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Transcript of 990317 Meeting with ACNW in Rockville,Md Re DOE Viability Assessment & High Level Waste Program. Pp 1-105.Supporting Documentation Encl
	ML20204F868
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Issue date:	03/17/1999
From:	; NRC COMMISSION (OCM)
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	REF-10CFR9.7 NACNUCLE, NUDOCS 9903250389
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N DISCLAIMER This is an unofficial transcript of a meeting of the United States Nuclear Regulatory Commission held on March 17, 1999, in the Commission's office at One White Flint North, Rockville, Maryland. The meeting was open'to public attendance and observation. This transcript has not been reviewed, corrected or edited, and it may contain inaccuracies. The transcript is intended solely for general informational purposes. As provided by 10 CFR 9.103, it is not part of the formal.or informal record of decision of the matters discussed. Expressions of opinion in this transcript do not neces.sarily reflect final determination or beliefs. No pleading or other paper may be filed with the Commission in any proceeding as the result of, or addressed to, any statement or argument contained herein, except as the Commission may authorize.

e h S-1 1 UNITED STATES OF AMERICA 2 NUCLEAR REGULATORY COMMISSION 3 4 OFFICE OF THE SECRETARY 5 6 MEETING WITH ACNW 7 8 .9 Nuclear Regulatory Commission 10 One White Flint North 11 11555 Rockville Pike 12 Rockville, Maryland 13 14 Wednesday, March 17, 1999 15 The Commission met in open session, pursuant to 16 notice, at 9:08 a.m., the Honorable SHIRLEY A. JACKSON, 17 Chairman of the Commission, presiding. 18 19 COMMISSIONER'S PRESENT: 20 NILS J. DIAZ 21 GRETA DICUS 22 EDWARD MCGAFFIGAN 23 JEFFREY S. MERRIFIELD 24 25 ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 i l

s. S-2 1 STAFF AND PRESENTERS SEATED AT COMMISSION TABLE: N 2 JOHN GARRICK, Member, ACNW 3 CHARLES FAIRHURST, Member, ACNW 4 RAYMOND WYMER, Member, ACNW 5 DR. KNOPMAN, Technical Review Board 6 DR. BULLEN 7 8 9 10 11 12 13 14 15 16 17 18 1 19 { 20 21 l 22 1 23 24 25 ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut-Avenue, NW, Suite 1014 1 Washington, D.C. 20036 (202) 842-0034

b S-3 1 PROCEEDINGS 2 [9:08 a.m.] 3 CHAIRMAN JACKSON: Good morning, everyone. 4 DR. WYMER: Top of the morning to you, Chairman. 1 5 CHAIRMAN JACKSON: Top of the morning to you. 6 Before we begin, I have a very serious prcsentation I have 7 to make. Given that this is Lt. Patrick's Day, my staff 8 decided that we needed to honor the tradition of one of our 9 Commissioners, so we gave him a three-leaf clover. 10 COMMISSIONER McGAFFIGAN: Very appropriate. 11 CHAIRMAN JACKSON: Good morning, again. This 12 morning we will have the third in a series of Commission 13 meetings on the Department of Energy's viability assessment. 14 The DOE previously briefed the Commission on its high level 15 waste program and viability assessment last month. 16 Yesterday, the Commission was briefed by the NRC 17 staff, the State of Nevada, the affected units of local 18 government, and the tribal governments, on their reviews and 19 views of the DOE viability assessment for the Yucca Mountain 20 site. 21 Today we will hear first from our own Advisory 22 Committee on Nuclear Waste and then from the Nuclear Waste 23 Technical Review .a. 24 The purpose, as all of you know, of the viability 25 assessment is to provide the President, the Congress and the i ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-4 ~ 1 public with information on the progress at the Yucca 2 Mountain site. Its purpose, also, is to identify the 3 critical issues that need additional study before a decision 4 can be made on whether to recommend the site for development 5 as a geologic repository for spent nuclear fuel and high 6 level radioactive waste. 7 As I mentioned yesterday, the Commission is 8 reviewing the viability assessment as part of its 9 responsibility for pre-licensing consultation with DOE. A paper documenting the staff review has been prepared by the 10 11 staff and presently is under Commission consideration. 12 The views of the ACNW and the Nuclear Waste 13 Technical Review Board will be of great aid to the 14 Commission in its review. The ACHW advises.the Commission on all aspects of 15 16 nuclear waste disposal facilities. As an independent 17 Federal agency, like the NRC, the Nuclear Waste Technical 18 Review Board evaluates the technology and scientific aspects 19 of the DOE high level wases management program and reports 20 its findings to the Congress and to the Secretary of Energy. So I welcome representatives of both organizations 21 22 to our meeting today and we look forward to hearing from 23 you. 24 Dr. Garrick, I understand, will begin the I presentation for the Advisory Committee on Nuclear Waste. 25 l 1 ANN RILEY & ASSOCIATES, LTD. ) l Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

1 1 S-5 l l 1 understand that Dr. Knopman will make the presentation on s 2 behalf of the Technical Review Board. 3 My colleagues and I may ask questions from time to 4 time during the presentation. We'll try to be disciplined, 5 since we had an almost four-hour meeting yesterday, but we 6 may ask questione, pertinent ones, but certainly at the 7 close of each presentation. 8 I understand that copies of your viewgraphs and 9 the statement of the Technical Review Board are available at 10 the entrances to the meeting room. 11 Unless my colleagues have anything they would like 12 to add, Dr. Garrick, please proceed. 13 DR. GARRICK: Thank you, Chairman Jackson. What 14 we want to do today is share with you the committee's views 15 on our review of the viability assessment, with an eye 16 towards beyond the viability assessment and the licensing 17 process. 18 We have to note that one of our members, which is 19 25 percent of our membership, is absent today, unavoidably, ~ 20 and we will surely miss him, but we will do our best to fill 21 in for him. 22 We are in the process of preparing a letter on f 23 this subject, and so we have to view what we say today as 24 work in progress. We will be sending you a letter probably 25 next week on the subject and we're hopeful that if something ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

4 S-6 comes out of this today, that we can take advantage of it in' 1 2 the preparation of our letter. We're delighted to be here and in the presence of 3 4 a full slate of Commissioners. 5 CHAIRMAN JACKSON: With a full slate of issues. 6 DR. GARRICK: The many times we've met with you, 7 there's been few times that we've had all five of you, and 8 we welcome the new member, Commissioner Merrifield, and we 9 welcome back Commissioner Dicus. It's nice to see you. As I said, what we want to do is talk about the 10 11 VA, but not just from the point of view of the VA; a look 12 towards the implications with respect to licensing, the 13 progression from the viability assessment to site 14 suitability and licensing. The committee, of course, has reviewed specially 15 16 selected parts of the viability assessment..Our overall impression of the documentation is one of considerable 17 18 positiveness. We believe that DOE has done the best job they've done so far in documenting the status of the Yucca 19-20 ~ Mountain project. The clarity of the documentation has 21 realized an important step forward, in our opinion. We have had the opportunity of meeting with DOE 22 and with.NRC staff on the viability assessment and so we 23 believe those meetings, together with our reviews, have 24 given us a pretty good snapshot of what's going on and a 25 ANN RILEY & ASSOCIATES, LTD. Court Reporters .1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

i S-7 l l 1 basis for our comments. 2 One of the things in slide three that we wanted to ] 3 do'was to sort of anchor our remarks to some basis that is 4 consistent with our role as advisors to the Commission. So 5 that means we want to understand what the licensing basis is 6 and present our comments and remarks therefrom; in 7 particular, we're talking about complying with the standard, 8 plus implementing regulations and guidance, and we have 9 tried to view the VA and where we go from here from that 10 perspective. 11 Of course, what that means is that there has to be 12 some basis for the measurement of performance; in this case, 13 we're talking about basically radiation risk. So we're 14 trying to keep focused on the tracking of that performance 15 measure. 16 The effort that is most effective in dealing with 17 the issue of the risk is the performance assessment. There 18 is a very strong reliance on the total systems performance 19 assessment. So we need to make sure that we understand the 20 evolution of the parameter that constitutes the basis for 21 performance measure. 22 The TSPA VA was a snapshot of DOE progress on 23 perfor. nance assessment and as f ar as focus is concerned, the 24' ACNW review has spent most of its time on the matter of the 25 technology attributes of the design and on the way in which ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 t

1 S-8 those technology attributes have been characterized in the 1 2 performance assessment that has been performed. In slide four, we talk about some of the important 3 t 4 issues that were considered. As we say, we're going to be ) 5 talking principally about the design, number one, and, number two, the logic engine for characterizing that design, 6 7 the performance assessment number two. When we review this, we like to do it in the 8 9 context of specific modules and we like to do it in the context of tracking what happens from rainfall te radiation 10 So we 11 uptake and all of the logical modules in between. talk about water entry to the disposal drifts, we talk about 12 13 waste package and cladding performance, what happens in the waste mobilization process, and the development of a 14 15 radioactive source, sourced radionuclide source term, the 16 transport of radionuclides in the unsaturated zone, and, 17 finally, to the saturated zone and the uptake of 18' radionuclides by biode and dose to humans. We have been quite tenacious on making sure that 19 20' the documentation, the analysis provides the modularization 21-of this mammoth project into phases or modules that seem to be logical and that the' interfaces and links between those 22 modules also seem to be logical and understandable. 23 So what that means is that in addition to the need 24 25 for a credible design, there must be a need for a way to ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

s S-9 1 analyze that design in such a way that all of this 2 information is synthesized into some sort of a performance 3 measure that we can understand and investigate as to its 1 4 credibility. l 5 Of the issues that are involved, and we heard a 1 ( 6 lot about those yesterday, as well, the ACNW believes that 7 water entering the drifts and a credible overall performance l 8 assessment requires considerable work and for,the license 9 . application to proceed. 10 CHAIRMAN JACKSON: Let me just ask you a question, I 11 Dr. Garrick. Given that statement, do you believe that the i 12 plan for additional work that DOE has described is adequate 13 .for addressing your concern, particularly with respect to 14 water entering the drifts? 15 DR. GARRICK: Our preliminary review is pretty l 16 . positive in that respect. We want to be careful to avoid 17 overstating the case of.the lack of data. We think, as a j 1 18 committee, that there's a lot of things that they can do, 19 given the time to license, but, more importantly, and we 20 wanted to come back to this later, given the long time 21 that's involved between now and the closure of this 22 facility, that can enhance the design and the performance of I 23 .the repository. l 24 As far as the DOE's plans, we think that most of l 25 them are relevant to doing that, but we have some comments ANN RILEY & ASSOCIATES, LTD. Court Reporters l 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-10 1 on some other things that we'd like to see. 2 COMMISSIONER MERRIFIELD: Madam Chairman. 3 CHAIRMAN JACKSON: Please. 4 COMMISSIONER MERRIFIELD: I have a follow-on 5 question to that. I was down at the Center for Nuclear 6 Waste Regulatory Analysis last week and was impressed by 7 some of the parallel efforts that they're doing down there 8 to follow along and have us ready to respond. 9 Similarly, are they doing the work necessary in 10 parallel with what DOE is doing? Do we have the right 11 activities underway at the center or are there additional 12 activities you think would be appropriate? 13 DR. GARRICK: Well, it's a good question. We 14 think there could always be more. The research program of 15 the nuclear waste field is quite limited and quite 16 constrained, as you know. We think that they have given 17 that constraint within the budgets they have, they are 18 picking important and useful things to do. But whether or I 19 not the research program is adequate to support the i 20 preparation of the licensing process,-we have some questions 21 about that. In fact, we're writing a letter on that subject 22 next week, too, or writing a report. 23 CHAIRMAN JACKSON: Please. 24 COMMISSIONER DICUS: This is another follow-up 25 question to the first two. What about time lines?

Say, l

ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

i S-11 1 like, from now to the possibility-of a' license application 2 and the work'that needs to be done? Are we in trouble with 3 that, is DOE in trouble with that? j 4-LDR. GARRICK: I think it's awfully easy to say we 5 are, but I think one of the closing comments that we want to 6 make is that-if we take advantage of the time that's l 7 involved in moving from here to closure, if we can somehow 8 move the licensing process in~the direction that 9 accommodates design flexibility, then we have a lot more 10 time between now and when they have to have a license. 11 And if we can pinpoint what it is they do need and 12 make that a part of the licensing process, but allow -- be 13 in a position to take advantage of the -- if there are some 14 changes that could be made, they can be made, and that we 15 can use the time between now and closure, especially given 16 that we're talking about times everywhere from 50 years to 17 300 years, depending upon the alternative that's under 18 consideration. 19 So we're not as pessimistic about the data as some 20 might be, - and I think some of the comments we make will 21 illuminate that issue a little. J -1 22 CHAIRMAN JACKSON: Dr. Garrick -- let me let { 23 Commissioner McGaffigan ask a quest 3rn. 24 COMMISSIONER McGAFFIGAN: You've just made a point 25 that I - ~I don't know if any of you watched yesterday's l ANN RILEY & ASSOCIATES, LTD. l Court Reporters i 1025 Connecticut Avenue, NW, Suite 1014 l Washington, D.C. 20036 1 l (202) 842-0034 j i l

4 S-12 1 briefing, but I asked about -- there's a lot of pressure on 2 DOE to get to a design that is going to be the basis for the 3 license by approximately May of this year. Yet, as you say, 4 it's going to be 50 to 300 years before the repository is 5 closed. 6 I asked whether there was sufficient flexibility 7 in our process. They cited the 6344 process in our proposed 8 rule, which is the allowance for minimal changes, tests and 9 experiments, without the requirement for a license 10 amendment, but then we would also have the license amendment 11 process to deal with suggested changes in any of the design i 12 characteristics as they go forward. j 13 Is there more that we need to do in the way of 14 building flexibility in than the process we currently 15 envision with the 6344 process in the proposed rule? 16 DR. GARRICK: I think that process, together with 17 the~ language that was picked up from Part 60 and carried 18 forward into Part 63, relative to alternatives and the 19 consideration of alternatives, probably provides the 20 mechanisms that are necessary to accommodate that. 21 But I think this is one of the important messages 22 that we wanted to carry, and you've anticipated'it,- and so 23 we,have it sooner rather than later. 24 CHAIRMAN JACKSON: As you go along, Dr. Garrick, 25 I'm particularly interested in this issue of multiple ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

I l a 4 l S-13 1 barriers and I know you're going to talk about it in l 2 defense-in-depth. 3 DR. GARRICK: Yes. 4 CHAIRMAN JACKSON: But let me give you a context 5 for the interest. There appears to be a need to have a l 6 discussion as to what defense-in-depth means for a 7 repository and what the interplay is between the engineered 8 features and the actual geologic environment. 9 So when you speak of the need to have design 10 flexibility and for our regulatory process to allow that and 11 you talk about a time line, I think it's important, though, 12 to posit that discussion within the context of the interplay 13 between the geologic and the engineered aspects of the 14 repository design, because if you're talking a geologic 15 environment and a design of a repository that is boring into 16 that environment, then the question of flexibility is an f 17 interesting one. 18 DR. GARRICK: Right. 19 CHAIRMAN JACKSON: As opposed to the usual 20 engineered features. 21 DR..GARRICK: That's right. 22 CHAIRMAN JACKSON: So I think we need to kind of 23 amplify-that. 24 DR. GARRICK: Well, if we haven't amplified that l 25 by the time we get through my wrap-up, come back with that ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

8 s S-14 1 question again and we will, because we agree with you 100 2 percent, and we have some specific thoughts on how to 3 display that interplay, and we will. 4 CHAIRMAN JACKSON: Dr. Fairhurst, did you want to 5 make a comment? 6 DR. FAIRHURST: Well, most of my talk has been 7 anticipated by a number of the questions now and I'm just 8 wondering at which point to start. 9 DR. GARRICK: So generally, how we want to proceed 10 from here is that I will talk a little bit about the TSPA or 11 about the concept of performance assessment and, as we said, 12 that was one of the two major issues that we wr".c to talk 13 about, and my colleagues, Dr. Fairhurst and Dr. Wymer, will 14 identify specific design issues in the context of 15 performance and then we will try to wrap it up. 16 So with respect to the performance assessment, we 17 have, under slide number five, the words of what we need, of 18 course, is a clear, integrated, probabilistic assessment. 19 Now, I think it's important for us to indicate what we mean 20 by that. 21 And we are in agreement generally with the Coast 22 Guard report that there needs to be a simple English version 23 of,the performance assessment. It's a mammoth effort. It 24 involves a tremendous amount of information and it's extremely difficult for experts to get their arms around it, 25 ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 o

