1, then *vhen they do the 4 ! quantification they mf3ht not come under our delta CDF goals 5 or guidelines.
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| 6 On the other hand, if.they want to choose a real 7 low one, so that they can come under the delta CDF and LERF 8 . ;uir.elines then they will have to live with it somehow when 9 they do their testing and monitoring later on. That is one 10 suggestion.
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| 11 DR. APOSTOLAKIS: I remember in one of our 12 meetings, the full committee meeting with Office of Research 13 Staff, that we urged them to do some research to see whether 14 there is any difference in what data we can collect that
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| ( 15 will tell us that indeed there is a different performance of 16 commercial grade equipment compared to the ones under 17 Gpecial treatment, and I don't know whether that ever took 18 place. ,
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| 19 MR / NEWBERRY: Can you comment, Tom?
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| 20 MR. KING: Yes. This is Tom King from the 21 Research Staff. That is in our FY 2000 budget to go do 22 that.
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| 23 DR. APOSTOLAKIS: Okay.
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| 24 MR. KING: So a feasibility study is what we are 25 going to do so we can at some point in the next fiscal year
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| 161 1 come back and talk to the committee about that.
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| ( 2 DR. APOSTOLAKIS: Good. So at this point, Mike, 3 my suggestion would be to go to page 34 and perhaps add a 4 sentence or two telling the world that the Staff does 5 appreciate the difficulty of estimating delta CDF and delta 6 LERF and *hese things, so that people will not find 7 themselves in bind here, that you are asking them to do 8 something that nobody including you can do.
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| 9 MR. CHEOK: Yes.
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| 10 DR. APOSTOLAKIS: I think that would be a good 11 addition.
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| 12 By the way -- I'm sorry? Yes, go ahead.
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| 13 MR. CHEOK: Part of our problem here is that 14 Appendix T is supposed to be part of 10 CFR Part 50, so as
| |
| () 15 part of rule language I am not sure what you just said can 16 be construed as rule language. Actually, a lot of the 17 language here is not rule language. It is Reg Guide 18 language and so we really have to do something about it.
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| 19 DR. APOSTOLAKIS: But you say "shall be 20 estimated" -- so you are allowed to use that in a rule but 21 you are not allowed to say that this estimation is damn near 22 impossible?
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| 23 [ Laughter. ]
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| 24 DR. APOSTOLAKIS: Just think about the language, 25 because it really struck me there -- what are they asking ANN RILEY & ASSOCIATES, LTD.
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| r 162 1- them to do? Something that is really -- since we are on 2 this page, I have a couple more comments.
| |
| i( ) Is it appropriate 3 to raise them?
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| 14 MR. CHEOK: Sure.
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| 5 DR. APOSTOLAKIS: The appropriate time?
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| 6 MR. CHEOK: Sure.
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| 7 DR. APOSTOLAKIS: Again, the assessment in
| |
| '8 changing risk, you say that the potential impact should be 9 evaluated. Now'for all possible configurations you are 10 asking them to do this?
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| 11 MR. CHEOK: Yes, we are asking them to evaluate it 12 for configurations -- if you are talking about external 13 events and low power and shutdown -- yes, qualitatively if 14 they don't have the PRA models.
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| /~N
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| () 15 DR. APOSTOLAKIS: Online maintenance -- all those 16 different configurations?
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| 17 MR. CHEOK: No , I think we're relying more on the 18 average that that maintenance unavailabilities so it's --
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| 19 DR. APOSTOLAKIS: But we have had some problems 20 with that.
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| 21 MR. CHEOK: That's right.
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| 22 DR. APOSTOLAKIS: And some of my colleagues feel 23 . verhstronglythatwhenyoutakesystemsortrainsoutfor 24' maintenance --
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| 25 MR. CHEOK: But I think we have a maintenance rule
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| ll. 163 1 a:Id tech spec requirements that would help alleviate that f 2 problem.
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| 3 DR. APOSTOLAKIS: Aren't we finding again 4 ourselves in the unfortunate situation where somebody {
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| 5 follows this, develops these categories and then when that i
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| 6 person goes to the maintenance rule they will realize that 7 they have to re-do it? I mean I thought that was NEI's 8 position in the maintenance rule, that you do it once and I 9 for all and then you go with it and this committee disagreed 1
| |
| 10 with that.
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| 11 We said, well, there are certain things you have 12 to do and make sure that you don't take too many things out.
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| 13 Now we are coming back to saying, you know, it's 14 really fuzzy what it means. It just says "an assessment 15 shall be evaluated" but the issue of configuration it seems 16 to be deserves a discussion here. Right, Mario? j i
| |
| 17 DR. BONACA: I would agree with that, j 18 DR. APOSTOLAKIS: John?
| |
| 19 MR. BARTON: I agree. I think you need some 20 discussion.
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| 21 MR. CHEOK: Okay, I'll put that down on my notes .
| |
| 22 as something I need to consider.
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| 23 DR. APOSTOLAKIS: Yes, and again the discussion 24 should reflect the fact that we are really not asking people l 25 to take, you know, the thousands of components in a plant i
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| II 164 i 1.
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| .1 and consider all possible combinations of them being out,
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| [ 2 because that is a problem that will cost so much money and 3 it's not worth doing, so somehow we have to bound it but at
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| .4 the same time make sure that people are sensitive to the 5 fact that there is concern.
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| 6 MR. CHEOK: Okay.
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| 7 DR. APOSTOLAKIS: So that is a little bit of a 8 check.
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| 9 -DR. SHACK: But this ranking wouldn't change what 10 they do for the maintenance rule, ;here they have to look at 11 the component out of service, whether it is risk significant 12 or not?
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| 13 DR. APOSTOLAKIS: Would it not? I thought the i
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| 14 whole disagreement was that some components that are of low l) 15 safety significance during power operations --
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| 16 DR. SHACK: May change.
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| 17 DR APOSTOLAKIS: -- may change and move up under 18 different conditions.
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| 19 DR. SHACK: But I thought the maintenance rule 20 captured that by saying you had to look at what you were 21 taking out of service, that you couldn't simply bin it that 22 way.
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| l 23- MR. BARTON: Yes, the rule as written, does make 1:
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| 24 you do that.
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| 25 DR. BONACA: Right -- a modification we are
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| 165 1 making.
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| () 2 3
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| DR. APOSTOLAKIS: So are you saying then that this rule should not say anything about that?
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| 4 DR. SHACK: What this rule says was you'll still 5 have to do that for the maintenance rule even though you 6 have done this on the average. When you go to the 7 maintenance rule and are taking things out, you will still 8 have to --
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| 9 MR. BARTON: -- to do what the maintenance rule 10 says.
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| 11 DR. APOSTOLAK!S: But right now it doesn't say 12 that.
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| 13 DR. SHACK: The maintenance rule unless it changes 14 will force you to do that.
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| O 15 DR. APOSTOLAKIS: Look, if you look at these two 16 pages here, there is a discussion on setting screening 17 criteria, Fussell-Vesely greater than .005, RAW greater than 18 2 and so if you get into that -- and then you are asking 19 them to assess the potential impact -- it seems to me you 20 ought to give people some idea as to what you have in mind 21 and include this discussion. Maybe the discussion is just 22 when you do the maintenance rule, you may have to do more --
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| 23 you know, that kind of thing -- but in terms of completeness 24 of discussion, it seems to me this has to reflect that plus 25 .the fact that what we are asking them to do is something ANN RILEY & ASSOCIATES, LTD.
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| 166 1 that is very difficult to do with the present state of the
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| [)/
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| N 2 art.
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| 3 Then this will be also an opportunity to say a few 4 words about how you bound this issue and you don't do, you 5 know, a million and a half --
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| 6 DR. SHACK: It sounds a lot like Reg Guide 7 language.
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| 8 DR. APOSTOLAKIS: Well, that is up to the-Staff to 9 decide what goes here and what goes there. I mean why 10 should the rule have numerical criteria then? Why doesn't i
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| 11 the rule say that for screening purposes a Fussell-Vesely 12 number should be defined in the Regulatory Guide that will 13 tell you what it is.
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| 14 DR. SHACK: The rule probably will say that.
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| () 15 DR. APOSTOLAKIS: Right now it doesn't?
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| 16 MR. BERGMAN: Right now it doesn't.
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| 17 DR. APOSTOLAKIS: Now there are a couple more 18 things.
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| 19 MR. BERGMAN: We generally don't reference Reg 20 Guides and rule language itself, so we may prefer to 21 actually have specific criteria here. That is an issue that i
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| 22 again needs to be worked out. l 23 DR. APOSTOLAKIS: Now the sensitivity analysis, on 24 page 34, ''The sensitivity of the componcat risk ranking to l 25 uncertainties in the parameter data ''.wuos should be O ANN RILEY & ASSOCIATES, LTD.
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| 167 1 evaluated. SSC categorization should not be overly affected
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| ( 2 by data uncertainties."
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| 3 I don't know what that means and I misspoke 4 earlier. It is Figure 4, not 7, in the paper by Cheok, 5 Parry and Sherry.
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| 6 -
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| There is one correct way for doing, for finding 7 the importance measures and you guys are addressing that in 8 this section, and you have a nice picture here -- it is 9 Section 7.1 -- Treatment of Uncertainties -- and that is to 10 cake the average value of the measure.
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| 11 MR. CHEOK: Right.
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| 12- DR. APOSTOLAKIS: Not to take the ratio of the 13 average values. Now that doesn't make any difference as 14 long as the uncertainties are reasonable -- let's put it ,
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| f 15 -that way, the left part of your figure.
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| 16 Now if the uncertainties become huge, then the 17 approximate value you get by dividing the mean values is not 18 quite the same as the mean value of the overall thing, which 59 is'the correct way of doing it, so as far as I am concerned 20 this is the way to do it, and there is no need for extra 21 sensitivity.
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| 22 Because I can see people now saying, well, gee, 23 why don't I take the failure rates at the 95th percentile 24 level and redo the importance measures, and now I'm turning 25 the whole thing upside down, but that's not the idea.
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| 168 1 The idea is to treat the uncertainties correctly,
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| .( 2 and then again, we'know that these measures are just input 3 to the expert panel.
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| 4 It's not that we're relying on these things, but I 5- think some sort of reference to how to do it correctly and 6 changing the language _of this paragraph is required, because 7 the issue.of sensitivities -- I mean, from day one, when we 8 were talking about the draft, you know, 1061, which became 9 1.174 -- there were words there, again, that made me 10 uncomfortable, because people can play sensitivity games and 11 show you, you know, strange results, because we know that 12 the failure rates have distributions, right?
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| 13 If I take all of them at the 95th percentile 14 level, I will get a different categorization.
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| () 15 So, the idea of the importance measures is take 16 the ratio of the frequencies of the minimum cut-sets, for 17 ' example, and then average that ratio over all the epistemic 18 uncertainties.
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| 19 Now, most people don't do that. They take the i
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| 20 averages of the minimal cut-set frequencies and divide, I 21 right?
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| 22 MR. CHEOK: Right.
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| 23 DR. APOSTOLAKIS: And your figure 4 shows that 24 this is reasonable except perhaps when you have huge 25 uncertainties, and I think this is a great insight and you
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| 169 1 should take advantage of it, but don't ask people to do
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| () 2 3
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| sensitivities, you know, taking into account data uncertainties, because then you don't know what you're going l 4 to get, plus it's conceptually not quite right.
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| 5 So, these two pages really are loaded with stuff, 6 and I'm just offering these comments, okay? 3 I
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| 7 MR. CHEOK: Okay. I 8 Requirements of the PRA -- I guess we are saying ;
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| 9 that you do need a PRA, at least a level one, full-power 10 internal events PRA. You cannot just expert panel 11 everything.
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| g 12 We would like you to consider external risk, 13 external initiators, and low power and shutdown operating 14 conditions.
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| O)
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| ( 15 If you do not have PRAs for external events or low 16 power and shutdown operating conditions, you have to address 17 these initiators as part of the expert panel, and basically, 18 we have some guidance right now as to how the expert panel 19 can consider these, and in summary, what we are saying is 20 that the expert panel has to consider that, for each of 21 these operating conditions and for each initiating event, 22 you have to assure that there's enough success paths to 23 bring you to a safe shutdown state that is in HSSC category.
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| 24 So, you're basically doing a qualitative PRA using
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| \
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| 25 insights from your internal events analysis. J 1
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| 170 1- ~PRA quality -- right now, what we say is that your i
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| ) 2 PRA has to conform to some consensus PRA standards, and I 3 guess we mean the ASME standards right now being written, 4 and where you do not conform to these standards, we would 5 ~like the-licensee to document why they don't conform to 6 these standards and why this non-conformance does not affect
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| '7' the results of the categorization and the risk determination 8 process.
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| 9 DR. APOSTOLAKIS: Now, you are assuming here that 10 this standard will be blessed by the NRC. Is thac correct?
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| 11 MR. CHEOK We have a member -- Mary Drouin here 12 is a member of the standards committee, and I guess 13 eventually it will be blessed or we will come up with 14 something that -- I'll let Mary address this.
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| () 15 MS. DROVIN: Well, George, we'll either end up 16 addressing it in toto -- if we do, that's because everything 17 in there is -- we like it and it meets our needs. Of 18 course, if the standard that is produced by ASME and phase 19 two by ANS -- if it doesn't meet our needs, then we would, j 20 you know, somehow supplement it and we would endorse it with 21 exception or addition. l 22 DR. APOSTOLAKIS: Well, that's not what it says j 23 right now, but that's okay. That's a detail.
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| 24 MR. CHEOK- The next thing is PRA updates.
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| 25 When the PRA is used for this process, we will 1 ANN RILEY & ASSOCIATES, LTD.
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| 171 1 require that this PRA be updated on a frequency similar to i t
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| I")
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| V.
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| 2 what we're doing to the FSAR nowadays. l 3 These updates become mandatory when plant changes 4 or when new information comes and invalidates the input that 5 was used to justify moving SSCs to the LSSC category to 6 begin with.
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| 7 DR. APOSTOLAKIS: Now, what exactly do you mean by 8 PRA update? This is a concept of a living PRA?
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| 9 MR. CHEOK: Living in the sense that we are 10 updating the PRA with operating data, not one that's -- not 11 a risk monitor-type living but one that's been updated to i
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| 12 reflect plant changes. 1 13 DR. APOSTOLAKIS: And the data?
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| i 14 MR. CHEOK: And data.
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| () 15 DR. APOSTOLAKIS: So, in essence, then, 16 indirectly, you are telling them that they have to do it in 17 a Bayesian way with full uncertainty analysis, because I 18 don't see how you can do it if you have a point estimate.
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| 19 Right? Most of the IPs, I understand, are point estimate, 20 aren't they?
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| 21 MR. CHEOK: Most of the IPs are point estimates, 22 yeah.
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| 23 MS. DROVIN: No , they aren't.
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| I 24 DR. APOSTOLAKIS: They aren't? I 25 MS. DROVIN: Most of them did mean -- they just O ANN RILEY & ASSOCIATES, LTD.
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| 172 1 did not report.the values in terms of -- when they gave 2 their.CDF, it was a mean value.
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| ([ ) They propagated the data 3 uncertainty through the_ calculation.
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| 4 DR. A90STOLAKIS: They did propagate the 5 . uncertainty?
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| 6 MS. DROVIN: Yes, most of them did.
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| 7 DR. APOSTOLAKIS: Okay. So, it will be easy for 8 them to do it.
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| 9 MS. DROVIN: What they didn't do was the modeling 10 uncertainties.
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| 11 DR, APOSTOLAKIS: Yeah. But if they did that, 12 then it's great, because it's easy to go back and update and 13 propagate again.
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| 14 MS. DROVIN: I wouldn't say every single one, but
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| ) 15 I would say the majority of them did do -- did propagate the 16 data uncertainties.
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| 17 DR. APOSTOLAKIS: Because my impression was that 18 it was mostly point estimate.
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| 19 MR. CHEOK: Point estimates was the one that was 20 mostly reported, but I think the problem that George is --
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| 21 most people actually did do the propagation of the 22 uncertainties. The problem is I think the fidelity of the 23 . data gathering to get the distribution to begin with has not 24 been looked at very closely.
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| 25 MS. DROVIN: And I would add that's the major ANN RILEY & ASSOCIATES, LTD.
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| 173 1 point here, is what Mike has brought up, is where the real 2 concern is.
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| 3 DR. APOSTOLAKIS: So, if we go to the no prior 4 approval business again, it seems that there are a lot of 5 subjective judgements that go into the whole process, even ;
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| 6 if one follows the process to the letter, that making a 7 blanket statement that, as long as you follow the process, 8 everything is okay, is probably not appropriate.
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| 9 MR. CHEOK: I think the no prior approval thing is 10 one of the issues that you need to bring up with the public 11 and with the management and with the Commission.
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| 12 DR. APOSTOLAKIS: On the other hand, you know, to 13 say that you will review all these massive changes is 14 probably unrealistic, too, because you know, it will take 15 you forever.
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| 16 MR. CHEOK: Right.
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| 17 DR. APOSTOLAKIS: And I don't know what the best 18 way would be. I remember vaguely sometime we discussed the 19 possibility of -- or not the possibility, actually the 20 requirement that the PRA be reviewed by an independent )
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| 21 panel.
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| 22 MR. CHEOK: That's one of the requirements of the 23 ASME standards.
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| 24 DR. APOSTOLAKIS: Okay. And you will have access 25 to the findings of that panel.
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| 174 1 MR. CHEOK: It will be available for the staff to
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| _2 look at.
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| 3 So, the PRAs can be used as one input to the 4 expert panel. I think Appendix T lists a list of 5 considerations or guidelines that the expert panel has to 6 consider on top of what PRA gives them.
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| 7 EspecirJ1y when you take into account the 8 cornerstones of the OSI program, the PRA would give you CDF l 1
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| 9 and LERF insights. We need to look at things like, if an (
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| 10 SSC is required for emergency preparedness, if the failure 11 of an SSC could affect the functionality of another high 12 important SSC, the special effects -- that's not well taken 13 care of, at least not well documented in the PRA, and also 14 things like exposure, occupational exposure, things like
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| () 15 that.
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| 16 So, we have a list of guidelines for the expert ,
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| 17 panel to look'at and_to rank SSCs either as high or low 18 according to this list.
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| 19 DR. APOSTOLAKIS: Is that a list on page 37?
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| 20 MR. CHEOK: My copy does not compare directly with 21 yours. Yes, it is. That's the list.
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| l 22 DR. APOSTOLAKIS: I have a couple of comments.
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| 23' MR. CHEOK: All right.
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| o '24 DR. APOSTOLAKIS: It says, in determining the 25 importance of SSCs for each of these functions, the O ANN RILEY & ASSOCIATES, LTD.
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| rn 175 1 following factors should be considered: (1) safety function
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| () 2 3
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| being satisfied by SSC operation; (2) level of redundancy existing at the plant to fulfill the SSC's function. Why?
| |
| 4 I mean all that is in the importance measure.
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| 5 MR. CHEOK: It's also in the PRA, also.
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| 6 DR. APOSTOLAKIS: Well, the importance measure 7 comes from the PRA, but the degree of redundancy, the level 8 of redundancy is in the PRA, and it is reflected on the 9 importance measures.
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| 10 .MR. CHEOK: This list is for all SSCs, and I think 11 if you can see that an SSC is modeled well in the PRA, I can t i
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| 12 -now actually go through a lot of these items and say that lA U'' ' '
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| 13 it's either important or not important according to what my 14 PRA tells me.
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| A
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| (,,) 15 On the other hand, there are SSCs that are not 16 modeled.
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| 17 DR. APOSTOLAKIS: But maybe you should limit it, 18 then, to those, because it says requirements of the 19 qualitative assessments.
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| l 20 In other words, the expert panel now has received l 21 the input from the PRA, and now they're beginning their 22 deliberations, and what you are doing here, you are asking 23 them'to go back and look at things that are already built 24 into the importance measures, and I think -- and a lot of 25 those guys, I suspect, will have no idea what the importance O ANN RILEY & ASSOCIATES, LTD.
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| 176 1 measures really represent.
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| () 2 3
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| So, they will take it very seriously. Well, gee, look at the safety function and the level of redundancy, and 4 I think that it should be clearly stated here that the 5 importance measures represent this body of knowledge, okay, 6 so the redundancy is there.
| |
| 7 Now you have to look at things that are not --
| |
| 8 either are not there or are not treated well.
| |
| 9 Like in item six, emergency operating procedure 10 instructions and so on -- that's typically not in the PRA.
| |
| 11 So, I would rather have them look at that, in combination 12 with the importance measures.
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| 13- Then we go to the next one, and it says for SSCs 14 not modeled in the PRA. Nell, again, don't we have to 15 understand why they are not modeled? I mean they are not 16 modeled for some reason, 17 Either they were irrelevant to the scope of the 18 PRA, which then the expert panel should be informed of --
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| 19 surely you don't mean oversights, I mean mistakes.
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| 20 MR. CHEOK: No. In this sense, I also mean those 21 things that are implicitly taken into account in the PRA. ,
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| j 22 In other words, we assume that this one component works -- !
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| 1 23 we assume that room cooling, for example, works for pump I
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| 24 operation to be successful.
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| 25 DR. APOSTOLAKIS: So, you are really addressing l
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| 177 1 the issue of the basic assumptions of the PRA, and I think
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| () 2 you should state it in that way, and this is where our 3 earlier comment regarding the different configurations comes 4 into the picture, because some of those systems that may 5 become significant under certain configurations may be 6 treated very cavalierly when the plant is at power.
| |
| 7 My colleague, Mr. Barton, is nodding, so I guess 8 'that's true.
| |
| 9 So, this is the kind of thing that I would expect 10 to see here, because this business of SSCs not modeled in 11 the PRA use too much, and unless you really know what the 12 PRA does, that may be a misleading statement, to say, oh, 13 gee, the PRA picks up transients, you know, or they didn't 14 model this or let's do something about it. No, there must
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| () 15 be a reason why it was not modeled.
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| 16 MR. CHEOK: .Okay. I will clarify that list --
| |
| 17 those two lists.
| |
| 18 The last two things I'm going to talk about, real 19 quickly,.is that we do require performance monitoring and 20 corrective action.
| |
| 21 Again, we'll try to focus the monitoring onto the 22 HSSCs, because those are the components that actually --
| |
| l 23 again, since this is all relative, those are the components 24 'that make it so that, you know, you have LSSCs that are less ;
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| 25 important.
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| l
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| 178 1 The last thing I-want to talk about is the
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| [ 2 Appendix T. That lists the requirements of an expert panel 3 in terms of procedures needed, the training needed, the 4 expertise, membership, and the decision criteria.
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| 5 That's all I have.
| |
| 6 JR. APOSTOLAKIS: This no prior approval -- 50.59 7 is part of this, right?
| |
| 8 MR. BERGMAN: To a limited extent. We're actually 9 proposing at this time that we would not change the scope of 10 50.59 per se but, rather, the change in special treatment 11 would not be subject to 50.59, but you could not change the 12 functional capabilities of the SSC without going through 13 50.59.
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| 14 So, it's different from the other rules in this (O j 15 effort in that respect.
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| 16 DR. APOSTOLAKIS: Okay, I'll have to think about 17 that.
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| 18 MR. NEWBERRY: You were getting at the point with 19 respect to prior review and approval, weren't you?
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| 20 DR APOSTOLAKIS: Yeah. I'm trying to see whether 21 our actions are consistent, self-consistent. We may have I 22 minimal, let's say, not prior, but minimal prior approval l 23 for these kinds of things, but then if someone wants to make 24 a small change and claims it's under 50.59, we may say no. l 25- So, is it overkill, really, in the 50.59 area and j i
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| 179 1 here we're too liberal? I don't know. I have to think 2 about that.
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| (
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| 3 MR. BERGMAN: Well, I think, in terms of reduction 4 of treatment, we're being very consistent in this whole
| |
| .5 effort.
| |
| 6 DR. APOSTOLAKIS: But it's the cross-consistency.
| |
| 7 MR. BERGMAN: Right. The fact that they're, 8 quote, "out of scope" of these treatment rules doesn't take 9 them out of scope of the regulations.
| |
| 10 DR. APOSTOLAKIS: Okay.
| |
| 11 MR. REED: Right now we view that, if you comply 12 with this 50.69 and Appendix T, that that's essentially 13 redundant to 50.59 for the special treatment.
| |
| 14 DR. APOSTOLAKIS: So, this has already changed.
| |
| j ) 15 MR. BERGMAN: It is a living document, yes.
| |
| 16 The last slide is the issues, most of which we've 17 already discussed.
| |
| 18 Selective implementation was addressed in 9300, 19 and there's two aspects to selective implementation. One is 20 do you need to do every rule in the effort or can you just 21 do subsets of them, and our approach is implying that, in 22 fact, yes, you can do subsets of the rules.
| |
| 23 There may be constraints on -- you need to do 24 enough such that we don't have to issue any exemptions, but 25 you may not have to do every single rule in there.
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| pc 180 1 The other one is do you need to categorize every
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| () 2 3
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| SSC in the plant or can you do only a portion of the plant, and we're undecided on that yet.
| |
| 4 The effect on other regulations -- I mean 98-300
| |
| .5 said Part 50. We have, in fact, found that these changes 6 will affect rules outside of Part 50. We have identified j 7 some parts where it's clear we're going to need to consider 8 that impact, and there is sort of an iterative effort in 9 there.
| |
| 10 As we more clearly define the change to each rule, 11 we may identify others.
| |
| 12 Staff review requirement -- we've already 13 discussed how much will we need to do.
| |
| 14 The South Texas exemption may give us some A( ,) 15- insights on what it's going to take for the staff to agree 16 to this.
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| )
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| 17 And the last was actually talked about in the box.
| |
| 18 The box slide is the identification and control of the 19 treatment attributes for Regions I, II, and III.
| |
| 20 DR. APOSTOLAKIS: Very good.
| |
| 21 So, risk information here means essentially 22 importance measures, right, Mike?
| |
| 23 So, I think a good discussion of importance 24 measures would be appropriate here.
| |
| 25 Anything else that anybody -- I'm sorry. Scott?
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| ' 1 l
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| 181 l
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| )
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| 1 MR. NEWBERRY: I was just going to tell you -- I I
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| /\ 2 mean, as late as yesterday, Gary and his staff are
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| : v. ..
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| 3 struggling with Appendix T. I think that's fair to tell the 4 committee, and changes are being made. 3 l
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| 5 I mean they're weighing these issues, you know, )
| |
| 6 To minimize staff review, that means a real detailed 7 appendix, perhaps unlike anything we have ever seen, or do 8 you want to go into the regulatory guideline? And so, we're 9 struggling with that.
| |
| 10 The comments today shed light on it for us, and I 11 think we're going to need a lot of comment, and we'll have 12 more discussions with the committee on Appendix T.
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| 13 DR. APOSTOLAKIS: Good.
| |
| 14 DR. SHACK: This last bullet is one that puzzles n
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| kj 15 me. Does that somehow mean you're going to have to rewrite 16 every one of these rules?
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| 17 MR. BERGMAN: No.
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| 18 MR. REED: Good question.
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| 19 MR. BERGMAN: Yeah, it is a very good question.
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| 20 We're hoping we can -- yeah, put up the boxes chart again - ;
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| 21 - that it can be a relatively simple statement.
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| 22 For example, in Region II, the current non-safety-23 related but high safety-significant SSCs -- they need to 24 apply the treatment rules to the extent that they are 25 addressing those. attributes that make them safety h
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| 182 1 significant and only those attributes in terms of additional
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| -2 assurance.
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| 3 We don't want to rewrite 20 rules in 50.69, and as 4 we go in, we've got to balance how much of that occurs, and 5 at some point, it may be smarter to create separate rules.
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| 6 DR. SHACK: Okay. So, it's this language that 7 you're going to use that tells you how much of the special I l
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| 8 treatment you're going to have to give to this component, l 9 then.
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| 10 MR. BERGMAN: Right. l l
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| 11 DR. SHACK: That's going to be fun.
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| 12 MR. REED: Well, yeah. In box 2, I don't like to 13 use the words "special treatment," but I like to think of it 14 in terms of maintaining the assumptions in the PRA, for 15 whatever it is, you know, availability and reliability 16 -assumptions in there.
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| 17- What do you have to do to maintain and make sure 18 that those assumptions are valid? Remember, these things 19 are coming in -- they're outside the design basis. You're 20 going to see them because they're in the PRA.
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| 21 You're going to say, okay, I knew I had this risk 22 stuff over here, now I'm defining it a lot better, I know 23 ' where it's coming from, and basically, I'm saying, for this 24 stuff, I want to make sure the assumptions remain valid, and 25 I've got to do something to maintain that. That's how I i
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| i 183 1 view that.
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| 2 MR. NEWBERRY: The issue applies to all three
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| (
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| 3 boxes that would be in the scope of 50.69.
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| 4 DR. SHACK: That last bullet's a killer.
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| 5 MR. NEWBERRY: We'll look for significant issues 6 in Appendix T and the issue you just brought up, Bill.
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| 7 They're both significant.
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| 8 DR. APOSTOLAKIS: It was a mistake to put it back 9 up.
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| 10 MR. NEWBERRY: I knew it.
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| 11 MR. REED: Just one of many, I think.
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| 12 DR. APOSTOLAKIS: I don't recall, from reading 13 this document, what you plan to do to the special treatment 14 components depending on the box they are in. Did you tell
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| () 15 us that and I missed it?
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| 16 MR. BERGMAN: That was a late development in the 17 paper that occurred since we sent it to you.
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| 18 DR. APOSTOLAKIS: But you did not address it in 19 your presentation either.
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| 20 MR. BERGMAN: Only to the extent it was in that 21 issue four, but it wasn't in detail. Since then, we've 22 developed the concept much further.
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| 23 MR. NEWBERRY: At this point, we do not have 24 language to give you that would be meaningful.
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| 25 DR. APOSTOLAKIS: I just wanted to make sure that ANN RILEY & ASSOCIATES, LTD.
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| 184 1 you did not address it today. So, I didn't miss it.
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| () 2 3
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| MR. NEWBERRY:
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| MR. REED:
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| No, we did not.
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| No, you didn't miss it.
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| 4 DR. APOSTOLAKIS: So, what's left, then, for us to i
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| 5 understand at some' future time, I guess, is what you're ]
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| J 6 going to do with the boxes.
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| 7 MR. NEWBERRY: Yes.
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| )
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| 1 8 MR. REED: Yeah.
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| 9 DR. APOSTOLAKIS: Any other questions from the !
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| i 10 members? Any comments from the public on this presentation?
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| Il (No response.)
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| 12 DR. APOSTOLAKIS: Well, thank you very much, j 13 gentlemen. This was very informative. And when are we 14 going to see you again? At the full committee. Shall we
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| () 15 decide what they're going to talk about? How much time do 1
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| 16 they have next week.
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| 17 MR. MARKLEY: And hour-and-a-half.
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| 18 DR. APOSTOLAKIS: I guess you have to shorten what 19 you presented today.
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| 20 I think perhaps some of the issues related to 21 schedule you can play down and maybe spend more time on the 22 quantitative input. Again, I'm not asking you to have j i
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| 23 answers but just say, you know, this is what we plan to do. ,
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| l 24 MR. NEWBERRY: Do you want us to bring our box? I 25 DR. APOSTOLAKIS: The boxes, yeah. Address the O ANN RILEY & ASSOCIATES, LTD.
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| c-185 1 issue of what to do with box 2, and maybe if you have some
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| () 2- preliminary thoughts as to how you plan to change pages 33
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| : 3. and 34 to address some of the issues we raised today. As 4 far as I'm concerned, you can copy whole sections from your 5 paper, Mike, and put them in the rule.
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| 6 Now, I know that somebody will object to that, but.
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| 7 that's the kind of stuff that the expert panel should know.
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| 8 Maybe you can develop videotapes and audiotapes.
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| 9 And that's it. I don't have any other comments.
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| 10 MR. NEWBERRY: Thank you for your comments today.
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| 11 DR. APCSTOLAKIS: Now, the next presentation is.by 12 NEI, but we will take a break first. Be back in 10 minutes.
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| 13 [ Recess.]
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| 14 DR. APOSTOLAKIS: Okay. We are back in session.