S-15 1 much less the public. 2 So what we're talking about here is the need for 3 improved technical clarity,' particularly with respect to the 4 model itself, and I'll deal with that in the next slide. 5 But the second thing we need is once we kind of 6 understand the pieces and parts of this model and how the 7 linkages occur from rainfall to dose, through the various 8 modules, we need to see very clearly the supporting evidence j 9 to it. 10 And I like to use the word supporting evidence, 11 because sometimes when we use the word data, there is a much 12 narrower view of what constitutes the supporting basis of an 13 analysis than if you broaden it. 14 We're here talking about every: .; from the laws 15 of physics to laboratory measurements, to field 16 measurements, to the results that we can get.'n the 17 international community of which they are extensive. The 18 whole spectrum of information that one can reach for in 19 supporting an analysis. 20 So those two things are very critical. So with 21 respect to the first one, namely, technology clarity and 22 what we mean, we're always looking to try to find a top 23-review, if you wish, of the total model in such a way that 24 we can map from the components of something that is 25 reasonably comprehensible and totally in terms of it being ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

= S-16 1 an integrated model, from that to specific components and 2 subparts of the model. 3 So one of the important requirements in projects j 4 such as this, in our opinion, is to make sure that there 5 exists something that we can always fall back on as a place 6 to put things when we discover them in the details of the 7 analysis. 8 So that means there has to be clearest definitions 9 of modules, interfaces, inputs, outputs. Now, there's been 10 a tremendous amount of progress on that, but we think there 11 can be a great deal more. 12 One of the things that we look for in th'is era of 13 risk-informed thinking is.the consistency of probabilistic i 14 thinking; you know, it's not enough to think about doing one 15 part of the analysis deterministically and another part of 16 the analysis probabilistically, unless there is a rationale 17 developed that connects those two. 18 It is very difficult right now to come to complete 19 closure on that because of the complexity of the model. 20 We're certainly looking for traceability and continuity of 21 the performance measure calculation. The answer to the so 22 what question. Everything we do along the way, we ought to 23 be able to say, well, what's this got to do with the issue 24 of risk, how important it is. 25 As a matter of fact, I want to, at this point, ANN RILEY & ASSOCIATES,.LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-17 1 insert a backup slide that you do not have to make my point, 2 because I think an example sometimes is much better. I 3 apologize that the example is not from the waste field, but 4 rather from the reactor field. But with a little 5 imagination, I think we can translate it to the waste field. 6 It's a little difficult to read, but let me just 7 tell you whr.c it is. Some of the -- and it's an example, in 8 my opinion, of a graphic that really is what we mean when we j i 9 say we're looking for tools and displays and presentations I 10 that add to the clarity of what's going on and that can give ) 11 us insight with respect to the underlying issues, such as 12 defense-in-depth, such as the issue of uncertainty, such as 13 the issue of what are the most important contributors. 14 Here is a real result from a reactor analysis. 15 And if I can do the translation for you, let us suppose that 16 the curve that has the -- this is a probability density, a 17 series of probability density functions and the various 18 curves are risk curves as a result of certain phenomena. 19 We see a risk curve if the only contribution came 20 from seismic, we see one if the only contribution came from 21 storms or winds, we see one for fire, and then we see one 22 that's called internal, which embodies all of the things 23 inherent to the plant that could go wrong and how that 24 contributes to the total risk. 25 Now, let's, for a moment, just assume that the l l l t ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-18 1 total risk was the peak risk curve for the repository, and, 2 of course, there is uncertainty about that. This 3 immediately tell us the basis of the. analysis, what that 4 uncertainty is, and we can start investigation what's behind 5 all of this as to why this uncertainty spread over two and a 6 half orders of magnitude. 7 Let's suppose that where the word internal is, we 8 have rather the waste package failure, the risk due to waste 9 package failure. And let's suppose where we have fire that 10 here we have the risk due to the failure of the natural 11 setting. 12 Now, what this tells us immediately is what kind 13 of balance we have with respect to the contribution to risk 14 as a result of the engineered barriers and the waste 15 package. Then, of course, these others, let's suppose the 16 wind is not wind, but volcanic activity. Then, finally, 17 we'll leave seismic as seismic. 18 There are several things that this kind of 19 presentation will tell you and I've already mentioned a 20 couple of them. But another thing that it tells you is a 21 great deal about how much analysis is needed. For example, 22 if you look at seismic here, here we have the seismic risk 23 is covering something like eight orders of magnitude.

Now, 24 in isolation, somebody would say, well, that's terrible, 25 we've got to reduce the uncertainty from eight orders of ANN RILEY & ASSOCIATES, LTD.

Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-19 1 magnitude down to something more reasonable. 2 Well, the point of this whole presentation is it's 3 not terrible because it doesn't make hardly any contribution 4 to the risk. 5 So the fact that we have eight orders of 6 magnitude, as long as know that, and that's what I mean by 7 quantification, knowing what your uncertainty is, as long as 8 we know that and you have the supporting evidence behind 9 that. We know what it is, we know it's not important. And 10 so it's not taken out of context. It's not grappled in the 11 context of pure science alone. It answers the so what 12 question. 13 So I wanted to present that because I think it's 14 relevant to what I would call the movement towards how we're 15 viewing defense-in-depth, the movement towards how we're i 16 viewing the impact of uncertainty, the movement towards how 17 we're going to important ranks contributors, and it's really 18 what we're pushing for when we talk about risk-informed in 19 such jargon as Monte Carlo analysis, realizations, 20 abstractions and response surfaces. 21 CHAIRMAN JACKSON: Then that raises the natural 22 question, which, in a way, goes back to my original question 23 when I was asking about water infiltration. 24 DR. GARRICK: Right. 25 CHAIRMAN JACKSON: And that is, is there a way or ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite ~1014 Washington, D.C. 20036 (202) 842-0034

S-20 l 1 are you examining for each of these contributions to risk, 2 can you say something about whether or what needs to be done 3 to be able to get to that so what answer and whether the 4 path that DOE is on will allow them to address that and 5 whether -- and this gets back to Commissioner Merrifield's 6 question -- whether the path that we're on in terms of our 7 own analysis will allow us to render a judgment as to 8 whether -- 9 DR. GARRICK: Yes. 10 CHAIRMAN JACKSON: -- the so what question. 11 DR GARRICK: My answer to that is that-I think we 12 can do this. I think that the truth of the matter is that 13 the more I review the DOE documentation, the more confidence 14 I have that you can recast the information into these kinds 15 of presentations. 16 Now, I'm sure, as we do that, we'll find holes and 17 I'm sure that it won't all come out maybe as clearly as we'd 18 like. But I think the information is there to do this kind 19 of analysis and begin to get a risk-informed basis for 20 deciding on issues about what we should be doing with 21 respect to water seepage into the drifts and what have you. So I think a lot of what we're talking about is 22 23 there. I think that what we're not often doing is taking 24 advantage of the fact that we need to present this with all 25 the uncertainties. Sometimes we don't want to do that ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

s S-21 1 because we would rather hold back and'have the uncertainties 2 reduced before we present them. But there is great 3 advantage, in my opinion, in doing it however little the 4 knowledge is. 5 So I'm confident that the answer to the question 6 is yes, it can be done. 7 CHAIRMAN JACKSON: But there are two pieces which 8 you seem to have essentially said. One has to do with 9 knowing what the uncertainties are, however large they may 10 be, but also knowing in terms of the so what question -- 11 DR. GARRICK: Yes. i 12 CHAIRMAN JACKSON: -- what the relative importance 13 is from an overall risk perspective of the particular aspect 14 of the risk with whatever its associated uncertainties are. 15 DR. GARRICK: Right. 16 CHAIRMAN JACKSON: Commissioner Merrifield. 17 COMMISSIONER MERRIFIELD: Dr. Garrick, a couple of 18 times during your presentation this morning you have 19 intimated your confidence with the recearch api the 20 information that's being provided by DOE. One of the issues 21 that.came out of our. briefing yesterday from the staff was a 22 number of concerns about the quality assurance. 23 DR. GARRICK: Yes. 24 COMMISSIONER MERRIFIELD: While you can have good 25 research, if you're not able to appropriately back that up l ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-22 1 ano demonstrate that it is valid, that does bring in a 2 question. I'm wondering the degree to which you've looked 3 at the quality assurance issue and whether your confidence 4 in the DOE is at all moderated by that. 5 DR. GARRICK: We have not lookee at the quality 6 assurance issue to the depth that the sta:'t has. We have 7 tried to look at the technical issues. 8 Whether or not the quality assurance template can 9 be put on a lot of the source material that they have is 10 something we would have to do more work on to be able to 11 answer. 12 I would hope that we're not in a situation where 13 the 15 years of work that's gone on has to be erased because 14 of the absence of a quality assurance program that meets the 15 standards of the NRC. So thcre has to be some work done 16 there to see how much of that can be recovered and captured 17 and qualified in a QA sense. 18 COMMISSIONER MERRIFIELD: AS you look at that, 19 will you also be conducting analysis as to whether you agree 20 21 DR. GARRICK: Oh, yes. 22 COMMISSIONER MERRIFIELD: -- with the staff's 23 determination -- 24 DR. GARRICK: Yes. 25 COMMISSIONER MERRIFIELD: -- about the ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-23 1 appropriateness of the standards? 2 DR. GARRICK: Absolutely. Absolutely. 3 COMMISSIONER DIAZ: But the quality assurance 4 issue is not only looking back, but is looking forward, 5 right? 6 DR. GARRICK: Yes. But I'm a little more worried 7 about the back, capturing the work that's been done.

But, 8

yes, you're absolutely right and part of the issue yesterday 9 that was discussed is that there is not enough quality 10 assurance program in place yet, even though there is a 11 dialogue going on and discussion to achieve one. 12 CHAIRMAN JACKSON: Not to prolong this, but what 13 you're really saying is that you believe that the types of 14 data exists or supporting information to make these kinds of 15 judgments, but you're not prepared to render your own 1 16 statement or judgment as to the quality of it. l 17 DR. GARRICK: That's right. 18 CHAIRMAN JACKSON: Okay. But then that leads to a 19 second part'. I think that if you're then looking at it, I i 20 think it's important for us to understand or at least for 21 you to look at it and tell us that you understand where 22 quality assurance questions would have the greatest effect l 23 or where one has to go at the quality assurance questions to 24 be able to put things into the proper context. l 25 What I mean by that is there can be a type of 1 ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 L

a S-24 1 quality assurance in terms of the qualification of the 2 information that would affect the uncertainty. 3 DR. GARRICK: That's right. '4 CHAIRMAN JACKSON: But there is a type that could 5 affect the ability to make a judgment about the relative 6 risk or the relative importance, and I think that's where 7 one has to be able to do some bounding in both instances. 8 DR. GARRICK: I agree with you and I would hope 9 that the TSPA and the TPA of the NRC would provide a lot of 10 guidance on what aspects of the supporting evidence need the 11 greatest attention with respect to quality assurance. 12 I'm in trouble with my colleagues here because of 13 the time. 14 CHAIRMAN JACKSON: You're not in trouble with us. 15 DR. GARRICK: But let me proceed. So going back 16 to slide six and the last bullet, so what I'm suggesting 17 here, as an issue of clarity, is that we should be very 18 focused as far as the presentation is concerned on first 19 principals. We should not allow ourselves to get too 20 consumed in the mechanical details. 21 The Monte Carlo does not create probabilities. 22 It's only a method of doing probability arithmetic. What is 1 23 really important is to understand where the probabilities 24 come from and how they're assigned to the basic parameters. 25 Okay. With respect to the supporting evidence ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 ]

S-25' 1 issue, we believe that this is a critical issue in this 2 project because of-the dependence on expert elicitation, 3' expert judgment, and also the issue of QA that we just 4 mentioned. 5 -I think it's important for the data packages that 6' are. prepared to be prepared in such a way that it's very 7 responsive to the issue of whether the information is based 8 on measurement, expert judgment, where it comes from, et 9 cetera, and we're of'the opinion that more packaging, 10 bet.ter, improved packaging of the evidence base is possible 11 and that probably we're better off in the data arena than we 12 think, that where we're not so well off is in the 13 characterizing of that underlying data in a way that makes 14 it easier to understand the linkages that I have talked 15 about. 16 When we talk about expert judgment, what we want 17 to do, and to give a specific example of what we mean, we 18 want to'be able to bypass the expert. We want to be able to 19 go to the supporting evidence to the expert that was the 20 basis of the expert's opinions. To me, that's extremely 21 important. If we can't do that, then I think the expert 22 elicitation process is going to receive great challenges. Let me move to the issue of defense-in-depth, and 23 24 I think we've said almost enough about that, but there's 25 obviously some important issues here. ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

o i S-26 1 It's clear to us at least that the. Department of 2 Energy has not come to terms with defense-in-depth, 3 especially in the same context as it has been used as a 4 basic regulatory tenet by the Nuclear Regulatory Commission 5 since its beginning. 6 What we mean when we talk about defense-in-depth 7 is a pervasive concept that we're talking about 8 defense-in-depth with respect to the prevention of 9 accidents. We're talking about defense-in-depth with 10 respect to, if we have an accident, being in a position that 11 we have put in procedures and equipment that we can 12 terminate it in a most expedient manner. 13 And then we're talking about if we somehow fail in 14 that, that we have mitigating systems that indeed are quick 15 response and that also have defense-in-depth. So we're not 16 just talking about redundancy, diversity, independence and 17 balance. We're not just talking about multiple barriers. 18 We're talking about a philosophy of design that is pervasive 19 through the'whole process, from concept to operation and 20 beyond, from operation to accident and accident management. 21 We think that the NRC has provided some guidance 22 on this in-a variety of documents. The one thing about the 23 guidance that is very critical, and we have highlighted it a 24 little bit, is that the contribution to performance should 25 come from both the natural setting and the engineered ANN RILEY & ASSOCIATES,.LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

o S-27 1 barriers. At least we need to know what that is. 2 There needs to be a little greater effort on this 3 whole issue of being able to quantify the contribution of 1 4 individual barriers. The whole idea here is to quantify. 5 We no longer have subsystem requirements, but that doesn't j 6 mean that we don't want to. understand what the capability is j 7 of subsystems. In fact, the emphasis is on quantifying the 8 capability of the subsystem requirements in relation to the 9 performance measures. That's the focus. That should be the 10 emphasis. 11-Some people have interpreted that the absence of 12 prescriptive subsystem requirements means that we're not 13 interested in subsystem performance. We are clearly 14 interested in subsystem performance and linking that to -- 15 its relevance to system performance. 16 So with that, if there are more questions, 17 excellent, but otherwise, I'd like to move from the 18 performance assessment aspect of our presentation to the 19 design review aspect of our presentation, and the first 20 speaker will be member Dr. Fairhurst, and he will talk about 21 principally the natural setting, and the second will be Dr. 22 Fairhurst and he'll talk principally about the engineered 23 systems. 24 DR. FAIRHURST: Thank you, John, and I'm only 25 going to do the first part. Let me quickly try to ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

a S-28 1 summarize. First of all, I certainly and I don't think any 2 'of the committee found any showstoppers. That was a very 3 valuable component of reading the VA. And with respect to 4 flow and engineered design, you can summarize it almost in 5 two words, water-water, because -- and this is not a new 6 problem. 7 This is a fractured medium. Let me just say, the 8 first review, the first report ever published about the 9 problems of radioactive waste isolation was in 1957, by a 10 group of geologists and. scientists, the outcome of a 11 conference of Princeton University, and they came to two \\ 12 general conclusions. j 13 If you'll excuse me, I'll just read them. The 14 first one was, "The movement of gross quantities of fluids 15 through porous media is reasonably well understood by 16 hydrologists and geologists. But whether this is accomplished by forward movement of the whole fluid mass at 17 18 low velocity or whether the transfer is accomplished by 19 rapid flow in ribbons is not known. In deep disposal of 20 waste in porous media, it will, in many cases, be essential 21 to'know which of these conditions exist. This will be 'a 22 difficult problem to solve." That was in 1957. 23 The second one, I'll read it and then I'll come 24 back to the first, it was "The education of a considerable 25 number of geologists and hydrologists and the ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

o 1 I S-29 1 characteristics of radioactive waste and its disposal 2 problems is going to be necessary." i 3 Now, that has happened. That problem as been at 1 4 the forefront not only of work in this country, but in 20 { 5 other countries worldwide. The STREPA project in Sweden was 6 an international project which lasted for a decade, which 7 was focused very much on this problem. 8 So when we say that the mountain scale, with the 9 unsaturated zone at Yucca Mountain, which, by the way, there 10 are 20 other countries dealing with this, the United States 11 is the only one that has to deal at Yucca Mountain with the 12 flow in the unsaturated zone. All of the others are in j i 13 saturated rock. 14 So we have a unique problem, but also a common 15 problem, and there is a considerable uncertainty about that 16 infiltration. It existed for 40 years plus. So it's 17 unlikely that these uncertainties are going to be reduced 18 significantly over the next two to three years, even though 19 there are some things that will definitely change. 20 There is some knowledge that over the many 21 thousands of years, the conditions will become wetter in 22 that region, and since we have a long time-frame to deal 23 with, that is being reexamined. 24 So it's unlikely that we'll see, in the license 25 application, much change from the VA analysis with regard to ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 b

S-30 1 the mountain scale infiltration problem. 2 So the first thing, water is going to get in, and 3 then from that, we have -- ) 4 CHAIRMAN JACKSON: Let me ask you a question. 5 DR. FAIRHURST: Yes. 6 CHAIRMAN JACKSON: Can that existing uncertainty, 7 which you don't expect to be reduced much over the next few 8 years, be considered acceptable with some appropriately 9 conservative assumptions about the repository design? 10 DR. FAIRHURST: The key issue is the uncertainty, 11 yes. There are certain things that are not terribly 12 uncertain. For example, we know how much comes in pretty 13 well. Where it goes is what we don't know. 14 Now, our main concern is how much will get to the 15 drifts. So my second point was that there is water moving 16 through and we'll accept that. There is not going to be any 17 alternative to accepting it. - 18 The important thing is to keep it away from the 19 drifts and find out how much gets into the drifts. More 20 specifically, we want to keep it away from the waste 21 packages, and, more specifically than that, we want to keep 22 it from getting at the radionuclides inside the waste i 23 packages. 24 CHAIRMAN JACKSON: And you know the USGS has 25 recommended that there be an expert elicitation on ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 ) I (202) 842-0034

n S-31 1 quaternary climate and on paleohydrology. l 2 DR. FAIRHURST: Yes. Yes. Yes. 3 CHAIRMAN JACKSON: Do you agree with that? 4 DR. FAIRHURST: Yes. I think that is something 5 that is a very good use of expert opinion, because it will 6 -- it will probably suggest, I think, the feeling is that some of the assumptions of DOE are overly conservative in 7 8 that regard and it will help illuminate that. It's a good i 9 thing. 10 USGS is the unparalleled leader in that kind of 11 work. And so yes. And so -- 12 COMMISSIONER McGAFFIGAN: Madam Chairman. 13 CHAIRMAN JACKSON: Yes, please. 14 COMMISSIONER McGAFFIGAN: Could I ask your 15 opinion? The USGS wrote a report in November about th' 16 viability assessment and they dealt with this issue of how much water is going to get onto the waste packages and they 17 18 basically say most water, in either case, I won't go through 19 the cases, most water would bypass the waste canisters. Such behavior has been confirmed by experiments. 20 This is a case.where they claim there's experiments in the 21 exploratory studies facility in which large rates of 22 23 infiltration have been artificially maintained above an 24 alcove and water entry into it observed. Both theoretical and experimental results thus 25 [ ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 l

S-32 ' indicate that focused flow into drifts'is extremely 1 2 unlikely, and then they conclude it should not be assumed 3 for the TSPA. That's their view. You had the State of 4 Nevada ~here saying there's rapid flows and that should 5 disqualify the site instantaneously. So there's a range of view here and they dismiss 6 7 USGS as a DOE subcontractor. 8 What do we -- how important is this to narrow by 9 2002? 10 DR. FAIRHURST: Well, you added by 2002. 11 COMMISSIONER McGAFFIGAN: By the time of the 12 license application. 13 DR. FAIRHURST: Yes. Obviously, USGS is proposing what you might call a less severe situation than DOE is 14 15 examining and I think that.is a good conservative strategy 16 for DOE. And if that turns to be -- if USGS-can prove that, 17 everybody will welcome it. It actually speaks to the second 18 slide that I have, saying that the seepage into the drifts with dripping onto canisters is'a process of particular 19 20 importance. 21 However, the exact prediction of the locations, 22 the changes with time, the amount and the chemistry of 23~ 'in,-flow is not feasible. If you walk along the tunnel, flow will come through one 24 you'll'see a thousand fractures, and-there is not a person in the world who will tell you 25 ANN'RILEY & ASSOCIATES, LTD. N._ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-33 1 which one that was before it goes there. O So it's an uncertain process. But the -- so l 3 performance assescrant will then continue a rely on expert 4 judgment and conservative assumptions to deal with this 5 issue. 6 Now, I'm coming to the question that you asked 7 about seepage into the drifts. We feel there is an 8 opportunity for some significant improvement by doing future 9 analyses. The niche test is going on, which is the one that 10 is being done by USGS personnel, and there will be definite 11 refinements to those numerical models. 12 Now, there's a lot of work going on to this by 13 different contractors and, in fact, this is extensively 14 studied in the Swedish program, too, and there are 15 theoretical models which would suggest that if you have a 16 tunnel and a porous medium around it, that there is, through 17 capillary diversion, the water will tend to go around rather 18 than through the tunne.l. 19 However, you've got a fractured medium here with 20 fractures going in it which are very sharp and how water 21 will be -- how that will affect the process. And then there 22 is another one that has not been studied by anyuody really, 23 although it's being looked at somewhat in the heated drift 2e experiment, is the effect of temperature. 25 As you raise the temperature of this rock, you ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-34 1 will do an awful lot of changing around and you may know 2 something now in niche tests, but you must add the 3 consequences of high thermal load. This speaks to something 4 that I will talk about later, as to whether you talk about 5 hot or cool repository. 6 So the answer directly is yes, there is a lot of 7 activity in that, and we expect to have some refined 8 judgment certainly in two to three years, but I see no 9 reason to stop the work for that point. 10 COMMISSIONER McGAFFIGAN: But their point was more 11 -- if I could follow-up -- that, yes, there is going to be but they don't think the seepage ends up getting 12

seepage, 13 onto the waste canisters very often.

In either case, most 14 water would bypass the waste canisters. 15 The previous sentences have granted there may be 16 water getting into the drifts, but they believe, reading one 17 of the prior sentences, the water tends to adhere to the rock or drift mining wall and move down the wall and as film 18 19 flow, et cetera. 20 DR. FAIRHURST: Yes. 21 COMMISSIONER McGAFFIGAN: So that's their view. I 22 don't know whether that can be documented or how much -- 23 DR. FAIRHURST: It is a view. It is a view I'm sure that will be contested by a lot of people because the 24 25 proof is not yet there. I'm not saying it's wrong. ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-35 1 COMMISSIONER McGAFFIGAN: Right. 2 DR. FAIRHURST: And that's what we have to do. 3 Let me talk now.-- just talking about following the natural 4 system. We've gone now through the unsaturated zone and 5 into the saturated zone; that is, allowing that -- we're 6 hoping to prevent any radionuclide contact of water, but we 7 have to allow that it might happen and that some of it may 8 be traveling to points where it will be -- there will be 9 uptake into human system. So we have to examine that. 10 There, again, we have conflicts, hydrology and 11 there are uncertainties. There's some potential for some 12 drilling, which will give us some new data which will 13 improve our confidence, but the uncertainties will remain. 14 And the key issue is how much dilution will occur. It's the 15 concentration and how much you take out of a well in the 16 final uptake. 1 17 So those are issues that are still to be resolved 18 from all the processes and so as a consequence, we will have i 19 to have quite conservative assumptions and they will have to 20 be defended on that basis as conservative assumptions. 21 I've given a very quick run-through of a very 22 large subject. I have to turn to a second one now. Given j 23 .that water will possibly come into the drifts, how do we 1 24 design the repository to avoid this contact as much as j 25 possible. i ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 l L..

S-36 Really what you're saying is tha; we'll have to 1 have a very robust system of engineered barriers and that is 2 3 to inhibit any access to the waste. And as I think you know, there's been a tremendous 4 i 5 activity on the part of DOE in the last year or so, year and 6 a half, looking at various alternative engineered designs. 7 Those engineered alternatives, there's a lot of details, but 8 in simplification, they really boil down to two; whether you 9 have a hot repository - in other words, whether you allow the rock temperature to go above the boiling point of water, 10 which that reaches about 96 degrees Celsius, or whether you 11 12 keep it low. 13 The aim, of course, of the hot repository is to essentially put an annulus around the repository where the 14 water would -- any water that contacted it would be boiled 15 16 off and wouldn't be able to get in. So that was the attraction of the hot repository idea and it's an 17 interesting possibility, but there are some suggestions that 18 19 it may be more complex to analyze. It can cause damage to the rock, because the natural stresses out there are of the 20 21 order of ten mega pascals. By the time you get through So it's a 22 heating it up, you add about another 120. 23 significant change, although the rock will break before it 24 gets up to that temperature. With the low temperature design -- I may also say 25 ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 t J

S-37 1 that a high temperature design is not all bad. One of the 2-interesting things we found, it's in one of the backup 3 slides, but I won't bother with it, is if you have a seismic 4 event during that the period that that is very hot, the rock 5 is actually clumped toge.ier, those joints, because it's 6 being pressed under thermal. expansion and it won't fall out, 7 whereas if.it is cold, it has a much better chance of 8 falling out. 9 So there are pros and cons. The low temperature 10 design avoids the uncertainties about the thermal effects, 11 but it allows the greater chance of humidity and moisture 12 coming to canisters and potential corrosion. 13 So there are -- the other advantage of the low 14 temperature design, although it's limited, is that every 15 other country is considering a low temperature design. So 16 you've got a lot of other people with knowledge of that, but 17 it's not all transferable, because, again, they're all in 18 the saturated zone and we are not. 19 We have a question about whether clay -- you have 20 a funny situation where you possibly may not be able to put 21 clay in there because it's too dry. It doesn't have enough 22 water to keep it expanding. l 23 COMMISSIONER DICUS: I have a question, please. 24 DR. FAIRHURST: Yes. 25 COMMISSIONER DICUS: Are you leaning in one i i ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-38 direction or the other on these or are you neutral? 1 2 DR. FAIRHURST: At the moment, I'm interested to see if there is an advocacy for the low temperature design, 3 because I know a lot more about the high temperature design 4 5 already. That was a standard and I'm anxious to see what 6 the arguments are for. There are also some side issues, and 7 that is whether or not the drifts are back-filled or not. 8 That does, in fact, also affect those two. So I think that what will happen, by the time of 9 10 license application, in fact, by May, there will be a decision of some preferred alternative, but it's quite 11 probable that there will be several designs that could 12 satisfy 10 CFR Part 63 over a 10,000 year period. 13 14 We feel, however, that there will be concerns about expressed, whether it's part of the regulation or not, 15 the fact that the dose rises beyond 10,000 years and number 16 17 of the designs. So we want to urge -- I may modify the 4 statement that I've got there in the second bullet to say } 18 i that NRC should seek -- continue to seek additional 19 / information that the 10,000 year safety performance will 20 provide reasonable assurance to the public to protect public i 21 22 health and safety over the long term. The other thing, there has been a recent 23 development to suggest extending the open period of 24 and this is a very pre-closure to 300 years, a possibility, 25 4 ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-39 s 1 personal view perhaps, but I think it's shared by some 2 others, that that extension to 300 years is not a trivial 3 thing to talk -- you may say it trivially, but it 4 significantly complicates the maintenance of effective drift 5 support systems. 6 To give you an idea, in civil engineering, there 7 are lots of drift support systems, but I don't think any -- 8 a lot of them are innovative and currently rock bolt and -- 9 rock bolts have only been around about 30-40 years as a 10 design support system. So nobody can tell you how they will 11 last, particularly in a heated environment over 50 or 100 12 years, and'to suggest to go to 300 years is not a trivial 13 thing. 14 So I would actually suggest that we stick as much 15 as possible to the 50 to 100 years and then allow the people 16 100 years hence to decide whether they want to keep it 17 another 200. 18 I was at a conference in Europe recently and 19 people were aghast at the U.S. suddenly introducing an 20 extension to 300. Nobody else wants to talk anything above 21 100. 22 So with back-fill, as I say, that reduces -- 23 there's pros and cons there. That reduces the vulnerability 24 to damage from rock falls. It stops rock falls, because it 25 can't fall. And it reduces the vulnerability of seismic ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-40 1 effects, and it helps eliminate some concerns regarding 2 possible consequences of igneous events. But it does increase the temperature of the waste 3 4 package, because it insulates it. 5 COMMISSIONER DIAZ: Let's see. On this issue of 6 the plus 10,000 years, we have a project that has 7 significant amounts of uncertainties. 8 DR. FAIRHURST: Yes. 9 COMMISSIONER DIAZ: And now you're suggesting that that's not what 10 we even try to go beyond 10,000 years -- no, 11 you're saying? 12 DR. FAIRHURST: No. I'm saying that a 10,000 year 13 standard is probably appropriate, but one should -- if there 14 are -- for example, if there are designs which would indicate a better performance over a long period of time, 15 16 why not choose it, because it will give the public a much 17' greater feeling of confidence. There are good reasons for 18 sticking to 10,000. 19 Finally, let me talk about staff capability of 20 NRC. Just to try to put it in context, again, this effort put forth by the DOE to try to come up with alternative 21 designs -- it's got several hundreds of engineers and design 22 engineers, working intensively and looking at all kinds of 23 24 options, and they're generating a tremendous amount of 25 information. i ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

p S-41 1 I think it's obvious that NRC staff is going to 2 have to evaluate those things proposed by DOE. And in order 3 to get somewhat, if you like, of a level playing field, the 4 issue there is that you've got a lot of people with design 5 engineering experience. We're moving from.this period of, 6 40 years ago, wanting geologists and hydrologists. We're 7 now moving toward geotechnical engineers are needed. 8 And I want to emphasize that, because the question 9. that you asked about uncertainty. Geotechnical engineers 10 have a different philosophy of design than many other 11 engineers because of the complexity and uncertainty of the 12 geological media. Actually, it's called design as you go. 13 You have to excavate and when you excavate, you have to have 14 a design ready that can accommodate a variety of surprises. 15 Just to give you an example, two weeks ago, I was 16 in Yucca Mountain and they just excavated into the Solitario 17 Canyon faults and everybody was there because we were 18 learning an awful lot about whether was that a water 19 conduit, was it a water barrier, how far from that was the 20 rock disturbed, because you would not put canisters in a 21 region that was near a fault. 22 No amount of work, of theoretical work can tell 23 you that. You have to go in and find out. One has to have 24 that design as you go philosophy and that's why we believe 25 -- it's not a criticism of existing staff, it's a question ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

i S-42 1 that one needs some augmentation of that capability in order 2 to be able to expect NRC staff to respond and' analyze what's 3 being presented to them. 4 And we believe that in that context, it might be 5 useful, since this is such a rapidly evolving and changing 6 situation, you can't guess, if somebody could be hired. Six 7 months later you may need somebody different. So part-time 8 consultants -- 9 CHAIRMAN JACKSON: So we have to design our staff 10 as we go. 11 DR. FAIRHURST: That's right. Well spoken, well 12 taken. It's a very nice way to finish to say that we design 13 as you go with the staff. It's very rapidly changing. 14 So with that, I think I'll leave it for any 15 questions you may have. 16 CHAIRMAN JACKSON: Thank you. Dr. Wymer? 17 DR. WYMER: I'm going to talk about engineered 18 . barrier and the engineered barrier system. 19 CHAIRMAN JACKSON: Closer to the mic. 20 DR. WYMER: There? 21 CHAIRMAN JACKSON: Closer. 22 DR. WYMER: Closer. 23 CHAIRMAN JACKSON: The mic has to be closer to 24 you. 25 DR. WYMER: Oh, it moves. ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-43 1 DR. GARRICK: Flexibility. 2 DR. WYMER: We need to design as we go here. You 3-heard a lot about the engineered barrier systems. We had a l 4 workshop last year, you recall, and then we had a meeting 5 here and then we wrote you a letter about it, and you heard 6 quite a bit in the subsequent briefings you've had. Even 7 yesterday you heard some more. 8 So it's a little hard for me to present something 9 new, but I'm going to try to give a little bit different 10 emphasis that might be useful. 11 First, I should say that of the designs that DOE 12 has come up with, and they've come up with five so far 13 possible designs which differ mainly with respect to thermal 14 loading, which influences the temperature the repository 15 will go to, with some additional variations with respect to 16 whether or not they have back-fill and some other minor 17 variations, but largely they're related to temperature. 18 But none of these five designs changes what are 19 the important contributors ultimately to dose that a person 20 at 20 kilometers from the repository. These contributors 21 are, as you've heard, the waste package performance and the 22 zircalloy cladding on the fuel, spent fuel degradation, 23 rad,ionuclide transport. And nothing in the design changes 24 affects the importance of these things, although they -- the 25 design changes affect the importance in different ways, put l l ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 l