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| () 15 Now we will hear about the industry activities to 16 support Part 50 reform.
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| 17 Please identify yourselves.
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| 18 MR. BRADLEY: We have Adrian Heymer from NEI. I'm 19 Biff Bradley from NEI. We also have Parviz Moieni from 20 Southern Cal Edison San Onofre Station, which is one of our 21 pilot plants, here today.
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| 22 I'd like to start out by saying I appreciate the 23 opportunity. We did hear a lot of information from the 24 staff this morning that we hadn't had the privilege to hear 25- before. So, a lot of the reaction we can give today doesn't )
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| l I
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| 186 1 really involve a lot of input from the rest of the industry.
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| () 2 3
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| We can give you our reaction on -- you know, our
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| -personal reactions on some of the things we heard, 4 particularly Appendix T, which I heard people quoting from 5 ages 35 and 37 and such. We haven't seen it. We have no 6 clue what's in there.
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| 7 " gDR. APOSTOLAKIS: So, our meetings do serve some 8 purpose.
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| 9 MR. BRADLEY: Right. Clearly, you know, given 10 that Appendix T is going to delineate the staff's 11 expectations for the essential elements of this process, 12 it's extremely important that we have an opportunity to look 13- at that, given'that we're charged with writing a guideline 14 to implement that, so to speak. So, we are coming at this
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| -t O) s, 15 with a different -- a knowledge base that you guys have that 16 we don't.
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| 17 MR. BERGMAN: I'd just like to remind people that 18 we are holding a meeting on the 13th of October to go over 19 these documents, and we do anticipate releasing them in 20 advance of the meeting to facilitate discussions.
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| 21 The other thing I'd just like to say by way of 22 introduction is, one, we recognize this is very conceptual 23 at.this point, and it's early on, appreciate a lot of the 24 thought the staff's put into it.
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| 25 I think, in general, our thinking is along the ANN RILEY & ASSOCIATES, LTD.
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| 187 1 same lines as the staff. There are a few areas of deltas
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| () 2 3
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| that we'll talk about here today.
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| The other thing is I'd like to acknowledge this is 4 a complex task, and we've spent the better part of probably 5 six months now with a lot of industry meetings at both the 6 executive level and the working level, PRA people and plant 7 people, trying to come to grips with how this would be done, 8 and it is by no means simple.
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| 9 There are a lot of complicating factors. Some of 10 the big ones are~the optional nature of the change and also 11 the fact that option two is proceeding ahead of option 12 three. So, you have a problem where you're trying to 13 establish a regulatory scope, but all the existing technical 14 requirements are still in place for some interim period of
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| () 15 time.
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| 16 You know, clearly, in a perfect world, it would be 17 better if we could do all this at the same time, but that's 18 one of the complicating elements that we have to deal with.
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| 19 Our objective -- I don't think this is much 20 different, maybe stated slightly differently, but it's 21 pretty much the same objective that the staff presented.
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| 22 It.is important, I think, from an industry 23 standpoint that we retain the voluntary and selective nature 24 of the implementation. We have to recognize that, even 25 under the existing licensing basis, there's a tremendous
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| 188 e
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| 1 various in the way the licensing basis is applied at the 2 fleet of plants. <
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| /)
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| 3 Because of that, there is a large spectrum of 4 desires on the part of the plants and the companies with 5 regard to how they might want to use this.
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| 6 Clearly, there will be variability of results-7 after you apply this, but we have to bear in mind, there is 8 already variability in the licensing bases, and so, we do 9 need to preserve as much flexibility as possible through a 10 voluntary and selective approach in order to keep a large 11 industry interest in this activity.
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| 12 DR. APOSTOLAKIS: I really wonder how voluntary 13 it's going to be in the long run.
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| 14 I mean you know that the staff is requesting
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| () 15 authorization to risk information when the licensee is not 16 using risk information.
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| 17 So, this idea of a two-tier system -- I'm not sure 18 that will be there for a long time, but at the beginning, at 19 least, it has to be voluntary, unless the licensee chooses 20 not to interact with the NRC anymore.
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| 21 MR. BRADLEY: We have looked at the issue relative 22 to NRC's proposed policy to be able to request risk 23 information for licensee submittals. I think the difference 24 there is those are voluntary changes to your licensing 25 basis.
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| 189 1 Here we're talking about your existing licensing
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| ( 2 basis, and I think the concept of mandatory changes to that 3 is a fairly significant issue with regard to the whole 4 underpinnings of the regulation. I mean we certainly view 5 this as voluntary.
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| 6 I just wanted to mention there are what we view as 7 five elements of the whole regulatory reform effort, and one 8 that didn't really get mentioned this morning but it is 9 important is the oversight process is being fundamentally 10 revised, and that's well along.
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| 11 It's going to be implemented by next year, and 12 it's a real driver for the additional regulatory reform 13 activities we're talking about today, because essentially 14 you're going to have an oversight process that is risk-() 15 informed, and it's going to be out of kilter with the 16 regulatory underpinnings, both the assessment and inspection 17- process, those things. It is important.
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| 18 That's a real driver for regulatory reform from 19 the industry's perspective, is to make sure that we can 20 modify the regulations so that the oversight process is 21 consistent.
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| 22 That's been able to proceed more rapidly. It 23 doesn't require rule-making, and the pace of change there 24 has been pretty profound.
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| 25 I'd also like to mention we have existing O ANN RILEY & ASSOCIATES, LTD.
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| u ..
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| a 190 1 applications going on. We're all aware of those. You guys
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| () 2 3
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| have discussed those in many meetings in the past.
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| We don't want to lose the pace of reform we have i
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| 4 on those, in the areas of tech specs, ISI, IST. QA, of i i
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| 5 course, we know about the difficulties in implementing that. I I
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| 6 We're talking about option two and option three 7 today. There are also some administrative and process 8 requirements, things such as reporting requirements that may 9 need to be cleared up, ultimately, to achieve uniformity of 10 this.
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| 11 What are the industry's activities? We heard a 12 lot about what the staff was doing.
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| 13 One of our major activities that we have underway 14 is to produce the guideline for categorization and
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| () 15 treatment. I guess we heard a lot today that was new to me 16 with regard to how the staff was proceeding in this manner, 17 with regard to 50.69 and Appendix T.
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| 18 I guess, as I understand it, 50.69 would discuss 19 treatment and Appendix T would discuss the categorization or 20 how you use risk information to develop the scope.
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| l 21 Our view up to now has been that our guideline 22 would address both those areas, and I think what we're 23 looking for is to be able to realize NRC's goal of being 24 able to implement these changes without substantial advance i
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| 25 review and approval following the pilot programs, and we l O ANN RILEY & ASSOCIATES, LTD.
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| i 191 1 view that the guideline would have to be at a level that
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| () 2 3
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| would enable that, and our view is that the staff would approve that and that, by usirg the approved process, 4 licensees should be able to implement these changes 1 5 following the pilot programs without advance review.
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| 6 Again, you know, it's important to us to see, 1 7 October 13th, to be able to see what the staff has 8 developed. That's critical to use being able to produce a 9 guideline. 1 10 Our schedule right now is to have that before the 11 staff in draft by the end of this year. There's quite a bit 12 of work that remains to be done.
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| 13 We do have four pilot plants. These represent the 14 four reactor vendors -- South Texas, San Onofre, ANO-1, and
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| (
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| (~)% 15 Fermi.
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| 16 I would like to mention South Texas. As you know, 17 they've already docketed exemption requests to try to 18 achieve their goal of implementing their graded QA program.
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| 19 We view South Texas as not so much an industry 20 pilot, as more of a test case for the feasibility of being l
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| 21 able to make these changes.
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| 22 The methods they are using are their own. They 23 may ultimately be consistent with what the industry as a 24 whole decides to use, but'they've basically chosen to 25 proceed ahead of the pack, and the remaining pilots will be ANN RILEY & ASSOCIATES, LTD.
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| 192 1 using the industry guideline and will be trying to do this 2
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| (( ) in a manner that would reflect a wider industry --
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| 3 DR. APOSTOLAKIS: Are they using any methods that 4 we are not aware of? I thought they were relying also on 5 importance measures.
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| 6 MR. BRADLEY: I think that remains to be seen. In j 7 writing the guideline -- I mean I recognize that the 8 applications that have been done -- QA, IST, and the 9 maintenance rule -- have all used importance measures.
| |
| 10 We spent a lot of time in the last year on 11 revising A-4 of the maintenance rule for the configuration 12 assessment, and fairly early on, we recognized that you 13 couldn't use the existing maintenance rule risk ranking, l 14 risk categorization as a means to develop the scope for the 15 A-4 assessment because of the problems with the single 16 component at a time nature of the importance measures.
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| 17 In writing the guideline, that, I think, is still 18 an open question with regard to whether it will be purely 19 based on importance measures.
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| 20 We are looking more at a delta-CDF kind of 21 concept, similar to 1.174.
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| 22 A lot of the discussions this morning are j 1
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| 23 pertinent to the issues we're looking at, you know. How do l l
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| 24 you take -- how do you capture into the delta-CDF the effect 25 of taking things out of regulatory scope and putting them
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| L l>
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| 193 into commercial scope, and you know, those are the key 1
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| 2 issues that we're aiming at, but as I'll talk about later, f~')i s_ l j
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| 3 basically our approach is very similar to a 1.174 type '
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| 4 approach, looking at the delt2-CDF. )
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| 5 I don't view where we're going to end up as just 6 doing -- using importance' measures as a risk categorization.
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| 7 I tnink it will require more than that, ultimately.
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| i 8 I know the pilots -- some of these pilots have 9 substantial investments already in doing that -- for 10 instance, San Onofre with IST -- and this is all still 11 preliminary work in progress, 12 So, I mean they may have different views and more 13 hope that they can use those at least -- I'm sure as part of 14 the process, but I don't view it as purely using risk
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| () 15 importance measures to categorize the scope. I think it 16 . will involve more than that.
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| 17 DR. APOSTOLAKIS: You mean more than just the 11 8 expert panel, because the staff is proposing to use more 19 than that. I mean the expert panel is supposed to bring 20 those extra considerations, I guess.
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| 21 MR. BRADLEY: I'll talk a little bit more about 22 this as we go through here. i l
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| 23 DR. APOSTOLAKIS: Okay. l 24 MR. BRADLEY: The activities of the pilot plants -
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| 25 - there's two areas. One is to actually implement the i i
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| l 194 1 process.
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| ] 2 The way the schedule is laid out, we will put the 3 guideline in front of the NRC staff, and after several 4 months they've had to look at it, the pilot' plants would 5 begin their initial implementation of the guideline, and 6 that would go on over a period of about a year, I believe.
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| 7 Ultimately, the pilots, in 2001, would go forward )
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| 8 with the exemption requests.
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| 9 There's been a lot of discussion about the scope 10 of the exemption requests. There's a fairly broad scope of 11 rules that's on the table here. There have been questions 12 in the meetings we've had about whether we need pilots for 13 all the regulations that are on the table.
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| 14 I think, from our standpoint, that's an )
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| l ) 15 impractical, given the large number of regulations and the 16 finite capabilities of the pilots to do this work on 17 schedule.
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| 18 In our discussion with the pilots, I think the 19 three regulations we hear most -- the most interest in in 20 terms of piloting-the process are the maintenance rule, 21 Appendix B, and EQ. Those are what generally are viewed as 22 very good tests of the applicability of this, and I guess 23 we'll-have further discussions on this whole issue, but I do 24 view it as a difficult undertaking if it's expected that the 25 pilots would pilot the entire set of regulations that are on
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| y 195 i
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| 1 the table.
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| [)
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| ^ %.)
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| 2 Another issue is the industry response to the 3 advance notice of proposed rule-making.
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| 4' Previously we had been working on a petition for 5 . rule-making.
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| 6 After further dialogue with the staff and 7 recognition that the schedule they laid out is aggressive or 8 more so than we could have achieved through petitioning, 9 we've reconsidered that, and I know believe that, rather 10 than. petitioning for rule-making, we will proceed along the 11 plan that the staff has laid out.
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| 12 However, we had already developed the petition, 13 the guts of it, and our intent would be to use a lot of that 14 material in responding to the ANPR.
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| 15 This is just a slightly different way of saying, I 16 think, what the staff already said about Appendix T, but we 17 view our guideline, as I mentioned, as the vehicle for
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| '18 implementation, again with the intent of having a level of 19 detail that would provide that without the need for NRC 20 advance review, that would be used for both the pilot 21 . exemptions and then ultimately as -- I guess we would view 22 as some type of reference material in the rule, similar to 23 the way, I guess, the regulatory guide for the maintenance 24 . rule references NUMARC 93-01'as an example.
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| 25 I guess I would view that, ultimately, the rule
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| 196 1 and the implementation guidance would reference our j ) 2 . guideline as a means to meet the rule.
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| 3 The major elements of our guideline, as we 4 envision it now, would be as you see here -- existing 5 licensing basis considerations, the risk-informed evaluation 6 process,.and then the issues of treatment.
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| 7 Let's talk about these one at a time.
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| 8 This is a very, very simplified process chart for 9 the guideline. Again, there are more elements. This isn't 10 really a flow chart but just a summary of the major elements II of the guideline, and I think it's fairly self-evident how 12 this proceeds.
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| 13 It's not out of kilter with what the staff laid 14 out, but basically, you do start with the entire population
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| () 15 of SSCs in the plant, and the two issues that have to be 16 considered are the existing licensing basis -- why is an SSC 17 designated as being in the regulatory scope today, what put 18 it there, and there need to be some grounds on what you have 19 to look at in that regard, and then the risk importance 20 evaluation and then the integrated scoping decision based on 21 the results of those two evaluations, and the output of that 22 being three categories.
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| 23 Now, what you see here are different categories in 24 what the staff laid out, and I'm going to talk about our 25 view of those categories, and I think it is fundamentally a O ANN RILEY & ASSOCIATES, LTD.
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| 197 1 little different than what the staff just presented with
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| ); 2 their two-by-two matrix, so I'll talk about each of those as 3 we go along here.
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| 4 The scope of the evaluation would be essentially 5 all ' he SSCs in .the plant. Clearly, there would have to be 6 some rules on what the boundary of the plant is, and when I 7 you get into risk space, you start taking credit for things l 8 that may not be in the plant boundary -- reliability of the 9 grid or the city water system or the, you know, combustion 10 turbine down the street or what have you, and there will 11 have to be some rules on that, but. generally what we' re 12 talkingaboubisthingswithintheboundaryoftheplant.
| |
| 13 It's similar to the scoping for the maintenance rule.
| |
| 14 We talked about some of the categories. There's i 15 probably others -- safety-related, important to safety, non-16 safety-related. All the components in the plant would 17 essentially be looked at. j 18 Now, clearly, there are going to be some systems 19 that can be screened out. Our method would be a multi-20 tiered system where we'd be able to do some type of 21 screening evaluation on a system basis before we got into a 22 component-by-component evaluation.
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| 23 It can actually work both ways. You may have some 24 systems that you know aren't going to be important based on 25 the screening rules.
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| 198 1 You could also have systems that you know are
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| () 2 3
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| important and that are. going to be in the regulated scope, and maybe you don't need to go through.a bunch of risk 4 insights to get to that conclusion, so you may be able to 5 bypasr that step.
| |
| 6 Those are just some of the things we've talked 7 about eidt the pilot plants.
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| 8 Ultimately, the pilot plants will be looking at 9 selected systems. I think our intent there would be to get 10 a broad' range of systems, some of which may bring components 11 into the regulated scope, some of which take components out 12 of the regulated scope.
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| 13 I don't know if it's really feasible for the
| |
| , LG" 14 ' pilots to look at all the SSCs in the plant on the schedule
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| () 15 that's been laid out. That's something we still have to 16 discuss and agree to with the pilots.
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| 17 Before I tal'k about this current licensing basis, 18 I did want to mention -- I guess, based on what I heard this 19 morning, I would say there is possibly an area of 201 difference.
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| 21 The matrix the staff proposed for how theca things 22 would be categorized basically said that all -- everything 23 that's now safety-related would be retained as safety-24 related and that you would have two categories, safety-25 related and high safety significant, safety-related low
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| 199 1 safety significant, and then that you would have non-safety-D
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| [d 2 3
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| related high safety significant and non-safety-related low safety significant.
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| 4 Again, we were looking at that for the first time.
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| 5 I think that's fundamentally different from our view or 6 intent of how this would work.
| |
| 7 Our view is that you should be able to remove some 8 of the currently safety-related components from that 9 category, from the regulated scope. I think that's a 10 significant point of desirability for the plants in being 1 11 able to proceed with this.
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| 12 As you know now, there's currently a substantial 13 variation in the number of SSCs that are on the Q list for i 14 the various plants, orders of magnitude variation, and these pIj 15 plants all meet the existing licensing basis.
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| (
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| 16 To say that a plant that has 100,000 items on 17 their Q list is going to have to keep all those as safety-18 related -- I think that isn't the way we've envisioned this 19 up to now, until the time we saw that two-by-two box.
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| 20 I think our view as that you should be able to go 21 in and apply these methods and that, even for things where ,
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| 22 you haven't been able to change the option three regulation, 23 you should be able to show that a lot of your SSCs that are 24 currently on the Q list don't need to be maintained as 25 safety-related, and I think the concern is one way to view 1
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| l 200 l
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| 1 what the staff laid out is there is no way to take things 2 out of scope but there are things being put into scope. It 3 looks like a one-way gate, the way that was proposed, and 4 maybe I'm reading it wrong.
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| 5 DR..APOSTOLAKIS: That's not the way I understood 6 it.
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| 7 I think what the staff told us was that it would 8 create confusion, plus there may be other legal issues, 9 changing the terminology from safety-related to safety 10 significant. So, they ke p that terminology and they add 11 this extra thing of signtfbc~ance,' but the net result of all 12 this, which they didn't discus's'today, may be the same as 13 yours. .
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| 14 In other words,4 you''may still be in the safety-15 related category but afet so there is
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| +-
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| .g,. psignificant,
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| ,y 16 relaxation in the speci'a1.ggeatment.
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| e s i, ; - * ,
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| 17 So, ultimately, '' pr.od'u ct may be the same, in
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| . $Q , . . )
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| 18 other words. .Q.7) - , j 19 DR. BONACA:
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| Isn'.t''Ebat
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| . j,e. .. what the South Texas 20 project is doing? dh; '
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| )
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| ?
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| 21 MR. BRADLEY: I can't' speak to the details of
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| '22 their exemption request. I guess it wadn't my understanding 23 that they were going to maintain as safety-related all the 24 SSCs that were -- thaq,they,took out.
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| 25 DR. BUNACA':". ,M9k; understanding was that they were C $(
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| 201 1 pulling them out.
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| 2 MR. BRADLEY: Right.
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| 3 DR. APOSTOLAKIS: So, the important thing is 4 whether you do with a matrix or whether you do with a 5 classification.
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| 6 MR. BRADLEY: These things are really more --
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| 7 DR. APOSTOLAKIS: If the result is the same, then 8 it doesn't matter.
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| 9 MR. BRADLEY: If, in fact, that's true, I think 10 these are more than -just semantics issues, though.
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| : 11. I think, you know, you talked about the confusion 12 aspect of this, but I think the industry would view the fact 13 that this doesn't provide you with the opportunity to take 14 things out of the safety-related category is a potential 15 concern.
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| 16 DR. KRESS: Are you considering the ones that 17 don't opt to go with the risk-informed regulation?
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| l 18 MR. BRADLEY: It's more the ones that do. l 19 DR. KRESS: More the ones that do. j 20 MR. BRADLEY: Right.
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| 21 DR. KRESS: My impression was that that would be 22 an end result.
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| 23 MR. BRADLEY: Our view has been -- I guess the 24 staff is saying you don't need a regulatory definition of l
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| 25 safety significant. I mean up to now our view has been you j
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| 202 ;
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| 1 I
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| would establish a regulatory definition of safety j rs (s_/ ) 2 significant and that you would be able to optionally apply 3 that definition and the set of safety significant SSCs in I 4 lieu of safety-related SSCs for a given regulation and that, 5 to the extent those overlap, fine, but those things that 6 were no longer safety significant wouldn't be within the 7 purview of that regulation or would be subject to commercial 8 treatment.
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| 9 Now what the staff is saying is no, those will all 10 still be safety-related. 1 l
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| 11 That's just an issue we'll have to discuss
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| )
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| i 12 further.
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| 13 MR. BERGMAN: I think you'll find that what you're 14 calling commercial T is probably equivalent to Region III, i (3
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| () 15 and we're saying, for Region III, it must maintain its --
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| 16 meet its functional requirements, and I think they are very l 17 similar at that point.
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| 18 But the issue of are they properly classified 19 today is safety-related. You don't need rule-making to fix 20 that. Licensees can change that designation today. If it's 21 improperly categorized as safety-related, they car change 22 that classification today.
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| 23 MR. BRADLEY: That's true, although I think, as 24 the South Texas experience with graded QA has pointed out, 25 really being able to extract the real benefit of that change
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| [~)
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| 203 1 requires the more involved, you know, treatment with i
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| () 2 exemptions to the other regulations.
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| i l
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| 3 I'm just identifying that as one area, I think, I 4 -where our thinking is fundamentally a little different at 5 this time.
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| 6 With regard to the current licensing basis, we {
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| 7 talk about the process considering traditional engineering 8 methods. I guess our view is that the one you do that --
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| 9 essentially, also, you know, it's the same thing, really.
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| 10 You've got to consider the existing licensing basis and why 11 is the equipment regulated today.
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| 12 There's a hierarchy of the licensing basis, 13 regulations, the implementing guidance for the regulations, 14 orders, tech specs, license conditions, and then you get 1
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| (<- 15 down into licensee commitments, letters on the docket.
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| ( ,f i
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| 16 There's a whole hierarchy of things that evolves, the 17 regulatory pedigree of some component in the plant, and our 18 view is, in order to make this process work, that we should 19 be able to trmcate the look at that at the level I show 20 here and that'is that you consider the existing analyses,
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| [ 21 the regulatory requirements, regulations, and the 22 implementing documents, that in order to reconsider an SSC 23 you need to look at all those things and evaluate why it's 24 there now, but in terms of looking at commitments you made, 25 you know, 10 years ago as a result of an inspection finding, i
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| y 204 1 or an LER.or what have you, we don't believe that that kind
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| ( '2 of level is necessary.
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| 3 I guess I didn't really see the CLE element or s
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| 4 hear much discussion of that in the staff's presentation, 5 but it does seem to be something that comes up in the
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| )
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| 6 meetings ~we have, particularly-with the other branches.
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| 7 They've spent a -- invested a good part of their 1
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| 8 life developing the CLB, and it appears to me that you do
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| '9 need some understanding up front of the treatment of the CLB 10 to make this work, because essentially you're developing a 11 new licensing basis. l 1
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| 12 The risk importance evaluation -- we've already 13 had a lot of discussion of that today.
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| 14 We've had considerable discussion of this in the
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| () 15 industry, meetings we've had with the working group and the 16 task force.
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| 17 In general, the consensus is that the 1.174 18 approach is a pretty good way to go.
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| 19 You know, you have different ba.seline CDFr and
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| : 20. LERFs today. In the fleet of plants as a whole, he meet the 21 safety goal, but there is substantial variation plant to 22 plant, and there'are questions such as, well, does a plant 23 with a low CDF get more wiggle room in this transition than 24 a plant with a higher CDF, and there's issues of that 25 . nature. I O
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| 205 1 Is it relative? Is it absolute? You know, how do 2 you take all those kind of factors into account?
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| 3 And basically, I think 1.174 had to tangle with 4 all those issues in its long evolution, and if you look at 5 the process they have there with the very small change 6 region and the small change region where, one, you can 7 basically look at just the delta, and then, if you go into a 8 larger delta, you do have to take into account your baseline l
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| 9 CDF and LERF.
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| ]
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| 10 I think that's a fairly reasonable approach, and I 11 would view our ultimate approach as being similar to that.
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| 12 DR APOSTOLAKIS: Remember, though, that deltas 13 that are allowed in 1.174 are independent of the present i
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| 14 CDF.
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| 15 MR. BRADLEY: Right. But the capability to go to 16 the larger delta, the small change delta, is contingent on 17 some demonstration of your complete baseline CDF.
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| 18 DR. APOSTOLAKIS: When it comes to relaxing 19 special treatment requirements, why shouldn't the current 20 CDF and LERF play a role?
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| 21 In other words, if I'm already down to 10 to the 22 minus 6, why should I have to worry too much about these
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| ]
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| 23 things?
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| 24 That comes back to my comment at 8:30 that if I 25 add extra protection systems, my role in Fussel-Vesley are l l
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| 206 1 not affected, f
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| (v ) 2 So, I'm still asking for all these special 3 treatments when, in fact, I've spent a lot of money putting 4 extra systems there to protect me, and that doesn't sound 5 reasonable to me.
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| 6 A plant that has, you know, redundancy to the j 7 level of one out of three, one out of four, why should they 8 have to have the same QA requirements as a plant that has j 9 the minimum redundancy required and its core damage 10 frequency is close to 10 to the minus 4?
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| 11 MR. BRADLEY: That's a very fundamental question, 12 you know, and if you look at the PSA applications guide, we 13 tried to develop a sliding scale.
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| 14 DR. APOSTOLAKIS: I remember that. But in that
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| ,m
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| (_) 15 case, maybe the argument -- I think it would be easier to 16 make the argument in the present case, because you're not 17 talking about --
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| 1 18 MR. ERADLEY: Part of what drove that is just f 19 pragmatism. I think we believe that, by accepting the 20 existing risk level of the plants as being adequate 21 protection and then being able to make small changes around 22 that, that that's something that's achievable in the fairly 23 near term, where if we start trying to look at the more 24 fundamental issues of plants with lower CDFs being able to, 25 you know, make more change, then you get into the issue, j l
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| 207 1 well, gee, it's actually a much larger percentage of their
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| () 2 3
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| baseline if they're allowed to make the same level as a higher plant. It works both ways, and it's complicated, and 4 we're just trying to proceed in a manner that will move this 5 along.
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| l 6 DR. APOSTOLAKIS: There is nothing sacred about
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| -7 percentages, though.
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| 8 MR. RUBIN: .Dr. Apostolakis?
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| 9 DR. APOSTOLAKIS: Yes.
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| 10 MR. RUBIN: I'm Mark Rubin from the PRA branch, 11 NRR.
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| 12 If I could add -- sure, the baseline risk is an 13 important consideration and we're struggling now on how to 14 factor it into the decision process.
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| 15 In the draft of Appendix T -- I'm not sure if this 16 was the one that got modified after 1-T or before -- we were 17 looking at a straw-man approach to factor total CDF into the 18 allowed impact which helps you scope the components that you 19 can move.out of the regulated class.
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| 20 DR APOSTOLAKIS: What page is this?
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| 21 MR. RUBIN: It's on my page 37, but it's not your 22 page 37.
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| 23 DR. APOSTOLAKIS: So, it's a different document.
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| 24 The heading of the subsection?
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| 25 MR. RUBIN: The heading of the subsection -- it's ANN RILEY & ASSOCIATES, LTD.
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| 208 1 after the assessment of change in risk.
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| [\_/') 2 DR. APOSTOLAKIS: Before the requirements of the 3 PRA.
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| 4 MR. RUBIN: Yes, sir.
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| 5 DR. APOSTOLAKIS: In my version, it just repeats 6 what 1.174 says.
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| 7 MR. RUBIN: In my version, it has different 8 criteria fcr the absolute impact or the magnitude of the 9 impact based on what baseline risk is, and we're trying to 10 arrive at some reasonable way to f actor the concept, because 11 we certainly agree.
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| 12 DR. APOSTOLAKIS: Okay. That's a good development 13 that you are thinking about, but it's not in my version.
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| 14 MR. RUBIN: Sorry about that. It changes every
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| ('\
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| t
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| ) 15 two minutes.
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| 16 MR. BERGMAN: Are you referring to the statement 17 plans with the baseline CDFs 1E to the minus 4, etcetera?
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| 18 MR. RUBIN: That's correct.
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| 19 MR. BERGMAN: That should be in your version.
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| 20 DR. SHACK: We have two criteria. We have a 1E -
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| 21 - you know, an E minus 5 and an E minus 4 distinction.
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| 22 DR. APOSTOLAKIS: Page 34, you say?
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| 23 DR. SHACK: Yeah.
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| 24 DR. APOSTOLAKIS: Yeah, but this is just what 25 1.174 requires. But Mark is saying now they're going beyond
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| 209 1 that. In 1.174, the only place where the CDF plays a role 2
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| ( is at the goal level, where Region I is increased, expanded.
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| 3 But I think what Biff and I are talking about here 4 is that, when you are actually making the decision, using 5 your matrix, for example, two-by-two matrix, it should not 6 be only the important measures or the delta-CDP, delta-7 LERF.
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| 8 Another approach might be to say the absolute 9 value of CDF and LERF plays a role, that for a plant that 10 has very low values already, maybe we should be more 11 lenient, because they already have other built-in protective 12 measures. That's essentially what we're saying.
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| 13 MR. BRADLEY: Right. How do you consider all 14 those things?
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| ) 15 DR. APOSTOLAKIS: So, it's a slightly different 16 version.
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| 17 MR. CHEOK: When I was talking earlier about 18 letting the licensee determine the un-availabilities and 19 reliabilities of the SSCs, that's what I'm kind of referring 20 to.
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| 21 If you only have three trains, you can claim less 22 credit for your LSSCs. Thereby, your delta risk might be a 23 little larger than you would if you had only two trains.
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| 24 DR. APOSTOLAKIS: Which equivalently means look at 25 the absolute value of the CDF, because then, if you do it on ANN RILEY & ASSOCIATES, LTD.
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| l 210 '
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| 1 a train-by-train basis, it's going to be huge, because now I' 2
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| (, T/ they can look at-individual systems and use the absolute 1 3 value of the unavailability of the system as a basis of 4 decision which will make it, you know, an extra three i 5 volumes, perhaps. But if there is no prior approval, who 6 cares?
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| {
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| 7 This is really an important issue, I think, 8 because you may want to do that. You may want to do that, j 9 to look at the individual systems, rather than the total j 10 CDF.
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| 11 MR. CHEOK: Right. I agree. l 12 DR. APOSTOLAKIS: Or at least part of the 13 contribution to CDF, because let's say the CDF is driven, as 14 it very often is, by seismic considerations, okay? So, you
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| () 15 have the seismic risk there representing, you know, 50 16 percent or more, or 60 or 70 percent of CDF, and then you 17 are struggling with the internal events analysis, which is 18 completely dominated by the seismic risk.
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| 19 Should you really be using the absolute value of 20 the CDF which is really seismic risk to make decisions on 21 the internal event analysis? You may want to use only the 22 results of the internal event analysis.
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| 23 So, this is something that I think deserves some 24' consideration.
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| 25 MR. BRADLEY: One of the practical aspects that O ANN RILEY & ASSOCIATES, LTD.
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| 211 1 led us ,tx) propose more of a delta kind of approach is that,
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| () 2 if you are looking at absolute values, you get into the 3 completeness issue, you know, internal plus external plus 4 shutdown and low power, which most plants today aren't in a 5 position to really profess a baseline CDF that's inclusive 6 of all the things that need to be in there. So, for 7 pragmatic considerations, we think that a delta approach is i i
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| -8 more feasible right now.
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| 9 I might note that you mentioned seismic. I think i 10 that, if you look at the areas where difficulties could crop 11 up as we move along here, seismic and fire are areas that 12 are prone to more uncertainty, you know, for plants that do 13 tend to have their profiles dominated by those kinds of 14 things, how they would proceed given that our -- I think the
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| ( 15 staff as well as we believe, you know, the internal event 16 PRA would be the minimum requirement, how you treat those 17 things even if it's qualitative is going to be important, 18 and there's a lot of work going on now in fire, NFPA-805, 1 19 those kinds of issues that could have an impact on the 20 ultimate outcome of this effort.
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| 21 This is pretty much consistent with what the staff 22 said, that -- and this, in conjunction with the next slide, 23 basically that our expectation is that you would use a level 24 one internal events PRA with a simplified kind of LERF --
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| 25 that's on my next slide, I'm getting ahead -- as a minimum ANN RILEY & ASSOCIATES, LTD.