S-44 1 different stress on different things, depending on whether 2 or not you have drip shields and what kinds and so on. 3 As Dr. Fairhurst indicated, the robustness of the 4 whole repository system depends in large measure on the use 5 of multiple barriers and the contributions that they make. 6 So I'm going to try to concentrate on those areas. 7 COMMISSIONER DIAZ: Excuse me. 8 CHAIRMAN JACKSON: Please. 9 COMMISSIONER DIAZ: Have you seen this estimate 10 that the engineered barriers are now 99.3 percent of the 11 total -- you want to make a comment on that? 12 DR. WYMER: Yes, we've heard that. It depends on 13 what you do. In the present analysis, there certainly is a 14 great deal more emphasis, maybe it is 99 to one, between the 15 engineered barrier system and the natural environment. But 16 I don't think that's been really demonstrated and I think 17 there are ways, and I'll talk about it just a little bit, 18 ways to change'that ratio substantially, possible ways, and 19 these are the kinds of things that I will suggest as things 20 that might be looked at or at least analyzed with respect to 21 whether or not they should be looked at in-depth, and I want 22 to get into that just a little bit toward the end of my 23 presentation. 24 CHAIRMAN JACKSON: You mentioned that the major 25 differences among the five designs really relates to the ANN RILEY & ASSOCIATES,.LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

r. 1 e S-45 1 assumptions about thermal loading. l 2 DR. WYMER: Yes, that's right. I 3 CHAIRMAN JACKSON: But that none of these j 4 differences change the important contributors to the 1 5 ultimate dose. 6 DR. WYMER: That's right. They don't change that 7 list. 8 CHAIRMAN JACKSON: They don't change the list, but 9 they change the relative -- l 10 DR. WYMER: That's right, the relative .11 contribution. 12 CHAIRMAN JACKSON: -- contribution of those j 13 contributors. 14 IMt. WYMER: That's exactly right, I think. -15 CHAIRMAN JACKSON: Okay. 16 - DR. WYMER: So since the multiple barriers are an -17 important compliment to those, as Dr. Garrick has pointed 18 out, they're certainly not the only compliment of 19 defense-in-depth. You do need to have a clear understanding 20 of what the contributions of the individual engineered 21 barriers are in the near field and one of the ways that the -22 Department of' Energy has analyzed the importance of the 23 contribution of the individual barriers just by what they 24 call a process of neutralization, which' effectively means 25 that they reduced the contribution of an individual barrier, j ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 l Washington, D.C.. 20036 (202) 842-0034 l'

i 1 i S-46 1 taking the barriers one at a time, to a very low value, and 2 then they see what the outcome is on the ultimate dose that 3 people receive. 4 But in reading what's written and then listening 5 to the presentations and in listening to responses to 6 questions, I don't really understand exactly what they're 7 doing, the neutralization of barriers. The reason I don't 8 is because there are a lot of coupled effects of the 9 barriers. You can't just simply take a barrier out and then 10 see what's left, because one module in the model feeds the 11 next and, in particular, this is of great importance with 12 respect to the chemistry of + hat goes on and the chemistry 13 is extraordinarily complex. So you can't just neutralize a i 14 barrier. 15 Now, I asked the question in one of the recent 16 meetings of the DOE people, well, how do you take care of 17 these coupled effects and the interaction of these effects. 18 Well, the answer, as I understood at least, and I l l 19 admit that people can't present their deep understanding of 20 something in a few minutes discussion standing up at a 21 microphone, but my understanding of it at least was they did 22 sort of on the side calculations and said, okay, we realize 23 there's coupled effects here, now we're going to do a little 24 calculation to see whether or not this coupled effect' will 25 importantly influence what happens with respect to l J002 FILEY & ASSOCIATES, LTD. Court Reporters i 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 1 1

r-S- 47 1 neutralizing these barriers and this way they are able to 2 essentially discard the coupled effects by side calculations 3 or side considerations. 4' That was my understanding and I didn't find that 5 particularly satisfactory. It didn't satisfy me, at least. 6 Now, maybe I need a little bit more detailed discussion of 7 what they have, in fact, done. I think I do. But so far my 8 understanding is that I don't think that the interaction of 9 one system and effect on the next is handled at least in a 10 transparent, easily understood way. 11 Now, on the next viewgraph, which is number 20, I i 12 come down to some of the things that the horses that have 13 been beat until.they're dead, having to.do with timeliness 14 of being able to -- by that, I mean being able to get 15 results in time to feed the license application requirements 16 and the quality assurance of the data. 17 Those are significant potential problems. Dr. 18 Garrick has indicated that they're not necessarily 19 showstoppers, but it raises an important problem-for the NRC 20 staff, I believe, in that they have to make some judgment, 21 which will be a difficult judgment, on how much data is enough and how much expert elicitation is enough and whether 22 23 or not that is good enough. 24 Expert elicitation, for example, relies in large 25 measure on'what assumptions are made, which the experts are ) I ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avt.iue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034'

S-48 1 making their judgments and insof ar as the assumptions 2 change, the results of the experts' opinions change. And some of the kinds cf assumptions thac are made 3 4 are those with respect to, say, the compocition of the water 5 that enters the drift and it drips onto package. And 6 depending on whether or not you're using the J-23 water or you're actually using a new sample that you've taken, these 7 8 things would quite dramatically change the results of the 9 expert elicitation opinion. 10 So there are uncertainties. But anyway, the principal uncertainty so far in the analyses have to do with 11 12 the corrosion of the waste package, and that's what I think 13 Commissioner Diaz was talking about with respect to this 99 At least one of the big contributors was what 14 to one. 15 happens to the waste package. Well, it is true, as you 16 heard yesterday and youve heard before, that the database 17 for alloy-22, which is the present favorite for the 18 corrosion resistant material in the' waste package, the data 19 are good and they're very encouraging and there's a lot of 20 work going on, several places, including at the center for nuclear waste repository analysis, and insofar as it goes, 21 22 it looks okay. But it's hard to get enough data on a short 23 24 time-frame to give you a warm fuzzy feeling about what this l thing will -- how this package will behave in the long term. 25 ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

l f S-49 1 And the same thing is true of the zircalloy cladding on the 1 l 2 fuel and to a certain extent on the vitrified high level l 3 defense waste. But not enough is known, although a lot is l 4 known about the vitrified waste, that zircalloy cladding has 5 been looked at for a long, long time with respect to its 6 corrosion, but under quite different condit' .ls than exist 7 in a repository and especially under conditions of 8 temperature fluctuations and temperature going up and down. 9 And then take one point in particular about the i 10 alloy-22. We've heard, and it may well be true, that there ) 11 is a temperature regime in which corrosion will most likely 12 occur at a significant rate and above that temperature and 13 balow that temperature, corrosion will be negligible; above 14 it because there is no water and below it because the rate 15 of corrosion is so slow that it's negligible. 16 So the verification of that temperature regime is 17 an important thing to be looked at and, as I understand it, 18 is being looked at, but we need data, we need information. 19 I want to talk & bout the chemical processes and 20 the contributions of back-fills and that will be the next 21 viewgraph and my last viewgraph. 22 There is a great deal of discussion in the TSPA VA 23 about the chemical complexity of the system and nothing I 24 can think of has not already been thought of and mentioned 25 in what has been written. ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-50 1 But what's lacking is a detailed comprehensive 2 treatment of the chemical complexity and the chemical 3 complexity is of fundamental importance because it deals not 4 only with the corrosion of the waste package and of the 5 cladding on the fuel, but it deals very importantly with the 6 rate of dissolution of the fuel material itself, which is 7 primarily uranium dioxide, and it deals with the possible 8 formation of secondary phases, which could seriously and 9 importantly impede the release of radioisotopes, actonizing 10 fission products from the waste package. 11 Now, these chemical effects have been looked at 12 one at a time and they've been considered and they've been 13 analyzed and there have been calculations made, but it is my 14 opinion or judgment that the situation is so complex that 15 nothing like the EQ3/6 computer code can deal with all of 16 the complexities. 17 For example, if you do have secondary phase 18 formation, if you don't know what the composition'of the 19 solid phases are, you cannot make thermodynamic predictions 20 of what the solubility is and you can't derive this kind of 21 information from an analysis of the liquid phases. 22 You have to know what the compositions are. So 23 basically I'm saying you need a valid database before you 24 have a valid computer code that will analyze the system. 25 It's my view that the system is so complex and requires such ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

I. i S-51 1 1 a large database, that the only true way to get at the real l i 1 2 effects are to use the real solutions, the real systems that. 3 exist in nature and conduct your experiments and do 4 experiments and gather data. 5 Now, these are not hard things to do and, speaking ) 6 as a chemist, I bemoan the fact that we've spent ten years 7 looking at the geology and, to over-emphasize the case, two 8 years looking at the chemistry. 9 When the chemistry is of great importance with 10 respect.to releases of fission products, actinides. 11 COMMISSIONER DIAZ: Excuse me. I see all of your 12 chemicals in here and I have a favorite universal solvent, 13 which is uranium. Are they modeling the uranium properly in 14 the chemistry? 15 DR. WYMER: They're doing something that I think 16 is very good and that is using the Pina Blanca analogy and 17 that gets at the -- one form of uranium, which is probably 18 very similar to what's in the fuel, although not certainly 19 identical to what's in the fuel. 20 So insofar as the uranium chemistry and the 21 uranium dissolution is concerned, yes, they're probably not 22 doing bad. What they're -- what is very difficult to deal 23 with is what happens to the uranium after it is dissolved, 24 what complexes does it '.orm. We all know that the uranile 25 tricarbonate complex is. It is very stable and tends to I l l ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-52 l l 1 solubilize things quite well. We all know that there's a 2 fluoride insoluble compound, there's chloride complexes, 3 there's sulfate complexes, silicates form solid phases. 4 It's very complex and so to say we understand how 5 the uranium will dissolve pretty well by analogies and by 6 exrarience, it's not the same as saying we know then next 7 what's going to happen. Those are entirely different 8 questions. 9 One thing, I don't want to get into the design of 10 the repository, since that's not the role of the NRC, but I do want to say something which sort of verges on that with 11 12 respect to what is in the drift and what you could put in 13 the drift that would dramatically, I think, change the rate l 14_ of release, in particular, of technetium and neptunium from the drifts, and that has to do with the amount of iron 15 16 that's in the drift, and there is a lot of iron in there, both in the materials of construction of the drifts and on 17 18 the waste package, and there could be additional metallic 19 iron put in as part of a back-fill of material, such that you could reduce the technetium and reduce the neptunium to 20 forms which were not nearly so readily transported out of 21 22 the drift and through the environment, especially if there is,a path through alluvium which has substantial absorption 23 properties for -- not for the neptunile ion and not for the 24 protecnotate ion, but for reduced forms of those elements. 25 ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

I' l l S-53 1 And so it seems to me that there is a -- that's a 2 potential fruitful area to look at. Now, people talk about 3 and say, well, there's going to be a lot of oxygen in the 4 drift and that will oxidize the iron and it won't be in a 5 reducing state anymore. 6 Well, there are things you can do to reduce the 7 amount of oxygen that gets into the system, seal it up, for 8 example, and then the only oxygen that comes in is what's 9 dissolved in

n water that comes in, and you can make a 10 pretty good case that it's easy to get enough iron to deal 11 with the oxygen that comes in and dissolved in the water for 12 five to 10,000 years.

13 So there's a lot that could be done. With that, I 4 14 think I'll quit. I want to say one more thing. It's not 15 necessary to have all the answers to all these questions at 16 the time you license a repository. I think you can take the 17 next 50 years or 100 years and work on these things and 18 decide whether or not you want to put in a back-fill, 19 whether or not you want to tailor that back-fill to deal i 20 with some of these specific elements. 21 I don't know whether it will work or not. I just 22 think it has not adequately been addressed. 23 CHAIRMAN JACKSON: Thank you. 24 DR. GARRICK: I promise to wrap it up in a couple, 25 three minutes. The committee has indicated that the safety ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-54 1 case for Yucca Mountain probably requires greater emphasis 2 with respect to the issue of technical clarity, particularly, 3 with respect to the basic structure of the model, for 4 analyzing the mountain, and, secondly, with respect to 5 displaying and making as tractable as possible the 6 supporting evidence to that modeling. 7 We consider these to be two very important issues. 8 We also consider that primary effort here is one of bette; 9 characterization and representation of information that is 10 largely already available. 11 The committee has identified two issues that we 12 thi'ik stand out as extremely important, obviously, seepage 13 into the drifts aad waste package performance. I think one 14 of the things that cor5d be confusing is that is the date of 15 issue, but if you deal with the date of issue in the context 16 of what the analysis is suggesting is important, and even 17 though we're not very confident about new data for the 18 saturated zone having much of an impact on the license 19 between now'and licensing time, we are increasingly confident about the availability of new data to address the 20 question of seepage into the drifts and the infiltration 21 part of the analysis, as well as waste package performance. 22 So the data question has to be put in context with 23 24 the what's important to the performance measure. And if you 25 do that, I think you see you develop a different ANN RILEY & ASSOCIATES,.LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-55 1 perspective, as opposed to isolating these issues and 2 talking about them in the context of what might happen in a 3 few years. 4 We believe that there probably is going to have to 5 be more guidance on implementing multiple barriers approach. 6 Part 63 talks about that performance has to come from both 7 the natural setting and the engineered barriers. I think 8 there needs to be some genuine guidance on what is meant by 9 that. 10 We have identified that it's very important to be 11 able to see clearly the impact of individual barriers to 12 overall performance and that this is not a simple problem 13 because of the fact that the chemistry is affected and, in 14 some cases, the neutralization process assumes that a 15 chemical affect is if it's there, even though, from another 16 perspective, the barrier is not there. And we need to 17 better address the question of contribution of individual 18 barriers. 19 We have talked about repository design 20 alternatives and how it imposes differing regulatory 21 considerations. Obviously, with respect to the pre-closure 22 issue, it's going to be a much different problem if we go 23 for 300 years than it is if we go for 50 years, and we need 24 to address that. i If we're talking about 300 years, we're talking j 25 \\ ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 l

I S-56 1 about licensing something longer than anything we've had any 2 experience with, even in the pre-closure period, much less 3 the post-closure. One thing that's not on this diagram, but I think 4 is this issue of 5 you've heard a lot of from all of us, design as you go, where we think that there needs to be more 6 serious consideration of the matter of flexibility in the 7 design and how we can take advantage of the times that are 8 9 available before we close the repository and, at the same i 10 time, not get ourselves in a position of making a commitment to a project that doesn't fully comply with the reasonable 11 assurance to the safety of the public and the environment. 12 13 So with that, we will close our formal remarks. 14 CHAIRMAN JACKSON: Let me ask you this question. So should the flexibility in design that you keep stressing 15 rest with the engineered barrier system or are you talking 16 17 about design within the geologic environment? 18 DR. GARRICK: Talking about the total design. If, for example, we can do some things that give us a very high 19 confidence that water just isn't going to get in the drift, 20 21 then, of course, the uncertainties associated with the f ) saturated zone become much less of an issue and the need to 22 too. 23 do,a lot of research may become less, 24 CHAIRMAN JACKSON: Let me just ask it in a j ] 25 practical sense. Let's imagine the schematic of the ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 2 84 b34

i-S- 57 1 repository. 2 DR. GARRICK: Right. 1 3 CHAIRMAN JACKSON: And it has some tunnels and it 4 has this and side tunnels and it's designed a certain way, 5 these tunnels are put in a certain part of the mountain, and j 6 so forth and how you have your waste packages, your 7 engineered barrier system, and you say you design as you go. 8 Now, what are you talking about when you talk 9 about the geologic environment that you would change within 10 the 50 to 300 year period with respect to this system of 11 tunnels and where they're placed? That's what I'm really 12 asking. 13 DR, GARRICK: Yes. 14 CHAIRMAN JACKSON: Because you don't change the 15

geology, 16 DR. GARRICK:

No. 17 CHAIRMAN JACKSON: All you change is the inherent 18 cavern that you're putting the things in. So explain to me, 19 when -- 20 DR. GARRICK: Well, you're not changing the -- 21 CHAIRMAN JACKSON: -- you talk about flexibility. 22 DR. GARRICK: You're not changing the geology, but 23 you are changing what you know about the geology. You are, 24 by making specific and selected measurements that are guided 25 by the evidence that you've put forth to date, you are able ll ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-58 ! 1 to identify where you could get the best bang for your buck. 2 With respect to, for example, measuring the water flow into 3 the -- 4 CHAIRMAN JACKSON: But that's a measurement. 5 DR. GARRICK: Yes. 6 CHAIRMAN JACKSON: When I talk about design, I'm 7 thinking of something you do to the repository of what's in 8 it, whether you're changing the thermal loading, the spacing 9 of things, whether you're changing what the waste package 10 looks like. You're not talking about drilling the tunnel 11 somewhere else. 12 DR. GARRICK: Right. Right. Right. 13 CHAIRMAN JACKSON: I just want to be sure that I 14 understand what you're talking about. 15 DR. FAIRHURST: You're quite right. Once you put j k 16 a set of tunnels in, and you've got a lot of tunnels to put j l t 17 in, 18 CHAIRMAN JACKSON: Right. 4 19 DR. FAIRHURST: And you're not going to put them 20 all in right away. It is not beyond reason, and I'm not 21 saying one should do this, that you could put tunnels in 22 multiple levels. That would change your thermal loading. If,you go to a hot design, you could move -- make sure that 23 I 24 if you find a fault and you examine it and say we stay this 25 far away from it, you have to be allowed that flexibility. ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 l

) S-59 1 But I think even more important in that 2 flexibility is the one that so many people are criticizing, 3 is the waste package design. I mean, there is no reason why 4 you can't modify that waste package design with another ten 5 years of experience. It would be stupid not to. But that's 6 flexibility. 7 CHAIRMAN JACKSON: No. All I'm trying to say is 8 that when you talk about it, let's not make it cryptic. 9 Let's be very clear. 10 DR. FAIRHURST: Yes. 11 CHAIRMAN JACKSON: Of how large a flexibility 12 you're talking about, because the statement has been made, 13 and Commissioner Diaz brought it up, that the feeling is 14 that DOE at this point is putting so much stress on the 15 engineered barrier system and one just wants to be clear. 16 DR. FAIRHURST: Yes. 17 CHAIRMAN JACKSON: And what we need to hear 18 clearly from you, that if you're really talking things to 19 the extent of thermal loading, the actual physical design, 20 as well as the waste package, then we need to be clear that 21 that's what you mean, and that's all I'm saying. 22 DR. FAIRHURST: If I could just come back to the' 23 question of the USGS and other people's attitude about 24 certain things. I think the USGS has probably the best 25 sense of anybody what really exists, about where che water ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-60 1 is going to go. But the problem is, in the license 2 application, is proving it and we've got to come up with the 3 type of distribution that Dr. Garrick talked about, and 4 that's the work. 5 It is not that the geological barriers don't have 6 a role to play. It's proving and reducing uncertainties in 7 that, which is a little easier, to some extent, for some of 8 the metallic canisters, et cetera. There's a more 9 reproducible -- 10 CHAIRMAN JACKSON: The VA review process, do you 11 feel that it's confirmed the soundness of the NRC approach 12 of focusing on key technical issues and using the issue 13 resolution status reports for their acceptance criteria? 14 DR. GARRICK: I think the simple answer to that is 15 yes. I think the issue resolution reports have been ) 16 extremely valuable and I think it has allowed the DOE to 17 make its connection between its repository strategy, the 18 safety strategy criteria, its 19 factors, and the key 19 technical issues. 20 This is something that's concerned the committee 21 for a long time, is whether or not the key technical issues 1 22 are really dynamic and reflective of what we're learning as 23 we proceed. 24 I think the viability assessment was pretty 25 helpful in mapping from the repository safety strategy and ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

) S-61 1 its four basic elements to their 19 factors,.to the key 2 technical issues, but we think there is a lot of work there 3 that'still needs to be done. 4 CHAIRMAN JACKSON: Thank you very much. 5 Commissioner Dicus, f 6 COMMISSIONER DICUS: No further. 7 CHAIRMAN JACKSON: Commissioner Diaz. 8 COMMISSIONER DIAZ: Yes. Let's see. First, kind 9 of a little request in here. You're putting a few things 10 together to send to the Commission. I think it would be 11 helpful to the Commission if you would comment on any 12 potential impact that the viability assessment has on the 13 present draft of Part 63; if there is anything you see in 14 there that we need to consider as part of the Part 63, any 15 relationship, something that we might not be aware of, but 16 the specific impact on Part 63. 17 DR. GARRICK: Okay. Thank you. 18 COMMISSIONER DIAZ: And that's one thing. The 19 other is a little more esoteric, and if my fellow 20 Commissioners allow me. I'm kind of looking at the overall 21 issues that you deal together as far as research, 22 development and engineering. 23 Of course, we all know these are not linear ~ 24 functions. Knowledge doesn't accumulate as a function of 25 time. And the fact is it is an S curve. You put a lot of ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

1 o S-62 1 effort, you get nowhere, and then you put a little more 2 effort and it starts going up and then you keep doing it and 3 keeps increasing. Then you can put in more effort and 4 you're not getting anywhere again. We all have run into 5 that quite frequently. 6 The thing that I'm kind of missing is, when each 7 and all of these important issues are put together, where 8 are we in the S curve? Because the S curve is only 9 terminated in real life by an engineering decision. We have 10 enough at this point -- we don't have it all. We're not ) i 11 going to have it all. We keep going up another thousand 12 years, because we are in that part of the S curve. We're 13 only adding a little tiny bit of spending, enormous amount 14 of money, but not really getting much father anywhere. 15 Obviously, there are issues in which we are not on 16 the flat part of the S curve and there are issues in which 17 we are and what the nation needs is to know which issues can 18 be intercepted by engineering and say we know enough, even 19 if the uncertainty is there, when we play it in your 20 probability curve, okay, which, by the way,.is just exactly 21 as what happens when you put a fast burst of neutrons in a 22 medium and you let it go as a function of time, it's exactly 23 the same. 24 I mean, this process is repeated in nature over 25 and over again. So the issue is, where are we in the S ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington,_D.C.-20036 (202) 842-0034

f' S-63 l l 1 curve on the main key issues and are we intercepting them 2 with engineering at the right point, and that is a 3 tremendous issue, beca.use that's what the nation really 4 wants to know; can engineering intercept, create a design 5 that will be effective in doing what it's supposed to do, or 6 do we still need to go further in these things. 7 And the definition on key issues of where we are, 8 to me, would be of great value. 9 DR. GARRICK: Thank you. 10 CHAIRMAN JACKSON: Commissioner McGaffigan. 11 COMMISSIONER McGAFFIGAN: I'd first like to make 12 the point that I think Dr. Fairhurst just made a fairly 13 profound point in talking about the uncertainties in the 14 non-engineered systems and the fact that those uncertainties 15 are large and that keeps DOE focused more and more on the 16 waste package, where they can come up with new materials. 17 I am worried about over-conservatism. If I go 18 back to the chart that Dr. Garrick showed us at the outset, 19 contributors to risk, there's a danger that, in listening to 20 all this discussion, that what you end up doing is taking .21 the far element -- you know, you have all these risk curves 22 and because of uncertainties, we say, gosh, we're going to -,we'll go to that point here, we'll go to that point, we 23 24 .just take the 99th percentile of each of these elements. 25 And then I'll assume away that I get any benefit ANN RILEY & ASSOCIATES, LTD. l Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

O e S-64 whatsoever from the Yucca Mountain site and rest entirely on 1 2 the waste package, in which case you legitimately get 3 questions from Nevada, why isn't it in Ed McGaffigan's back 4 yard in Arlington, because you can make the standard there, 5 too. 6 And I don't think that's true, by the way, and I'm 7 not willing to engage in that experiment. But people do say 8 -- I have seen it said in the last week that 100 millirem 9 standard you can meet anywhere. I don't think that's 10 correct. But the -- how do we deal with getting the sort of 11 curves that Dr. Garrick talked about as opposed to building 12 conservatism upon conservatism upon conservatism and getting 13 14 -- you know, the USGS says a long chain of overly-conservative model elements can only lead to 15 16 correspondingly low probability of occurrence of the 17 resulting repository system behavior. We have previously seen the climate models, 18 19 associated infiltration rates, seepage flow model, as 20 overly-conservative, and to this list we can add saturated zone transfer model, which assumes only minor dilution of 21 22 radionuclides, regardless of climate. All this over-conservatism is not without cost, 23 24 naturally. It comes in the form of engineered barriers that 25 are correspondingly conservative, so as to protect against ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

e S-65 1 overly conservative estimates of seepage in placement 2 drifts, et cetera. 3 We can quickly turn a 25 millirem standard into a 4 25 microrem standard or a 25 picarem standard, I guess, if I 5 pile enough conservatism onto things. How are we going to 6 guard against that? 7 DR. GARRICK: I think this is a fundamental 8 question and, in my opinion, it's the question that was the 9 principal driver for thinking on a more risk-informed basis 10 and pushing for answers to what's the issue got to do with 11, risk. 12 I think the first thing that I would do is ask for 13 these curves and get that information in a form that I at 14 least know where to look to challenge it or to verify it. 15 I think this is something that is an underlying 16 basic issue associated with this kind of project. It was 17 that way in the early years of the reactor project. We 18 found we were spending a lot of time on issues that were not 19 going to eventually be the principal cause of accidents 20 later in the years. 21 One of the reasons that they weren't is we did 22 spend a-lot of time on then, but on the other hand, when the 23 accident finally came around, we realized that most of the problems came from the support systems which received very 24 25 little attention in the licensing process. ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NN, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-66 1 So all I can say about that is that we need to push forward the process of doing our analysis in such a way 2 3 that we better expose what's important, so that we can 4 answer the so-what question. 5 That's not an easy task, but I'm convinced it's 6 doable. 7 CHAIRMAN JACKSON: Commissioner Merrifield. 8 COMMISSIONER MERRIFIELD: I have no questions. I just want to express my thanks to the committee for the work 9 I 10 that it's been doing in terms of reviewing these areas. certainly look forward to the additional information you'll 11 I did have some 12 be providing us within the next few weeks. 13 questions in those areas, so those will be of great interest 14 to me. 15 CHAIRMAN JACKSON: I want to thank the advisory 16 committee members. I also want to thank, ahead of time, the very indulgent members who are here from the Nuclear Waste 17 18 Technical Review Board, especially since I'm going to say 19 that we will take a five-minute break. 20 [ Recess.) 21 CHAIRMAN JACKSON: I think we will proceed. I welcome to the table Dr. Deborah Knopman and Dr. Daniel 22 23 Bullen, from the Nuclear Waste Technical Review Board, and we look forward to hearing your remarks this morning. ) 24 25 DR. KNOPMAN: Good morning, Chairman Jackson. ) 1 l ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-67 1 It's good to be back. Commissioners, ladies and gentlemen, 2 it's a pleasure to be here today. My name is Deborah 3 Knopman. I'm a member of the U.S. Nuclear Waste Technical 4 Review Board. As many of you know, all boara members serve 5 part-time and most of us have other full-time jobs. 6 I am director of something called the Center for 7 Innovation and the Environment of the. Progressive Policy 8 Institute, in Washington, D.C. My technical expertise is in 9 hydrology,' environmental and natural resources policy 10 systems analysis and public administration. l i 11 With me today is another board member, Dr. Daniel 12 Bullen, who is director of the nuclear reactor laboratory 13 and associate professor of mechanical engineering at Iowa 14 State University, in Ames, Iowa. His technical expertise 15 includes performance assessment, modeling of radioactiye 16 waste disposal facilities, and materials performance and 17 radiological and severe service environments. 18 Our chairman, Dr. Jerrod Cohen, who is President 19 of Carnegie Mellon University, would have liked to be here 20 today to make this presentation, but he is out of the 21 country on university business. I'm not sure what.

Anyhow, 22 Dr. Cohen sends his regrets.

23 Let me begin by briefly summarizing who we are and j 24 what we do. The board was created in Congress in 1987, in 25 the '87 amendments to the Nuclear Waste Policy Act, and is ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 m

S-68 1 charged with evaluating the technical and scientific aspects 2 of DOE's high level waste program. This includes site 3 characterization activities at Yucca Mountain and activities 4 relating to the packaging and transport of high level 5 radioactive waste within -- and spent nuclear fuel. 6 The board is independent within the Federal 7 Government. We're not part of DOE or any other agency. All 8 of'our 11 members are nominated by the National Academy of 9 Sciences and appointed by the president. Dr. Bullen and I 10 have served as members of the board since January of 1997. 11 You asked the board to provide our views on the 12 viability assessment at Yucca Mountain that was recently, 13 published by DOE. We are pleased to do so, but we must 14 preface our remarks by noting that the board's review of 15 this document is ongoing and these are preliminary views 16 that we present today and these views may evolve as our 17 review continues. 18 As you know, the purposes of VA were to summarize 19 the scientific information that had been collected over the 20 last 15 years, presents a conceptual design of a repository 21 and waste packages that might be suitable for the site, 22 estimate how well such a repository would isolat'e waste from 23 the human environment, identify additional studies and 24 costs, and prepare a license needed to evaluate the site, 25 prepare a license application, and then estimate the overall ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

O' S-69 1 cost of disposing of the waste. 2 It's an evaluation. The VA is an evaluation of 3 progress, on-site characterization, and it was meant ~to 4 provide a technical basis for deciding whether to continue 5 studying the site. 6 The VA is not and was never intended to be a 7 determination of whether the Yucca Mountain site is suitable 8 for development as a permanent geologic repository. The 9 suitability decision projected for 2001 requires the 10 completion of further site studies, repository design work 11 and analyses of repository system performance. 12 So far, neither the board's review of the VA nor 13 its other reviews of the program has identified any features 14 or processes that would automatically disqualify the site. 15 We think the VA is clearly the most significant 16 milestone thus far in the characterization of Yucca 17 Mountain. There are many parts of the VA that present 18 cutting-edge scientific analysis in a comprehensible format 19 and the board has commended and continues to commend the DOE 20 for the successful completion of this assessment. 21 In a assembling the VA, DOE integrated very large 22 amounts of data and analyses, established a preliminary 23 repository design and set priorities for work to be 24 completed before decisions are made about site 25 recommendation and licensing. ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D C. 20036 (202) 842-0034

o S-70 1 Most important, I think, from our board 2 perspective, the process of integration has had the effect 3 of focusing the objectives of the scientific investigations. In particular, the VA highlighted the very close connections 4 between the repository design and the priority list of key 5 6 uncertainties about the natural system. 7 For example, such site characteristics as the j movement of water and vapor at temperatures above boiling 8 and the effect of high temperatures on rock stability are 9 10 important only because of the VA's high temperature 11 repository design. In a low temperature or below boiling 12 point design, these uncertainties would be less significant and might not need to be resolved for making a suitability 13 14 determination. It's a very important connection and we 15 think this permeates the whole evaluation process. The board concurs with the DOE that the VA is 16 simply a snapshot of current knowledge about the site that 17 Congress can use to make an informed decision on whether to 18 19 continue funding. Today we will discuss our board's general views 20 about the site and design of the repository for the site 21 22 based on our review of VA. We do conclude, we have concluded that Yucca Mountain continues to merit study, as 23 the candidate site for a permanent geological repository and 24 that work should proceed to support a decision on whether to 25 ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 642-0034