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| 212 1 to support this, but to address other elements of the risk f w- t
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| () 2 spectrum, you would need to look possibly qualitatively or 3 using semi-quantitative methods.
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| 4 Also, we agree that the scope we come up with does 5 have to address the dynamic plant configuration issue, it 6 can't be a static, you know, risk characterization using 7 importance measures alone.
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| 8 Equipment out of service does have an impact on 9 the overall risk importance, and you have to look at the 10 dynamic plant configuration.
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| 11 A lot of these discussions are going on right now 12 in the A-4 rule-making on the maintenance rule, are really 13 ahead of the -- a lot of what we're doing on A-4 is going to 14 pave the way, I think, for this process.
| |
| if )I 15 As I mentioned, we realized pretty early on that 16 you couldn't just do importance measures to set the scope of 17 .the maintenance rule, and what the maintenance rule applies 18 'to, in some ways, you could argue that other regulations 19 need to apply to, that since you will have equipment out of 20- service, on-line, or in shutacwn in a given plant at any 21 time, and that has to be factored in. ;
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| 22 I already mentioned the first bullet.
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| 23 One other thing that I don't think the staff 24 mentioned, but one thing we're looking at in maintenance 25 rule space ~and that might come to play here -- the
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| F-213 1 significance determination process which has been developed
| |
| () 2 for the -- to determine the significance of inspection 3 findings for the revised oversight and assessment process -
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| 4 - it's basically a -- I think you guys have seen it.
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| 5 It's basically what I might call a semi-6' quantitative method. It's sort of a de-constructed PRA 7 based just on decades and it looks at initiating event 8 frequencies, mitigation capability, equipment out of 9 service, and basically it's a binning kind of approach.
| |
| 10 It's cruder than a PRA, but for some of those 11 areas where you haven't modeled the components in your PRA, 12 we believe a method similar to this or modeled on this might 13 be a useful approach to allow plants to proceed with the 14 regulatory scope determination.
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| () 15- So, we are looking in our guideline at some use of 16- the SDP-type process as part of that overall process, not to 17 supplant the PRA, but --
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| 18 DR. KRESS: What does SDP stand for?
| |
| 19 MR. BRADLEY: Significance determination process, 20- DR. APOSTOLAKIS: Is there a document out there we 21 can read?
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| 22 MR. BRADLEY: Does someone from the staff know 23 where that's captured? Is it in 99-007? It's SECY 99-007.
| |
| 24 I'm amazed that the ACRS hasn't had an opportunity to throw 25 rocks at that yet.
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| ! 214
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| ! 1 MR. MARKLEY: They have.
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| l 2 MR. BRADLEY: Oh, okay. It's actually a pretty
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| \ (''J) x-
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| '3~ interesting approach.
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| 4 DR. APOSTOLAKIS: So, this is not an industry 5 approach.
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| ~6 MR. BRADLEY.: No, it's.been developed by NRC
| |
| '7' basically to categorize the risk significance of inspection 8 findings. You determine that a piece of equipment has been 9 out of service, you know, for the last three months, and you 10 become aware of that.
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| 11- Well, what is the significance of that in 12' inspection space? It's a risk-informed method that the 13 staff is using, that they are proposing to use.
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| 14 The one that's developed now addresses internal o
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| '() 15 events and power operations. I think they're looking to 16 expand it,.but it's an interesting thing. It deserves a 17 look for this purpose.
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| 18 We're also proposing that as a screening method 19 for the maintenance rule A-4 implementation. So, it's 20 getting a lot of play right now.
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| 21 I think the scope decision -- this is pretcy 22 obvious. Basically, we also would recommend some type of 23 expert panel approach to integrate the results of the CLB 24 and risk importance reviews and make the final scope 25 determination.
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| j d
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| 215 1 We also agree that you'll need a performance
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| ()
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| 2 3
| |
| monitoring feedback loop aspect to this.
| |
| living process.
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| It would be a I don't think we disagree that you'll need 4 some level of PRA update frequency to support it once it's 5 in place.
| |
| 6 I mentioned the integrated effective change.
| |
| 7 I think we talked about this a little bit this 8 morning, you know, how do you actually come about trying to 9 -determine what the integrated effect of this change is, and 10 this is the whole issue of the level of commercial-grade 11 equipment performance versus something that's in the 12 regulated scope.
| |
| 13 How do you represent that in some way that you can 14 develop a number that tells you what the integrated effect
| |
| () 15 of this change is and allows you to compare it with, say, 16 the acceptance guidelines of a 1.174-type process.
| |
| 17 Those would be elements of our guideline and still 18 works in progress.
| |
| 19 I don't think we fundamentally disagree with 20 anything the staff said there, and we look forward to taking 21 a look at Appendix T to see what they say in detail.
| |
| 22 DR. APOSTOLAKIS: Well, so far, unless I'm wrong, 23 you haven't really disagreed.
| |
| 24 MR. BRADLEY: No.
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| 25 DR. APOSTOLAKIS: You've just expressed concerns
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| 216 1 that maybe the two-by-two matrix will lead to undesirable -
| |
| 3 , MR. BRADLEY: I think we've --
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| 4 DR. APOSTOLAKIS: But we don't know.
| |
| 5 MR. BRADLEY: Right. The thinking of the staff 6 and the industry has evolved along similar lines on this 7 thing.
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| 8 DR. APOSTOLAKIS: So, it's a fair assessment.
| |
| 9 MR. BRADLEY: The perspectives aren't that 10 different. .
| |
| 11 DR. APOSTOLAKIS: Okay.
| |
| 12 MR. BRADLEY: Regulatory treatment of SSCs -- a 13 very important aspect of this whole effort is the regulatory 14 treatment. This is really where the rubber meets the road
| |
| () 15 and where any benefit to the industry will actually arise.
| |
| 16 You know, we can spend a lot of time developing a 17 perfect categorization process, but if the output of that is 18 applied and a treatment is set up, you know, that's where 19 the benefit is.
| |
| 20 So, really, in a sense, coming to grips with an 21 understanding of how these things will be treated that fall 22 into the various bins is essential and really needs to 23 proceed as quickly as possible.
| |
| M4 I think once the industry has a better 25 understanding of the treatment aspects, there could be a lot ANN RILEY & ASSOCIATES, LTD.
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| a 217 1 larger buy-in to this effort.
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| / ) 2 You know, we may have more pilot plants coming V
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| 3 forward, be able to test more regulations, but right now, 4 think there's tremendous uncertainty about what does it mean 5 when something that was once safety-related is now, you 6 know, either still safety-related and low safety significant 7 or is not non-safety significant and you have to rely on 8 commercial treatment to preserve functionality, and when we 9 have meetings with the staff, some of the push-back we 10 always get from the other branches is, well, you have to 11 prove that to me.
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| 12 It seems to revert right back to where we are now 13 once we start having that discussion of, you know, give me 14 the paper and prove to me that what you're doing is O)
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| ( 15 equivalent -- what do you mean by functionality, how do I 16 know you're not going to let it rust away in place or, you 17 know, all that.
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| 18 So, these elements are very important, and both 19 the -- I guess 50e69 and the guideline -- we really -- it's 20 imperative, I think, that we get an understanding of how the 21 treatment would work. l 22 With regard to the safety significant SSCs that 23 were formerly safety-related, these things are -- were 24 safety-related and they're still safety-related, safety 25 significant -- it's conceivable you could even change the O ANN RILEY & ASSOCIATES, LTD.
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| 218 1 regulatory treatment of those, even though they're staying
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| () 2 3
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| in the regulatoq/ envelope.
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| That's because the process that you've just gone 4 through should have elucidated the aspects of that SSC that 5 make it important, and it may be that the way it's being 4
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| 6 regulated now could be improved even though it still stays 7 in scope.
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| 8 So, one of the options we've preserved -- and 9 we're still talking about that -- is being able to change 10 the way something is regulated even if it stays in the 11 scope.
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| 12 So, something that never went out of the safety-13 related scope, but is it possible to still improve that 14 based on the insights.
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| () 15 The next category is the things that come into 16 scope.
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| 17 This is important, very important. This is 18 another issue of some angst on the part of the industry, and 19- there's a lot of plant-specific variation here.
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| 20 South Texas, you know, has done a lot of work in 21 this area. They are'a -- you know, a large dry PWR with 22 three trains, and they don't see a lot of things coming in -
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| 23 - they see some things coming into scope.
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| 24 It's not so clear that that equation will play out 25 the same way for the whole fleet of plants. If you look at O ANN RILEY & ASSOCIATES, LTD.
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| 219 1 the IPE results and such, the BWRs, for instance, do tend to
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| /'73 2 find that a lot of currently non-safety-grade systems are i
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| -^<-)
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| 3 risk important -- feedwater, condensate, things of that f 4 nature, hard pipe vent.
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| 5 There are a lot of things on a plant-specific 6 basis that may come into scope, and this is just important 7 as the last one, you know. What does that mean? I mean 8 there's certainly a -- you know, and the bounding condition j 9 is that means my feedwater system is now procured to 10 Appendix B, or the condensate system. You know, those kind 11 of things, those -- I don't think we view that as an 12 acceptable outcome of this.
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| l 13 Now, in a lot of these cases, these are very high- '
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| 14 reliability systems that you have to have to produce power
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| () 15 and we've already spent many years getting the reliability 16 of these systems up, and we can use performance monitoring-17 type methods, and I think our view is, for those types of 18 systems, we can implement performance monitoring 19 requirements and reliability goals would be our, you know, 20 performance-based approach, is what we view as the way to 21' regulate these types of' things that come into scope, 22 particularly things like feedwater and condensate.
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| 23 Standby systems -- it may be different. You know, j 24 if you have a system where you can't really use a 25 performance-based approach, you know, how -- what does that l
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| i ANN RILEY & ASSOCIATES, LTD. l ON Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
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| 220 1 mean?
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| [')
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| V 2 Are we going to have pedigree now for systems that 3 , previously didn't? It's not clear, you know, and that's 4 something we've got to work with the staff to achieve an 5 understanding on.
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| 6 This is the commercial T. I guess this is our 7 equivalent of your bin 3.
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| 8 - We do recognize there's an element of these things 9 that's going to be in limbo for some interim period of time 10 while the option three regulations are revised and that 11 you're still going to have technical requirements that say 12 this is in regulated scope, but your option two evaluation 13 says it's low safety significant.
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| 14 What we've talked about in our meetings with the (A/
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| 15 staff is a licensee commitment or some type of regulatory 16 requirement to maintain functionality.
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| 17 Use commercial controls, but it would be a little 18 more than that. There would be some type of regulatory 19 handle there that says you will maintain functionality and 20 there's some codification in some manner of what your 21 commercial controls are.
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| 22 However, for this category of components, we still 23 believe you should be able to truncate your CLB and not have 24 to maintain all the things you may have ever committed to on f 25 your docket over the last 20 years or whatever for these l l
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| F l 221 1 things, but you should -- its function is what we're talking
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| () 2 3
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| about here.
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| These are not categorized as safety significant.
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| 4 They're only there because the pertinent regulations haven't 5 been revised through option three.
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| -6 Finally, we have the non-safety significant.
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| 7 Again, there's been some discussion in our meetings with the 8 staff -- commercial controls. Basically, we're not 9 suggesting that these items are going to be removed from the 10 plant.
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| 11 The question really becomes -- and I guess we've 12 had a lot of requests from the staff -- describe to us what 13 commercial controls are, even for these things that are non-14 safety significant, you know, how will they be controlled, r 15 but the intent here is there wouldn't be any regulatory l 16 requirement to maintain functionality, but there would be l
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| 17 some implicit aspect of this whole process where we would )
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| 18 maintain these as commercial control of these items.
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| 19 The next slide is just a list of regulations that 20 we've identified, not that different from the list NRC 21 identified.
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| 22 We didn't necessarily use the explicit criteria 23 and flow chart that they did, but the result was very much 24 the same, and if you look at the list of regulations here -
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| 25 - 50.2, definitions; 50.12, exemptions; 50.34, FSAR content; O ANN RILEY & ASSOCIATES, LTD.
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| l- I i
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| 222 1 50.36, tech specs; 50.49, EQ; 50.55, codes and standards; I \ 2 50.59, the change process, the maintenance rule, FSAR V
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| 3 update. ,,
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| 4 These are all excellent -- I mean these are the 5 rules that have an impact on day-to-day operations and are 6 the ones that need to be reviewed for this program. So, not 7 much disconnect, I think, in our view and the staff's as to 8 what regulations are on the table here.
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| 9 Finally, 50.59 -- the staff mentioned their view 10 that the scope of 50.59 might not need to be addrecsed.
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| 11 I guess that remains to be seen in our 12 perspective. Given that we are potentially making changes 13 to the scope of equipment that would be under regulatory 14 control, the FSAR is in the current scope of 50.59, whether (Q_j 15 some of those items are or are not reflected in the FSAR.
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| 16 I guess I'm not a 50.59 expert. I know there's 17 been a lot of effort put into 50.59 over the last couple of 18 years, and I think part of the rationale here is just leave
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| : 19. it alone, because no one has the stomach to go back and try 20 to deal with it again, and there have been some changes that 21 will be made to it that do make it more palatable for this 22 application, the questions on the imposition of the minimal 23 increase kind of words into 50.59.
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| 24 Adrian, you've had more discussions on this, if 25 there's something more you want to say.
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| 223 1 MR. HEYMER: Our initial developing thought is
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| . 2 that perhaps in 50.69, I think, as the staff called it, you 3 would include a change process, and that change process 4 would be applied to the risk-informed regulations or risk-5 informed activities.
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| 6 DR. APOSTOLAKIS: So, the risk-informed 50.59 7 would be in 50.69?
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| 8 MR. HEYMER: You could call it like that, or you 9 could break it out and call it something different, but I 10 mean that's one option that you've got.
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| 11 DR. APOSTOLAKIS: And what is the advantage of 12 this, that we are.not revisiting 50.59?
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| 13 MR. HEYMER: It just says that this is the change 14 mechanism for risk-informed regulations. It deals with the 15 scoping issue that's on the table and that's being 16 discussed.
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| 17 It might take a look at the nine questions. We're 18 split at the moment on whether or not we would just deal 19 with the scope and then perhaps look at the eight questions 20 later or perhaps deal with the complete change.
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| 21 Now, whether it's in 50.69 or it's a separate 22 regulation within the option B set of requirements, we're 23 still discussing.
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| 24 We would focus -- at the moment, our thoughts are 25 that we might focus on the safety functional attribute, how j
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| 224 1' :that's' impacted, perhaps use some criteria that might be
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| ,I'T. '
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| 2 similar to Reg. Guide 1.174 or the significance
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| .\j .
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| 3 determination process.
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| 4- DR. APOSTOLAKIS: Risk-inform 50.59?
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| 5, MR. HEYMER: Yes. We're just thinking along those 6 lines.
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| .7 DR. APOSTOLAKIS: Every time we say that, you 8 know,. people come back and say, well, yeah, but the vast 9 majority of changes. under 50.59 do not affect anything in 10 the PRA.
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| 'll MR. HEYMER: That's why we say something similar )
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| 12 to Reg. Guide 1.174, but it's also perhaps a process that's 13 very akin to the significance determination process, and 14 perhaps there's a screening mechanism up there before that
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| -( 15 that says are you affecting any safety functional attribute, 16 does.the change affect that, and if it does or doesn't, then
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| : 17. 'you can go your ways.
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| 18 That's our just preliminary thoughts on the 19 matter. !
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| l 20 DR. APOSTOLAKIS: Can we say that delta-CDF is I 21 less than 10 to the minus 6, no prior approval?
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| 22 MR. BRADLEY: You'd probably have to do something j 23 with LERF, too. I don't think you could just do CDF.
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| 24 DR. APOSTOLAKIS: And LERF. Okay.
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| 25' So, we'll have a two-sentence rule that will
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| 1 I
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| I 225 1 revolutionize everything.
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| () 2 3
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| MR. REED: This is Tim Reed from the staff.
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| can't hold myself back from these 50.59 discussions, but I
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| 4 .when we were looking at it, Adrian, you know, we see two
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| '5 difficult issues.
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| 6 The first one was mentioned. The categorization I 7 process, you know, going from what we had, box 1 to box 3, 8 or your going to commercial T, I think that's the easier 9 one. 1 10 I think that the whole process of the re-11 categorization, the expert panel, it basically does the 12 50.59 job, and there's no need to do 50.59 again. That's 13 the easy one.
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| 14 But the stuff that comes into scope, these SSCs
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| () 15 that come into scope -- they're coming into scope for 16 reasons that are outside the design basis, and so, if you 17 try to apply 50.59's criteria to them, they're meaningless, 18 because 50.59 only means things for design basis events.
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| 19 And so, if you brought them in and let's say you 20 put them in your FSAR nnd you say 50.59 applies to them, 21 what's that mean?
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| 22 So, I can understand -- very much understand the 23 problem, and I don't know if you were thinking this, but 24 when you put it in -- perhaps into 50.69 now, into that 25 regulation, you're only dealing with things that are coming ANN RILEY & ASSOCIATES, LTD.
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| 226 1 in from this out-of-scope stuff, and it sorts of puts in a
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| ( 2- separate place in the regulations and leaves 50.59 intact
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| : t. .3 for all the design basis stuff.
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| 4 I don't know what the criteria are yet. My own 5 mind was, if you look at it and the plant risk basically 6' stays the same, no prior NRC review and approval, if the
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| .7 risk goes up maybe you have prior NRC review. That's a very 8 simple, you know, Tim Reed thought.
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| 9 That's a big, big effort. It's a very difficult 10 job, and that would definitely complicate 50.69.
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| 11 MR. HEYMER: On your first point, we agree, and on 12 the second point, we were following along the same thought 13 pattern, and that's why we thought that somewhere in this
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| -14 you need a change process.
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| 15 DR. APOSTOLAKIS: I think a combination of these 16 things can risk-inform 50.59 without any problem.
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| 17 MR. ERADLEY: I think the questions in 50.59, as 18 revised, may work. I think -- my view, again, personal, but 19 the scope, you know, of the analyses, the scope that 50.59 20 covers somehow included the risk-informed evaluation process !
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| 21 you used to scope stuff in -- maybe that would solve the )
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| 22 problem, because the questions could be construed as being 23 the right ones, you know, and they do have the minimal kind 24 of language in there that you need to do that.
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| 25 DR. APOSTOLAKIS: So, this is now an open issue ANN RILEY & ASSOCIATES, LTD.
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| l 227 l
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| 1 again, risk-informing 50.59?
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| l
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| () 2 3
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| MR. BRADLEY:
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| schedule --
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| The final slide we have is on 4 DR. APOSTOLAKIS: I have to get used to the time-5 scale of regulations, you know. I wrote this attachment to 6 the letter in July of '98. This is September '99 and 1
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| 7 nothing has happened, but in the time-scale of regulations, 8 I wrote it yesterday. So, it may still come back.
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| 9 MR. BRADLEY: I guess the view of most of us the 10 less we have to mess with 50.59 to make this work, the 11 better off we'll be, just for the difficulties involved.
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| 12 We all know from bitter experience how hard it is l
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| 13 to weigh into that regulation. So, if we can adapt what we 14 have to make it work --
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| O
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| ( j 15 DR. APOSTOLAKIS: I think the industry has taken l
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| l 16 the point of view that the scope of 50.59 will remain the 17 same.
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| 18 That's why they're reluctant to explore other 19 things, and what I'm saying is we can make it a more j 20 powerful tool, you know, just make it risk-informed, and l
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| 21 then a lot of the stuff you have to do now will really be l 1
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| 22 within, and I think you alluded to that by saying earlier 23 that the scope has to be revisited.
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| 24 Okay. Enough on 50.59.
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| 25 MR. BRADLEY: I think the schedule the NRC staff ;
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| Ci ANN RILEY & ASSOCIATES, LTD.
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| 228 1 has laid out is very aggressive, and the industry will do 2 what we can to support that schedule.
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| (}
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| 3 The guideline -- our schedule is to have that 4 guideline done by the end of this year, pilots submit i
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| j 5 exemptions the middle part of next year, get the exemptions i
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| ! 6 granted the middle part of 2001, and then optimistically,
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| ! 7 we'd look at industry-wide implementation of option 2 being 8 about two-and-a-half years off.
| |
| 9 It's very aggressive. This is a large animal 10 we're trying to tackle here, and somehow -- I think, if you 11 look at the prototypes for what we want to do, where we've 12 been able to.go on the assessment and oversight process is a l 13 great prototype to follow here.
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| 14 We've laid a lot of the groundwork, you know, j
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| ( 15 through the applications -- ISI, IST, QA. We've had a lot 16 of those discussions, and now we can build on that and look 17 at the process we use to get quick results in the assessment 18 process and try not to reinvent all the issues that we've, 19 you know, consternated over and all this evolution to get to 20 this point.
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| 1 21 We need to be able to rapidly move forward to make !
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| 22 this work. So, the schedule -- we were pleased with the 23 schedule the staff laid out, and well do everything we can 24 to-support that.
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| 25 DR. APOSTOLAKIS: Would you like to say anything
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| ( , ANN RILEY & ASSOCIATES, LTD.
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| 229
| |
| -1' else?
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| ( 2- I see Dr. Moieni here. What is SCE doing? Are 3 you one of the pilots?
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| 4 DR. MOIENI: Yes.
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| l 1
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| -5 DR. APOSTOLAKIS: Are you following a different I i
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| 6- -approach from'that of STP? Are you doing similar things? I 7 Or you don't know? I 8 DR. MOIENI: We are hoping that, basically, as i
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| 9 -Biff said, the guideline -- the NEI guideline document would l i
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| 10 not be much different from.other risk-informed IST submittal 11 that we submitted last year, December '98, or even from 12 South Texas projects graded QA.
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| 13 So, it may have some basically new elements, but 14 ~the essence would be similar, so we are going to follow 15 that.
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| 16 DR. APOSTOLAKIS: Are you helping NEI write this?
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| '17 DR. MOIENI: Yes, a task force.
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| 18' DR. APOSTOLAKIS: And South Texas also is helping l
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| :19 .you.
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| 20 MR. HEYMER: We've got a group within the 21 industry, South Texas, San Onofre, all the pilot plants plus !
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| 22 a few others that represent probably about 50 percent of the 1
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| 23 industry now to help us write this guideline, and that's why 24 we're interested in seeing the staff's paper, because then 25 we can.perhaps refine it to meet a schedule for submitting I
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| ; , )
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| 230 1 it by the end of the year.
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| [<J') 2 DR. MOIENI: One of the things that we are -- and 3 I think other pilots are really looking for is the South l
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| 4 Texas project exemptions. This is really key for us. We gr. f 5 want t6 see basically what happens.
| |
| 6 Even though, as Biff said, South Texas project is
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| )
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| 7 not a pilot specifically for this, we really believe it is a I 8 good pilot for this option 2.
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| l 9 Even though there are plant differences, even 10 though the approaches could be a little bit different from 11 the NEI guideline document, we still believe they follow 12 similar approach and we are looking forward to see the 13 exemption request granted by the NRC early next year and 14 then follow the guidelines document and be a pilot for
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| ( ) 15 option 2, 16 DR. APOSTOLAKIS: What South Texas is doing is not 17 a pilot for option 2. Why are they doing it?
| |
| 18 MR. BRADLEY: They're doing it to -- as you may 19 recall, they gc't approval to implement graded QA. They got 20 constrained by a crazy quilt of other regulations that 21 prohibited them froin doing that. That's what they're doing.
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| 22 DR. APOSTOLAKIS: Okay. Anything else you would 23 like to say?
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| 24 Any of the members have any comments?
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| 25 [:No response. ]
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| /~'h, ANN RILEY & ASSOCIATES, LTD.
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| 231 1 DR. APOSTOLAKIS: Okay. Thank you very much, 2 gentlemen, appreciate your coming here.
| |
| [%))
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| 3 Now, we have to break and come back at one 4 o' clock, because the schedule is to discuss option 3 at one 1 5 o' clock, but I would like to tell my colleagues that I plan 6 to draft a letter -- I think we have to write a letter, 7 risk-informing Part 50, next week, and the schedule is 8 already very tight.
| |
| 9 We have at least five other letters that are 10 important to write. So, it would be good to try to put 11 together a draft letter before Wednesday, and I will need 12 your help.
| |
| 13 So, what I'm planning to do is ask you at the end 14 of the meeting, aroun,d three o' clock -- I'll go around the O)
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| ( 15 table and you give me bullets, points that you would like to 16 see in the letter regarding options 2 and 3.
| |
| 17 Now, how many of you will still be here at three 18 o' clock? I know Dr. Press will not be. Anybody else? And 19 Bob, you will not be?
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| 20 DR. UHRIG: I will be.
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| 21 s DR. APOSTOLAKIS: Oh, you will be. So, everybody 22 else is here.
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| 23 Can you give,me a piece of paper with some bullets 24 before you go, and Tom is doing the same. Unless you want 25 to meet at 12:45 to discuss these things. Do you want to do
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| ~
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| 232 1 that? Is that all.right? Okay.
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| () 2 3
| |
| So, let's say that we will get back together here at 12:45,-and then the staff will begin the presentation at 4 one o' clock. The formal presentations will start at one 5 o' clock as scheduled. Okay? And then,.for option three, 6 you know, the other guys will be here and will give you !
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| 7 their input.
| |
| 8 Thank you very much again. We'll reconvene at 9 1:00, 10 ,
| |
| [Whereupon, at 11:53 a.m., the meeting was 11 recessed, to reconvene at 1:00 p.m., this same day.]
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| 12 13 14 I 15 16 17 18 l
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| 19 20 21
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| 24 )
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| | |
| 233 1 AFTERNOON SESSION 2
| |
| ( [1:10 p.m.]
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| 3 DR. APOSTOLAKIS: Back on the record, i 4 The next presentation is by Mr. King and Ms.
| |
| 5 Drouin, discussing the proposed Commission paper and option 6- three, the performance study and risk-informing the 7 remaining sections of 10 CFR Part 50.
| |
| 8 MR. KING: For the record, my name is Tom King.
| |
| 9 With me is Mary Drouin. We're both from NRC's Office of 10 Research.
| |
| 11 As you recall, SECY 98-300 had several pieces to 12 it. What you heard about this morning was the piece that 13 dealt with risk-informing the scope of Part 50 as it relates 14 to special treatment rules.
| |
| 15 The complimentary part of that was what are we 16 going to do about the technical requirements in Part 50, in 17 terms of risk-informing them. And what the Commission 18 approved us proceeding with was a study of those technical 19 requirements and coming back to them at the completion of 20 that study with recommendations on what technical 21 requirements ought to be changed and what those changes 22 ought to be.
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| 23 They asked that our plan for doing that study i i
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| 24 provided to them for approval at the end of October. Wha'.
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| 25 we sent you yesterday was a draft of that plan. It's still ANN RILEY & ASSOCIATES, LTD. ,
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| . l L^' _' a- K {
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| 234 1 some work in progress,-it still has some things to be 2 cleaned up, and what our presentation will do this afternoon 3 is to sort of walk you through what our plan is for doing 4 that study.
| |
| 5 Again, what we're providing is a plan; not a 6 rulemaking plan, but a plan for doing a study. Therefore, 7 it's a smaller package than you got to look at for this 8 morning's option two discussion, and, also, being a plan for 9 doing a study, we don't have to resolve everything at this 10 point.
| |
| 11' There will be a number of things that will come i 12 together as we do the study and implement the plan. So 13 you'll hear some of that today. You may think some things
| |
| : 14. are a little fuzzy, but,that's the nature of putting the 15 plan together and actually getting in and being able to do 16 the work.
| |
| 17 What I want to do is walk through how we intend to 18 do the study. That will include the approach, the results 19 of the workshop that we had a couple of weeks ago, the 20 issues that we're facing, which many of them are the same 21 issues you heard about this morning. So you will see we've 22 got a very similar approach as the option two folks have.
| |
| 23 Then we'll come in and talk about the schedule and 24' future ACRS interacti.ons and so forth.
| |
| 25 I can skip this. We all know what the three i
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| 235 1 options are in SECY 98-300. SECY 98-300 also laid out what 2 we called desired characteristics of a risk-informed Part
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| [\s /^')
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| 3 50. One of the comments we had gotten from this committee 4' in putting 98-300 together was what do you want this thing 5 to look like when you're all done. So we put in the SECY 6 paper, 98-300, this set of eight items which we really 7 characterize as what we would like to achieve by risk-8 informing Part 50.
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| 9 I'm not going to read them all, but clearly we 10 want to make sure Part 50 now focuses on those things that 11 are most safety-significant, gets rid of those things that 12 are not safety-significant, are not commensurate with -- the 13 burden is not commensurate with safety.
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| 14 We want to be able to accommodate the plant-() 15 specific nature of risk.
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| ~
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| So there needs to be some 16 provision for allowing plant-specific items to be factored 17 into this process.
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| 18 We certainly think doing this will provide a more 19 consistent, coherent regulatory framework. The plant 20 oversight process is already going through a risk-informed 21 process. I would expect when we're done with Part 50, the 22 reactor inspection and oversight program then will be tied 23 much more closely to what this revised risk-informed Part 50 24 will look like. ,,
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| i 25 And then clearly we have the practicality issues f)
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| 236 1 associated with risk-informing Part 50. We believe these
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| () 2 3
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| criteria will be good when we get through with the study to come back and-look at again to see are the recommendations 4' we came up with, do they really achieve these eight factors 5 or how well do they achieve it, and that can be used as a 6 measure to help us judge were we successful, are the 7 recommendations we're providing to the Commission consistent 8 with what we're really trying to achieve. So that's how we 9 intend to use these things.
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| 10 I just want to, on the next slide, talk about some of the 11 high level ground rules for doing the study and the approach 12 we're taking. Again, as in option two, whatever we come up 13 with, if-it's implemented in Part 50, it's going to be 14 voluntary on licensees. So we're not talking about any of
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| _(
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| 15 this being mandatory.
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| 16 But when we go in and look at Part 50 and make 17 recommendations, they could fall in several categories.
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| 18 They could be revising requirements that are on the books 19 today to better focus on safety.
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| 20 They could result in adding some new requirements.
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| 21 Maybe there are some gaps in there that risk assessments say 22 ought to be filled, and,this program would try and fill 23 those or recommend that those be filled. And they could 24 also end up deleting things, things that are unnecessary or e.
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| 25 inconsistent or out of date. l
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| 237 1 So it could end up really covering any of those
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| () 2 3
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| three outcomes.
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| DR. APOSTOLAKIS: So a revision of 50.59 will be 4 under revising a specific requirement?
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| 5 MR. KING: 50.59 could fall under here. If you 6 look at the third bullet, it says we're going to focus on 7 the technical requirements. We're not going to go in and 8 look so much at process requirements. Except 50.59, we've 9 had some discussions, it's come up in NRR's discussions on 10 option two, as to how far do we want to go on 50.59, how far 11 do you want to go in option two, and how much then would 12 carry over into option three.
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| 13 So 50.59 is-a candidate for being dealt with under 14 option three. At this point, I can't really say how far
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| () 15 we'll go, but it is o'n our plate as something to look at.
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| The only th'ings'at this point that we are going to 16 17 exclude is the fire protection regulation, because that's 18 being looked at separately, and we're not going to go in and l
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| 19 try and risk-inform the ASME codes that are referenced or ]
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| i 20 the IPEEE codes that are referenced in the regulations.
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| 21 Those will be pretty much givens and we'll try and work 22 around those and see what else needs to be risk-informed. .
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| 23 We're not starting with a clean sheet of paper.
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| 24 We're taking a look at what's on the books today and how to 25 change it. The work that you heard about this morning on ANN RILEY & ASSOCIATES, LTD.
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| i 238 1 risk-informing _the scope, the criteria and approach that was 2 taken there, we would expect to apply a lot of that to this
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| 3 effort when we get into -- you know, the option two is just 4 applying it:to the special treatment requirements, but I
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| '5 think the concepts and the criteria and the approach can be 61 equally applied to the design requirements, as well.
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| 7 So we would build upon what's being done in option 8 two and apply it to the design requirements. We're not 9 going to go reinvent something new.
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| 10 We expect to retain the design basis concept in 11 that I would still expect, when we're all done, we'll have a 12 set of design basis accidents. They may not look like the 13 set we have today, but they will be risk-informed, and I 14 would expect there will be a generic set that would apply,
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| () 15 maybe there will be a set for P's and a set for BWRs, but 16 there would be a generic set. But then we also need to 17 allow some plant-specific consideration for unique features 18 or unique initiating.gvents that may exist at plants. )
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| 19 So there will be a dual set, one generic, one I
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| 20 plant-specific, but it will still be a design basis concept. )
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| 21 So what's on the books, a future plant designer could take 22 it and have some guidance as to how to develop a future -- .
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| 23 apply it to a future design.
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| 24 We're talking about an approach that makes small 25 changes around the plant's current risk profile. The Reg
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| 239 1 Guide 1.174 approach. We're not trying to use this to drive
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| ( 2 everybody's core damage frequency down to some new value or 3 the LERF down to some new value. It will be looking at the 4 risk profiles that are out there today, which the Commission 5 has accepted and they meet the adequate protection 6 requirements of the Atomic Energy Act and so forth, and 7 we're going to look at how can we make changes around that 8 risk profile that will meet the objectives that we talked i
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| 9 about.
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| 10 Again, we're only thinking about light water 11 reactors when we do this. We had some feedback, why don't 12 you make it general enough that HTGRs could fit in, but 13 we're not doing that. It's LWRs only.
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| 14 DR. BONACA: I have a question regarding the
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| ( 15 design basis concept.'
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| 16 MR. KING: Yes.
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| 17 DR. BONACA: The design basis accidents were 18 really hypothetical accidents used to design the plants.
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| 19 MR. KING: Yes.
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| 20 DR. BONACA: So there is a direct tie between 21 those assumptions and'the structures, systems and components j 22' that are in place.
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| 23 MR. KING: Yes.
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| 24 DR. BONACA: So I'm trying to understand why you 25 o would c~me with different sets of design basis accidents i
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| 240 1 now.
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| () 2 3-MR. KING: Two reasons. One, future plant designers are interested in what we're doing and this would 4 clearly be of use and of interest to them, but it also will 5 help existing plants. For example, if the large break LOCA 6- is no longer the design basis accident has to be analyzed on 7 a core reload, that you bring in some other LOCA, that
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| 8 impacts operating plants. So it's that -- it affects both.
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| 9- DR. BONACA: All right. So there are certain 10 parameters that may b'e affected. All right.
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| 11 MR. RUBIN: If I could add, just very briefly.
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| 12 This was the diesel example, large break LOCA, as Tom just 13 mentioned, is a really good one because industry has 14 ' identified a lot of the design requirements, ten-second
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| () 15 diesel start that had been questioned for a number of years 16 on the effect on reliability.
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| 17 I think in$the design basis accidents, more likely 18 ones or more risk-informed might change, for example, having 19 to test the diesel starts,. focus the attention on more 20 likely higher consequence events.
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| 21 MR. KING: Part of putting this plan together, we 22 had a workshop, as I mentioned, and Mary is going to talk 23 about that and the outcome from that workshop.
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| 24 DR. BONACA: But still you will have a hybrid. I 25 mean, some accidents I understand you would change. Even O ANN RILEY & ASSOCIATES, LTD.
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| 241 1 for newer. plants, you would still have certain demonstration
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| requirements of some type for your vessel design, for all those things. So you will have really a hybrid set of 4 deterministic and probabilistic requirements coming or 5 assumptions in some of them.
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| 6 MR. KING: I don't envision the outcome of this to 7- be a total rewrite of'Part 50. I envision it will be 8 selected technical rules that will have a risk-informed 9 alternative to what's in the books today. Some plants may
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| ! 10 not want to take any of them, some may want to pick and 1
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| 11 choose, some may take all of them.
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| 12 Things like vessel, design the vessel to the ASME 13 code, have the fracture mechanics criteria, the inspection 14 and so forth, that may not change. We may, as a result of
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| () 15 risk assessment, say that stuff still is valid, it still l 16 ought to stay on the books, and we may not be proposing any 1
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| 17 change.
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| 18 DR. BONACA: The reason why I'm asking this is l
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| l 19 that this is a very extensive process once you get into 20 that, because you also have to balance which accident l 21 analysis you will change and which one you will not change, l
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| 22 and that brings about a lot of considerations of designs.
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| 23 MR KING: 'Yes.
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| 24 DR. BONACA: So this is going to slow down that 25 process quite extensively just because you can't just do it i
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| 242 1 in a day what took however many years to build.
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| ( 2 I'm just asking these questions to understand the 3 timeframe in which this effort can be developed.
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| 4- MR. KING: We're going to talk about the time, 5 but, remember, the study -- the outcome of the study or 6 recommendations to the Commission as to what rulemakings we 7 ought to pursue, that's not a rulemaking itself. If the 8 Commission approves proceeding with those rulemakings, then 9 we're into several year time-framing and it's not a simple 10 process. It's back in with NRR putting together rulemaking 11 plans, similar to what they've got for option two, for other 12 things, and it takes time.
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| 13 DR. BONACA: And the other thing you want to come
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| -14 up with is a. pretty consistent package. I mean, we 15 criticize oftentimes ,the deterministic process for having 16 created a hodgepodge'of requirements which have no 17 consistency at times, and here, if we don't do it right, we 18 are at risk of getting even more of a hodgepodge of 19 requirements and confusion.
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| 20 MR. KING: Yes. Well, the intent is to take the 21 hodgepodge and maybe put some order and sense into it.
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| 22 DR. BONACA: Okay. That would be good.
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| 23 MS. DROUIN: Mary Drouin, with Office of Research.
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| 24 One very important aspect, of course, in this endeavor is 25 getting stakeholder feedback and interacting with the ANN RILEY & ASSOCIATES, LTD.
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| I 243 l
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| 1 stakeholders as we move forward. We do have planned a whole
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| ()- 2 series of public workshop's and we had the first public 3 workshop on September the 15th.
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| 4 It was very well. attended by the industry. We 5 presented, at the workshop, this preliminary plan that we're 6 going through today and we did receive quite a bit of z 7- feedback.
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| 8 Also, we had presentations from the stakeholders.
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| 9 NEI gave a presentation. We had a presentation from South 10 Texas on their option two. DOE -- not DOE, but a 11 representative who is working on DOE, who are doing a 12 similar endeavor, looking at the regulations for future 13 plants and how to risk-inform them, gave us their insights.
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| 14 We also had some presentations from a couple of consultants.
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| () 15 I will get to, in a minute, some of the thingE ''
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| 16 learned from that.
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| 17 We will be , holding future workshops, as I said. l 18 We're going to try and hold them at some key milestone 19 places, when we have some proposed changes and when we have 20 some recommendations, and right now we're tentatively 21 looking in February and in August to have some more 22 workshops. I l
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| 23 Also, one of the insights that came out of the !
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| 1 24 workshop that -- besides just having workshops, because we 25 have a very aggressive schedule here, and trying to have l
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| 244 1 some interaction in real time is critical, so it was decided n
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| i n 2 that we are going tc develop a web site. We hope to have G
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| 3 this web site up and working by November.
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| 4 The intention behind the web site is that as we go 5 along and we have some preliminary results or views that we 6 can share, to put them out on the web site, and it will also 7 give a mechanism that the stakeholders can give us their 8 views as we move along and we don't have to necessarily wait 9 for these two critical workshops.
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| 10 At the public workshop that we had back on the 11 15th, as I said, we presented our plan. We also had 12 presentations from various,stakeholders. Then we spent the 5
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| 13 entire afternoon just having an open discussion, which was 14 very valuable. We got many ideas, not just from the
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| /~N
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| ( ) 15 presentations, but other people who attended the workshop.
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| 16 DR. UHRIG: Was this here in Washington?
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| 17 MS. DROUIN: It was here in Washington at the 1 18 Double Tree. Yes. Right before Hurricane Floyd. Anyway, 19 in looking at what was discussed and what we heard, we don't 20 feel that we heard any clear recommendations or suggestions 21 from the stakeholders on what specific regulations or 22 requirements that we should just immediately undertake.
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| 23 Nonetheless, there were two that were mentioned, 24 50.44 anu 50.46, but there didn't seem to be saying here's 25 your very top priority and go after it.
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| 245 1 MR. BARTON: What is .44 and .46?
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| () 2 3
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| DR. APOSTOLAKIS: .Tell us what these are.
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| MS. DROUIN: That's the gas control, the hydrogen.
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| 4 MR. KING: Combustible gas control is 50.44 and 5 50.46 --
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| 6 MS. DROUIN: And 46 is the ECCS.
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| 7 DR. APOSTOLAKIS: Okay.
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| 8 MS. DROUIN: Also, there were -- when you looked 9 at current reactore versus future reactors, there were 10 different views that we got in terms of different 11 approaches, and we shouldn't use the same approach in 12 modifying Part 50 for current reactors as we should for
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| : 13. future reactors.
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| 14 For current reactors, it was more recommended to
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| () 15 go after specific things and risk-inform them, but when we 16 start looking at future reactors, we might want to consider 17 perhaps maybe a complete total rewrite and starting almost 18 from scratch using a risk-informed foundation from the 19 beginning.
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| 20 DR. APOSTOLAKIS: You can't do both at the same 21 time, can you? So I don't know -- are they essentially 22 proposing that you postpone the comprehensive revision 23 because we're not building any reactors at the moment?
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| 24 MS. DROUIN: I would think so.
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| 25 MR. KING: I think the folks that were there i
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| 246 1 representing the DOE programs that's looking for
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| () 2 3
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| requirements for future reactors, they would like us to fold that into what we're doing today and they said they're 4 willing to come meet with us and work with us, maybe almost 5 as a pilot activity and sharing their views and our views 6 and seeing if they can get their views factored into what-7 we're doing.
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| 8 DR. UHRIG: ' Pebble bed?
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| 9- MR. KING: No. This is advanced light water 10 reactors.
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| 11 DR. UHR.IG: Advanced light water reactors.
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| 12 MS. DROUIN: Yes.
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| 13 MR. KING: Yes. We told them we're not dealing 14 with anything other than light water reactors in this 15 activity.
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| 16 DR. APOSTOLAKIS: I share a concern, however, with 17 -- I wrote a note befbre the conversation we had. You have l
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| 18 two separate objectives there. I believe, for existing 19 plants, the main objective right now is the one of burden 20 reduction and focusing on safety issues.
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| 21 The newer plants, you have really somewhat of a 22 different objective. You have a number of different l 23 objectives, and I question whether you can achieve both.
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| 24 MR. KING: What they said was the future plant l 25 folks are looking at. reducing capital costs. They are not t ,
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| 247 1 so much worried about OEM costs in their activity, but they
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| say capital costs have to come down 30 to 35 percent to be competitive with coal and gas and the only way to do that is 4 be able to not put in as much concrete and steel and piping.
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| 5 So they're looking at this activity to get rid of 6 some things, whether it's get rid of systems or whether it's 7 change containment design basis, so maybe you can make a 8 smaller containment, I'm not sure, but their thrust is 9 capital cost.
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| 10 DR. APOSTOLAKIS: So what's the net result of this 11 or you haven't decided? Individual recommendations for the 12 current generation or are;'you going to take a comprehensive 13 -- do you know? Still discussing it?
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| 14 MR. KING: In starting out, I think we're going to
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| () 15 try and do both. If we get bogged down, I think the 16 priority will go to focusing on those things that deal with 17 operating plants, but I.think as an initial approach, we're 18 going to try and look at both.
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| 19 DR. APOSTOLAKIS: Nobody wanted 50.54 to be 1
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| 20 revised, license renewal? ;
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| 21 MR. KING: Part 54? Part 54. No, I don't 22 remember anybody mentioning Part 54 at the workshop.
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| 23 MS. DROUIN: I don't either. I don't either.
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| 24 ThenasTomdiscussedear}1ier, it was already within our 25 scope to keep the design basis concept and that was also O ANN RILEY & ASSOCIATES, LTD.
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| et 248 1 feedback that that was a good idea, that we didn't get any l f~)
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| v 2 input that they wanted something different. In fact, they 3 didn't want anything different.
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| 4 DR. APOSTOLAKIS: Is there any other way to do it?
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| 5 MR. KING: We had one stakeholder who wanted to j 6 regulate to the QHOs.
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| l 7 MR. MARKLEY: We heard from him.
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| 8 MS. DROUIN: You heard from him. I 9 DR. BONACA: I'm sorry. I missed it. He wanted 10 to what, regulate? !
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| )
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| 11 MR. KING: Put the safety goal QHOs in the 12 regulations and let people design a plant and demonstrate 13 they meet it. g 14 MS. DROUIN: The QHO.
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| O( jj 15 DR. APOSTOLAKIS: That's granting licensee 16 flexibility.
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| I 17 MR. KING: . Don'tlwant to do that.
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| 18 DR. APOSTOLAKIS: That's it.
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| T
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| - 19 MR. KING: That was only one stakeholder. l 20 MS. DROUIN: The other thing which we've heard j 21 many times before and we recognize this, that everyone felt l
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| 22 the problems weren't so much with the regulations 23 themselves, but more with implementing documents, when you 24 start looking at the regulatory guides and the standard 25 review plans and how those documents interpret the O
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| 249 1 regulations, that the problems are really down at that
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| () .2 3
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| level.
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| MR. KING: And we'll be looking down at that 4 level.
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| 5 MS. DROUIN: Yes.
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| 6 MR. KING: Because I think you have to, or you're 7 not going to get much mileage- out of this effort.
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| 8 MS. DROUIN: In l'ooking at what we have put 9 together in the plan, there are two phases to it. The first 10 phase, which is just a studv phase, a study looking at the 11 feasibility of making changes and recommending.some proposed 12 changes to various requirpments, and that's what we're going 13 to be doing over the next 12 months, over the next year.
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| 14 Then at that point, we'll write a paper to the 15 Commission, with some recommendations, and then dependent on
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| -16 what the Commission will approve, then move forward doing a 17 detailed analysis in support of rulemaking for those 18 changes, which is phase two, which will come later on.
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| 19 Anyway, in looking at phase one, there are three 20 primary tasks in doinh'it,. We want to first go through and 21 identify what these candidate requirements are, looking at 22 the regulations and the DBAs, and, of course, all the 23 implementing documents. So that in and of itself, just 24 going through and understanding how all this fits together 25 and coming up with these candidates.
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| 250 1 The next part, of course, will be go through and
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| [) 2' prioritize them. Then onbe we come with a prioritization of
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| 3 which ones to go after first, then come up with some 4 proposed changes to those.
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| 5 This is kind o(*a high level explanation of the 6 plan. We're going to go through each one of these tasks and 7 go into more detail of what we intend to do on those, and 8 Tom is going to walk through that.
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| 9 MR. KING: As Mary said, the first thing we're 10 going to do is go through and screen what are the candidates 11 that we want to focus on. The way we plan to do that is 12 basically look at three factors. By candi. dates, this will 13 include rules, reg guides, SRPs that ks'il look at.
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| 14' We're going to y6 in and see where do we feel
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| () 15 there's unnecessary burden, either on the licensee or on 16 NRC, and that could be from excessive. conservatism in 17 methods or criteria based upon today's knowledge, today's 18 methods, we know we could do better, or on realistic 19 assumptions, too many failures, too many extreme conditions 20 have to be assumed one after the other, and it just doesn't 21 make sense when you look at it from a risk standpoint.
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| 22 We'll'be getting the other technical divisions in 23 Research involved, the thermal hydraulics folks, the 24 mechanical folks, and we'll also involve some coordination 25 with NRR, because they'Jre very familiar with the licensing Y
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| y 251 1 basis. So we'll be having discussions with them to make (r) 2 sure we understand what's there and the basis for it.
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| 3 In looking at design basis accidents, both 4 initiating events and what the event scenarios ought to be, 5 we'll be doing some screening using some frequency values.
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| 6 We've put some ideas of what those screening criteria would 7 be. We think, for example, initiating events, anything that 8 has a frequency greater than ten-to-the-minus-six per 9 reactor year ought to be a candidate for an initiating 10 event.
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| 11 DR. APOSTOLAKIS: I don't understand what that 12 means. A candidate for what?
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| 13 MR. KING: To be in the design basis as an 14 initiating event. If,it's an initiating event that's so
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| ,a
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| () 15 infrequent, then maybe, from a risk perspective, it ought 16 not be considered.
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| 17 DR. APOSTOLAKIS: So now we're mixing the 18 comprehensive revision with a specific group review 19 revision.
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| 20 MR. KING: Like I said, we're taking an approach 1 21 that right in the beginning is going to look at both.
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| 22 DR. APOSTOLAKIS: Because the first bullet really 23 refers to what exists today.
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| 24 MR. KING: Yes. Yes. But it's --
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| 25 DR. APOSTOLAKIS: The second bullet now refers to
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| 252 1 the comprehensive revision.
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| [J \ 2 MR. KING: Right.
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| 3 DR. APOSTOLAKIS': You may want to expand the list 4 of initiators. .
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| 5 MR. KING: Or contract it, one or the other.
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| 6 DR. APOSTOLAKIS: How would you contract it?
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| 7 DR. BONACA: If the initiating frequency is less 8 than one-ten-to-the-minus-six, he won't consider it.
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| 9 MR. KING: Yes.
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| 10 DR. BONACA: You can't think of many candidates.
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| 11 DR. APOSTOLAKIS':' I thought that was already in 12 the books. Isn't it, Mario?
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| 13 DR. BONACA: What? !
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| 14 DR. APOSTOLAKIS: Initiators with frequency less O
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| ( ,/ 15 than ten-to-the-minus-six were not considered. I remember 16 vaguely seeing that someplace.
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| 17 MR. RUBIN: That may be for external event l 18 frequency, because that number is in the SRP for assessing l , l 19 external hazards. le .
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| 20 DR. APOSTOLAKIS: I think we're going to have a 21 problem if we mix things. Maybe it's early enough in the ;
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| 1 . ;'
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| 22 proceso to naybe advibe you to clearly . identify what j 1
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| .Y 23 criteria apply to the partial revision of the regulations 24 and what criteria for the comprehensive revision, because 25 the first one is really the existing and the second one is l ANN RILEY & ASSOCIATES, LTD.
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| . 253 1 the broader view.
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| O v
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| 2 MR. KING: Well, the other two, core damage and 3 large early release, those were to look at the scenarios 4 that lead to core damage and large early release and what's 5 contained in those scenarios, which would really affect your 6 description of your design basis accident. Like single 7 failure criteria may not be reasonable anymore.
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| 8 DR. APOSTOLAKIS<: But do we have -- maybe the 9 reason why some core damage frequencies are less than ten-10 to-the-minus-seven is because you have the existing design.
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| 11 MR. KING: Yes, but that's where you go to the 12 third bullet, looking at the existing design, there may be 13 things that are low risk because they're very high quality, i
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| 14 highly reliable. But if you tiake a look at them using some 15 risk achievement wort 1 me,asures, yo'u'll fin,d out that, hey, 16 those are important. We Still want to maintain today's 17 requirements on those,,and'that's the third! bullet.
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| 6 18 DR. APOSTOLAKIS: Which one, risk significance?
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| 19 MR. KING: Risk significance.
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| 20 MS. DROUIN: Also, I would add, this is a very 21 complex process and you should not interpret what's on here 22 inthesensethatit'Msequential. This is all very 23 iterative. And as you se,e on this slide, the next slide and
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| 24 the one thereafter, they're all call'ed task one, because 25 you're constantly iterating back through the process.
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| l 254 1 DR. BONACA: Let me just go back to the comment I
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| [v } 2 made before on design basis and the mix of deterministic and 3 probabilistic.
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| 4 I want to size my ECCS system in a way that if I )
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| 1 5 have a LOCA, loss of. coolant accident, I will be able to 6 deal with that, irrespective'of how frequent that accident
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| ]
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| 7 is. So I have to perform a calculation, maybe with less 8 conservatism, and I agree with the first bullet there, to 9 size my ECCS system, the timing of it, size of it, different 10 kind of features of it.
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| 11 MR. KING: But which LOCA are you sizing it for?
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| 12 DR. BONACA: Again, one with less conservatism 13 maybe. Okay. But I'm saying that irrespective of the j 14 ,
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| initiating event frequency, I need that result to size my
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| ,~
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| ( ) 15 equipment. See what I'm trying to say?
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| 16 That's why I think when you look at frequency of 17 initiating events to determine which ones go in your set, 1
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| 18 you now stumble on -- '
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| 19 MR. KING: et's go back to large break LOCA.
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| 20 There is some frequency distribution as to the 1. rce break I l
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| 21 LOCA is probably the least likely of any of the L ?As to l l
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| 22 occur. '
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| 23 DR. BONACA: That's true.
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| 24 MR. KING: And you work back to the small ones and 25 they're more likely to occur. You could use this screening
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| 255 1 value to say, okay, large break LOCA is ten-to-the-minus-() 2 eight or whatever, I'm not going to design for that anymore, 3 require people to design hnd analyze to that anyme a, I'm 4 going to come back to something that's more in the ten-to-5 the-minus-six neighborhood, and what LOCA does that 6 represent.
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| 7- I don't know, maybe it's an eight-inch pipe break 8 or something like that.
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| 9 DR. APOSTOLAKIS: Pursue that a little bit. Let's 10 say, what is the frequency of a large LOCA now? It's ten-11 to-the-minus-four per year? What is it? PRA?
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| 12 MS. DROUIN: Large LOCA is less than 1E-minus-13 four. Typically, a value of IE-minus-four, but out of the 14 recent AEOD studies, they're saying it's more on a value of 15 1E-minus-six. -
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| 16 DR. APOSTOLAKI5:'*Okay. Now,.what does it,mean to 17 design against a large LOCA?
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| 18 MR. KING: What'does it mean in terms of plant 19 requirements?
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| 20 DR. APOSTOLAKIS: Does that include, for example, 21- the pipe' design? ,
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| 't 22 MR. KING: Pipe, emergency diesels, a whole bunch 23 of stuff.
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| 24 DR. APOSTOLAKIS: So if you remove it new, if you 25 remove it from the design basis, maybe the pipe will be E :
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| 256 1 . designed differently and maybe'the large LOCA frequency then 2 would be greater than ten-to-the-minus-six.. That's 3, something that is.not' clear, in my mind.
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| 4 MR' KING:
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| hatjsanissue.
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| 5 'DR. APOSTOLAKIS: but you remove it from the 6 existing design. e .-
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| .7 _MR. KING: I agree.
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| : 8. DR._APOSTOLAKIS: If I start designing against 9 that,.maybe_the pipe Will be thinner.
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| 10 MR. KING: But you may still keep the same codes 11 and standards for piping design, but now instead of assuming 12 this double-ended guillotine rupture, you've got something 13' smaller which does affect diesel start time, could affect -
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| i .
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| 14 -
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| .15- DR. APOSTOLAKIS: M point is that maybe the 16 double guillotine brgpk will become more likely now.
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| 17 MR. KING: I understand your point and that's an 18 issue that's got to be looked at.
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| 19 DR. BONACA: There will be a shift there and you 20 have to calculate that. I think it's when you get into 21 calculation to size fundamental elements of the plant is 22 whenIbecomeuncomfortab[e. And I'm not saying that you 23 don't have a good argument there. I'm only saying that I 24 guess I'm too deterministically-based to -- I would like to 25 -- I understand what you're saying there.
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| I 257 l 1 MR. KING: You're arguing for a don't get into the
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| (( ) 2 design stuff, just get into the stuff that --
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| 3 DR. BONACA: Well, I'm arguing that some specifics 1
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| 4 are there to size equipment that you were going to know to 5 be successful under the most limiting conditions. Now, when )
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| l 6 you begin to -- I understand where you're going now.
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| 7 You'resayfhh,well,youknow, leak before break, 8 large piping of that kind will not -- a guillotine break l 9 will not happen, and probably you're right. j l
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| 10 DR. APOSTOLAKIS: See, but th'e fundamental
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| , t 11 question is something is insignificant now because I have
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| : 12. designed it according to certain criteria. If I design l
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| 13 something else to a n,ew set of criteria, that something may 14 not be significant anymore. I don't know how -- I mean, h 15 unless you do a PRA again and you repeat all the l 16 calculations to convince yourself that even under the new 17 design, the large LOCA is still ten-to-the-minus-six.
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| 18 But remember, in this part of task one, you just j 5
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| 19 identify it as a potential candidate.
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| 20 DR. APOSTOLAKIS: I understand.
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| 21 MS. DROUIN: So as you go through the rest of task 22 one and looking at the history of the requirement, which 23 we're going to get into, a,nd.why it.was there and what it's i
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| 24 doing, well, then, that may no longer be a candidate. It 25 might be thrown out, or y'ou might'end up picking up one that i i
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| p 258 i
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| 1 you didn't identify..-
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| [d 2 3
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| DR. APOSTOLAKIS:
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| valid argument.
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| I understand that and that's a All I'm saying is that this conceptual 4 problem of finding something as insignificant in the present 5 case and then changing the requirements, that may not be 6 insignificant in the new case. Somehow you have to --
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| 7 MS. DROUIN: But my point, you haven't made the 8 decision here to change it. You've only made the decision 9 to look at it.
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| 10 DR. APOSTOLAKIS: /And when you look at it, you can s-11 say a lot about it. .
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| 12 MR. KING: Absolutely,,your concern has to be 13 looked at.
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| 14 MS. DROUIN: Yes.
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| 15 MR. SIEBER:',Isn't'the fact, though, that the
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| 'i 16 reason why reactors can, withstand some,of these pretty 17 severe accidents is because the.ASME code specifies pipe 18 thickness and materials and weldments and supports, and on 19 your slide five, you say you aren't going to touch that.
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| 20 So all those criteria still remain in place. It's 21 just what you look '.L,from a risk standpoint which allows i
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| 22 you to resize aur L &y systems.
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| 23 DR. BONACA: The point that George is making is a 24 good one, however, that y6u may decide that because of all 25 this knowledge, you rr.e no,t going to consider anymore a N '. l O ANN RILEY & ASSOCIATES, LTD.
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| 259 1 guillotine break. Therefore, that will cascade into lesser 2 thick piping and all kinds of s, tuff'i which, in turn, will
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| (
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| 3 .make frequent anything that waEnft frequent before.
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| .e-4 DR. APOSTOLAKIS: Anyway, I think we have an 5 understanding. Just out of curiosity, would it be helpful 6 here to'also develop somdthing like a master logic diagram, 7 top-down diagram, revisiting the'whole idea of initiators 8 and so on and show the logic of it?
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| 9 You know what a master logic diagram is. The 10 PRAs, especially in the e'arly days, it was a real good 11 communication tool to say why do we worry about LOCAs, 12 transients and so on, because public health has to be 13 protected; that meana you have to release radioactivity, 14 that means you have to have damage to the core and the
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| () 15
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| ~
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| containment failure,.then you have two branches, how can the 16 core be damaged; well, what do we do there; we produce heat 17 and remove heat. ,
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| J .
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| 18 So you look',.atLthe various disturbances there, 19 whatwillhappentotbbcontainmentandsoon, and that 12 0 would be a great, I think, diagram to compliment this, not 21 to replace. So that you will show now if I take a risk- 1 1
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| 22 informed approach, what would be my initiators that I would 23 consider down here. .
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| 24 The diagram itself would not do it. You still 25 have to consider all these things that you have here, but I i i
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| 260 1 think the diagram wili help two ways. First of all, it may 2 give you some idea as to enhance this kind of thinking, but, (v) 3 second, primarily, I think, as a communication tool, it 1
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| 4 would be great to show the systematic way that you are l 5 thinking. {'j 1
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| 6 I think most PRAs do show these. They copy each 7 other, but still they're there. I've always felt that it's 8 valuable more as more of communication than actually helping 9 you find initiators.
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| 10 MS. DROUIN: We've already started doing something l
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| 11 that doesn't look exa'ctly like a master logic diagram, but j 12 it does a similar thing.
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| 13 DR. APOSTOLAKIS: That would be a good idea.
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| 14 MR. KING: 'tbink that's a good idea. The
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| (~'\ 15
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| ( ) systematic way to illustrate what we're doing.
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| 16 DR. APOSTOLAKIS: Now, I would expect here to see 17 things like this thing about earthquake and large LOCA.
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| 18 Will that be a candidate here to be considered? Would that i
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| 19 count as an initiating event or what?
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| i 20 MR. KING: What? Say that again, which LOCA?
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| l 21 DR. APOSTOLAKIS: The large LOCA.
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| l 22 MR. KING: Yes.
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| 23 DR. APOSTOLAKIS: In an earthquake. Is it part of 24 thedesignbasisnowphatyouconsiderbothatthesame 25 time? -
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| 261 1L MR. KING: Yes. That would fall under the item
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| () 2 3
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| that I call unrealistic assumptions.
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| DR. APOSTOLAKIS: So it's not --
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| 4 MR. KING: You're starting to add all these low 5 frequency things together in the same scenario. That's what 6 is meant by those words.
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| 7 DR. APOSTOLAKIS: Because each one is still there 8 as an initiating event. .
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| 0 .
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| 9 MR. KING: Righ't.
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| l 10 DR. APOSTOLAKIS: In separate parts of.the 11 analysis. ;
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| 12 MR. KING: And then these criteria down here would 13 be a way to screen hob unrealistic they are.
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| i 14 DR. APOSTOLAKIS: Okay. I
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| () 15 MR. KING: And then as Mary said, once you go 16 through the screenind, process and identify those things that 17 look like they're candidates''to be risk-informed, then what 18 we want to do is target those to make sure we understand why 19 they are the way they are,3 before we start embarking on
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| (,
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| 20 changes. ,
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| 21 This is just a list of the kind of things we would 22 go in and look at, dig into the reg guides, the SRPs, talk 23 to the NRR folks, make sure'it's clear, we understand what's 1
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| 24 there'and why it's there, and then, with that good 25 understanding, go in pnd see what makes sense to change.
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| = .
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| 262 1 In addition, we need to think about --
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| () 2 DR. APOSTOLAKIs: Wait a minute, wait a minute, 3 wait a minute. Let's go back to ten. Throwing the words 4 out, identify the purpose for each requirement, defense-in-5 depth, marginal uncertainty.
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| p3 '
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| 6 Someofusyould'thinkthat'swhyyouhave 7 defense-in-depth. It's nht a separate thing. If you had no 8 uncertainty, you would not need defense-in-depth.
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| 9 I think maybe you ,can point out again that some of 10 these policy issues qegar, ding -- that are of defense-in-11 depth in the new system really have to be resolved by the 12 Commission before you guys go too deeply into this.
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| 13 MR. KING: Fel1, that's one of the things we'll l
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| 14 talk about when we get to,the schedule, but my view is when l
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| () 15 we go in October with this plan, what we're going to ask for 16 ' Commission approval on i's that general approach that I j l
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| 17 talked about early ont and we're going to ask for approval of
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| : V 18 those screening criteria.'
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| jyzl9 Then we owerthe Commission a report later on.
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| .: . 1 20' We're proposing to go.back to the Commission around the 7
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| 21 February-March timeframe, after we've done the screening, 22 after we've taken a regulption and run it through this whole 23 process, and then go bac.k a'nd have them approve the criteria 24 we would use to actually'make the risk-informed changes or 25 comeupwiththereedhmendationforrisk-informedchanges, t.;
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| m
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| . 263 1 which then would get into what do we mean by defense-in-
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| [ T 2 depth, what kind of margin do we think is reasonable to V
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| 3 retain, what's the spl,i.t,between prevention and mitigation, L. : .
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| 4 thosekindsofquestipns,.whatriskcriteriaarewegoingto 5 use.
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| 6 We're going to Yhlk'hbout some of that later on.
| |
| 7 DR. APOSTOLAKIS: I mean, here, you're just 8 identifying the purpose, just the history .
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| 9 MR. KING: Yes.
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| 10 DR. APOSTOLAKIS: You are not really taking any 11 action.
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| 12 MR. KING: 2This is history. This is history.
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| 13 DR. APOSTOLAKIS: Because so'ebody m says, yeah, .
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| 14 this was in the name of defehse-in-depth and defense-in- i
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| ()
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| J 15 depthremainsaprinckpiethat'saboveeverythingelse, then 16 the natural conclusion of that is that in the new system, t
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| 17 you would have to do that.