S-71 1 recommend the site to the President for repository 2 development, f 3 We think the 2001 date anticipated for this 4 decision is very ambitious and much work remains to be 5 completed. At a minimum, significant progress on the work 6 identified by the board in its November 1998 report and by 7 DOE in volume four of the VA will be required to support a 8 technically defensible decision. 9 The board supports continuing focus studies of 10 both natural and engineered barriers at Yucca Mountain to 11 attain a defense-in-depth repository design and to increase 12 confidence in predictions of repository performance. 13 In November of '98, the board issues a report 14 outlining its views on the future research needed to address 15 uncertainties about the performance of the repository 16 system, including both the engineered and natural barriers, 17 and the board concluded in that report that although there 18 are economic and technical limits to reducing uncertainties 19 about the performance of the proposed repository system, 20 some key uncertainties can be reduced further over the next 21 few years through a focused research effort. 22 The board reali?.es there will always be 23 uncertainty about the performance of a repository far into 24 the future and that eliminating all uncertainty is not 25 possible or necessary. ANN RILEY & ASSOCIATES, LTD. l Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 I (202) 842-0034

S-72 1 However, the board believes that identifying 2 important sources of uncertainty, estimating the magnitude 3 of those uncertainties, reducing critical uncertainties, and 4 evaluating the effects of residual uncertainties on expected 5 repository performance are essential for supporting a 6 technically defensible site suitability decision and license 7 application. 8 The board notes that the VA relies heavily in some 9 cases on the formal elicitation of expert judgment. This 10 was necessary and we think extremely useful, given the lack 11 of field and laboratory data in certain areas and the 12 equivocal nature of some of the data in other areas. 13 However, as the experts themselves pointed out, 14 expert judgment should not be used as a substitute for data 15 that can be obtained directly from site laboratory or other 16 investigations. 17 In the board's view, every reasonable effort 18 should be made to minimize uncertainty through repository 19 and waste package design. Additional data then can be 1 20 sought to addres's uncertainties rather than relying so heavily on expert judgment to support decisions about the 21 suitability of the site and a possible license application. 22 23 After reviewing the VA, the board concludes that a significant amount of additional scientific and engineering 24 work will be needed to increase confidence in a site 25 ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-73 1 suitability decision and license application. Alternative 2 responsibility designs should be evaluated that have the l 3 potential to reauce uncertainties in projected repository l 4 performance and thereby reduce the scope of additional 5 necessary scientific study. 6 Regardless of the design adopted, however, 7 long-term scientific studies will be needed.to establish a 8 solid foundation for projecting repository performance 9 thousands of years into the future. 10 Let me go into this in a little bit more detail 11 As you all know, the DOE has spent many years and many 12 dollars studying the Yucca Mountain site and designing the 13 engineered components of the repository system compatible 14 with the site. These efforts have produced a large amount 15 of data, but significant uncertainties remain about the 16 ability of the VA reference design to safely isolate 4 17 radioactive waste. 18 In part, this is a problem inherent in 19 extrapolating repository performance for thousands of years 20 from data acquired over a much shorter period. 21 Uncertainties also are associated with specific 22 characteristics of the Yucca Mountain site, especially the 23 difficulty in predicting the nature of water movement 24 through the fractured unsaturated rocks of the mountain and 25 the possible entry of water into repository tunnels and its ANN RILEY & ASSOCIATES, LTD. i Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 l (202) 842-0034 l b

S-74 1 contact with waste packages. 2 Uncertainties like would be exacerbated by the 3 high temperatures of the reference repository design, which 4 may reduce tunnel stability, enhance waste package 5 corrosion, and perturb water movement in ways that are 6 difficult to predict. 7 Predicting the performance of waste packages, 8 which play a crucial role in the performance of the VA 9 reference repository design, is a critical area that.needs 10 more study. Candidate waste package materials rely on the 11 presence of a thin passive layer to protect the underlying 12 metal from the oxidizing environment that will be present in 13 a Yucca Mountain repository. 14 I will just add, the mountain breathes, so there 15 is likely to be oxygen in that mountain all the time. 16 Improving the basic understanding of long-term 17 passivity is essential because at present, there seems to be 18 no documented natural or manmade analogs.that can be used to 19 demonstrate whether this mode of protection would persist 20 over the desired period of time. 21 Research also should be continued on the 22 susceptibility of the passive layer to known modes of 23 corrosion, especially potentially catastrophic failure 24 modes, such as stress corrosion cracking. 25 The board believes that the scientific and ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

e O O S-75 1 engineering work completed to date, as extensive as it is, 2 should be supplemented to improve the technical foundation 3 for evaluating the suitability of the site for preparing a 4 license application. The board agrees with a DOE 5 commissioned peer review panel which found that two types of 6 additional cata are needed to improve the credibility of the 7 total system performance assessment part of the VA. 8 First, fundamental data that are essential to the 9 development and implementation of the models, and, two, data 10 sets designed to challenge conceptual models and test the 11 coupled models used in TSPA VA. There are substantial 12 uncertainties about the performance of a repository based on 13 the VA reference design that can be resolved only by 14 considering alternative repository and waste package designs 15 and by collecting additional scientific data. 16 In volume four of the VA, the DOE has identified 17 and set priorities for a suite of additional studies to 18 produce information needed for repository licensing, 19 assuming that the site is determined to be suitable for l 20 development as a repository. 21 The planned studies include data collection 22 analysis and engineering design as appropriate for the three major barriers discussed by the board in its November ' 98 23 24 report, and we include in that unsaturated zone, the 25 engineered barrier system, and the saturated zone. l 1 ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 200?6 ( (202) 842-0034 1

S-76 1 Among the most important are geologic, geochemical 2 and hydrologic studies, including those planned for what we 3 call the east-west across drift, also called the enhanced 4 characterization of the repository block project. These studies are aimed at understanding the 5 magnitude and distribution of seepage into the repository 6 7 under present conditions and under past conditions when the 8 climate was very different. They include systematic 9 analysis of the rock samples being collected, esp- .lly for 10 chlorine-36 and other indicator isotopes. Flow and seepage. tests at different locations 11 12 along the drift, moisture monitoring activities, tests in 13 the lithophyssal zones that would host the majority of waste packages, and studies of the Solitario Canyon fault, the 14 i 15 active fault bounding the repository, that may also serve as 16 a main conduit for percolating water. 17 Of equal importance are studies for supporting \\ projections of the performance of the engineered barrier j 18 19 system,.which, in the VA reference design, plays a critical role in isolating radioactive. wastes for tens of thousands 20 ) 21 of years. The studies identified by the DOE in volume four 22 of,the VA appear to be appropriate in the sense that they're 23 24 technically feasible, likely to produce useful information that will improve the understanding of long-term repository 25 ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 l

y-S- 77 ~ 1 performance. There is no guarantee, however, that 2 completion of these studies will lead to successful 3 development of a repository at the site. Studies could show 4 the site to be unsuitable. 5 They could raise new questions requiring further 6 study. On the basis of current information, however, the 7 bnard is pleased that volume four identifies an appropriate 8 suite of studies to be pursued in the years ahead. 9 The board is concerned that some of the planned 10 studies identified in volume four of the VA may be deferred 11 because funds are not available to carry them out in a 12 timely manner. Deferring scientific and engineering studies 13 will delay the assembly of a more credible technical basis 14 to support the site recommendation anticipated in 2001, and, 15 if the site is found suitable, license application in 2002. 16 The current VA repository design, a credible basis 17 does not yet exist. For some additional thoughts on alternative 18 19 repository design and to complete our presentation, I would 20 like to turn my colleague, Dr. Bullen. 21 DR. BULLEN: Thank you, Dr. Knopman. High 22 temperatures in the VA repository design cause large 23 uncertainties about how the site would behave both before 24 and after repository closure. The board believes that a 25 repository design with a lower waste package surface ANN RILEY & ASSOCIATF.S, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 ('n~' 842-0034

S-78 1 temperature merits further detailed analysis. 2 Such a design has the potential to reduce 3 uncertainty, simplify the analytical bases required for site 4 recommendation, and make licensing easier. 5 In fact, I'd like to repeat that last two sentences, that the board believes that repository design eith a lower waste package surface temperature merit further E detailed analyses. Such a design has a potential to reduce 9 uncertainties, simplify the analytical bases required for 10 site recommendation, and make licensing easier. la Combined with improved waste package shielding, 12 the design could also simplify pre-closure performance 13 confirmation by enhancing access to tunnels, thus reducing 14 or eliminating the need for separate performance 15 confirmation drifts and permitting direct access to 16 performance confirmation instrumentation near the waste 17 packages. 18 The following factors influenced the board's~ 19 thinking on repository design. Lower temperatures could 20 significantly reduce coupled thermal hydrologic and thermal 21 geochemical processes. Maintaining near field temperatures 22 below the boiling point of water after repositorp closure by 23 ventilation of aging could reduce uncertainties about the 24 movement of water and associated geochemical processes in 25 the repository's natural barriers. ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-79 1 This could increase the confidence in the analyses 2 of repository performance required for a site suitability N 3 determination. For a given environment, chances for 4 degradation of corrosion resistant waste package materials 5 would be significantly reduced if peak waste package surface j 6 temperatures were reduced. J 7 High repository temperatures are. expected to 8 increase the mechanical degradation of repository rocks. i 9 There is little, if any relevant experience to draw on for 10 predicting the long-term effects of repository heating and 11 subsequent cooling on drift stability. 12 The DOE is evaluating alternative repository 13 designs that may be appropriate as the basis for a license j 14 application and the reference repository design presented in 15 the VA is expected to change as the alternatives are 16 considered. 17 The board strongly urges that analyses of j 18 alternatives should not be limited to enhancements to the 19 reference design, but should give serious consideration to 20 true alternatives to the reference design, including a 21 design that limits waste package surface temperatures. 22 If Yucca Mountain is found suitable and 23 construction of a repository is authorized, the board 24 believes that there will be a need for a long-term science 25 program to reduce uncertainties about the performance of i ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-80 engineered barriers and interaction between the repository 1 2 and natural processes. 3 An important goal of these studies should be 4 identification of unknown failure modes or unexpected 5 evolution of natural processes that could adversely affect 6 the performance of the major barriers of the repository. 7 Thus, these studies may be more extensive than the 8 performance confirmation activities now anticipated for a 9 repository. For example, if the waste package design 10 continues to rely strongly on corrosion resistant metals 11 protected from corrosion by a passive layer, long-term 12 scientific studies need to be carried out to improve the 13 basic understanding of the processes that could affect the 14 passive layer. 15 Long-term studies of the natural barriers also 16 will be needed primarily to verify projections of water 17 movement within the unsaturated and saturated zones near the 18 repository. For a high temperature repository design, 19 fundamental studies of coupled thermal hydrologic and 20 thermal geochemical processes will be needed. 21 For a low temperature design, a less extensive program of monitoring in situ water movement may be 22 23 adequate. Whether the long-term scientific studies are a 24 decade-long program or a much longer will depend in part on 25 how the repository design evolves. There is no doubt, ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-81 1 however, that a program of some sort will be needed to 2 increase confidence in estimates of long-term repository l 3 performance. 4 The ultimate goal of the studies at Yucca Mountain 5 is to determine that a repository at the site can safely 6 isolate wastes from the human environment. The DOE proposes 7 to demonstrate safe waste isolation through.a..five-part 8 post-closure safety case consisting of the following. 9 Assessment of expected post-closure performance, 10 design margin and defense-in-depth, consideration of 11 disruptive processes and events, insights from natural and 12 . manmade analogs, and a performance confirmation plan. 13 The board believes that this proposed strategy is 14 an appropriate way to evaluate a Yucca Mountain repository. 15 Although each component, especially defense-in-depth and the 16 performance confirmation plan, requires significant 17 additional development. 18 Multiple lines of evidence will provide a more 19 convincing demonstration of repository safety than would any 20 individual component of the safety case. TSPA, including 21 sensitivity and uncertainty analyses, is the appropriate 22 core analytical tool of the safety case. TSPA is the 23 analytical technique that pulls together relevant 24 inforcation about the performance of the repository system, 25 determines which features or parameters could strongly ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

o S-82 1 influence perforniance, and estimates the uncertainty in 2 projections of performance. 3 TSPA has limits, however, and the DOE will need to 4 aggressively pursue the other four components of the safety Judging how realistic the bottom line TSPA estimates 5 case. 6 of repository performance are in the VA is difficult. In 7 fact, a DOE presentation to the board at its most recent 8 meeting stated that the VA's performance assessment cannot 9 be used to do the following; cannot assess compliance with 10 regulatory criteria, cannot show defense-in-depth for the 11 design of the repository system, as we saw earlier this 12 morning, cannot assess the importance of small design 13 changes, and cannot determine the suitability of the overall 14 repository system. 15 Because of a general lack of data to support 16 critical assumptions in the mathematical models, some of the 17 assumptions in the TSPA VA are likely to be overly 18 conservative and others may be non-conservative. Numerous I 19 examples are presented in the recent report of the TSPA VA peer review panel, which I understand is actually being 20 21 presented today in Las Vegas. 22 Assessing the realism or at least verifying the 23 conservatism of TSPA projections of repository performance 24 is an important goal of the additional studies called for by 25 the board. The board does not believe, however, that ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-83 1 underlying -- that relying solely-on TSPA to demonstrate 2 repository safety will ever be possible. l 3 For that reason, the other four components of the 4 . cost-closure safety strategy should be developed 5 aggressively as compliments to TSPA. An implicit or 6 explicit sixth component of the safety strategy should also 7 be considered; designing the waste packages and the l 8 repository to minimize uncertainties in projected repository 9 performance. 10 The VA concludes Yucca Mountain remains a promising site for a gev_ogic repository and work should 11 12 proceed to support a decision in 2001 on whether to 13 recommend the site to the President for the development as a 14 repository. The board agrees that Yucca Mountain continues 15 to merit study as the candidate site for a permanent 16 geologic repository and that work should proceed to support 17 a decision on whether to recommend the site to the-President 18 for development. The 2001 date anticipated for this decision is 19 20 very ambitious and much work remains to be completed. At a minimum, progress on the work identified by the board in its 21 22 November 1998 report and by the DOE in volume four of the VA 23 will be required to support a technically defensible 24 decision. The board supports continuing focus studies of 25 l ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

o S-84 1 both natural and engineered barriers at Yucca Mountain to 2 attain a defense-in-depth repository design and to increase 3 confidence in predicting -- in predictions of repository 4 performance. 5 This concludes our prepared remarks and we would 6 be happy to answer any questions that you may have. 7 CHAIRMAN JACKSON: I have a comment and then a 8 question, which you may think that you've already answered. 9 It strikes me that perhaps TSPA and whac it means, total 10 system performance assessment, may be a misnomer if, in 11 fact, these other four elements of what you feel should 12 comprise a safety case; that if it can't address design, it doesn't have 13 margin and defense-in-depth, if you can't 14 the consideration of disruptive processes and events, if it 15 doesn't have folded into it insights from manmade and 16 natural analogs, and it has no performance confirmation plan, how can you make an assessment or a prediction of 17 18 expected post-closure performance? 19 That's my question, but let me put it another way. 20 To what extent is the DOE reference design a natural setting 21 driven design vice being a conceptual design, which is then 22 studied for the effect of the environment on it? Do you 23 understand what I'm saying? 24 DR. KNOPMAN: Yes. 25 CHAIRMAN JACKSON: To what extent is one really ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

Q l S-85 i 1 looking at a truly coupled modeling? Because if you' don't, 2 you're never going to get into the issue of design margin I 3 and defense-in-depth. l l 4 DR. BULLEN: If you look at the history of the 5 design that we see in TSPA, you'll go back about six or 6 seven years and you will understand that at the time, it was 7 thought that the mountain was relatively dry. And since the 8 mountain was relatively dry, the waste package design and 9 the hot repository concept was thought to be a very good 10 strategy for isolating waste from the accessible 11 environment. 12 Since that time, we've built exploratory studies 13 facility, we built the enhanced characterization repository 14 block, we've discovered chlorine-36, we've changed the 15 estimate of the percolation rates that are coming into the 16 mountain, and we've also changed the prediction of what that 17 percolation rate might be in the future with the future 18 climate changes. l i I 19 That design that was formed in the basis of the 20 multipurpose container six or seven years ago is probably 21 not the design that you would pick now had you had that 22 information six or seven years ago. So the evolution of the de, sign, which the license application design selection 23 24 process is currently underway, is addressing those issues. 25 And if you look at the five designs that were ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 l (202) 842-0034 4