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| 18 MR. KING: .Right. ;
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| 19 DR. APOSTOL4KIS: 'IE, on the other hand, the 20 Commission says, no, pefense-in-depth is really a tool for 21 ' achieving certain thi gs -- .
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| 22 MR. KING: Yes.
| |
| 23 DR. APOSTOLAKIS: -- then you look at it in a 24 different way. ;
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| 25 MR. KING: Yes. To me, the key questi.on in this O
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| LN- -
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| l , 264 1 whole thing is this s11de. To me, it's fairly 2 straightforward to go through and identify those things that 3 bother you, that either,the industry will say these things 4 are costing us money or we'll say these things don't make
| |
| , 5 sense from a risk standpoint.
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| l 6' The tough questioz) is I don't like what's there, 7 whatdoIlike,whatwillj . change it to, and that's where 8 you get into the role of defense-in-depth and the risk l 9 criteria that you're going to use to make those decisions.
| |
| l 10' That's what this slide really gets to.
| |
| 11 These are tiiings that are going to have to be 12 considered and maybe -- I think we talked about most of 13 these, except -- already, between this morning and this 14 afternoon, but the one we haven't talked about is the 15 anticipated operational occurrences. There are, in the 1
| |
| 16 design basis envelope., these events identified that are 17 things that are going,to happen one or more times during the 18 life of the plant, whether it's a turbine trip, a loss of 19 off-site power and so forth.
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| 20 The plant has to be designed to cope with those 21 and it has to be designed t.o cope with those with either no 22 radiationreleaseorkve~ry'smallamount. 1 1:
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| l 23 We don't want-t'o throw those away. I mean, even i 24 _though a risk assessment would say there is no risk there, 25 the fact that they db occur means that you want the plant to r
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| m
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| , 265 1 have a good design to be able to handle those.
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| 2 So my view is that, at this point, we don't want 3 to touch those. We probably want to leave those alone. But 4 it is an item that weineed to put before the Commission and Y '.
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| 5 maybe the committee n8eds"to think about it, but it's 6 something we need to look.at'in this risk-informed process.
| |
| 7 DR. APOSTOLAKIS: Of course, all of this, again, 8 will heavily be related to the goals, if the Commission 9 decides to revise high level goals, land contamination and 10 things like that, and those then are impacted.
| |
| 11 MR. KING: Clearly all of this stuff up here could 12 be impacted by that kind of decision.
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| 13 DR. APOSTOLAKIS: Also, in the third bullet, risk 14 metrics, you are reconsidering the whole thing and you are
| |
| () 15 16 still stuck to CDF an curves be considered?
| |
| LERF, would the frequency consequence 17 MR. KING: I think at this point, nothing is 18 thrown out. Certainly, CDF, LERF, risk achievement forth, 19 Fussel-Vesley, they're all candidates to be considered.
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| 20 DR. APOSTOLAKIS: But these are already being 21 used.
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| .)'"
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| 22 MR. KING: es ['
| |
| 23 DR. APOSTOLAKIS: I'm talking about frequency 24 consequence curves, which, in this country, they are not ei . * .
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| 12 5 used. But, for examp1'e, if you use a frequency consequence '
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| j 266 l' curve, then you can d,o what Ridge Farmer did 32 years ago,
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| [ }
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| 2 for the anticipated operational occurrences, you are forcing 3 the curve to turn around. I remember his words in the
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| ~
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| 4 paper, "We want thesd:to .-
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| be less frequently largely because 5 of the nuisance value of dnticipated occurrences."
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| . .) :
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| 6 In other words,'there is no risk there, so the 7 curve would have gone' straight up. The frequency 8 consequence straight up, but when it comes to very low I i
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| 9 consequences, high frequency, he forces the curve to turn !
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| l 10 around, largely due to the nuisance value. j 11 So there are clever ways of doing things like that 12 using one metric. So;that's the kind of thing that perhaps '
| |
| 13 you want to -- take a':~ f resh 'a look, that's all I'm saying.
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| 14 MR. KING: Nothing'is off the table at this point.
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| (O) 15 DR. BONACA: BuIt I think that it's important for 16 anyone making the decisions also to have a clear 17 understandinghereoflthislayeringofexpectationsthat 18 were set up in the original design, because if you use just 2
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| 19 the CDF and LERF, you.'reajust using the highest material 20 there. There is no intermediate.
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| 21 You've got to understand what we're going to 22 replace the existing body of regulation with and what the 23 expectations are going'to be and so on.
| |
| 24 So that's a. good point here, but it would be 25 interesting to have almost like a summary. I would like to I 1
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| ^
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| 267 1 see it presented in a way that if I'm looking at a logic 2 diagram that George was mentioning before, I can also look l
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| 3 at the other, the old logic diagram, really, which was based 4' on the expectations for anticipated transient and all those 5 things.
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| l 6 MR. KING: I understand your point and I think we 7 need to, as we get into tilis, do that. Again, at this 8 stage, we're not proposi[g" answers to these things. These 9 . are just being put forward as things as we get into the y,
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| 10 study that have to be dealtewith.
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| 11 Again, my okn view is this is the heart of th'e 12 whole thing.
| |
| 13 DR. APOSTOLAKIS: That heart depends on another 14' bigger heart, the safety goals.
| |
| 15 MR. KING: True.
| |
| 16 DR.APOSTOLhKIS: The Commission says go with what 17 we have now, then you do'it in a certain way. If they say 18 no, we're changing a hew things, then you do it in a 19 different way.
| |
| 20 Is the Commission aware of these things that are 21 to be revised in the safety goal policy statement?
| |
| m 22 MR. KING: At th'e Commission briefing.on September 23 7, we made these connections with the Commission.
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| 24 DR. APOSTOL'AKIS: Good.
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| l 25 MS. DROUIN: And which risk metrics and criteria I ANN RILEY & ASSOCIATES, LTD.
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| 268 l
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| l 1 you choose and the re,ason we had it on there is because we
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| ( 2 have not pre-decided and.it's not just CDF or LERF, because 3 it could be highly dependent on which requirement you go 4 after and which one i*s best suited to make that risk-5 informed. f:1 6 DR. APOSTOLAKIS: Fine.
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| l 7 MR. KING: Okay. The next, task two then is once 8 we've got these candidates and we understand them, how do we
| |
| ! 9 decide which are the onesiwe want to work on first.
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| So we 10 got this prioritization step in,there. ,
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| 'll That will probably'be based'upon some qualitative ,
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| 4 , ; l 12 judgment. There may be som,e', quant!'itative cost-benefit kinds 13 of considerations, but! onb of th'e things the Commission 14 asked us to do was to -- if there are things that come out 15 cf our study that are,' obvious candidates for change, don't 16 wait till the end; let's tring those up right away.
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| 17 This would be a step that could identify some of l 18 those and, also, when we go to the Commission with a study, 1
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| 19 we may have so many t'hings on our plate that by December of 20 2000, we can't look at'.all of them. So we want to look at ,
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| l 21 the ones that are most,*important and then go to the j l 22 Commission and proposs'a follow-on activity to look at the ;
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| 23 rest. [ .
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| 24 So we feel this prioritization is important to get 25 in fairly quickly,in the study process.
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| l '. 269 1- MS. DROUIN: The only thing that I would add here, I
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| () 2 3
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| I think this is one step in particular that we really need some industry feedback, because whereas we can point to what 4 our resources are, where the best benefit in terms of 5 reducing ~ unnecessary burden from the licensee, we don't have
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| : u. v , .
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| 6 that data. $" /
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| 7 So that's feedbbck that we really would like from 8 industry, from the sthkeholders. ,
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| e 9 MR. KING: 5es. I think the biggest piece of )
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| 10 missing information is the burden piece and it's really 11 -industry is in the best position to identify that. We 12 brought that up at the workshop. We've got some verbal 13 commitments to work w(ith'us on that, but that's really where l
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| r .
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| 14 we -- we can't develop th'at.ourselves. We've got to have '
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| () 15 their help on that. .
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| 16 Then task thr'ee, you've got the candidate list, I
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| a 1 17 you've put them in priopity order. Then you've got to go in 18 and come up with a recomme~ndation to the Commission. That 1
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| 19 involves using the cr'iteria we talked about a couple slides _
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| 1 20 ago and it's going to involve some work, some engineering 21 work.
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| 22 The recommendations that we want to present are 23 not going to be in the form of a proposed rule or a proposed
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| : c. .
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| 24 reg guide. What they.'re, going to be is they're going to lay
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| 25 out to the Commission [the scope and nature of the changes ll ANN RIL2Y & ASSOCIATES, LTD.
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| 270 1 and do enough work to establish the feasibility. In other O
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| V 2 words, that you do, by making these changes, you actually do 3 make improvements, whether they're improvements in safety or 4 improvements in unnecassary burden reduction or consistency.
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| .5 Then if the Commission says yeah, we agree, then l
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| 6 the more detailed work that,you'would need for regulatory
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| 7 analysis and so forth would take place.
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| 8 So what we had in mind was, for example, if we w
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| 9 identify a large break LOCA scenario that we think is too j 10 many excessive conservatisms, we do analysis like analyze 1
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| 11 what's on the books today and then analyze it in the best j 12 estimate fashion and that would identify the potential 13 improvements you could make, and then you'd have to decide, I
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| i 14 okay, I want to get rid of some of this unnecessary j 15 conservatism and make some judgments on what you would 16 change the new scenario to, the new assumptions to, and then 17 do another calculation to show what benefit you gain by 18 making these changes,'and then go back to the Commission and 19 recommend, in a conceptual way, a ballpark way, what changes 20 we think would make sense to make.
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| '21 So that's really what this task three is all 22 about. I want to mention this fourth bullet down here. We 23 also have to decide, for example, if you take peak clad 24 temperature, do we want to just come up -- do we think the 25 2200 degrees in the regulations now is excessively 1
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| 271 L'
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| 1 conservative, do we w' ant to just change it to some new peak 2 clad temperature that we think makes sense or do we want to take a look at the_ basis for that number, are we trying to 4 prevent cladding failure,,.are we trying to limit the number 5 of cladding failures or the types of cladding failures, or
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| : 6. are we really just trying to prevent a full core damage 7- accident.
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| 8 Today's 2200 degrees and 17 percent oxidation have 9 one basis as to what 'they're trying to achieve, but from a 10 risk-informed standpoint,4we might want to go in and take a 11' look at those bases ahd see do we want to change those, as 12 well. So that aspect ( is thrown in, as well.
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| 13 AsMarysaid,;h'saniterativeprofess.
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| This is 14 the iterative slide,ewhich shows how we.go through and each 15 task sort of -- we have to go in and test, come up with a 16 . recommendation at each point and then go back and test it.
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| 17 You might have to cycle through several times 18 before you come out at the.end and say yes, I do meet those 19 desiredcharacteristics,I'wanttogoforwardwiththis 20 . recommendation. ,
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| 21 MS. DROUIN: At each step of the process, it's a 22 learningthingandso^whekheryou'reintheveryfirsttask 23 when you identify an'd' ihen when you start getting into the 24' prioritization or even wh'en you start getting into the 25 changes, you might learn new things that put you back to ANN RILEY & ASSOCIATES, LTD.
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| l 272 i 1 either, say, okay, this is no longer a candidate or I've 1
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| [--},
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| N 2 looked at it the wrong wa*,y because everything, when you get 3 into one requirement feeds.into another and how they -- it's 4 this tapestry that could. tot. ally unravel if you don't 5 constantly look at it,2an integral fashion.
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| 6 .MR. KING: l. Cine thing we want to do to try and test l
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| 7 - out the method'we're using for the study is to take one rule l
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| 8 and just run it throppA the whole process quickly. It was l
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| 9 suggested at the work'shopf5'O.44, the combustible gas control 10 rule, would be a good one,to do that, where you go in, 11 identify those things ~that look like candidates for change, k 12 make sure we understand the basis, come up with some l 13 recommended revisions-to it, test it against the criteria, 14 desired attributes cr'iteria, and then use that to refine the
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| ~
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| 15 criteria that we're using for screening, for deciding on 16 changes for dealing with these questions that we talked 17 about, and try and do all of that by January, so that that 18 will then help bring the rema'ind'er of the process to give it .
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| I 19 a test, bring it to some form that we think is a fairly j 20 final form, and then we would send that to the Commission as 21 what we're going to use for doing the ren. of the -- looking 22 at the rest of the regulations.
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| 23 So anyway, "it's a trial run, as quickly as we can 24 do it, to test out this whole thing.
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| -25 Issues. We've got a number of i=9ues that have to l
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| I 7[ 273 1 be dealt with in the ,
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| tudy, and we've talked about most of 2 these before.
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| 3 DR. APOSTOLAKIS: We've discussed them.
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| 4 MR. KING: See if there's anything new here.
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| 5 DR. APOSTOLAKIS: That's fine. They have to be 6 resolved.
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| 7 MR. KING: .Ye s.. " They have to be resolved. At 8 this point, they're open questions._
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| 9 DR. APOSTOLAKIS: Does anybody disagree? So let's 10 go to 18.
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| 11 MR. KING: Okay'. Schedule. As I said, the test 12 case, we're shooting for January to have that done. At that 13 point, we would have a wo'rkshop that would focus in on the 14 results of the rest case, as well as try and finalize'the 15 criteria we're going to uh'e for the rest of the study, 16 elicit some feedback, come.back to the committee, this 17 committee, and present the criteria or final criteria and !
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| 18 approach that we're going to use for the rest of the study.
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| 19 DR. APOSTOLAKIS: So ACRS, you mean the 20 subcommitt.ee or the com ithee?
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| 21 MR. KING: *I would expect you would want a 22 subcommittee and I w6uld ' expect we would want a full b: ' ,:
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| 23 committee. We would like'a. letter.
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| 24 DR APOSTOLAKIS: Are we writing a letter this 25 time? .
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| '5 . 274 1 MR. MARKLEY: To whatever extent you choose.
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| 2 MR. KING: Ve would like a letter, at this point O)
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| L.
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| 3 in time, on what we p,re,sent today and whatever we present at 4 thefullcommitteenektw'dek. We would like a letter on
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| 5 ' ' "
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| that now. : -
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| l l 6 DR. APOSTOLAKIS: It's the same letter as the one l
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| 7 for option two. .
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| 8 MR. MARKLEY: You can package it together, yes.
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| 9 MR. KING: Then from March through approximately 10 August, we would go through and apply that process to the
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| * 11 other candidate chang'es. Again, havela workshop, shooting 12 for September. Based,'upon_that, finalize the
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| =
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| 13 recommendations, come,bac)C to.the committee around the 14 November timeframe, a, rid our target date to get back to the 15 Commission with recomin,endations is December of next year.
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| 16 Again, if t'he list is too big of things that look 17 like they're candidates'for change, my view is what we would '
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| 18 do in December of 2000 is go as far as we can on the highest I
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| 19 priority ones, come b'ck a o t''the Commission with those, not s '
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| 20 hold everything up wajlting till we get through the whole 21 list, and then recommend that *.ee have a follow-on work to 22 look at the rest of tflem.
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| 23 So our target date is to give the Commission 24 something in December"2000. If it's the whole list, if it's 25 a partial list, remai}n's,tobeseen.
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| p- e 275 1 DR. APOSTOLAKIS: Any comments from around the 2 table?
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| 3 MR. BARTON: It's a lot of work in a short time, f
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| 4 DL. APOSTOLAKIS: A lot of work.
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| 5 MR. BARTON: Short time.
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| 6 DR. APOSTOLAKIS;.. Okay. .
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| Thank you very much, 1
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| l 7 again, Mary and Tom.
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| ~
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| 8 We will takg''a'br.eak.
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| We're ahead of schedule 9 anyway. So back at 2's af'ter,the hour. '
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| 10 [ Recess.]
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| * 11 DR. APOSTOLAKIS,: Okay. We're back in session.
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| 12 Now we will hear from industry on option three. Mr. Heymer.
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| 13 MR. HEYMER:# ~ Good afternoon, again. My name is 14 Adrian Heymer. I'm a project manager at NEI on the reg
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| () 15 reform group. .
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| 16 Thismight[takealittlebitlongerthan15 17 minutes, but I'll try':and move forward as fast as I can.
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| 5 18 DR. APOSTOLAKIS': We'll help you. You can be sure 19 about that. .
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| 20 MR. HEYMER:' Improving the technical requirements 21 associated with the NRC-regulations is part of this overall 22 approach, which we think is a full-phased parallel effort, 23 improving the oversight'p'rocess, the scope of SSL's governed
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| .s -
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| 24 by the regulations, which were discussed this morning.
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| 25 Then comes improvement of technical requirements, C -
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| .':. 276 1 whichwe'regoingto'dischss, and then the administrative
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| and process impro"ements,'which, in some ways, is a catch-t 3 .all for stuff that tumbles out more on the process side, 4 and, as Biff Bradley said this morning, that's things like 5 50.72, 50.73.
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| 6 The industry's oversight'on this is predominantly 7 through the NEI risk-informed regulation working group, 8 chaired by David Helwig, of Comed, but there's also owners' 9 group activity and soine activity in the co-committees, and ;
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| 10 we're endeavoring to coordinate these actions through the 11 setting up of probably an iss,ue task force just.for this 12 specific activity.
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| 13 I-think our view is consistent with that of the 14 NRC, is identify what we see'as the potential candidate 15 regulations, assess the bhnefit, look at th'e options, make 16 sure that we assess what the real benefit is, prioritize the 17 list of candidates, ahd move forward on rulemaking.
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| 18 It's not nepessarily in that order. We think that 19 some areas, such as on 50.44, we've already,got a lot of 20 information, there has al' ready been a lot of work and )
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| 21 activity in that regard, and we think you could move 22 forward, use that as 'a test case, and probably initiate l
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| 4 23 rulemaking as soon as possible, just on the information that i 24 we have to date. .
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| 25 Work has already started in some areas associated
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| 1 277 1 with LOCA and post-accident sampling and I think these
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| () -2 3
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| should also -- this work heeds to be factored in with what we -- with the studies that are going on. !
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| 4 I guess the.important thing is that where we are 5 today, we want to build on what we've learned over the past 6 30 years. We want to bu'ld i on regulating and operating 7 experience. We want to incorporate'new information. And 8 after 30 years, I think ih's an opporcunity to sit back, 9 take stock, see where we re and see how we can improve the 10 process as we move forward into a restructured generating 11 environment.
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| 12 The risk-informed activities that have already 13 been started or are still in hand, such as those associated 4 .
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| 14 with tech specs, ISI and JST, we should expedite those and
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| () 15 perhqps try and push them a'little bit further than we are j 1
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| 16 planning to do at the moment, just through the common j l
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| 17 -interactions.
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| 18 Our main goal is to improve the efficiency and the !
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| 19 effectiveness of the regulations to get smarter, and in 20 doing that, when you talk about technical requirements, I l
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| 21 agree with some of the statements made here today, you've 22 got to be careful. What initially is the most obvious and 23 straightforward approach may not, in fact, be the smart 24 thing to do. So I think you've got to sit back and assess 25 it, and that's where we support the NRC's view that let's
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| 278 1 assess these, let's look at the benefit, let's look at the
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| () 2 3
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| alternatives, and then make a decision, rather than just charging forward on the first thought process. !
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| 4 The other issueris, and it's not just the u* ,
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| 5 regulations, it's the reg guides, it's the inspection 6 manuals. Some of the'regulat. ions -- in fact, most of them
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| .~'
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| 7 are just general statements.and.E'nglish is a language that 8 has its roots in many other languages. Some people say it's 9 a language for lawyers, but you can read'and interpret words
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| ~~ '
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| 10 in various ways.
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| 11 The only problem is, for the past 30 years, we've 12 had a set of words that we've interpreted in one specific 13 way, things like safety-related. You say safety-related to 14 people in the industry and that means a specific thing.
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| () 15 When you go through a change process, if you say 16 safety-related, that still means the old words, the old 17 interpratation. So p*erhapslin some cases, you may need to 1
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| 18 change the rule just to affect the. cultural change as much 19 as the technical change.
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| 20 I think more of an issue than the regulations is 21 the interpretation in the reg guides. Recently, we've
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| : 22. contacted the industry, based on the statements that were 23 made at the workshop, and have asked them to provide us 24 additional information on what reg guides do they think 25 should be changed and what is.the benefit, with the aim of ANN RILEY & ASSOCIATES, LTD.
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| ; 279 n e 1 providing that-feedbgek to the staff.
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| 2 We expect more 'significant language type changes
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| -3; or more changes to the guldance documents than we do to the 4- regulations.
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| 5 This is.just an. initial set, our initial cut.
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| ;6 What we did is we sat down'and we said what are the criteria 7 that we would look at. Tl)ere are six of them here. There 8 were a.few others, but th'ese'are the main ones. We then
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| : 9. used that criteria to go through the regulations and try and 10 identify the set of regulations that we would look at and 11 assess under option th ee or p'hase three, as we tend.to call 12 it.
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| s 13 It's by no meansf.the final set. We did show them 14 to the risk-informed regulatory working group. They're 15 still thinking about the list of regulations we gave them.
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| 16' We've also asked the industry to provide us additional i 17 input, which we hope to feed back to the staff probably by 18 the end of November.
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| 1 19 At that' point, I'm just reading what's on the l
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| 20 slide. 1 1
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| 21 I guess changing the regulation that would 22 minimize the need fob eke'mptions, although it's not 23 specifically part of-option three, the one that springs to
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| '24 mind is fire. protection in that.' instance, and there is a 25 fairly intensive effort going on in that regard.
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| 280 1 The other important thing here is what we found is
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| () '2 when we went through the regulations, that there are -- in a 3 number of areas, a change that is made, for example, in 4 50.46 cascades down into various other regulations.
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| 5 What we-tried to do is to say, well, what sort of 6 . regulations are those and where would that come out, and we 7 included that in our list.
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| .L 8 This is the list. I'm going to touch on this and
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| *L 9 speak to this a little bit more in-depth in the following 10 slides. Some of these are placeholders. As we said this 11 morning, on 50.59, we might, in fact, implement a change 12 process, a complete change process for 50.59 under option 13 two. So there are some placeholders here.
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| 14 On 50.54, we're not sure whether or not you can O
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| \,,f 15 actually make changes under 50.54 before you've actually
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| '1'6 done all the other regulations, because a number of the 17 license conditions are linked in some way to some other 18 specific regulation.
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| 19 As regards priority --
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| 20 DR. APOSTOLAKIS: Now, your list is not different 21 from the list that the staff showed?
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| 22 MR. HEYMER: No, no. Not at this point in time.
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| 23 As regards priority, we think the one that sort of stands 24 out is 50.46 and Appendix K. One, because a number of other 25 regulatory requirements sort of flow from these, a lot of i ANN RILEY & ASSOCIATES, LTD.
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| 281 1 the guidance documents are linked to these regulations, and
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| /V') 2 the industry has already started work and I believe at least 3 one'of the owners' groups is coming in to talk to the NRC in 4 the next couple of weeks specifically about 50.46 and 5 perhaps what are those plans in that area.
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| 6 And while we are talking about owners groups, it 7 is our intent to try to bring the owners groups together so 8 that we don't have four separate owners groups going into 9 the NRC staff and talking about 50.46 or LOCA, but rather go 10 in as an industry rather than as four separate entities. So 11 there is a coordination element in here.
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| 12 Some of the changes on 50.46 associated with 13 assumptions, input to the analysis, and it's not necessarily 14 the first thing that springs to your mind. A lot of people (O) 15 say it's pipe break size. Well, if it isn't a large break 16 LOCA, what size of pipe are we talking about; then there was 17 the question that was discussed when the NRC were providing 18 their presentation; well, if you don't focus on the large 19 break LOCA, do you change the design in any way that makes 20 that perhaps a little bit more probable.
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| (
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| 21 So I think you need to look at that, but you need j 22 to look at some of the other approaches that are out there, ,
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| 23 look at the different scenarios. Perhaps there's more i
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| 24 ' benefit in looking at a specific scenario than just going i 25 after the large break LOCA.
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| 1 282 l 1 The other thing you've got to look at is, is there
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| ) 2 a generic benefit to the industry. A large break LOCA may 3 be of benefit to some plant and may be minimal benefit to 4 the others. That comment has been made.
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| 5 As regards the scenarios, obviously, one that 6- springs to mind is the loss of off-site power. Other areas, 7 decay heat, peak cladding temperature, and so forth, and I 8 think here, especially with .46, it is let's assess it, 9 let's see, let's think about it, and don't go charging into 10 it. We can't afford too many false starts and we've got to 11 get-it right. So we need to move forward with care.
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| 12 The other thing is once we've sorted ourselves out 13 on 50.46 and the LOCA issue and Appendix K and the 14 methodologies, I think that may open up some other areas,
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| () 15. such as in the fuel design and fuel requirement that are 16 ligked to.some of the general design criteria in GDC-28, I 17 think.
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| 18 As I spoke about earlier, we think 50.44 is a 19 candidate. A lot of work has been done and we think we 20 could move forward with rulemaking in this area next year.
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| 21 I think we've'been working at this since --
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| 22 certainly for at least ten or twelve years, if not longer.
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| 23 I think we do have enough information to move forward.
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| 24 On the technical specifications, there is some 25 activity already going on outside of this area associated l
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| 283 1 with end states, surveillance requirements, allowed outage j 2 _ times, and when do you actually have to go to shutdown from
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| )
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| 3 a 303 issue.
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| 4 I think those need to be expedited. I think, 5 having looked at those, we will then get a better idea of do 6 we really need to change the regulation beyond perhaps what 7 we're changing under option two.
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| 8 The other thing that option two brings to mind is 9 that as you go through option two, you may identify some 10 areas that are candidates for option three. So I think this 11 will be an evolving' structure. For example, especially 12- those SSCs that go into the commercial T or box three, as 13 the NRC staff called it.
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| 14 On equipment qualification, the synergistic t ) '15 effects, the margin, and some of the way that the lanrjuage 16- is-written, I think, we could improve in the interpretation 17- on that. On the TMI requirements, again, somewhat linked 18 primarily to 50.44, but control room habitability, post-19 accident sampling, some of the QA requirements, the way 20 - they're written in there, I think we might want to take a 21 look at; the how to's as opposed to the what's.
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| 22 Again, that may be linked more to the guidance 23' documents and the standards than the specific regulation, 24 although I think we're going to have to change 50.34.
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| 25 On codes and standards, 50.55 (a) I think is like
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| n 284 1 12 pages. It's not an easy regulation to read. I think we
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| () 2 can probably go further, a number of people have suggested 3 we can go further on the ISI/IST than we have at the present 4' time, and I think that's worthwhile taking a look at.
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| 5 I think there is a terminology and a consistency 6 in language that we need to focus on, so that the codes and 7 the standards use the same language and terminology that we 8 use in the regulatory world, maybe to ease the 9 interpretation issues. .
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| 10 I also think that once you get into this and you 11 move forward and get a better handle on what we're doing 12 under the 50.46 and Appendix K, you might want to go back 13 into the codes and standards and adjust them from the 14 technical design basis, but, again, I think you're going to O( ,/ 15 have to look before you step forward in that regard, because 16 we have had a pretty good record over the last 30 years of 17 operating.
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| 18 A lot of conservatism is in there and before you 19 remove it, especially when you're talking about some primary 20 coolant pressure boundary and criteria that relate to that, 21 I think you've got to be a bit careful. You want to make 22 sure there is water in the pool before you go off the ten !
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| I 23 meter board. !
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| 24 On Appendix J, a number of people want to take a j 25 look at this, but Appendix J is very much like the primary ;
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| : 3. ANN RILEY & ASSOCIATES, LTD
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| L 285 1- coolant pressure boundary. You want to be careful with it.
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| 1 3 2 I think it's how you explain the changes is just as
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| 3 important when you're talking about containment as actual
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| ! 4 what you're, in fact, doing.
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| 5 There are some hard systems within containment 6 that perhaps don't need the same degree of testing that we 7 apply today.
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| 8 MR. BARTON: Is Appendix J looking for -- you've 9 already got some relief on Appendix J with respect to the 10 timing of testing. Now you're looking for eliminating some i 11 of the components, the scope of testing or what?
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| l l 12 MR. HEYMER: Perhaps eliminating the testing 13 requirements or removing the limitation that's in there, in
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| -14 some of the guidance documents, which I believe is a O 15 timeframe of five years. That's not to say we're never
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| 16 going to test them. That's going to say that you're going l 17 to.have to have some form of evidence or some criteria to 18 say the testing of these is not as important as some of the l
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| 19 others. I 20 If you had a hard pipe going through containment l 21 that's Class II qualified, the piping out of boundary, if ,
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| 1 22 you like, is the containment boundary, the isolation valve l
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| l l
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| 23 is a nice to-have feature that's out there, should the pipe l
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| 24 be broken for some reason. That's what we're saying. It's 25 worthwhile taking a look at that, at this point in time.
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| 286 1 MR. BARTON: You're looking at eliminating some of 2 the testing, some of the scoping of Appendix J.
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| {}
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| 3 MR. HEYMER: The GDCs, I think, are an example 4 where the language is very much, in many cases, engineering 5 motherhood. There are some specifics there, but I think 6 what flows from the GDCs that you need to look at.
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| 7 And on Appendix E, which is emergency planning, I 8 think we're not looking at the off-site plan at all, but we 9 certainly think we could make some improvements on the on-10 site plan, perhaps along the lines of manning levels, how 11 many people must you have that are required to come in at 30 12 minutes notice, how many people at one hour notice, so 13 forth. So that's where we stand on that.
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| 14 The preliminary list, it's a very cursory overview
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| () 15 on oversight. We've been really focusing on the oversight 16 process and option two up until now. We're just beginning 17 to move on option three and really take an extensive lock at 1,8 that. We take to heart the comments of the staff that we 19 need to give them input for this to happen and we're going 20 to try to do that certainly in the near term, and we'll 21 definitely have that information for them by their next 22 workshop.
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| 23 We think it is worthwhile pursuing this. It's the 24 focus on the right stuff, those things that do have safety-25 significance. I think the direction in which we're moving ANN RILEY & ASSOCIATES, LTD.
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| 287 l 1 gives us a degree of flexibility that helps us to maintain
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| /~%
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| 2 safety in a competitive generating environment.
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| ( } It's a more 3 efficient and effective use of resources and we do think it 4 will be the basis for improving the ALWRs as they're 5 designed today or for any new plants that come along.
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| 6 I guess in conclusion, we support the staff's 7 initiatives or the NRC's initiatives, we agree with their 8 plan. We think it's a necessary and natural step forward.
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| 9 If you look at where the industry is today,_do 10 they need it? Probably not. But as you look forward sort 11 of eight years from now, they're probably going to need 12 something along these lines to continue to move forward and 13 make improvements to the plant while maintaining safety.
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| 14 DR. APOSTOLAKIS: Adrian, you are using the words
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| () 15' risk-informed performance-based approach, and we have heard 16- next to nothing on performance-based today.
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| 17 MR, HEYMER: Yes.
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| 18 DR. APOSTOLAKIS: Are you going to make that an i 19 issue and request that the staff pay serious attention to 20 performance-based regulation?
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| 21- MR. HEYMER: I think the performance-based element 22 is in the oversight process. I think we heard it this ;
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| I 23 morning as regards to once you've recategorized it, you're ;
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| 24 going to have some monitoring criteria.
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| 25 If you look at box three and probably box two, ANN RILEY & ASSOCIATES, LTD.
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| 288 1 you're going to have some commitments to functionality which
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| ~'l (d 2 3
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| I~think are going to be linked.to monitoring and the performance of-the equipment.
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| 4 As'regards the technical requirements, we haven't 5- really thought how the' performance element comes into that, i 6 because at the moment, we see it more in the oversight l
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| 7 process. So that's where we see that being buried.
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| 8 The last point on there is on communication and 9 coordination. We are talking about changing the way we do 10 . business, improving it. Change is never easy. I mentioned 11 the example of the term safety-related and for that, there's 12 many others, and the way.we've interpreted regulations, it 13 means something to me, it may mean something totally 14 different to Mark Rubin and Tom Bergman there that sit
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| ( 15 across the table.
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| 16 So I think it's worthwhile and it's very important 17 to have not only constructive interactions between the 18 industry and the NRC, but constructive interactions within 19 the industry and with the general public to explain this.
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| 20 I think what we did and what we're doing under the 21 first part, which is the oversight process, sets a framework 22 for those interactions; a lot of workshops, a lot of 23 information flowing, and that's really where we are today.
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| 24 It's not very specific. We're just getting 25 started, but at least -- and I went through it fast, in the O ANN RILEY & ASSOCIATES, LTD.
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| 289 1 inte* Jest of time, but I think it's an important element that
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| () 2 3
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| while some people see we're going to do step one, step two is a question mark. I think once you look at some of the 4 advances we can make through the technical requirements, I 5- think more people will come on board with the risk-informed 6 performance-based approach.
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| 7 DR. APOSTOLAKIS: Now, again, your first bullet 8 says industry fully supports NRC initiatives. Is this sort 9 of a general statement or you're referring to what we heard 10 regarding options two and three?
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| 11 MR. HEYMER: As regards the overall approach, 12 which covers oversight, option two, and what we've heard so 13 far on option three. I mean, I think there are some 14 variations as what we heard today in option two. We're in
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| () 15 the same book, we're in the same chapter of the book. They 16 may be on page 22 and we are on page 15, but I think that's I 17 down in the details.
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| 18 DR. APOSTOLAKIS: Good. Any comments, questions?
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| 19 Staff? Public?
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| 20 Thank you very much, Adrian. Appreciate it.
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| 21 The final presentation for the day is by Mr.
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| I 22 Riccio, on the revision of 10 CFR Part 50. Would.you tell 23 us who you represent? l 24 MR. RICCIO: Certainly. My name is James Riccio.
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| 25 I'm the staff attorney for Public Citizens Critical Mass r ANN RILEY & ASSOCIATES, LTD.
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| 290
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| 'l Energy Project. It's a pleasure to be here in front of the I
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| 4
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| .(~. ) 2 ACRS. It's one of the few places I feel that you can come 3 here to legitimately debate about the issues and I've been 4 coming to your meetings for about a decade.
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| 5 That being said, I have heard a lot of things 6 around these tables that have given me eason for concern 7 with the direction that the NRC is heading with this risk-8 informing Part 50.
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| 9 I keep on hearing that we're here because we want 10- to reduce thn burden on the industry, and, quite honestly, 11 that is not, to my mind, a legitimate concern for this 12 agency. This agency's concern is to check the public health 13 and safety, not look out for the financial interests of this 14 industry. And the reality is the reason we're here is
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| () 15 because the industry doesn't feel it's going to be able to 16 withstand the competitive environment in which they're now 17 entering into.
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| 18 The public views this as another item in the long 19 line of deregulatory efforts that have been underway at this I l
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| 20 agency, some of which I have had the plearure in i 21 participating in those workshops, as well.
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| 22 We've had reduction of requirements marginal to 23 safety, we've had cost-beneficial licensing actions, we've 24 - had the tech spec re-write, which dropped the limiting 25 conditions for operation by 40 percent, and now we're -- all l''}
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| 291 1 these efforts weren't, obviously, enough to make nuclear
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| ;O 2 power competitive in the new environment, so now we're going V
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| 3 to basically try to apply PRAs to Part 50.
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| '4 We have several -- I have several problems with 5 how this approach is being taken and part of it goes back to 6 the design. basis of these reactors. Your PRAs are premised 7 upon the fact that your reactors meet their design basis.
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| 8 It's my understanding and my belief that they don't and 9 until this agency can explain to me how, for instance, you 10 had Haddam neck operating for 28 years without an emergency 11 core cooling system that would have performed its function 12 or how you could allow Maine Yankee to operate since its 13 construction with cable separation problems or how Big Rock
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| -14 Point could basically have a borated water storage tank that O
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| Q 15 wouldn't have functioned for 13 years, we're going to have 16 problems as to whether or not we meet the design basis.
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| 17 These are just minor examples of what I think is 18 still a pervasive problem in this industry.
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| 19 DR. APOSTOLAKIS: Do you have a document where you 20 list those? I would like to read about it.
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| 21 MR. RICCIO: Actually, I have it. Those are 22 listed in my report and I'd be happy to send it along to 23 you.
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| 24 DR. APOSTOLAKIS: I would appreciate that. Would 25 you send a copy to Mr. Markley?
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| r 292 1 MR. RICCIO: Certainly. I have one here,
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| [3 V
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| 2 actually.
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| 3 DR. APOSTOLAKIS: Thank you very much.
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| 4 MR. RICCIO: Having said that, I've been coming to 5 these meetings for a good deal of time and I don't mean to 6 throw back your own words at you, but I've heard a lot here 7 that gives me reason for pause; things like PRA means never 8 having to say you're certain; things like this is regulation 9 by religion.
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| 10 If what you've done with Farley or if what the 11 agency has done with Farley is an example of how this is 12 going to work, I have real concerns. There are three 13 analyses that were done. You did a deterministic that said 14 inspect, you did an analysis that was part deterministic,
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| () 15 part probabilistic, and that said inspect, and then there 16 was the purely probabilistic analysis and that said you guys
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| '17 are okay.
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| 18 That's where the agency relied upon. They relied 19 purely upon the probabilistic assessment, when the other j 20 assessments said you really should be taking a look at ;
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| 21 Farley's steam generators.
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| 22 You also have DPOs on the books in regards to I 23 steam generators that really, to my mind, haven't been 24 resolved. Some of the comments, we haven't seen enough 25 accident scenarios that have gone into the steam generator O ANN RILEY & ASSOCIATES, LTD.
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| 293 l' to give these Commission the comfort level that they
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| ( 2 supposedly have.
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| }
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| '3 I guess what's going on here is I see the safety 4 net. Instead of seeing the net, I see the holes. The 5 reason that -- at least the reason that NEI has used before 6 the oversight committees that they're pushing this agenda is 7 that because of the improvement in safety and the good 8 operating history that this industry has had over the last 9 few years.
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| 10 We will debate that till the end of our days. But 11 there was a comment made by the ACRS years ago that struck 12 me, and I'm going to paraphrase it, but to think that you're 13 safe because you've oper-.ted safely for a finite period of 14 time, the belief that that means you believe you have an
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| () 15 adequate level of safety is a psychological trap and I 16 believe this agency and this industry are walking into a 17 psychological trap. .
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| l 18 And I don't recall the gentleman's name who 19 brought that up, but it was very legitimate at the time and 20 I think it's even more so legitimate now.
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| 21 He brought up examples like, you know, prior to 22 Chernobyl, the Soviets thought they had an adequate level of 23 safety and it turned out not to be. Prior to the Challenger 24 explosion, we thought we had a -- NASA thought it had an 25 adequate level of safety and it turned out not to be.
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| l 294 1 Right now, this industry believes that it has an f~D 2 adequate level of safety, but it doesn't have enough d
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| 3 history. One of the reasons -- one of the examples of that 4 is the fact that I look at your core damage frequencies and 5 less than one-times-ten-to-the-negative-seventh, that has no 6 basis in reality. You're talking one-times-ten-to-the-7 negative-four even has no basis in reality.
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| 8 If you look at the history of this industry, 9 you've had two core melt or two core damage accidents in 10 less than 2500 reactor years, and that doesn't even include 11 the three test reactors that were melted down, two in Idaho 12 and one in Pennsylvania.
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| 13 So to tell me that you have a core damage 1
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| 14 frequency of ten-to-the-negative-four to ten-to-the- )
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| 15 negative-seven doesn't really wash.
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| 16 I hear the industry saying, oh, we want to instill 17 some reality into the situation. Well, look at that 18 reality. Maybe the large break LOCA isn't very realistic, 19 but neither are your core damage frequencies.
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| 20 We also -- and it puts a chill down my spine to 21 hear people talking about maybe we can risk-base away 22 containment. I've been coming -- like I said, I've been 23 coming to these meetings for a good deal of time. I was at 24 the meeting where Mr. Catton talked about the direct taurus 25 event and how the fact that if you didn't know exactly what f~N ANN RILEY & ASSOCIATES, LTD.
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| ! 295 L 1 you were doing, you were going to reintroduce all the I (-s) j 2 radionuclides that you had scrubbed through the spent fuel 3 pool right back into the environment.
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| 4 Unfortunately, that never made it into the 5 transcript.
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| 6 I also have a pretty good memory of the original 7 version of -- is it 1250, NUREG-1250, on containments? I'm 8 sorry, I don't recall the exact NUREG number.
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| 9- But the original version of that said that an 1
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| 10 early containment failure could not be ruled out for any of 11 the designs inspected. Of course, that was removed when it 12 went to final draft.
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| 13 I guess what I'm saying is I see large holes in 14 your safety net. I don't believe that risk-informing Part
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| ) 15 50 is going to improve safety. I think it's going to reduce 16 the margin of safety that I think right now may not be 17 adequate.
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| 18 I'm going to participate in this process. There L 19 will be others from the public that will participate in this 20 process. I think you'd better include in your schedule the l
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| 21 likelihood of a lawsuit, because -- and this is not just my 1 22 idea. I'm getting people from your agency leaking me 23 information, saying you have to sue on this. I'm getting 24 stuff saying discovery will reveal an amazing story.
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| l 25 I don't have access until I get to that point to i
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| w-296
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| .1 get that information. You gentlemen do. And I hope you
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| (. 2' 3
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| take.a really hard look at this, and I'll be back the next time you have another meeting and we may -- potentially when l 4 you do the full committee, and I hope that -- I guess this 5 is the only place you hear a legitimate debate.
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| 6 And I read the debate about Farley and I realize g 7 your concerns. I'm just sorry the agency didn't act upon 8 them. And I'm hoping that the agency and the industry will 9 be a little bit;more circumspect in the future when they j 10 decide to regulate or deregulate on the basis of a l
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| 11 probabilistic risk assessment.
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| 12 I thank you for your time, and hopefully we can 13 get you all out of here on time.
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| 14 DR. APOSTOLAKIS: Yes. Maybe we can have a couple 15 questions, 16 MR. RICCIO: Certainly.
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| 17 DR. APOSTOLAKIS: Is it possible that all this 18 activity on risk-informing Part 50 and also the regulatory i 19 guides of the last two years, that it gives perhaps a !
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| 20 distorted view of what risk-informed regulation is all )
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| 21 about? l 22 What I mean by that is that the industry has 23 already seen some of the holes you referred to being plugged 24 by immediate action by the staff when the PRA said this is l 25 bad, like the station blackout rule and all these things.
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| 1 O ANN RILEY & ASSOCIATES, LTD, Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 l
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| 297 1 They came out of the PRA, so they made the regulations more 2 stringent.
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| (
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| 3 And, in fact, that's why the industry, according 4 to what we were hearing from NEI up until about two and a 5 half years ago, was really very cool towards PRA, because 6 they viewed this as a tool of additional regulations, 7 justifying additional regulations.
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| 8 So finally they revolted, political situations 9 change and so on. So now the last three or four years, the 10 emphasis has been, perhaps inappropriately so, at least for 11 the agency, on finally using these tools to reduce burden.
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| 12 So leaving aside for the moment your concern about 13 how realistic the PRAs are, which I believe is a valid 14 question to ask, perhaps we're getting a distorted view of
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| () 15 risk-informed regulation by looking only at the activities 16 of the last three years, when, in fact, for the last 20 17 years, this agency was more than happy to create new 18 regulations.
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| 19 MR. RICCIO: Chairman Jackson did say -- I
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| '20 remember her saying that this is a double-edged sword.
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| 21 DR. APOSTOLAKIS: Yes.
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| 22 MR. RICCIO: That when we take a good hard look at 23 risk, there is a potential that we may actually increase 24 regulation.
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| 25 DR. APOSTOLAKIS: And we already have done this.
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| 298 1 MR. RICCIO: And you have already done that in
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| .I 2 Certain instances in the past.
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| 3 DR. APOSTOLAKIS: Yes.
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| 4 MR. RICCIO: My concern is that because of the 5 economic pressures that are being placed upon this industry 6 to compete and perhaps also I'm nanging out a little bit too 7 much with the industry, that I've just been -- all I've been 8 hearing is reduce burden, reduce burden, reduce burden.
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| 9 And I have little confidence that when an item does come up 10 that could potentially increase the regulatory burden, that 11 the agency isn't going to get slapped with having to do a 12 back-fit and, of course, they're going to be challenged on 13 it.
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| 14 So in my mind, the reason the industry is
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| () 15 interested in this is basically to drop their costs as much 16 as possible, because it's a forward-going cost of operation 17 at this point. They already have -- they're getting their 18 stranded costs through the deregulation that's going on at 19 the state level. So the capital costs are being taken care 20 of.
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| 21 They're selling the reactors for ten cents on a 22 dollar in sweetheart deals. So those things are being taken 23 care of, on the one side. '
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| 24 I feel that when this -- when push comes to shove 25 on something that may actually need to be increased, that ANN RILEY & ASSOCIATES, LTD.
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| 299 1 you're going to see this agency being slowed down by the 2 same industry that wants to deregulate.
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| ( And I do feel that
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| ( 3 there has been, over time, a -- you've made very legitimate 4 efforts to try to reduce the burden on this industry.
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| 5 Reducing LCOs by 40 percent, that's a significant 6 chunk. If I reduced the stoplights on my way to work by 40 7 percent, I'd get there a heck of a lot faster, but I 8 wouldn't get there any safer.
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| 9 When I see that all of this deregulatory effort is 10 being done on top of what has already come down the pike, l 11 and I've been around for these other reductions in j 12 requirements marginal to safety, and some of those actually 13 were significant to safety, at least according to NRC's 14 regulatory review.
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| (G) 15 So my confidence level and the public's confidence l
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| 16 level, at this point, is not very good. The things that 17 help the public -- and when I speak of the public, we're 18 talking about a small handful of people here in DC and we're 19 talking about the people that are put at risk around the 20 reactors. Basically, wherever there is a dump or a reactor, 21 we have a constituency.
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| 22 And when I look to those people, the things that 23 concern them are -- like I said before -- the thing like the i 24 Haddam Neck ECCS that wouldn't have functioned for 28 years.
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| 1 25 How is that captured by your PRA? How does the cable
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| 300 l J
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| 1 separation problem at Maine Yankee captu. O in your PRA?
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| 2 And I've heard comments from around this table, 3 yeah, let's see a model fire. I think we're moving in a 4 dangerous direction and I think we're moving there for the
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| {
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| 5 wrong reasons. I believe that the agency has the ability to 6 re-regulate, but, unfortunately, I think if we continue to l k
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| 7 head in this direction, you're going to melt another reactor j 8 and we'll be right back in this room trying to figure out 9 how to put these regulations back in place, so that whatever 10 remains of this industry will-have a life.
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| 11 DR. APOSTOLAKIS: So essentially then your l 12 criticism or your concern is that tool that is being used 13 for reducing burden is not mature enough. It does not 14 reflect the reality or may not reflect the reality out there 15 at some facilities.
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| 16 MR. RICCIO: It doesn't reflect reality. The 17 testimony I can pull from right around this table where 18 that's -- I'm not pulling these from thin air. These are 19 things that I've learned from listening to this committee
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| '20 for a decade now, and it's those things that give me pause 21 for concern.
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| 22 DR. APOSTOLAKIS: I'm just trying to understand 23 your position. Are there any comments from other members?
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| 24 DR. BONACA: I think that we, as a committee, we l
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| 25 feel cautious about these issues, because we recognize them
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| l j 301 l i
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| L 1 and in recent times we have made a very specific statement l
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| ~
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| 2 regarding, for example, using risk information to a larger
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| (~/)
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| 3 degree to take a component.out of service. We felt that 4 that was an important step. l 5 Now, I know.that that's a burden to the industry.
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| 6 They would have liked to see it differently, but I think l 7 that that's a necessary thing. So that's -- certainly, the 8 points you're making are important and we have to be 9 sensitive to those.
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| 10 MR. RICCIO: And if I could add one more thing.
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| 11 The things that are going to help in terms of public 12 confidence, transparency and consistency. This isn't very
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| -13 transparent and I'm atraid once you're done, it's not going 14 to be consistent, in the least, because of the voluntary
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| () 15 nature of this entire project. You're going to end up with 16 a regulatory morass when you're through.
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| 17 You're going to have one reactor being regulated ;
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| 18 differently than another reactor, which you may feel is 19 appropriate, but it doesn't lend to consistency. It 20 wouldn't lend to consistency between regions. It's not 21 going to lend to consistency within regions, and that's 22 going to be a problem.
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| 23 This agency has a hard enough time applying the 24 regs when they're deterministic and on the books. So when 25 we get to the point of where you have two different systems f'} ANN RILEY & ASSOCIATES, LTD.
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| 302 1 operating at the same time, I think you're going to get into 2 trouble.
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| 3 I thank you for your time and your consideration.
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| 4' DR. APOSTOLAKIS: Thank you very much. Is there a 5- question from the staff perhaps?
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| 6 MS. DROUIN: The only thing that I would say is 7 that we keep hearing the word burden. It's unnecessary 8 burden. I think that's a very important point. We're 9 talking unnecessary burden.
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| 10 .DR. APOSTOLAKIS: He may not think it's
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| /
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| 11 unnecessary.
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| 12 MR. RICCIOi If you hadn't melted a couple of 13 reactors, maybe we could say.it's unnecessary.
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| 14 DR. APOSTOLAKIS: Thank you very much, Mr. Riccio.
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| m 15 MR. RICCIO: Thank you. 1 l
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| 16 DR. APOSTOLAKIS: Can we go around the table very 17 quickly and have the members give me advice.regarding option
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| '18 three, points in the letter, or do you want to give them to
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| -19 me in writing?
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| 20 DR. BONACA: We can give you some thoughts now.
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| 21 DR. APOSTOLAKIS: You want to give me some 22 thoughts now. Okay. Well, Mario, you seem to be ready.
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| 23 DR. BONACA: Just one main thing is that in the 24 presentation we heard, there is an attempt to go to option :
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| 1 25 three to look at new reactors, new design, as well as !
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| i i
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| 303 1 existing reactors, and I' feel that this is a task complex
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| ~
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| 2 enough that that.may be a concern.
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| (
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| -3 I think that this task should have very clear 4 objectives.
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| 5 DR. APOSTOLAKIS: Perhaps forget about new 6 reactors?
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| 7 MR. BARTON: At this time.
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| 8 DR. BONACA: At this time. My feeling is that 9 that's one issue that I would like to propose to the 10 committee's consideration.
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| I 11 The other one that I want to -- the one is more of 12 a general thought, that in general, existing designs 73 preceded regulation and because the industry did not know 14 where regulation was going to go, there were significant (G) 15 margins being built into existing designs, and those margins 16 have really paid off in subsequent years, when new concerns 17 came up and new requirements were imposed. And so 18 regulation followed.
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| 19 Now here we are in a process of changing ,
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| 1 20 regulation to accommodate with actions in those margins. I J
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| 21 think that we have to be sensitive about that process. That 1
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| 22 we have to be sensitive enough that we know enough that we, 23 in fact, can reduce those margins, because there is much 24 more burden in going in this direction here, where we're 25 affecting a regulation in a way that will come up -- we ANN RILEY & ASSOCIATES, LTD.
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| I'.
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| l 304 1 discussed here on the LOCA issue, the ECCS issue.
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| ( 2 The ECCS issue could cascade into designs that l 3 have now different' kind of vessels, they have lesser piping 4 - or whatever because of -- and so we've got to be very 5 sensitive that we understand these issues.to the degree that 6 we can,.in fact --
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| 7 DR. APOSTOLAKIS: Speaking of understanding and 8 making sure that we know what we're doing when we-reduce 9 margins:and in light of what Mr.-Riccio just told us, I have 10 a question for Mary.
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| 11 Is there anything in the standard that will make 12 the licensees, when they do their PRAs, undertake a serious 13 effort to really make sure that what the PRA says is the way 14 the plant is? I mean, I'm not just talking about the simple
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| ()' 15 walk-downs. I think'it will go a long way towards giving 16 some degree of comfort to members of the public if they see 17 a systematic approach for checking that the plant, as built i
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| 18 -- that what the PRA analyzes is the plant as it has been i
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| 19- built. l l
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| 20 Is there something like that in there?
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| 21 MS. DROUIN: I'm going to answer this from a 22 personal perspective. It is critical and essential that the l 23 standard address that. :
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| i 24 My recommendation, and it is in there, whether 25 it's to the level of detail that it needs to be, can be O .
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| I 305 1 debated at another time, is what I personally call the plant
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| '2- familiarization.
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| 3 DR. APOSTOLAKIS: I think that's the wrong word, t
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| l 4 We're not talking about the familiarization.
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| 5 MS. DROUIN: But we can debate what it is.
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| 6 DR APOSTOLAKIS: I understand, I understand.
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| 7 MS. DROUIN: But the intent of that is getting to 8 that exact point.
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| 9 DR. APOSTOLAKIS: Speaking then personally as 10 well, I can assure you that will be an issue that will be 11 raised when this committee reviews the standard.
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| 12 MS. DROUIN: I look forward to that, because I 13 think it's critical.
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| 14 DR. APOSTOLAKIS: And the examples I will use will 15 be Mr. Riccio's examples. But this i.s a commitment .
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| 16 Because this has to be put to rest once and for all. We 17 can't have people, and not just interest groups, members of 18 this committee or other technical people, feel uncomfortable i
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| 19 with the PRA numbers. We have to show that, yes, we took 20 into consideration operating history, we did go out of our 21 way to make sure that what we're modeling is real.
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| 22 MR. BARTON: But it's still not going to solve the l 23 issues that Mr. Riccio brought up.
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| 24 DR. APOSTOLAKIS: I don't believe it will.
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| 25 DR. BONACA: But there is a communication process, !
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| 306 1 Mr. Chairman, that is fundamental. The point I mentioned
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| [V)- 2 before, the examples made refer to a specific condition 3 where a system will-not be able to deliver. That specific
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| -4 condition may be an extreme condition under all the possible 5 conditions under which they may operate.
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| 6 For example, all the NPSH issues have to do with 7 .assumingMhbmosphericpressureincontainment, which implies
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| \
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| 8 a fully open containment. There is no steam there, there is 9 no nothing, and you' test to see whether or not the pumps 10 will recirculate.
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| 11 Under those conditions, you have cavitation and 12 .possibly no recirculation. So deterministically, you call 13 the system failed.
| |
| 14 Now, in all the possible recirculation scenarios
| |
| () 15 you may have to consider, you will have to consider in the 16 PIU4. That would be a minute fraction of the spectrum of 17 conditions under which you have to perform.
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| 18 Therefore, you would call the system possibly 19 functional and even successful. There is a true 20 communication problem also from the industry, from .he i 1
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| 21 staff, in the way we treat conditions where a system is not 22 operable, but it's functional. We call it failed, because 23 it's not operable. Inoperable means it doesn't meet the 24 requirements imposed on the system, okay, are deemed to be 25- functional. And I think it's a fundamental issue of C
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| Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
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| 7--
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| l l
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| 307 1 communication that we have to make.
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| () 2 3
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| So from one end, we have to be conservative.
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| the other, we have also to be accurate and the From 4 communications from deterministic licensing are not 5 accurate.
| |
| 6 DR. APOSTOLAKIS: I agree with you, but we have to
| |
| : 7. also realize that perceptions are --
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| 8 DR. BONACA: I understand that. I'm saying, 9 however, that --
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| 10 DR. APOSTOLAKIS: Rational assessment is not j 11 always practice.
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| 12 DR. BONACA: Yes, but there is a communication 13 issue here that I'm just presenting.
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| 14 DR. APOSTOLAKIS: Sure. I understand that, and
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| () 15 I'm sure the staff is becoming more and more sensitive to 16 it. That's, I.think, part of the public workshops, to help 17 everyone-communicate better.
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| 18 So I've got one comment, that maybe they should j 19 not work on the comprehensive revision right now. j 20 Does any other member have -- l 21 MR. BARTON: I had that same comment.
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| 22 DR. APOSTOLAKIS: Anything else?
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| 23 MR. BARTON: No.
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| 24 DR. APOSTOLAKIS: Anything else, Jack?
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| 25 MR. SIEBER: I just don't think we ought to O ANN RILEY & ASSOCIATES, LTD.
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| F 1 308 1 reiterate the absolute necessity of an accurate PRA.
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| / 2 DR. APOSTOLAKIS: Or the quality. Yes,
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| %))
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| 3 absolutely.
| |
| i 4 MR. SIEBER: The standard produces a result that 1 l
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| 5 people'can have faith in, we have to understand the way this l 6 ASME standard is --
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| 7 MR. BARTON: You've got to talk into the mic, 8 Jack.
| |
| 9 MR. SIEBER: In any event -- j 10 DR. APOSTOLAKIS: I understand.
| |
| 11 MR. SIEBER: -- the need for a standard is there. {
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| l 12 DR. APOSTOLAKIS: I think we will put all this to 13 practice when we review the ASME standard. Do I hear 14 anything else from my colleagues? You know my e-mail
| |
| () 15 address if you have any.
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| 16 DR. BONACA: I just wonder if -- you know, this is )
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| 17 an important issue and a. sensitive issue and --
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| 18 DR. APOSTOLAKIS: This being the quality?
| |
| 19 DR. BONACA: This being the presentation we had 20 from Mr. Riccio, and I wonder if we should have that 21 presentation at the full committee.
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| 22 DR.-APOSTOLAKIS: Invite Mr. Riccio back? What do 23 you think?
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| I 24' MR. MARKLEY: He's welcome to come as a member of 25 the public. He can request time.
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| [D ANN RILEY & ASSOCIATES, LTD.
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| (ms/ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 l
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| c-
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| il L
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| ; 309 l
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| 1 DR. APOSTOLAKIS: Pardon?
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| 7\ 2 .MR.-RICCIO: I wasn't invited here, so I just V ~
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| showed up.
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| -3I 4 DR. APOSTOLAKIS: Well, maybe you can think about 5: this proposal by Dr. Bonaca and request time to address the 6 full committee. You only used 15 minutes. I'm sure we can j 7 accommodate that, because I think the committee should hear 8 your. views.
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| 9 MR. BARTON: I think so.
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| 10 DR. APOSTOLAKIS: So please consider that. Is 11 there still time'for the next meeting, next week?
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| 12 MR. MARKLEY: We'll make time, ,
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| 13 DR. APOSTOLAKIS: We are meeting next week. So 14 .t's i up to you. It's'up to you.
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| 15 -MR. RICCIO: Maybe.
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| 16 DR. APOSTOLAKIS: Maybe in November then, after ,
| |
| 17 you give us a chance to read your report and you wouldn't j 18 mind if we disagreed a little bit here and there. i 19 Anything else? We are adjourned. 'l l
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| -20. [Whereupon, at 3:23.p.m., the meeting was !
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| 21 concluded.] i i
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| 22 I 23 i 24 25 O ANN RILEY & ASSOCIATES, LTD.
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| Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
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| | |
| REPORTER'S CERTIFICATE This is to certify that the attached proceedings before the United States Nuclear Regulatory Commission in the matter of:
| |
| NAME OF PROCEEDING: MEETING: RELIABILITY AND PROBABILISTIC RISK ASSESSMENT AND REGULATORY POLICIES AND PRACTICES I
| |
| CASE NUMBER:
| |
| l i
| |
| PLACE OF PROCEEDING: Rockville, MD were held as herein appears, and that this is the original O
| |
| Q transcript thereof for the file of the United States Nuclear Regulatory Commission taken by me and thereafter reduced to typewriting by me or under the direction of the court reporting company, and that the transcript is a true and accurate record of the foregoing proceedings.
| |
| fA liY Mark Mahoney ,
| |
| l Official Reporter Ann Riley & Associates, Ltd.
| |
| I
| |
| | |
| REVISED 9/22/99 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS MEETING OF THE JOINT SUBCOMMITTEES ON RELIABILITY AND PROBABILISTIC RISK ASSESSMENT AND ON REGULATORY POLICIES AND PRACTICES -
| |
| ROOM T-283,11545 ROCKVILLE PlKE, ROCKVILLE, MD SEPTEMBER 23-24,1999 ACRS
| |
| | |
| ==Contact:==
| |
| Michael T. Markley (301) 415-6885
| |
| - PROPOSED SCHEDULE -
| |
| topic PRESENTEB TIME September 23.1999
| |
| : 1) Introduction 1:00-1:10 pm e Review goals and objectives G. Apostolakis, ACRS for this meeting: Status report on T. Kress, ACRS PRA Implementation Plan
| |
| - GAO report GAO/RCED 99-95
| |
| , - SECY-99 211
| |
| '- NRC Staff Presentation
| |
| : 2) 1:10-3:00 pm o Response to GAO report T. King, RES
| |
| * Discussion of SECY 99-211 G. Holahan, NRR e Commission briefing on September 7,1999
| |
| ** BREAK ** 3:00-3:15 pm
| |
| : 3) NRC Staff Presentation 3:15-4:00 pm o Discussion of strategy and T. King, RES and future direction of PRA G. Holahan, NRR implementation Plan
| |
| : 5) General Discussion and Recess 4:00-4:30 pm o General discussion and comments G. Apostolakis, ACRS by Members of the Subcommittee, T. Kress, ACRS items for Subcommittee report to the full ACRS C's G
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| 1 O
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| e l: , September 24.1999 '
| |
| 6)! Introduction 8:30-8:35 am o Review goals and objectives. G. Apostolakis, ACRS for this meeting: Options for risk- T. Kress, ACRS s informed revisions to 10 CFR Part 50 '
| |
| - ACRS report dated December 14,1998
| |
| - Staff Requirements Memorandum dated '
| |
| June 8,1999, on SECY-98-300
| |
| - July 13,1999 Subcommittee -
| |
| - 7) . NRC Presentation 8:35-10:15 am e introductory remarks D. Matthews, NRR I G. Holahan, NRR l
| |
| T. King, RES e Discussion of proposed Commission . T. Bergman, NRR j paper for Option 2 rulemaking plan T. Reed, NRR
| |
| - Discussion of Option 2 mission statement, evaluation matrices, screening criteria, and analysis of alternatives
| |
| - Schedule for proposed changes
| |
| " BREAK " 10:15-10:30 am
| |
| : 8) Industry Presentation 10:30-12:00 noon e Discussion of classification and regulatory S. Floyd, NEl treatment of structures, systems, and T. Pietrangelo, NEl
| |
| . components (SSCs), pilot project scope A. Heymer, NEl e Pilot plant applications NEl, et.al.
| |
| South Texas Project San Onofre Arkansas Nuclear One Fermi .'
| |
| " LUNCH " 12:00-1:00 pm
| |
| : 9) ' NRC Presentation 1:00-2:30 pm e Discussion of proposed Commission T. King, RES l paper on Option 3 to perform a study M. Cunningham, RES on risk-informing the remaining sections f of 10 CFR Part 50 l
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| j
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| | |
| 7- , ,
| |
| '4
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| - September 15,1999 public workshop
| |
| - Industry /public feedback on topics
| |
| ** BREAK ** 2:30-2:45 pm L 10) Industry Presentation - 2:45-3:00 pm
| |
| : e. Industry perspectives on Option 3 S. Floyd, NEl study for risk-informed 10 CFR Part 50 T. Pietrangelo, NEl
| |
| ; A. Heymer, NEl
| |
| : 11) Public Participation 3:00-3:15 pm
| |
| : e. Comments on revising 10 CFR part 50 J. Riccio, Public Citizen and September 15,1999 public workshop on Option 3
| |
| : 12) General Discussion and Adjournment 3:15-3:30 pm e General discussion and comments G. Apostolakis, ACRS -
| |
| by Members of the Subcommittee, T. Kress, ACRS items for discussion by the full ACRS-1 Mpft: Presentation time should not exceed 50% of the total time allocated for a specific Item. Number of copies of presentation materials to be provided to the ACRS - 35.