S-85

1 mentioned by the ACNW, you'll see that a majority of those 2

designs don't have corrosion allowance barrier on the 3 outside, which would make sense. Engineers wouldn't put a 4 corrosion allowance barrier where there is dripping water. 5 So what we see here in the TSPA and its analyses 6 is essentially a design that was frozen a while ago and analyzed and now DOE is making changes to that design to 7 8 address the license application and -- well, suitability 9 determination and license application in the future, based 10 on what they know now. And so the evoi.ution is taking place and that '11 - 12 design is, again, based on the environment, as we understand 13 it. So in answer to your question, the design, as we see 14 it, is evolving and the design is based on the mountain. It 15 wouldn't go into Commissioner McGaffigan's back yard because 16 we wouldn't pick that design or DOE wouldn't pick that 17 design to address the issue. 18 But the design that they see now or the evolution 19 of the design is a process that I think is important. 20 CHAIRMAN JACKSON: You were going to make a 21 comment 22 DR. KNOPMAN: I was just going to try to answer 23 your first question. 24 CHAIRMAN JACKSON: Please. 25 DR. KNOPMAN: But did you want to add that? ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

o S-87 1 CHAIRMAN JACKSON: No. Go on. 2 DR. KNOPMAN: I concur with my colleague on his 3 response.to the second question about the natural setting 4 design. What the board is saying is that TSPA is one of 5' what should lx3 multiple lines of evidence that feed into our 6 overall confidence in making predictions about performance. 7 It is a construct. It.is a.model of models, in 8 effect. But it's not the only way in which one can 9 integrate scientific information. We want it to be as rich 10 as possible. The board's comment about where TSPA is now 11 reflects TSPA VA. 12 Now, there may not be many changes in that -- in 13 the performance assessment modeling tools and strategy 14 between now and the time of a suitability determination, 15 that remains to be seen, but the fact is in its current 16 state, it is not -- should not be relied on solely as a .17 source of credible predictions. That's freely admitted. 18 But that doesn't mean it's not useful. It's 19 extremely useful in gaining insights into how the system -- 20 different parts of the system may function.together. 21 However, it's limited by our own understanding of those 22 coupling of processes. 23 CHAIRMAN JACKSON: Well, perhaps in the spirit of 24 plain English initiatives, I mean, it could be construed as 25 a misnomer because it really is a methodology of integrating ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-88 1 information, but within a certain boundary. 2 DR. KNOPMAN: Yes. I personally would prefer 3 partial system performance. 4 CHAIRMAN JACKSON: Yes. PSPA, right? 5 DR. KNOPMAN: I've had a problem with that all 6 along. 7 CHAIRMAN JACKSON: But let me.ask you a question. 8 You've talked about that there shouldn't be an over-reliance 9 on expert elicitation. 10 Can you give the Commission a concrete example of 11 where you think over-reliance on expert elicitation could be j 12 replaced, in a timely manner, by data collection and 13 testing? 14 DR. KNOPMAN: Yes. Let me start with the i 15 ' saturated zone, which our board believes does play 16 potentially a role in waste isolation. 17 Right now there is a dearth of data about the 18 saturated zone. During the expert elicitation process, the 19 estimates by the experts were literally all over the board 20 because of that dearth of data. We think that the drilling is proceeding rather 21 22 rapidly now with the -- Nye County has got a drilling 23 program, you may have heard something about that. Going 24 from zero to ten or 12 wells can produce some good 25 information about transmissivities and some of the -- some ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

i s c S-89 l 1 better understanding of the properties of the flow regime. ] 2 So I would say that is a very good example.

Now, 3

is it enough or adequate? That's to be seen. But going 4 from so little to what that Nye County program can produce, 5 I think, is a substantial advantage and possibly will allow 6 a much more confident view of what kind of dilution we may l 7 be looking at, what kind of reducing environment we might be 8 looking at, the geochemistry in the saturated zone is very ] 9 important. 10 DR. BULLEN: In addition to what Dr. Knopman said, 11 the expert elicitation panel on waste package performance 12 and waste package degradation cited a number of experimental 13 programs which could be done in the near term to answer the 14 questions like what is the range of susceptibility of 15 alloy-22 to crevi ' corrosion, which was the key question 16 that was identif;ica this morning in the ACNW presentation. 17 And those experiments can be done and, in fact, 18 the Center for Nuclear Regulatory Analysis has done those 19 types of experiments and had been actually unsuccessful in 20 making it happen'below the boiling point, which is one of 21 those things that says, well, maybe this material is pretty 22 good. 23 Those experiments are underway and most of them 24 are at our national laboratory and, in fact, that's where I 25 am, to take a look at those experiments. l l [ ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

o S-90 1 But these are questions that can be answered in 2 the short term that would greatly support evidence for a 3 suitability determination. And so that basically takes a 4 look at the expert elicitation, identifying things that 5 could be done, and then hopefully the DOE taking that 6 information and actually obtaining that data. 7 DR. KNOPMAN: I would add a third example about 8 what actually happens to moisture that possibly may enter 9 into the repository drift, and this is something we can go 10 and observe and these experiments are beginning to proceed 11 in the ECRB now, as we understand it, and they'll be sealing 12 off some parts of it. 13 So the speculation in the USGS review of VA about 14 what exactly happens to the drips, this can be -- we can do 15 some observations, it will make a big difference. 16 CHAIRMAN JACKSON: Now, you clearly have a point 17 of view, so my question is, are there any benefits that you 18 see of a high temperature design beyond the reduction of 19 water contact with the waste package. 20 DR. BULLEN: When the high temperature design was 21 proposed, with the limited infiltration rate, it was 22 probably the correct path to take. With the additional 23 information now, the board is seriously concerned that a 24 high temperature design does a number of things that may 25 pose more detriments than benefits. ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

r 1 l 1 S-91 1 Right now, there are significant, as you ] 2 mentioned, as you noticed in our testimony, there are i 3 significant uncertainties associated with the movement of 4 4 water, the changes in the chemistry, the stability of the j 5 rock, and so a high temperature design adds all that 6 uncertainty. 7 A below boiling point design improves waste 8 package performance and I would beg to differ with the 9 presentation this morning that it -- it does not necessarily 10 increase relative humidity near the waste packages, if the 11 repository is ventilated for extended periods of time. 12 Now, that is not in any of the designs long term 13 that are proposed, although the enhanced design analyses 14 does have a couple of ventilated scenarios that were being 15 evaluated. But the ventilation not only removes heat, it 16 removes water. So the longer we can keep the waste packages 17 in a benign environment and the longer we can avoid this 18 area of susceptibility in temperature, where crevice 19 corrosion of alloy-C22 or alloy-22 may be a problem, the 20 better off we are. So the board feels that there is a reduction in 21 22 uncertainty associated with a low temperature design and 23 that there would be an improvement in performance. 24 CHAIRMAN JACKSON: What are your thoughts on our 25 staff's concern that the design may not iterate to some l l ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-92 1 final one by the required deadline? 2 DR. BULLEN: In reading the staff's comments from 3 yesterday, there is a significant concern that they're going 4 to carry through or carry forward a great deal of 5 information and, in fact, just the analyses of the five 6 designs is going to be a challenge for not only our board, 7 but your staff. 8 So I would tend to agree and, in fact, I would be 1 9 very pleased, should they focus the design down to one and 10 carry that through. 11 DR. KNOPMAN: The board doesn't have a formal 12 position on how many designs should be carried forward. The 13 board's position on the low temperature design is that it 14 requires further analysis. 15 We're not cost experts. There are many aspects of 16 design, repository systems operations that we don't analyze. 17 So we want to make it very clear that while it looks to us 18 that this would be a way to reduce some of the nagging 19 uncertainties about the geological -- the natural barrier i 20 system, as well as the natural barrier system. l We're not investing in stock in a low repository 21 22 design either. I would'like to see that analysis done 23 seriously in a way to provide a choice, a good technical J 24 choice. 25 CHAIRMAN JACKSON: You've been very indulgent. ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

1 { S-93 1 1 I'm going to indulge my colleagues down the line. I 2 Commissioner Dicus. 3 COMMISSIONER DICUS: I don't have any questions. 4 CHAIRMAN JACKSON: Commissioner Diaz. l 5 COMMISSIONER DIAZ: If I go through your testimony ) l 6 in here, it appears to me that if I go back to my last 7 question, that you are saying that in a. series of critical 8 issues, we are not at the point of the S curve that we can 9 stop and put an engineering point on it. 10 The question is, have those issues, the ones that 11 are at that point, have they been catalogued by the board 12 and communicated? 13 DR. KNOPMAN: Yes, to some extent, and your staff 14 has catalogued them and I think in the area of volcanic and 15 seismic hazards, there is closure, in some sense. There are 16 a couple of issues that have been raised having to do with 17 extensional processes at Yucca Mountain. These are not 18 confirmed, but overall those issues, we think, have been 19 dealt with adequately. So I guess I would put that. 20 The climate issue is, I think, had been thought to 21 be in that category. I think that's going to get reopened 22 and probably should. It's an important boundary condition. 23 COMMISSIONER DIAZ: But there are certain issues 24 that you said are being now addressed that could provide 25 that little bit of extra information that is needed. ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-94 1 DR. KNOPMAN: The board very strongly advocated 2 the east-west cross drift or the ECRB, precisely because we 3 thought there would be a fairly large increase in 4 information in a relatively short amount of time about the 5 repository block itself and there has been. 6 We think it's not -- hasn't been -- we still 7 haven't tapped into the full potential of that tunnel to 8 provide us with the additional information, studies.. Some 9 things have gone slowly, particularly the chlorine-36 10 analyses that have been collected, but are being rather 11 slowly analyzed. 12 And I'd point out that, again, on the USGS review, 13 that the chlorine-36 evidence of fast paths wasn't even 14 mentioned in that review. 15 So these are things that can be -- that we can 16 learn a lot about in a relatively short amount of time that 17 would significantly add to our insight, I think. 18 COMMISSIONER DIAZ: And last but not least, on the f 19 same point. Has the board looked at the philosophy of 20 design as you go as a potential to increase reliability of 21 the state-of-the-art design rather than the ten years ago 22 design that was no good? 23 DR. KNOPMAN: Well, our board, uhich includes 24 ecologists and folks from other disciplines, I think, 25 generally endorse the idea of adaptive management.

However, ANN RILEY & ASSOCIATES, LTD.

Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 i J

S-95 l l 1 the board works very hard to not wander into the realm of 2 policy choices. So we don't have an opinion about how much 3 flexibility should be retained in the licensing process 4 within the design. 5 I'd point out, I was in Sweden last week, they're 6 wrestling with this very question, because they have a very 7 different kind of siting process and.the communities that 8 are under -- the communities that are considering whether 9 they want the repository want the design nailed down now 10 before they lay themselves on the line politically to make 11 the choice for further additional site characterization 12 work. 13 So this is a big question not just for the U.S., 14 but elsewhere, as to how much you lock in the design, but 15 the board doesn't have a position on that. 16 DR. BULLEN: I would like to emphasize one point 17 that draws on your analogy, is that different designs have I 18 different sets of S curves, as you made an allusion to, and 19 I guess the board would say that the S curves for a low 20 temperature design are different than those associated witP. 21 a high temperature design and your level of confidence on i ) 22 where you are on the curve is different. 23 CHAIRMAN JACKSON: Commissioner McGaffigan. 24 COMMISSIONER McGAFFIGAN: I'll follow-up briefly i 25 on the flexibility issue. It does strike me that having ANN RILEY & ASSOCIATES, LTD. I Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 2 84 b3 l

1 S-96 1 some flexibility in our process is important, because we are 2 going to learn something over the next 50 years, if this 3 project goes forward, and I think that the general process i 4 around here is license amendments, if it's a major change, l l 5 if they decide to put back-fill in at some point, for j i 6 example, and it's not in the license design, that you would 7 only do that if a safety case was made that that's an 8 improvement. f 9 So I think what you could tell the public is that j 10 we're building in the flexibility in in order to make safety 11 improvements. 12 If I were talking to the Swedish public, I think 13 I'd try to make that -- you know, we're going to do a 14 reference design based on what we know today, but there may 15 well be improvements in waste packages or other mechanisms 16 for making the repository even more safe, and we presumably 17 want a process that's flexible enough to adapt to those 18 sorts of changes. 19 CHAIRMAN JACKSON: But I think she's just saying 20 that that's a public policy issue. 21 DR. KNOPMAN: We, by the way, tried that on the 22 Swedes, just to say, well, wouldn't the communit'ies 23 themselves, and they said, no, they thought it would 24 undermine their confidence in what they were being told now 25 about performance, why you need to make it more safe. ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

^ S-97 r 1 COMMISSIONER McGAFFIGAN: Okay. Why do we have to 2 go from MS-DOS to Windows 98? Sometimes I worry myself. l l 3 The other issue, on the -- clearly, I hear a l 4 recommendation for -- not a recommendation, but a 5 recommendation for study of a lower temperature repository 6 and the use of -- you read twice the sentence about this 7 helping in the licensing case. 8 Are they ready to make that decision? If they 9 have to get -- there is all this-pressure for them to lock 10 into a design by May, which is two months from now. Is it 11 conceivable that they could lock into a lower temperature 12 design in May if they have to go to a single design? 13 DR. KNOPMAN: I think it's not an external 14 constraint really. My understanding is they believe that's 15 -- they're trying to respond to what they think will be the 16 licensing process. But it'r not any -- it's something that 17 they're making an internal judgment about, that that's when 18 they need it to happen. 19 COMMISSIONER McGAFFIGAN: But can they do these 20 other -- you mentioned operations issues that have to be 21 studied, cost issues, and somebody yesterday said this could 22 affect the total volume of waste that might be able to be 23 placed in Yucca Mountain; therefore, the issue of a second 24 repository, heaven forbid, might come up sooner rather than 25 later. l ANN RILEY & ASSOCIATES, LTD. l Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

S-98 1 Can they get all that body o'f work done in time to 2 pursue your proposal for this May decision they have to 3 make? 4 DR. FJNOPMAN: Assuming the 2001, keeping that in 5 place. I think that would have to be assessed. I don't 6 think we're really in a position to say one way or another 7 and it would be a matter of degree and comprehensibility and { 8 9 COMMISSIONER McGAFFIGAN: I think what's probably 10 driving the May decision may well be that they have to say 11 what sort of -- in the environmental impact statement, they 1 12 have to have a design and that's due, I think, later this 13 summer. 14 DR. BULLEN: Having watched the license 15 application design selection review workshop that started in i 16 January of this year, actually started late last year but 17 culminated actually last week in presentations that were 18 made in Las Vegas. They have done a very credible job of q 19 doing what we asked them to do and saying don't look at just 20 the enhancement to the current repository design. 21 They have taken a look at hot repositories, 22 they've taken a look at cold repositories, they've taken a l 23 look at different areas of mass loading and different waste 24 package configurations. i 25 And so the process is ongoing and the board has l i ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 1 i i

S-99 1 been following that very closely. In fact, we had members 2 at this meeting last week who talked about the five Gesigns 3 that you have seen as enhanced design EDAs, and I forget 4 what -- assessments or whatever the word night be. 5 But they are coming to closure on that process by 6 May and they will make a recommendation or there will be a 7 recommendation made to the Departmentaof Energy and we feel 8 that they've done a very credible job of attempting to do 9 this and it's an ongoing process and we're still reviewing 10 it. 11 So in answer to your question, yes, they are doing 12 it. How much will they get done and how credible will it i I 13 be? We still have to see. But they have done as we've 14 asked'and sort of opened the flood gates, if you will, and 15 allowed them to take a look outside the box. 16 DR. KNOPMAN: The alternatives within the -- as 17 you know, within the EIS do include a lower thermal loading. 18 COMMISSIONER McGAFFIGAN: I didn't know that. 19 DR. KNOPMAN: They have right now -- and they 20 designed -- you know more about EIS than I do, I think. 21 COMMISSIONER McGAFFIGAN: You know more about EIS 22 than I do, I think. 23 DR. KNOPMAN: They've designed the environmental 24 impact statement alternatives to be flexible in that because 25 there may be -- they don't want to have to redo the EIS as l ANN RILEY & ASSOCIATES, LTD. Court Reporters 1 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 j (202) 842-0034