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| ~O O '
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| ,j INTRODUCTORY STATEMENT BY THE CHAIRMEN OF THE SUBCOMMITTEES ON RELIABILITY AND PRA
| |
| . AND ON REGULATORY POLICIES AND PRACTICES 11545 ROCKVILLE PIKE, ROOM T-2B3 ROCKVILLE, MARYLAND SEPTEMBER 23-24,1999
| |
| - The meeting will now come to order. This is second day of the Joint meeting of the ACRS Subcommittees on Reliability and Probabilistic Risk Assessment and on Regulatory
| |
| , Policies and Practices. I am Dr. George Apostolakis, Chairman of the Subcommittee on
| |
| ! Reliability and Probabilistic' Risk Assessment. Dr. Kress is the Chairman of the j ~ Subcommittee on Regulatory Policies and Practices ACRS Members in attendance are: John Barton, Mario Bonaca, William Shack, Jack 1
| |
| Sieber, Robert Uhrig The purpose of this meeting is to review the proposed rulemaking plan and study for development of risk-informed revisions to 10 CFR Part 50, " Domestic Licensing of Production and Utilization Facilities." The Subcommittees will gather information, analyze j relevant issues and facts, and formulate proposed positions and actions, as appropriate, l .for deliberation by the full Committee. Michael T. Markley is the Cognizant ACRS Staff l Engineer for this meeting.
| |
| l The rules for participation in today's meeting have been announced as part of the notice l of this meeting previously published in the FederalRegisteron September 3,1999. ;
| |
| l A transcript of the meeting is being kept and will be made available as stated in the Federal l l . Register Notice. It is requested that speakers first identify themselves and speak with '
| |
| . sufficient clarity and volume so that they can be readily heard.
| |
| l We have received a request from Mr. Jim Riccio of Public Citizen for time to make oral l statements to the Subcommittees regarding matters discussed during this meeting.
| |
| (Chairman's Comments-if any) l e ACRS reviewed SECY-98-300 in. December 1998 and issued a report to l l Commission dated December 14,1998.
| |
| e in a Staff Requirements Memorandum dated June 8,1999, the Commission
| |
| ' directed the staff to pursue the proposed Option 2 and Option 3 approach.
| |
| I e The joint Subcommittees previously met on July 13,1999, to discuss staff plans on this matter, e ' The staff has met with NEl and licensee representatives several times to discuss options for revising 10 CFR Part 50 and possible pilot participation.
| |
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| p i
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| .Q The staff also held a public workshop on September 15,1999, to discuss possible changes under Option 3.
| |
| We will now proceed with the meeting and I call upon Messrs. David Matthews and Gary Holahan, NRR, and Thomas King, RES, to begin.
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| ,>O :
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| i j Risk-Informing Part 50, t i
| |
| Option 3, Plan l Presented to !
| |
| Advisory Committee on Reactor Safeguards :
| |
| I Presented by i Tom King
| |
| { Mary Drouin Office of Nuclear Regulatory Research U.S. Nuclear Regulatory Commission ;
| |
| September 24,199,9 l
| |
| Outline
| |
| = Introduction :
| |
| I = Public workshop i = Plan
| |
| = I Implementation of plan
| |
| = Issues
| |
| = Schedule O .
| |
| | |
| i BACKGROUND -- SECY-98-300 N
| |
| 1
| |
| = Option 1: Continue ongoing rule changes only (e.g., l 50.65) i j
| |
| = Option 2: Make changes to the overall scope of systems, '
| |
| structures and components covered by those sections of i Part 50 requiring special treatment...by tarmulating new i I i definitions of safety related and important-to-safety l
| |
| ; = Option 3: Study changes to specific technical I l requirements in the body of regulations, including general design criteria. Provide recommendations to the Commission.
| |
| Page 3 tO V
| |
| DESIRED CHARACTERISTICS OF A RISK-INFORMED REVISED PART 50 ;
| |
| i l = Continue to provide reasonable assurance of adequate protection of public health and i safety.
| |
| = Contain requirements on specific attributes of nuclear power plant design and operations commensurate with their safety significance.
| |
| a Safety significance would be assessed using principles of risk-informed regulation ,
| |
| including the following: ,
| |
| > consistency with the defense-in-depth philosophy
| |
| * maintenance of sufficient safety margins l
| |
| j
| |
| * consistency with the intent of the Safety Goal Policy Statement '
| |
| i = Requirements would accommodate the plant-specific nature of the safety significance of design and operational attributes.
| |
| a Provide a clear, consistent, and coherent set of requirements that would also facilitate l i consistency in treatment among the assessment, inspection, and enforcement programs. l a Provide a regulatory basis for all NRC reactor-related activities, including licensing, inspection, enforcement, and assessment.
| |
| = Performance-based to the extent practical.
| |
| * Practical to implement for both licensees and the NRC.
| |
| | |
| t o' PLAK: SCOPE AND APPROACH
| |
| = Adding provisions to Part 50 allowing staff to approve risk-informed 1
| |
| alternatives to current requirements, including:
| |
| i -Revising specific requirements to reflect risk-informed considerations (regulations, regulatory guides, standard review plans) ,
| |
| i -Adding new requirements or expanding current requirements to address risk- i l significant issues not currently covered
| |
| = Deleting unnecessary or ineffective regulations
| |
| = Focus on revising technical requirements a Excluded: fire protection, codes and standards
| |
| * Modify existing requirements, not total rewrite
| |
| = Apply scope definition developed under Option 2 to technical requirements i = Retain design basis concept (i.e., risk-informed design basis):
| |
| -Generic
| |
| -Plant-specific considerations a Small changes around current plant risk profile
| |
| = Light water reactors only r .. I O. !
| |
| i STAKEHOLDER INTERACTION
| |
| = Hold public workshops ,
| |
| m Develop Website l U
| |
| Pase 6
| |
| | |
| L i
| |
| l 1 G STAKEHOLDERS PERSPECTIVES !
| |
| Based on Public Workshop (September 15,1999
| |
| = No concensus regarding candidate changes for top priority ,
| |
| risk-informing 50.44 and 50.46 mentioned
| |
| = For current reactors, looking for relief (risk-informed) on specific issues a For future reactors, should consider more comprehensive revision
| |
| = Keep design basis concept
| |
| = Problems are more with implementing documents than the !
| |
| , regulations !
| |
| l Page 7
| |
| _ :::::17~~~~ ~~ ~ - ~ ~ ~~:~~~ . - _
| |
| ~
| |
| OPTION 3 FRAMEWORK FOR STUDY Phase 1: l A study of the technical I requirements to identify In d I: Identification ofCandidate I potential candidates for change seguirements and Design sosis
| |
| . and preliminary assessment of Axidena to be Rnhed the feasibility of the proposed changes for presentation to the
| |
| , p,,,,,,,g,,,,, ,f c,,,,,,,,
| |
| COMMISS10D l Requirements and Design Basis l Accidents to be Revised l Insk1: Identification ofProposed
| |
| , Phase 2:
| |
| Proposed changes endorsed by the i Commission, detailed analyses will i p be performed to support rule d making Page B
| |
| | |
| F e
| |
| TASK 1: IDENTIFICATION OF CANDIDATE :
| |
| D REQUIREMENTS AND DESIGN BASIS ACCIDENTS TO BE REVISED l
| |
| Perform Screening Process Considering Such Factors as:
| |
| : a Unnecessary licensee and NRC burdens i
| |
| - excessive conservatisim in methods and critena unrealistic assumptions l l
| |
| ! u Frequency ofinitiating event and event scenarios .
| |
| l initiating event: >lE-6/ry i
| |
| core damage: >lE-7/ry large early release: >lE-8/ry a Risk significance of design features / human actions
| |
| - risk achievement worth Page 9 TASK 1: IDENTIFICATION OF CANDIDATE !
| |
| REQUIREMENTS AND DESIGN BASIS l ACCIDENTS TO BE REVISED Understand Basis for Candidate Requirements
| |
| * Identify elements of the requirements; example-
| |
| -analysis methods and assumptions j
| |
| -ingle active failures of SSCs
| |
| ! -acceptance criteria I
| |
| = Identify the purpose for each requiremer.t l -defense-in-depth ;
| |
| -margin for uncertainty j j -accident prevention
| |
| -accident mitigation E Interrelationship with other requirements m Identify potential "conservatisms" u Identify potential " insufficiencies" r.
| |
| l
| |
| | |
| TASK 1: IDENTIFICATION OF CANDIDATE REQUIREMENTS AND DESIGN BASIS O ACCIDENTS TO BE REVISED Key Considerations for Risk-Informed Changes j
| |
| = Defense-in-depth ,
| |
| = Safety margin 1
| |
| = Risk metrics / criteria
| |
| = Monitoring and feedback
| |
| = Treatment of uncertainties and anticipated operational i occurrences l
| |
| Page il u
| |
| O l TASK 2: PRIORITIZATION OF CANDIDATE REQUIREMENTS AND DESIGN BASIS ACCIDENTS Perform Prioritization Considering Such Factors as:
| |
| = Magnitude for improving safety decisions: l
| |
| - requirement covers dominant risk contributors '
| |
| = Resources needed (to implement change)
| |
| - NRC and licensee cost and time to implement
| |
| = Amount of reduction in unnecessary burden
| |
| - less resources / time used than currently expended on existing i process Page 12
| |
| | |
| i 1
| |
| g TASK 3: IDENTIFICATION OF PROPOSED l V
| |
| l CHANGES TO REQUIREMENTS l a Criteria for risk-informing the regulations for:
| |
| -deleting unnecessary or ineffective regulations
| |
| -adding significant safety enhanced regulations
| |
| --revising specific requirements to reflect-risk informed considerations j 1 -prescriptive versus performance-based i i
| |
| a Evaluate the different options for revising a specific requirement
| |
| -Maintain the existiPr, DBA framework, but replace conservative acceptance criteria i
| |
| : with less conservatise criteria based on best estimate calculations.
| |
| -Revise the existitig DBA framework using risk-informed accident scenarios and acceptance criteria
| |
| ; ' For the other body of requirements, the mediods and acceptance criteria are revised
| |
| !
| |
| * For Example: Peak Clad Tsmperature Limit j -Based on engineering calculations that preclude cladding failures i
| |
| -Based on that no significant public risk occurs ! ,
| |
| -Based on a core damage frequency limit for LOCAs l l m Provide recommended changes to Commission ,,,,,, l 1
| |
| 1 J 1 IMPLEMENTATION OF ;
| |
| i APPROACH ii i
| |
| .- . g~ , f
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| mplementation Develop Fmal Changes l to Commission
| |
| \
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| No Page 14 i
| |
| | |
| OC mw' e.* +-ww.ne.m -as--%.m o IMPLEMENTATION l
| |
| ; Pilot Test Study Plan: i 4 = Select single " regulation" to test approach !
| |
| j 50.44 recommended
| |
| = Finalize screening factors and criteria
| |
| = Identify and resolve impeding issues
| |
| = Select remaining candidates and develop recommended changes l
| |
| , Page 15 O , i 1
| |
| ! ISSUES TO BE RESOLVED i
| |
| a Criteria for selecting candidates for changes j
| |
| -frequency ! ,
| |
| -risk !
| |
| -conservatism i a Criteria for recommending changes
| |
| -frequency I i
| |
| ! -risk
| |
| -conservatism
| |
| -defense-in-depth
| |
| -safety margin
| |
| -cost-benefit
| |
| --monitoring and feedback , ;
| |
| a Criteria for prioritizing recommended changes ....
| |
| I
| |
| | |
| i
| |
| ~
| |
| ISSUES TO BE RESOLVED !
| |
| O I .
| |
| U } !
| |
| 4 !
| |
| i e Treatment of uncertainties
| |
| ; -use mean values? l!
| |
| -use confidence level, what level?
| |
| i
| |
| -unanalyzed factors? !
| |
| l l
| |
| m How should the following be factored in:
| |
| -low power and shutdown risk?
| |
| -external event risk?
| |
| -risk from temporary plant configuration?
| |
| l
| |
| - cost-benefit considerations: for safety enhancements, for burden reductions?
| |
| -PRA quality?
| |
| -human performance?
| |
| i m Treatment of anticipated operational occurrences?
| |
| Ij
| |
| ! PROPOSED SCHEDULE a Risk-Informing Part 50, Option 3 Plan due to Commission, October 1999
| |
| = Finalize " test" case, January 2000 m Public workshop, February 2000
| |
| > = ACRS briefing, March 2000 m Preliminary results on recommended changes, August 2000 :
| |
| = Public workshop, September 2000 m ACRS briefing, November 2000 ;
| |
| = Status on Phase I to Commission, December 2000 ,
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| Atlet.ilirr Enamerms ewd Sysrem Sa/ery 60 (l998i 213-226 Ii Pubbshed by Eisener science Limned All nghis reserved. Pnmed in Northem Ireland g ,,,, , . ,tta.,s,.. n .t ,,....... m s,.s _
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| "o l V
| |
| Use of importance measures in risk-informed I regulatory applications i
| |
| J Michael C. Cheok", Gareth W. Parry *'* & Richard R. Sherry b
| |
| * ' Office of Nuclear Reactor Regulation. US Nuclear Regulatory Commission, Washington, DC 20$$$-000), USA
| |
| ' Advisory Committee on Reactor Sqfeguards, US Nuclear Regulatory Commission', Weshington DC 20555, USA j (Received 11 July 1997; accepted 30 September 1997)
| |
| The use of importance measures to analyze PRA results is discussed. Commonly used imponance measures are defmed. Some issues that have been identi6ed as potentially limiting their usefulness are addressed, namely: there is no simple relationship l between imponance measures evaluated at the single component level and those evaluated at the level of a group of components, and, as a result, some of the commonly used imponance measures are not realistic measures of the sensitivity of the overall risk to parameter value changes; and, imponance measures do not typically take into account parameter uncertainties which raises the question of the robustness of conclusions drawn from importance analyses. The issues are explored in the context of both ranking and categorization of structures, systems, and components (SSCs)
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| /]
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| Q with respect to risk-signincance and safety-signi6cance for use in risk-informed regulatory analyses. Published by Elsevier Science Limited.
| |
| 1 INTRODUCTION Various techniques, based on the use ofimportance mea- )
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| sures of some kind, have been proposed for ranking and j For several of the proposed applications of the risk- categorization of SSCs modeled in a PRA. For example, I informed regulatory process, one of the principal activities in the PSA Applications Guide' the Fussell-Vesely Impor- l is expected to be either the ranking or the categorization of tance, Risk Reduction Wonh, and Risk Achievement Wonh structures, systems and components (SSCs) with respect to were specifically identified as appropriate measures to use.
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| their risk significance, or with respect to their safety-sig. In his paper in the proceedings of PSA 96, Vesely raised a
| |
| . nificance. A distinction is made between ranking and cate- number ofissues related to the use ofimponance measures gorization. The purpose of ranking is generally to arrange in risk informed regulation.2 in this paper, the focus is on items in order of increasing or decreasing imponance. The exploring more fully two of these issues, namely (a) the risk purpose of categorization, on the other hand, is to allocate rankings apply only to individual contributions and not to these items into wo or more groups, according to some pre- combinations or sets of contributors, and (b) the risk rank-set guidelines or criteria. Another distinction is made ings are not necessarily related to the risk changes which between risk significance and safety significance. Depend- result from credible changes to contributor probabilities.
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| , ing on the application,it may be appropriate to categorize or Both these issues raise a concern about the validity of rank SSCs with respect to risk-significance, or with respect using component importance measures at all. In addition, to safety-significance. In the next section, we propose we address the concern about the ranking being affected by definitions of risk-significance and safety significance as uncertainties in the estimates of the probabilities of the basic applied to SSCs. events of the PRA model. First however, we define the Importance Measures, and introduce a Generalized impor-I tance measure which addresses to some extent the second of o}
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| v To whom correspondence should be addressed.
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| l Disclaimer: The results and conclusions contained .
| |
| inthethis twopaper issues on a single SSC level.
| |
| Finally. the relationship between the criteria for screening have not been formally approvea or endorsed by the U.S. Nuclear Regulatory Commission and represent solely the views and or ranking SSCs based on imponance Measures and opinions of the authors. the acceptance guidelines proposed for risk changes in the 213 e
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| | |
| 214 M. C. Cheok et 11.
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| draft Regulatory Guide on the use of probabilistic risk contribute most to a chosen measure of risk would be high- ,
| |
| - assessment in risk-informed (fecisions on plant-specific lighted for increased attention. The risk ranking in this type '
| |
| changes to the current licensing basis
| |
| * is discussed. of application can be based on the cu Tent best estimate risk model. .
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| The second type of application is associated with the 2 RISK SIGNIFICANCE AND SAFETY relaxation of requirements associated with the low signifi-SIGNIFICANCE cance group. Examples of such applications include the extension of test intervals for certain pumps and valves, in this paper, risk significance and safety significance are the reduction of inspection frequencies for certain piping regarded as complementary ways of identifying the role of segments, or the grading of QA for SSCs. In these applica-SSCs in determining the risk from operation of the plant. tions, caution should be applied when using risk significance Risk significance is perhaps easier to define in an opera- to categorize SSCs. SSCs that might be thought of as low tional sense than is safety significance. For example, an risk-significant as individual elements, may as a group, individual SSC can be identified as being risk-significant result in the loss of the redundancy or diversity of a set of if it can be demonstrated that its failure or unavailability equipment required for accident mitigation, to the point l contributes significantly to measures of risk, such as, core where the calculated risk increase would be signific. .. As damage frequency (CDF) and/or large early release an example, consider an Auxiliary Feedwater system with .
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| frequency (LERF). The Fussell-Vesely importance three pump trains. Because of the redundancy, the compo-measure, discussed later, is often used as a measure of nents in each individual train would not likely be risk-sig-risk importance. nificant. However, because of the function played by the .
| |
| Safety-significance, on the other hand. is more difficult to AFW system in the prevention of core damage, the compo-define. Conceptually, safety-significance can be thought of nents in all pump trains as a group could be safety-signifi-as being related to the role the SSC plays in the prevention cant (as discussed in the next paragraph). Since a relaxation of the occurrence of the undesired end state. One way to of requirements has the potential for resulting in an increase capture the most safety-sig..ificant SSCs might be to iden- in risk, it is important to address the potential for this tify those SSCs represented by the complementary cutset increase. Thus this would involve both the current best-esti-elements associated with the risk-significart SSCs. There mate model, and a re-evaluation of that model with the is a weakness in this approach however,in that the reason projected change to the SSCs in the low significance why an SSC is not risk-significant, and may not even show group incorporated.
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| up in the model solution, may be that the complementary The identification and categorization of the safety-sig-SSCs are very reliable. In the extreme case,if there is only nificant SSCs is not straightforward. However, one way to one compensating event (i.e. a two-element cutset),it would address this issue is to focus on the purpose behind the be hard to argue th.a the second event is not safety signifi- categorization. In the draft Re{ulatory Guide on Risk-cant. panicularly if the failure probai>ility of the first is Informed Regulation, DG-1061c a set of principles that relatively high. Following on from this,it could be argued must be addressed in an application for a change to the that all the SSCs considered when constructing the PRA current licensin.g basis of a nuclear power plant is proposed.
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| model (including those that do not necessarily appear in To be consistent with these general principles of risk-the final quantified model, either because they have been informed regulation, the impact of the change on overall screened initially, assumed to be inherently reliable, or have risk measures should be related back to the acceptance been truncated from the solution of the model) have the guidelines for those risk measures. It is the proposed potential to be safety-signincant, since they play a role in change that governs or dictates the categorization, and it j preventing core damage. is the potential impact of the change on the SSCs and on In general, there are two types of applications in risk- the measures of risk which ultimately determines which informed regulation. The first results in increased attention of the SSCs must be regarded as safety significant. It is being paid to the high significance group, and thus can be the group of SSCs for which changes can be made that argued to result in a reduction in risk. An example of such an satisfy these criteria that can be regarded as low safety-sig-application might be the selection of SSCs for goal setting nificant in the context of the application. Thus the real ques- l and monitoring as pan of the implementation of the Main- tion that is being asked in the case of categorization is, for tenance Rule.' (While, as pointed out by one of the which group of SSCs can the change be made such that it reviewers of this paper,it can be argued that the' increased meets the acceptance guidelines in terms of the change in attention in this case is not primarily to decrease risk, but to risk, maintenance of the defense in depth philosophy. and control the increase in risk from component degradation, the maintenance of safety margins. Thus an integrated deci-this application does provide an improvement in the future sion-making process is essential in the categorization risk over what would be the case were the rule not to be process.
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| implemented.) In these cases, the categorization according to To compare with the acceptance guidelines based on risk risk significance is more appropriate than the categorization measures, it seems logical that the most appropriate way to l with respect to safety significance since the SSCs that would address the categorization, particularly in the case of a m
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| | |
| .. 1 Importance measures in risk infonned regulatory applications 215 1
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| (.
| |
| potential risk increase, is through a requantificttion of the associated with the basic event. This measure is particularly
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| }
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| l risk measures. However, there are several applications, for example graded QA, for which there is no clear accepted useful for identifying improvements to the reliability of elements which can most reduce risk.
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| i '8 p- approach to the evaluation of the impact of the change on The Fussell-Vesely imponance is a measure of the frac-l Q SSC unavailability. It is for these applications in panicular that the use ofimportance measures has been proposed as a tional contribution of the basic event to the overall model risk when the basic event probability is changed from its means of establishing the membership of different base value to zero. As will be shown, the Risk Reduction categories. Wonh and the Fussell-Vesely imponance measures are related and the relative importance of basic events using l
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| both the RRW and FV measures is identical.
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| 3 IMPORTANCE MEASURES FOR INDIVIDUAL Some other measures which are used to assess the impor-5 BASIC EVENTS tance of PRA basic events include :
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| Originally, imponance measures were defined for indivi- Birnbaum importance Is = R,+ - RT dual basic events of the plant logic model, as discussed below. Criticality imponance le, = (R,* - RT )b = lsb Ro Ro 3.1 Commonly used measures where P,o = probability of basic event I at its reference value.
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| The three imponance measures that have been most The Bimbaum imponance (also called the reliability commonly used for ranking PRA basic events for use in importance) is an interval risk imponance measure which regulatory applications- are:
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| . is completely dependent on the structure of the system R7 model and is independent of the current probability of the Risk Achievement Wonh a, =
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| basic esent. The Criticality imponance measure is related to the Bimbaum imponance. However, the basic event prob-Ro ability and current risk level are also considered in this Risk Reduction Wonh r4 = imponance measure.
| |
| These risk imponance measures are relatively gross mea-1 Fussell- Vesely PV, = * = 1 R[_ sures of the imponance of a basic event and they generally
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| ~
| |
| Ro Ro suffer the following shortcomings: (1) they measure d ere,' changes in risk and the imponance of basic events only at the extrema (0,1) of the defined range of probability and (2)
| |
| R,* = overall model risk with the probability of basic they do not consider the credible (uncenainty) range for the l
| |
| * event i set to It basic event probability. An alternative measure of impor-l RT = overall model risk with the probability of basic tance which is based on credible changes to event probabil-i event i set to 0; ities is discussed in the next section.
| |
| Ro = base (reference) case overall model risk.
| |
| The Risk Achievement Wonh (RAW) yields the ratio of 3.2 A generalized risk importance measure the model risk with the probability of basic event i set equal to I (the event has occurred or the equipment is failed) to the' Schmidt et al.6 introduced the concept of a generalized base case model risk. The RAW presents a measure of importance measure which was defined as: I the 'wonh' of the basic event in ' achieving
| |
| * the present !
| |
| level of risk and indicates the imponance of maintaining AR, R,a,- Ro t
| |
| = (R,. - Rf \[ P,,,9 - P o)j l
| |
| the current level ofieliability for the basic event. As pointed out in Ref 7, the RAW of a component is not a very discri-K" g, minating measure, and has to be interpreted very carefully. where:
| |
| - While it can be an appropriate measure for assessing a tem-Ro, = the model risk with a new value for the prob-porary change in which an SSC is to be made unavailable,if g;3; g g,;g ,y,,, j; it is used in the context of assessing permanent changes,it is an extreme, bounding measure. However, it is commonly used as P =k obeilin' hic m i m its a vak i an intuitive measure of the margin provided by the component. Rearranging this equation slightly yields the general :
| |
| The Risk Reduction Wonh (RRW) yields the ratio of the imponance measure we will use in this discussion:
| |
| base case model risk to the risk with the probability of basic p p _p L-event i set equal to 0 (the event is impossible or the equip- p0= (R,' - RI) g8 ' j+1 ment is totally reliable) and represents the maximum decrease in risk for an improvement to the. element Funher reanangement and the use of the imponance L
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| | |
| 216 M. C. Cheok et al.
| |
| , Risk Impact C'utye and 1 Relationship of importance Measures g,
| |
| e, . #5 O'
| |
| I sl*9* * (Ri Ro =I afaf = les
| |
| . .1.
| |
| r, rv l
| |
| l 1,
| |
| : 1. #l -
| |
| r, A l
| |
| .. ,., , l be '* l Pa i I
| |
| Fig.1. Risk impact curse and relationship of imponance measures.
| |
| measure definitions given above yields: shewn in Figs 2 and 3. These two curves are for events R,. ,, P,. ,, I e ntained in the Surry Individual Plant Examination (IPE)?
| |
| - = lu - +- Fig. 2 shows the risk importance curve for an event which 8 '0 '' has a relatively low Risk Achievement Wonh and a rela-A similar relationship is derived in Ref 7. These imponance tively large Risk Reduction Worth (when compared with measures are considered general since P,, is allowed any the enteria given in NUMARC 93-01' ). Also shown on valid probability and is not restricted to a value of 0 or 1 as this figure is the risk importance curve (shown in bold) that is the case for a,, r, and FV,. Since the generalized envelopes those of the events which satisfy the NUMARC i importance is defined for all values of P,.,,, a contin"ous 93-01 criteria. The NUMARC 93-01 criterion for the RRW l
| |
| relationship exists between P,, and the generalized impor- (and FV) imponance is exceeded when the slope of the i tance measure. Vesely er al.8 have termed this relationship event risk imponance curve is greater than that of j a risk impact curve. (in this paper we will use the termin. the enveloping curve. (Note that in Figs 2 and 3, the risk l ology-risk importance curve.) The relationship as imponance curves have been plotted on a log-log plot to (
| |
| expressed above is linear with a slope equal to the critical- accommodate the range in probability values. A linear rela- l ity imponance and y-axis intercept equal to the inverse of tionship, when plotted on a log-log scale has curvature. In {
| |
| the risk reduction wonh (1/r, = RT/Ro). This general these figures, the larger the slope of the linear relationship. I imponance measure relationship has the additional prop- the larger the curvature.) On both Figs 2 and 3, the uncer-erty that when P,.,, equals unity the general imponance tainties on the event probabilities have also been shown in measure attains the value of the Risk Achievement Wonh the form of cumulative distribution functions.
| |
| (a, = R7/Ro). Fig.1 illustrates this relationship. As can be Fig. 3 shows the risk imponance curve for an event which shown, and as indicated on Fig. I the FV and Criticality has a large Risk Achievement Wonh and a relatively small Imponance measure are equal and are related to the Risk Risk Reduction Wonh. The NUMARC 93-01 criterion' for Reduction Wonh (see Ref 6 for a clarification of the condi- the RAW is exceeded when the risk ratio (y-axis value) at the tions under which the FV and criticality imponance are right-hand side endpoint of the risk imponance curve (at l identical): P,.,, = 1) exceeds a value of two.
| |
| Using the risk importance curves and the plausible slope n yl = FV = 1 - 3 change in basic event probability gives a different
| |
| #' perspective on the risk importance of the basic events Two illustrative examples of risk importance curves are compared to the perspective gained by using only the i
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| | |
| Importance measures in risk-informed regulatory applications 217
| |
| +
| |
| ,,,, Mak In1 onet Curve - Hic h RRW. Low R1Qg Ev:nt j._._- -
| |
| Surry EDG Unsch. Main.
| |
| A) g so 4
| |
| f t Lognormal j Mean = 6 SE.2 EF=3
| |
| ; 0 so RRW=1.07 RAW =1.90 5th ! 95th cro
| |
| - 0 00 f / ~
| |
| r u, O \ /
| |
| /
| |
| qg4 s#
| |
| g :
| |
| f
| |
| * i l 0.30 0 NuMARCOSC1 g Event Rak broeca Cwwe 0 20
| |
| ___E -
| |
| /
| |
| I C 10 l
| |
| 1.E.1 0 00 1 E.2 1.E.1 1E+0 1.E + 1 1.E +2 1 E+3 Pl,n/PI,0 O /
| |
| t Fig. 2. Risk impact curve-High RRW, low RAW event.
| |
| ]
| |
| RRW and/or RAW. For the event shown in Fig. 3, little with respect to the panicular application. all basic events I i
| |
| change in the risk occurs until the new failure rate is representing the affected modes of the panicular SSC I increased by more than an order of magnitude. Thus it should be considered as pan of a group. Funhermore, could be concluded that changes which potentially may many of the applications in risk informed regulation are impact the probability of this basic event (such as changes expected to have an impact on groups of SSCs, rather to equipment maintenance, testing, Q/A, etc.) are of little than on one individual SSC. Here again, the affected basic concern unless they increase the basic event probability by events have to be considered as pan of a group. In a PRA an order of magnitude or more. On the other hand, for the model, it is the usual practice to estimate the unavailabilities event shown in Fig. 2 where there is a relatively greater of several SSCs on the basis of a single parameter, e.g., the slope in the risk importance curve, relatively small changes same failure probability may be used for a large number of which either increase or decrease the basic event probability the MOVs in the plant. While the change being proposed could have a significant risk impact. Use of this approach to may not impact all the MOVs,it would affect a subset, for characterizing imponance can therefore give guidance on example, those in a redundancy group. The appropriate way how significant the impact of a change has to be to have an to model the impact of the change is to modify the relevant l impact on risk. parameter for that subgroup. Thus, it is the acceptability of !
| |
| the parameter change for that subgroup that is in question. j An additional complication that may have to be addressed i 4 IMPORTANCE MEASURES FOR MULTIPLE for many applications is that the group of SSCs considered BASIC EVENTS for the change may be inhomogercous. For example, it may include MOVs, AOVs, and pumps. Thus, there may be a A panicular SSC may be represented in the logic model by number of failure rates or probabilities that are affected.
| |
| several basic events. These different basic events can repre- Since the overall increase in the risk indices due to the A sent different modes of failure or unavailability of the SSC. change is what has to be controlled, what is of interest is QI A specific application may impact a subset of these modes.
| |
| Therefore, to obtain a measure of the importance of an SSC not the importance ranking or categorization of the basic events representing the affected modes of failure or unavailability of
| |
| | |
| 218 M. C. Cheok et al.
| |
| Risk Impact Curvo - Hioh RAW. Low RRW,5v:nt 1.E+4
| |
| ;U-
| |
| .,a.
| |
| % 7 " 1 ;1Z1 hi I
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| i$
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| ]
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| I!
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| [
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| ij p
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| l hj g q
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| Surry CR Failure to insert Lognormat Mean = 1.8E4 EF=10 l l l [ i jj l
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| RRW=1.002 RAW =1292 1 E+3 5thl n=50thd95th ms I /
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| ;n L
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| 00
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| = ,
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| E e aw cwve y
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| ~~: a f
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| ' = = = Event Unsestunty m / ) b 0 70 R i F N I !! !i 4 !/ !
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| l l' ' = L 0to 1.E*2 L
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| O i l. ,-
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| l M (i ' f i!ni Ib / !! '
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| 0 90
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| . a u ,
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| l e m 4 a a m 1.E*1 10 htP l il-- f.s J ll
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| _, 0 40 i
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| ..if m
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| iH
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| ,o e m i o i nu n0 o I!i ll f h I{i I ild . f jjl ij !]
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| h 0 0 $ b l l' 2f l 0.20 1 E+0 . .
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| i [ n il ! ; im FF i M @ !i:ii i di % M! hl 0 10 hid hl l!i h! 100 h 00 $! k l k.M $ k N b $ $ h m 1 a.1 1.E.1 1.E+0 1.E+1 1.E+2 1.E + 3 1.E +4 1.E+5 1.E+6 1.E.3 1.E 2 Pl n/Pi,0 Fig. 3. Risk impact curve-High RAW, low RRW event.
| |
| these SSCs taken one at a time, but of the SSCs taken as a basic events would be to evaluate the RAW by setting the group. It is the integrated impact of the changes that is of probability of each member of the group to 1.That this is not concern. an appropriate solution can be easily shown. Suppose the As demonstrated in Appendix A, there is no simple rela- cutset equation is of the form:
| |
| tionship between the importance measures of the individual members of a group and the Eroup taken as a whole. One R= AB(Ci + C3)+ DE(C2+ C4) question that needs to be answered therefore is whether it is + g(c, + c3)(c, + c,) + cy possible to develop importance measures for the groups of basic events that are the subject of a change. There are really Following the approach used in many of the standard PRA two parts to this question. The first is whether the impor- software codes, a simple substitution of probabilities for tance measures have a useful physical interpretation, and the each of the events, but setting the probability for each second is whether a meaningful group imponance measure member of the group C to I would result in a RAW of can be established.
| |
| 2AB + 2DE + 4F + GH RAW (C)= AB(C i +3 C ) + DE(C + C4)+ F(C 3 2+ C )(C 4 + C )+ GH The significance of a group of basic events,if it is to be An interpretation of this equation is that, for components measured using the equivalent of RAW, FV and RRW, in series, the effective unavailability of the series group is n, cannot be obtained directly from the individual basic where n is the number of components in series. Thus, the I
| |
| I event importances. Potential group importance measures effect of this simple substitution is the generation of non-are discussed below for those measures commonly used. minimal cutsets, and the group RAW would therefore be larger than expected, with the magnitude of the difference 4.1 Risk achievement worth being dependent on the number of components appearing in series in the logic model. This results because fault trees One possible approach to evaluate the RAW of a group of typically do not include success states. This also suggests I
| |
| | |
| Importance measures in risL-informed regulatory applications 219 that the substitution of I for each of the components in a the probability of that basic event, and provides one way system is not a good way of efaluating system importance, of looking at the defence in depth issue in a probabilistic Another approach is to evaluate the RAW for each of the sense.
| |
| O basic events of the group and add them. The RAW (C i) for a That it is difficult to generate a meaningful group C single basic event taken in the usual way is given by Birnbaum measure that can be used as a sensitivity measure RAW (C i )= A +A 3 2 M M I M )K2 M4)+GH 4 3 AB(C + C3 )+ DE(C2 + C4 )+ f(Ci + C 3)(C2 + C4 )+ GH That this has similar problems to the above formation can can be seen by considering that, when there are terms in the be seen by noting that the numerator of this sum would equation for R which involve multiples of p, this simple l contain a contribution of 4GH. relationship breaks down.
| |
| If the cutset equation were to be evaluated as a probability It might be thought that using the procedures discussed equation with appropriate Boolean reduction, as outlined above for the RAW, might produce meaningful measures.
| |
| below, this problem would be avoided: Then, for example,in evaluating a group %portance using
| |
| : 1. Take the cutset equation for the measure of interest t same equa nfr a , H a substMon of 1 were (CDF, LERF). made for each member of the gmup C, the resulting group
| |
| : 2. Rename the basic events representing the SSCs in the Birnbaum measure would be group under investigation so that they all have 13(C) = 2AB + 2DE + 4F l the same identifier. '
| |
| : 3. Boolean reduce the cutset equation. Following the same substitution and reminimalizing proce-
| |
| : 4. Calculate the risk index for the new basic event with dure as suggested for RAW would result in a ' group Birn-its value at unity, and calculate the RAW using the baum measure' of AB + DE + F. That neither of these is original, unmodified curset eqtiation of the base case an appropriate sensitivity measure can be seen by compar-evaluation (i.e. the denominator). ing them with the sensitivity measure evaluated in a later This gives an imponance measure for the group. In this
| |
| ''C*i ""
| |
| case the group is totally correlated in its effect as the prob-abilities of the individual members of the group are set to
| |
| , gp g. .
| |
| one. The difference between this approach and that taking L tk gmy event probabilities individually to one or zero can I be seen in the following. The Fussell-Vesely measure of importance for a single basic event basically represents the fraction of the risk mea-The substitution of C i, C2. C 3 , C4 by C and the re-reduc-tion of the equation would give m which the basic event contributes. i.e. it is the sum of the cutsets involving the basic event divided by the sum R = ABC + DEC + FC + GH of all the cutsets. The Fussell-Vesely measure obtained and by including all cutsets that contain one or more basic AB + DE + F + GH RAW (C) =
| |
| AB(Ci + C3 )+ DE(C: + C )+ F(Ci + C3 )(C + C4 )+ GH lt can easily be seen that this approach to evaluating a events of the group is given by:
| |
| AB(Ci + C3) + E(C: + C ) + F(C, + C 3)(C: + C4 )
| |
| FVW AB(C + C3 )+ DE(C2 + C4 )+ f(C i+ C 3)(C2+ C 4)+ GH group R AW cannot be expressed simply in terms of combi- This is a measure that assesses the contribution of the nations of the RAW measures for the. individual members of group in such a way that. any cutset that has a contribution the group. from any one member of the group is included Note, how-ever, that this is not the same result that would be obtained by adding the individual Fussell-Vesely measures. Since 4.2 Birnbaum importsnee measure this measure does not involve assessing changes. but is a simple ratio of contributors, this is an appropriate measure The Birnbaum imponance of an individual basic event is of group imponance.
| |
| evaluated by is = RT - RT For a single basic event, the sensitivity of the risk measure to the probability of that event, p, can be parameterized as R(p) = /s p + RT. The 4.4 Risk reduction worth
| |
| (
| |
| (')N ' value of the Birnbaum imponance measure therefore is that it represents the sensitivity coefficient of the risk measure to The risk reduction importance of a single basic event is the
| |
| | |
| 220 M. C. Chrol et al.
| |
| ratio of the CDF to the CDF calculited with the probability 6 THE ROLE OF IMPORTANCE ANALYSIS IN -
| |
| of the basic event set to 0. Substituting 0 for each member of DETERMINING SAFETY SIGNIFICANCE OR RISK the group to calculate the RRW is an appropriate way to SIGNIFICANCE FOR USE IN RISK INFORMED ,
| |
| calculate group imponance since, in thir, case, there is no REGULATION problem with non-minimal cutsets.
| |
| Given the above discussion, it is icasonable to question the 4 5 Generalized importance extent to which component level imponance measures can provide insights to assess the risk-significance and safety-Since the use of this measure is based on a linear sensitivity significance of groups of components, and whether other, equation, it will run Mto the same problems as those dis- more appropriate measures can be established, cussed for the Bimbaum importance measure. This is explored more fully in the next section. 6.1 Risk significance The group FV measure, where the numerator of the expres.
| |
| si n is obtained by summing the probabilities of all the 5 RELATIONSHIP OF IMPORTANCE MEASURES ,
| |
| cutsets which contam at least one basic event of the group TO RISK CHANGES appears to be a reasonable measure to assess the impact of the group of components before the change. Therefore, it is An issue that has been noted by Vesely2 , among others, is a reasonable measure of the nsk-sigmficance of the group.
| |
| that the importance measures are, for the most pan, not This should not be taken to imply that individual basic event directly related to the risk changes associated with the imp rtances are not of value. It is likely that, withm, the change being evaluated. That this is true for those impor-EmuP of interest, because of different roles of individual tance measures which are based on taking parameter values SSCs, or because of asymmetries for example, some or basic event probabilities to their extremes should be c mp nents, and specifically, some failure modes of com-obvious. The one exception appears to be the generalized p nents, may be more 'imponant than others.
| |
| imponance measure. and only then when the SSCs for which This group imponance measure cannot, however, be the change is being evaluated are unique, i.e., the associated related to the impact of the change smee it is not a sensitivity basic events only occur once in each cutset in which they Parameter, and funhermore merely reflects the status quo. A appear, and are independent from all other basic events. relevant question to asi- is, at what value of this Froup FV We have not been able to identify any one sensitivity Parameter can the group be considered to be significant. The measure related to imponance measures that can fill the current c mPonent and system level FV sigmficance cri-role of characterizing the change in risk, panicularly when teria, such as those given in Ref I I, are chosen to represent a group of components is affected by the change. As a a small (0.5% (component) and 5% (system)) contribution simple example, take a cutset equation and treat it as an t the total risk measure. The choice of criterion essentially algebraic equation, replacing each of the events in the determines how much of the rnk is being controlled during group ofinterest by a common parameter, and without per- the change forming a Boolean reduction, differentiate the equation with respect to that parameter. For the equation R = AB(C i + C3 )
| |
| screen for significance means that, for plants with different
| |
| + DE(C: + C4) + F(C i+ C3)(C + C )+ 4 GH, the algei base CDFs or LERFs, the contributions to these risk mea- !
| |
| braic equation would become R = 2ABC + 2DEC + 4FC sures represented by the basic events are, in an absolute I
| |
| + GH, and sense, different. Therefore, if we are interested in control- !
| |
| dR ling the change in risk in an absolute sense. it does not make
| |
| = 2AB + 2DE + 8FC sense to have a universally fixed value of FV as a criterion dC This is a sensitivity parameter that is valid when the for risk-significance, since the FV 1mportance measure is a changes in th; value for C are small, and the approximation relative measure (to the base risk).
| |
| Ag dRac 6.2 Safety significance dC is appropriate if the impact of the change on each member One approach that has been proposed as a means of identi-of the group is the same. This sensitivity parameter is, fying safety-significant SSCs is to use the RAW. The RAW however, different from any of the imponance measures of a basic event is essentially a measure of the impact of derived in the previous sections. As the magnitude of the removing the panicular basic event (i.e. setting its probabil-changes in C increases, higher order derivatives are needed ity to one). The group RAW measure, evaluated using the to assess the change in R. substitution and reduction technique suggested previously, Thus, it can be concluded that the sensitivity of risk to a seems a reasont.ble approach to dealing with a group. How-multi-component change cannot easily be related to compo- ever, it has to be recognized that RAW is a very extreme nent level imponance measures. measure, and that there are very few SSCs,if any, for which
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| | |
| m importance measures in risk informed regulatory applications 221 l the impact of a proposed change is to render them totally course would appear to be to perform a set of well chosen ineffective. If RAW is used as a criterion for categorization, sensitivity studies, based on realistic bounding estimates of I there is an imponant issue associated with the choice of an the changes on event unavailabilities to identify which of l p)
| |
| (,
| |
| appropriate numerical value, It is imponant to realize that, if the categorization is to be the SSCs in the group might be dropped out of the category.
| |
| Thus, by a process ofiteration, it should be possible to arrive used in the context of risk-informed regulatory decisions at a realistic identification of the non-safety-significant based on the safety principles and acceptance guidelines SSCs.
| |
| in DG-1061,3 that, using a ringle value of RAW as a uni- The above approach can be thought of as a top-down ;
| |
| versal criterion for establishing group membership can lead approach to categorization. Another approach would be to to inconsistent treatment of different plants. Consider the f build up the non safety-significant category using a bottom-following example: ]
| |
| up approach. In practical terms this could be achieved by Plant X: R = A B + C, where A = IE-4, B ranking the SSC basic events by their individual RAW {
| |
| = IE-1, C = IE-4, RAW (B) = 1.818; values, then starting from the bottom of the list. building Plant 2: R = A B + C, where A = IE-5, B Up a set that satisfies the group RAW critena developed
| |
| = IE-1. C = IE-5, RAW (B) = 1.818. fmm the acceptance guidelines and the plant specific CDF and LERF. A smular approach was suggested by the Boiling
| |
| , Now suppose that a universal screening criterion for Water Reactor Owners' Group (BWROG) in their topical safety significance is chosen using a RAW valse of 2. In report describing categorization of MOVs in response to this case both plants would classify their respective compo- Generic Letter 89-10, for reviewing the categorization of nent B as low safety significance. Suppose further that the the initially low ranked MOVs. For this group, they sug-change being considered had been assessed as increasing gested a substitution of I for each of the MOVs. and using component B's unavailability by a factor of two in both the increase in CDF tojudge whether the MOVs could really cases. In this case the increase in risk for plant X would be considered as low contributors. DG-1061 gives appropri-become IE-5, whereas, for Plant 2 it would become ate limits on the incre tses in CDF and LERF. A straight IE-6. Thus the same criterion would result in different substitution of I for each of the MOV values results in a impacts on risk depending on the risk profile of the plant, conservative estimate of the potential increase in CDF or and, in particular, on the base risk value. LERF. Replacing all the SSC basic events by the same event The question again, is how to set the criterion for cate- name and reminimalizing the cutset equation would be a
| |
| ~
| |
| gorization into low or high safety significance, using RAW, less conservative approach. This bottom-up approach can recognizing that, for a fixed value of RAW, the change in be made fairly flexible. For exanple, it is not necessary to allowable risk would be different from plant to plant, that sequentially add in the SSCs from the bottom of the list; the the acceptance criteria for the increase in risk applies to the list could be made up by picking and choosing from the low whole group, and that the setting of the event unavailabil- ranked SSCs. This would likely require seseral attempts to ities to unity is generally an extreme, unrealistic way of achieve the optimal set of SSCs. l modeling the impact of the proposed plant change. I One possible approach would be to accept the potentially unrealistic nature of RAW in the first instance, and to tie the 7 DEMONSTRATION OF ROBUSTNESS OF RAW back to the allowable increase in risk (AR). If this CONCLUSIONS FROM IMPORTANCE ANALYSES were the case, the allowable RAW would be determined by l (R + AR)/R. Thus RAW would depend on the base R, and, importance analyses are only as credible as the logic model given the acceptance criteria in DG-1061 for CDF as an upon which they are based. Furthermore, whatever approach example, could take any value above 1.01-1.1 depending is used, importance measures on their own cannot be used on the base CDF. Following this approach, it is clear that it without a demonstration that the results are robust with does not make much sense to define a universal criterion respect to a variety of uncertainties in the model. Since based on RAW.This value of RAW applies to the whole set the only uncertainties that are typically treated formally in of basic events. Ifit were considered useful to translate this PRAs are the parameter uncertainties, the discussion below to a component level criterion, it would be necessary to back will focus on those uncertainties and their impact on impor-out values of RAW at the individual basic event level that tance measures.
| |
| are consistent with this group value. This is clearly depen-dent on the nature of the group, and, in particular, w hen the 7,1 Parameter uncertainties and their impact on elements of the group are inhomogeneous, this is not easily importance measures done it points out however, that, for different applications, with different groups of SSCs, there cannot be a universal Consideration of the risk importance curve discussed screening criterion at the basic event level, earlier,in conjunction with the basic event uncertainty dis-Because of the extreme nature of the RAW measure,it is
| |
| (] tribution provides insights into the robustness of the event U likely that the SSCs identified as safety significant by this importance to risk with respect to the uncertainty in the process would be a large set. At this stage, the simplest event probability. For example, for the event shown on
| |
| | |
| 222 M. C. Cheok et al.
| |
| t - . . ~~~~. __
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| __._- ~ . . - - '~~'L':-_ _ . _ _ _ , _ _ . .~ ~ 2 :-_ _ . _ _~~ :. -:.; . :_'~.E .'.~_.
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| 000001 34 38 8 to 12 14 it 18 20 22 24 26 28 30 32 0 2 4 8 Event Number Fig. 4. Uncenainty in Fussell.Vesely imponance.
| |
| Fig. 3 (an event with RAW equal to 1292) the increase in Ref 11). However, these are not discussed here. This dis.
| |
| risk is less than 1% when evaluated at the 95th percentile cussion will focus on the FV 1mportance measure. The FV in the event uncenainty distribution. This result indicates imponance for an event X,is the ratio of the frequency of that the change in event imponance when the parametcr system failure resulting from failure of event X, to the total value is varied over the uncenainty range for the event system failure frequency. In tenns of the system minimal probability is relatively low. By contrast, the very large cutsets, the FV Imponance is the frequency of the union of value for the RAW would suFgest a much greater impor. all the cutsets containing X, divided by the frequency of the tance than might be warranted. The RAW is measuring the union of all the system model cutsets.
| |
| risk significance if the event failure probability changes from its base value to unity, without considering how cred.
| |
| ible is the assumption that the event probability equals 7[yV-1 c/
| |
| py' , a unity. On the other hand, for the event shown in Fig. 2 (high RRW, low RAW) the slope of the risk imponance k[aSi*j) curve is sufficiently large that the risk increase at the 95th percentile in its uncenainty distribution is significant, repre. where:
| |
| *' " "8 " '" "
| |
| irn nance of i e entis more ensi e to ti e nee ain "[*e "l# odel on the parameter value uncenainty charrtenzation.
| |
| However, this only addresses the uncutainty associated Using the above equation, the uncertainty in the FV with the event whose imponance is being evaluated. The imponance is determined by propagating the basic event following discussion summarizes a methodology for uncenainties throughout the PRA model using simple Monte Carlo (MC) or Latin Hypercube (LHC) simulation to assessing the uncenainties associated with risk imponance determine the distribution on the FV Imponance for each event.
| |
| measures, taking into account the uncenainty on all para.
| |
| meter values. It should be noted that the discussion in this Example results for a set of basic events from the section concerns the uncenainty on the imponance mea. NUREG.ll50'' Surry model are shown on Fig. 4. These sures themselves. There are other imponance measures, events represent the top 25 events (ranked by point estimate called uneenainty imponance measures which are intended FV 1mportance) and a number of other events with FV to identify the SSCs whose uncenainties contribute most to importance decreasing down to below the NUMARC 93-the uncertainty on the risk measures (see for example. 01 criterion for the component FV Imponance (0.5%).
| |
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| p Imponance measures in risk irtformed regulatory applications 223 T:ble 1. Summary of events from NUREG-IISO Surr) Pla t IRRAS modelincluded in study No. Event name . FV imponance Description g i NRAC-7HR 0.251 Non-recovery AC pwr w/in 7 h of LOSP/
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| 4 2 OEP-DGN-FS-DG01 0.248 Diesel generator #1 fails to stan 3 QSSBO 0.233 Power conversion system: Stm gen integrity 4 REC-XHE-FO-DGHWB 0.219 OP fails to rec a DG FM HW fail in 6 h 5 REC-XHE-FO-DGEN 0.180 OP fails to recover a DG within I h 6 OEP-DGN FS 0.169 Diesel generator fails to stan 7 REC-XHE FO-DGHWS 0.169 OP fails to rec a DG FM HW fail in 3 h 8 RCP-LOCA-750 90M 0.155 750 GPM RCP SEAL LOCA tt 90 min 9 NRAC 216 MIN 0.152 Non-recovery AC pwr w/in 216 min of LOSP 10 NRAClHR 0.136 Non recovery AC pwr w/in I h of LOSP 11 OEP-DGN FS DG92 0.129 Diesel generator #2 fails to stan 12 OEP DGN-FS-DG03 0.129 Diesel generator #3 fails to stan 13 OEP-DGN FR-6HDG1 0.118 DG 1 fails to run 6 h 14 BETA 3DG 0.104 Beta for CC failure of 3 DGs 15 BETA-2MOV 0.082 Beta for CC failure of 2 MOVS 16 REC-XHE-FO-SCOOL 0.078 OP fails to get RCP seal cool during SBO
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| . 17 AFW-XHE-FO-CST 2 0.070 Failure of OP to XCONN unit 2 CST I 18 SBO PORV DMD 0.066 PER valve RCS PORV demand PROB during SBO 19 BETA 2DG 0.065 Beta for CC failure of 2 DGs 20 NOTDG CCF 0.065 Success of the third DG after CCF of 2 21 OEP DGN FR-6HDG2 0.065 DG 2 fails to run 6 h j 22 OEP DGN FR-6HDG3 0.057 DG 3 fails to run 6 h 23 AFW-XHE-FO UNIT 2 0.055 {
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| OP fails to XCONN AFW transients j 24 OEP-DGN MA-DG01 0.049 Test and maintenaner on diesel generator I l
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| 25 R O.048 Failure to manually scram the reactor 26 OEP.DGN MA DG02 0.025 Test and maintenance on diesel generator 2 27 OEP DGN MA-DG03 0.024 Test and maintenance on diesel generator 3 28 LPI MOV-PG-1890C 0.02) LPl motor operated valve 1890C plugged !
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| 29 LPR MOV-FT-1860A 0.013 LPR motor operated valve 1860A fails to open 30 HPI XHE FO-ALTS3 0.011 OP fails to ree CCF of HPl discharge MOV 31 HPI-CKV-FT-CV410 0.007 Check valve CV410 fails to open p 32 HPl-XHE FO-UN2S2 0.005 OP fails to XCONN HPI to U2 for S2 D1 g 33 AFW MDP-FS 0.004 AFW MDP fails to stan 34 AFW XHE-FO-UISBO 0.003 OP fails to XCONN AFW SBO at unit 1 35 LPR-XHE.FO-HOTLG 0,002 OP fails to align the system for hot leg REC 1 Table I provides a description of these events and their generator (DG) failure to stan are correlated for DGs 1,2 point estimate FV importance. The results shown on Fig. 4 and 3 in the Surry model. Secondly, events which are basic provide the 5th 50th and 95th percentile values and the events of the same minimal cutsets will have their FV l mean values from the distribution determined from Latin importance correlated. Thirdly, all events are correlated l
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| - Hypercube simulation. Also shown are the calculated through the denominator in the FV Imponance which con-point estimate (PE) FV Importance values, tains the union of all cutsets. ,
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| An important item to note from this figure is that the in order to assess the extent of the correlation, the linear !
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| spread of the uncertainty distribution (5th to 95th percentile) correlation coefficient between the FV 1mportance was cal-is relatively broad-panicularly at lower values for the FV culated for all combinations (pairs) of events included in the Imponance (approaching three orders of magnitude). The calculation. Strong correlation was found to exit between a ;
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| broad uncertainty distributions for these events can pose a number of events. For example Events 2,11 and 12 (Diesel challenge when ranking events based on risk imponance Generators 1,2 and 3 Failure to Start) have correlation since a significant overlap in the distributions for events coefficients exceeding 0.99. This strong correlation results indicates that there may be significant uncertainty in the from the fact that the uncertainties in the basic esent uncer-relative imponarce and ranking for the events, tainty distributions are assumed to be correlated in the To obtain a better understanding of the significance of the model and these events tend to appear together in many uneenainties on the imponance measures to ris'. ranking, dominant cutsets. Event 1 (Failure to Recover AC Power several additional analyses were performed. It was recog- Within Seven Hours of a Loss of Offsite Power)is more nized that the event FV uncenainty distributions are not loosely correlated to Events 2,11 and 12 (conelation co-independent. In fact, they may be highly correlated. Three efficients between 0.4 and 0.5). In this case the basic event p principal sources of correlation can be identified. Firsdy, the uncenainty distributions are not correlated; howeser these v uncertainties in individual basic events may be correlated. events occur together in many cutsets.
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| For example the uncertainties in the probability of diesel As a measure of the robustness of ranking two events
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| l 224 M. C. Cheok et al.
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| 14l Mx i . j j j l .
| |
| X l 2 ,. ..
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| M M
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| . x..!
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| h X t I x ,
| |
| l l
| |
| .g . X y. .4 .
| |
| x M .
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| X X !
| |
| g f
| |
| - + ,
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| t y . i
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| .4 l ,
| |
| l X x X
| |
| ,3 .
| |
| ..l.
| |
| * X g O x M E '
| |
| X X
| |
| .o . . . - t ,
| |
| X X z*
| |
| g X M XX j
| |
| l
| |
| , x *x z. ,
| |
| . X '
| |
| X* xM
| |
| .2 - - - - - - - - - -
| |
| - - l -- - - - --e-- +- --+ - XX X+
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| i , l X* xX X
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| i 1 4 7 10 13 16 it RATIO OF EVENT t ,. a vRTANCES Fig. 5. Ratio of FV imponances-High confidence ranking.
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| based on point estimate imponance measures, calculations been suggested by Jamali", and more recently by Modarres were performed to assess the probability that the FV 1mpor- and Agarwal". However, it can be seen that to implement tance of one event exceeded the FV Imponance of a second this would require modifications to many of the commonly event.This calculation was performed by counting the num- used codes.
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| ber of observations from the Latin Hypercube simulations When categorizing rather than ranking SSCs, the issue is where the FV 1mponance for the first event exceeded the FV somewhat less important, especially if the categorization Imponance of the second event. A score of 95% was is done in a conservative manner, and in an integrated fash-selected as the test measure for robustness-that is, the ion that would account for factors such as defense in depth FV 1mponance of the first event must exceed the FV 1mpor- and safety margins.
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| tance for the second event in 950 out of 1000 observations.
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| For all cases where this test was met it was judged that the 7.2 Modeling uncertainties j first event could be confidently assumed to have greater )
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| imponance to risk than the second event. . There are uncenainties that are not addressed explicitly m Finally, to translate this information into a form that pro- PRA models. Typical are uncertainties associated with how vides meaningful information, the ratio of the point estimate the model itself should be structured. For example there FV Imponance for each event pair combination that passed might be an uncenainty related to the correct success criterion.
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| the robustness test were plotted against the calculated Typically, such uncenainties are dealt with by making an
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| ' correlation coefficient between these events. This plot is ascumption that the model chosen is the correct one. The shown in Fig. 5. The infonnation on this figure suggests user should be aware of such uncenainties and asse>s that a difference of about one order of magnitude (ratio of whether the choice of alternate modeling assumptions FV Imponance of ten) is necessary for a high degree might significantly alter the conclusions of the antdysis.
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| of confidence that one event is more important than another unless significant correlation exists between the events (i.e.
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| their uncenainties are associated and/or they consistently appear together le cutsets).
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| 8 CONCLUSIONS g An alternative approach to ranking under uncertainty has In order to address the issue of consistency with the NRC's i
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| J
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| . _____________________U
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| | |
| Imponance measures in rishinformed regulatory applications 225 4
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| * 1 safety principles and the acceptence guidelines as presentrd eds. R. E. Barlow. J. B. Fussell and N. D. Singpurwsils.
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| in DG-1061,it is important that some rational relationship SIAM Press, Philadelphia,1975, pp. 77-100. f
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| ' be established between the criteria used to assess safety 6. Schmidt, E. R., Jamali, K. M., Parry. G. W. and Gibbon,
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| ./7 significance using importance measures such as the Risk S. H.,lmponance measures for use in PRAs and risk manage. 1
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| \.y, Achievement Worth, and the acceptance criteria. it is . ment. In Proceedings of the International Topical Meeting on l
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| Probabilistic Safety Methods and Applications, San Fran- '
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| more straightforward to establish criteria for assessing risk cisco, CA, EPRI NP-3912 SR,1985, significance, using the Fussell-Vesely imponance measure. 7. Wall, l. B. and Worledge, D. H., Sorne perspectives on risk In panicular, since the applications may affect a large imp nance measures. In Proceedmus of PSA '96, Park City number of SSCs, and it is their mtegrated effect that is of
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| . Utah. September 29-October 3,1996
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| : 8. Vesley, W. E., Davis, T. C., Denning, R. S. and Saltos. N.,
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| anterest, any criteria based on imponance measures must Measures of risk importance and their applications, NUREG/ !
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| reflect this. Clearly, the values chosen must reflect both CR-3385,1983, US Nuclear Regulatory Commission. i the size and the constituency of the group. Because different 9. Virginia Power, Probabilistic Risk Assessment - Surry I applications address different groups of SSCs, it is difficult Nuclear Power Plant Units I and 2 - For the Individual Plant Examination: Final Report.1991- .
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| to establish a simple universal criterion at either the group or
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| : 10. Industry guideline for monitoring the effectiveness of main-the individual basic event level that would not be extremely tenance at nuclear power plants, NUMARC 93 01, Nuclear I conservative for the majority of applications. However, it Energy Institute, Washington, DC,1993.
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| , might be possible to establish a process by which appropri. I1. Cho, Jae-Gyeun & Yum, Bong.Jin Development and eleva-ate criteria could be established as a first step in the categor- 'I " *f an uncenainty imponance rneasure in fault tree
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| * .' ' "" 8 ""
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| ization of SSCs. This would need to be followed up with ' '
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| 3 58.
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| funher analysis using a mixture of qualitative arguments, 12. Benucio, R. C, and Julius. J. A., Analysis of core damage based on an understanding of the role of the component frequency: Sluny unit internal ev nts, e NUREG/CR-4550, Eroups, and well chosen sensitivity analyses to model the Vol. 3. pan 1 USNRC, July 1987.
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| maximum reasonably expected change to parameters to 13. Jamali. K., Rank random variables: A new tool in decision funher refine the categorization. An alternative to this top- making under uncenainty. Presented at the AAS Topical Meeting on Advances in Reactor computation. Salt Lake down approach which focuses on the risk-significant SSCs City, Utah, March 1982.
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| J l
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| is a bottom '.ip approach in which the set of non-risk- 14. Modarres M. and Agarwal. M., Considerations of probabil- (
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| significant SSCs is constructed from the bottom of the list istic uneenaimy in risk-based imponance ranking. In of SSCs ranked according to their RAW values.These alter- Proceedings of PSA 'M. Park City Utah. September 29-October 3,1996. l I
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| natives would have to be tested with real PRA models to see ;
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| )
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| e if the approaches are practical, and give meaningful results.
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| 'd The uncenainty in the probabilities of the basic events i
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| makes it difficult to determine a robust ranking of SSCs with APPENDIX A RELATIONSillPS BETWEEN respect to safety significance or risk significance, For those IMPORTANCE MEASURES FOR GROUPS AND applications that require categorization of SSCs, the INDIVIDUAL MEMBERS OF GROUPS uncenainty plays a much less imponant role. However. con-sideration of uncenainty should be a factor in the integrated Suppose the cutset solution for a simple system is as fog;g,g decision making process, particularly when considering the disposition of those events for which the uncenainty is con- S = ABC + DEF, siderably larger than that typical of the population of basic then events.
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| RAW (C)= AB + DEF l
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| ABC + DEF l REFERENCES
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| ' RRW(C)= ^
| |
| DEF
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| : 1. PSA Applications Guide, EPRI TR 1053%, August 1995.
| |
| and
| |
| : 2. Vesely, W. E., The use of risk imponances for risk-base applications and risk-based regulation. In Proceedings of PSA '96, Park City, Utah, September 29-October 3, py(c), #
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| 1996. ABC + DEF j 3. DG-1061, An approach for using probabilist:c risk assess-meri in risk-informed decisions on plant-specific changes Suppose now S = AB(C + C,) + DET, where i '
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| to the current licensing basis. USNRC, Draft Regulatory P(C)= P(Ci + C ), then Guide, issued for public comment, June 1997.
| |
| 4.10 CFR 50.65, Requirements for monitoring the effective-ness of maintenance at nuclear power plants. Office of the RAW (Cs)= ^ Agc+ pgf > RAW (C)
| |
| Federal Register, National Archises and Records Adminis-O d
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| tration, Washington, DC
| |
| : 5. Lamben, H. E., Measures of imponance of events and RAW (C:)= ABC + AB+ DET > RAW (C) l cut sets in fault trees. In Reliability and Fault Tree Analysis, ABC + DEF -
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| | |
| 226 M. C. Chrok et al. ,
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| i
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| *i and ,
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| end ;
| |
| +
| |
| RRW(Ci )= < RRW(C) RRW(C i )= ^ = RRW(C) = RRW(C2 )
| |
| EF ABC ,
| |
| ""0 ABC + DEF N " DEF + ABCi FV(C i )= ,g( ( + g ,= W :)
| |
| and While this is a simple relationship, for the more general ABC: case of a function whose cutset equatica looked like py(c,) AB(Ci + C2 )+ DEF S = (A + H + C i)(B + 1 + C ),2 the FV measures look like:
| |
| i +1 2)
| |
| ABC2 i FV(C ) = (A + H +i C )(B + l2 + C )
| |
| FV(C;)AB(C, + C2 )+ DEF C2 M + M')
| |
| Note that FV(Ci ) + FV(C2 ) = FV(C). py(c,3 Thus, for the special case of a Froup of components in (A + H + Ci )(B + l + C2 )
| |
| series, the Fussell-Vesely importance measure is additive.
| |
| Suppose now that S = AB(crc )2 + DEF where Thus there is no simple relationship between the Fussell-P(C)= P(crc ). 2 Then Vesely measures of the group and its elements.
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| The examples given above are of simple system models.
| |
| '+ < RAW (C)
| |
| For a more general configuration, some of the Froup of RAWi (C )= ^ABC + DEF components affected by the change may be in parallel and some in series, which would make the analysis more com.
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| '+ < RAW (C) plicated, and the relationship of the individual importance RAW (C:) = ^ABC + DEF measures to that of the group more complex.
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| O l
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| I 1
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| i e ;
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| J}}
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