~ S-100 1 design changes may be made, so they have a high, medium and 2 low thermal load as there are three alternatives, plus there. 3 is a no action alternative, which is cnother matter. 4 And so in principal, this shouldn't throw off I 5 their EIS process all that much, because they were to have 6 some credible analysis anyhow for these lower thermal 7 loadings. 8 COMMISSIONER McGAFFIGAN: That's a very good 9 point. I didn't know that. We're a commenting, not a 10 cooperating agency. So I think we're waiting to get the 11 draft rather than seeing it in advance. 12 CHAIRMAN JACKSON: Commissioner Merrifield. 13 COMMISSIONER MERRIFIELD: Going back to a questien 14 that the Chairman raised earlier, there is an issue about 15 the multiplicity of designs that are currently under study 16 and we are all grappling with the difficulties of that and 17 our lives would be made much simpler once the design is 18 fixed 19 I' raise this issue in the questioning we had 20 yesterday and aft'erwards, Commissioner McGaffigan made what 21 I thought was a very good point, and that is we can't fail 22 to recognize the fact that the decision of the EPA in terms 23 of what the appropriate standard would be is a key component 24 to this. 25' As you all know, we as a Commission decided to ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

t S-101 1 move forward with our Part 63 and included what we believed 2 would be the appropriate standard as a place-holder, a 25 3 millirem all pathways standard. 4 Although EPA has not indicated what its decision 5 will be, there are preliminary indications that they are 6 favorably disposed toward a 15 millirem standard with a 7 separate ground water pathway standard. 8 And so my multi-part question is, number one, have 9 you all taken a look at this issue and have an opinion on it 10 and, two, if you have, do ycu agree with virtually every 11 national and international body that it should be a 12 multi-pathway standard or do you agree with the EPA? 13 CHAIRMAN JACKSON: You can take the fifth, if 14 you'd like. 15 DR. KNOPMAN: The board is not entering inte the 16 debate on the standard. 17 COMMISSIONER MERRIFIELD: Do you have any position 18 'on the fact that this -- that ultimately the decision, which 19 we'll have to abide by, does play an important part and 20 vltimately the Department of Energy, making its decision on 21 a design, and, if so, have you articulated that to the 22 President? 23 DR. KNOPMAN: Let me say, I guess, on one issue 24 related to the standard, when you think about the range 25 between what the NRC has already proposed and what we ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C.-20036 (202) 842-0034

4 0 S-102 1 believe that the EPA may propose, these are numbers that, 2 when you look at the kinds of uncertainties around our 3 performance assessment, and our projections of dose, we're i 4 - in the best of all possible rarlds, I would say we've got 5 two to three orders of magnitude range of uncertainty in 6 those dose predictions. 7 So the difference between a 25 millirem per year 8 all pathways dose and a 15 millirem -- I mean, there are -- 9 I'm just saying there's a lot of uncertainty in the sysce.... 10 COMMISSIONER McGAFFIGAN: But the heart of the 11 difference, as Commissioner Merrifield has pointed out, is 12 not the 15 versus 25. That may well be something that is at 13 the margin. There is a two order of magnitude difference when 14 you use the current raximum contaminant levels for things 15 16 like technetium-99 and you end up with a de facto .2 17 millirem standard and the case to make for a .2 millirem 18 standard, as we heard yesterday, you know, just requires an 19 enormous amount of additional data and cost. 20 DR. KNOPMAN: Right. 21 COMMISSIONER McGAFFIGAN: And .2 millirem -- 22 CHAIRMAN JACKSON: Well, I think the better way, 23 rather than our preaching to them, it is better to -- 24 DR. KNOPMAN: No, I understand. 25 CHAIRMAN JACKSON: -- ask them, do you see a ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (2C') 842-0034

o S-103 1 significant difference in terms of the data and the approach 2 for capturing and analyzing that data that would be needed 3 to make the safety case using the one standard vice another? 4 DR. KNOPMAN: My own view is that it puts a 5 significant additional burden on saturated zone 6 characterization and geochemical analyses. I would stop 7 there. 8 CHAIRMAN JACKSON: 'Thank you very much. Let me 9 just thank you and thank also the Advisory Committee on 10 Nuclear Waste. Clearly, your views are very important to us 11 and will help us in our review of our own staff's paper on 12 the viability assessment, as well as in our interactions 13 with DOE and other stakeholders. 14 So unless there are any additional comments or 15 questions, we're adjourned. Thank you. 16 [Whereupon, at 11:38 a.m., the meeting was 17 concluded.] 18 19 20 21 22 23 20 25 ANN RILEY & ASSOCIATES, LTD. Court Reporto.rs 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034

CERTIFICATE This is to certify that the attached description of.a meeting of the U.S. Nuclear Regulatory Commission entitled: TITLE OF MEETING: MEETING WITH ACNW. PLACE OF MEETING: Rockville, Maryland DATE OF MEETING: Wednesday, March 17, 1999 was held as herein appears, is a true and accurate record of the meeting, and that this is the original transcript thereof taken stenographically by me,.thereafter reduced to typewriting by me or under the direction of the court i reporting company Transcriber: Natalie Renner Reporter: Mark Mahoney e I

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f Moving Beyond the Yucca Mountain Viability Assessment: Preliminary Views Dr. Debra S. Knopman, Member Dr. Daniel B. Bullen, Member U.S Nuclear Waste Technical Review Board presentation to the U.S. Nuclear Regulatory Commission March 17,1999 Rockville, Maryland r

Chairman Jackson, Commissioners, ladies, and gentlemen, good moming. It is a pleasure to be here today. My name is Debra Knopman and I am a member of the U.S. Nuclear Waste Technical Review Board. All Board members serve part-time, and most of us have other full-timejobs. I am director of the Center for Innovation and the Environment of the Progressive Foundation in Washington, D.C. My technical expertise is iri hydrology, environmental and natural resources policy, systems analysis, and public administration. With me today is another Board member, Dr. Daniel Bullen, who is director of the Nuclear Reactor Laboratory and associate professor of mechanical engineering at Iowa State University in Ames, Iowa. His technical expertise includes performance assessment modeling of radioactive waste disposal facilities and materials performance in radiological and severe service environments. Our Chairman, Dr. Jared Cohon, would have liked to be here today to make this presentation, but he is out of the country on university business. Dr. Cohon sends his regrets. Let me begin by briefly summarizing who we are and what we do. The Nuclear Waste Technical Review Board was created by Congress in the 1987 amendments to the Nuciear Waste Policy Act and is charged with evaluating the technical and scientific aspects of the Department of Energy's (DOE's) high-level nuclear waste management program. This includes site-characterization activities at Yucca Mountain and activities relating to the packaging and transport of high-level radioactive waste and spent nuclear fuel. The Board is an independent agency within the federal government, not part of the DOE or any other agency. The Board ha eleven members who are nominated by the National Academy of Sciences and appointed by the President. Dr. Bullen and I have served as members of the Board since January,1997. Introduction Today, you asked the Board to provide its views on the viability assessment (VA) of the Yucca Mountain site that was published recently by the DOE. We are pleased to do so, but we must preface our remarks by noting that the Board's review of the document is on-going a preliminary views we present today may evolve as our review continues. As you know, the purposes of the VA are to summarize the scientific information th been collected at the site over the past 15 years, present the conceptual design of a repositor waste packages that might be suitable for the site, estimate how well such a repository isolate wastes from the human environment, identify the additional studies (and their costs) needed to evaluate the suitability of the site and prepare a license application, and estimate th overall cost of disposing of waste at the site. The VA is an evaluation of progress on site characterization at Yucca Mountain and provides the technical basis for deciding whether to continue studying the site. The VA is not, and was not intended to be, a determination of whether the Yucca Mountain site is suitable for development as a pem.anent geologic repository. The suitab decision, projected for 2001, allows for the completion of further site studies, repos work, and analyses of repository system performance. So far, neither the Board's revie VA nor its other reviews of the program has identified any features or processes that wou automatically disqualify the site. ? I DrF300V1

\\ GeneralViews on the VA i The VA is the most significant milestone thus far in the characterization and evaluation of the Yucca Mountain site. Many parts of the VA present cutting-edge scientific analysis in a comprehensible format. The Board commends the DOE for the successful completion of this ) assessment. In assembling the VA, the DOE integrated large amounts of data and analyses,- established a preliminary repository design, and set priorities for work to be completed before decisions are made about site recommendation and licensing. The process ofintegration has had the salutary effect of focusing the objectives of the scientific investigations. In particular, the VA highlighted the close connections between the repository design and the priority list of key uncertainties about the natural system. For exa such site characteristics as the movement of water and vapor at temperatures above boiling and the effect of high temperatures on rock stability are important only because of the VA's high-temperature repository design. In a low-temperature (below boiling point) design, these uncertainties would be less significant and might not need to be resolved for making a suitability determination. The Board concurs with the DOE that the VA is simply a " snapshot" of current knowledge about the site that the U.S. Congress can use to make an informed decision on whether.to continue to fund studies of the site. Today, we will discuss the Board's general views on the site and on the design of a repository for the site, based on our review of the VA. The Board concludes tha Mountain continues to merit study as the candidate site for a permanent geologic repository and that work should pwed to support a decision on whether to recommend the site to the President - for repository development. 'Ihe 2001 date anticipated for this decision is very ambitiou work remains to be completed. At a minimum, significant progress on the work identified by the Board in its November 1998 :eport and by the DOE in volume 4 of the VA will be required to support a technically defensible decision. The Board supports continuing focused stud natural and englisied barriers at Yucca Mountain to attain a defense-in-depth repository desig and to increase confidence in predictions of repository performance. Uncertainties in Repository Performance In November 1998, the Board issued a report outlining its views on future research needed to address uncertainties about the performance of the repository system, including both the engineered and the natural barriers. The Board concluded in that report that although t economic'and technical limits to reducing, uncertainties about the performance of the propos repository system, some key uncertainties can be reduced further over the next few focused research effort. The Board reahzes that there always will be uncertainty about the performance of a repository far into the future and that eliminating all uncertainty i mmy, However, the Board believes that identifying important sources of uncertainty, estimating the magnitude of those uncertainties, reducing critical uncertainties, and ev effects of residual uncertainties on expected repository performance are essential for support technically defensible site-suitability decision and license application. r 2 DrF300VI

'Ihe Board notes that the VA relies heavily in some cases on the formal elicitation of expertjudgment. This was necessary and extremely useful, given the lack of field and laboratory data in certain areas and the equivocal nature of some of the data in other ueas. However, as the experts themselves pointed out, expert judgment should not be used as a substitute for data that can be obtained directly from site, laboratory, and other investigations. In the Board's view, every reasonable effort should be made to minimize uncertainty through repository and waste package design. Additional data then can be sought to address uncertainties, rather than relying so heavily on expertjudgment to support decisions about the suitability of the site and a possible license application. After reviewing the VA, the Board concludes that a significant amount of additiorv' scientific and engineering work will be needed to increase confidence in a site-suitability decision and license application. Altemative repository designs should be evaluated that have the potential to reduce uncertainties in projected repository performance, thereby reducing the scope of additional necessary scientific study. Regardless of the design adopted, however, long-term scientiGc studies will be needed to establish a solid foundation for projecting repository performance thousands of years into the future. Let me discuss the Board's views in more detail. Additional Scientific and Engineering Work is Naadad ..The DOE has spent many years (and many dollars) studying the Yucca Mountain site and designing the engineered components of a repository system compatible with the site. These effo have produced a large amount of data, but significant uncertainties remain about the ability of th VA reference design to safely isolate radioactive wastes. In part, this is a problem inherent in extrapolating repository performance for thousands of years from data acquired over a much sh period (years to dacadaa). Uncertainties also are associated with specific characteristics of Yucca Mountain site, especially the difficulty in predicting the nature of water movement through the fractured unsaturated rocks of the mountain and the possible entry of water into repository tunnels and its cootset with waste packages.. Uncertainties likely would be exacerbated by the high temperatures of the reference repository design, which may reduce tunnel stability, anhance wa package corrosion, ar.d perturb water movement in ways that are difficult to predict. Predictag the performance of the waste packages, which play a crucial role in the performance of the VA reference repository design, is a critical area that needs more st Candidate waste package materials rely on the presence of a thin passive layer to protect the underlying metal from the oxidizing environment that will be present in a Yucca Mountain repository. Improving the Sasic understanding oflong-term passivity is essential because, at present, there seem to be u dommented natural or man-made analogs that can be use demonstrate whether this taode of protection would persist over the desired period of time. Research also should be continued on the susceptibility of the passive layer to known modes of corrosion, especially potentially catastrophic failure modes, such as stress-corrosion crac The Board believes that the scientific and engineering work completed to date, as extensiv as it is, should be supplemented to improve the technical foundation for evaluating the s the site or preparing a license application. The Board agrees with a DOE-commissioned 3 DJF300VI

, o review panel which found that two types of additional data are need :d to improve the cred the total system performance assessment part of the VA (TSPA-V/ ): (1) fundamental data that essential to the development and implementation of the models and (2) data sets designed to challenge conceptual models and test the coupled models used in the TSPA-VA. There are substantial uncertainties about the performance of a repository based on the VA reference design that can be resolved only by considering alternative repository and waste package designs and by collecting additional scientific data. In volume 4 of the VA, the DOE has identified and set priorities for a suite of additional studies to produce information needed for repository licensing, assuming that the site is de to be suitable for development :.s a repository. The planned studies include data collection, analysis, and engineering design, as appropriate, for the three major barriers discussed b in its November 1998 report (unsaturated zone, engineered barrier system, and saturated zone). Among the most important are geologic, geochemical, and hydmlogic studies, including thos planned for the east-west cross drift. These studies are aimed at understanding the distribution of seepage into the repository under present conditions and under past conditions w the climate was very different. They include systematic analysis of the rock samples being collected, especially for chlorine-36 and other indicator isotopes; flow and seepage tests at locations along the drift; moisture-monitoring activities; tests in the lithophysal zones that wo host the majority of waste packages; and studies of the Solitario Canyon fault, the active fa bounding the repository that also may serve as a main conduit for percolating water. Of e importance are studies for supporting projections of the performance of the engineered sy 'em, which, in the VA reference design, plays a critical role in isolating radioactive w tens of thousands of years. i The studies identified by the DOE in volume 4 of the VA appear to be appropriate in the sense that they are technically feasible and are likely to produce useful information that wi improve the understanding oflong-term repository performance. There is no guarantee, however, that completion of these studies willlead to successful development of a repository a the site. The studies could show the site to be unsuitable, or they could raise new questions requiring further study. On the basis of current information, however, the Board is p volume 4 identifies an appmyriate suite of studies to be pursued in the years ahead. The Board is concerned that some of the planned studies identified in volume 4 of the V may be deferred because funds are not available to carry them out in a timely man scientific and engineering studies will delay the assembly of a more credible technical bas support the site recommendation anticipated in 2001 and, if the site is found suitab application in 2002. For the current VA repository design, a credible basis does Alternative Repository Design High temperatures in the VA repository design cause large uncertainties abo would behave both before and after repository closure. The Board believes that a repo with lower waste package surface temperatures merits further detailed analyses. Su the potential to reduce uncertainty, simplify the analytical bases required for si and make licensing easier. Combined with improved waste package shielding, the desi / 4 D W300VI

could simplify preclosure performance confirmation by enhancing access to the tunnels, thus reducing or eliminating the need for separate performance-confumation drifts, and permitting direct access to performance-confirmation instrumentation near the waste packages. The following factors influenced the Board's thinking on repository design. Lower temperatures would significantly reduce coupled thermal-hydrologic and thermal-geochemical pmcesses. Maintaining near-field temperatures bel.ow the boiling point of water after repository closure, by ventilation or aging, could reduce uncertainties about the movement of water and associated geochemical processes in the repository's natural barriers. This could increase confidence in the analyses of repository performance required for a site-suitability determination. For a given environment, chances for degradation of corrosion-resistant waste package materials would be reduced significantly if peak waste package surface temperatures were reduced. High repository temperatures are expected to increase the mechanical degradation of repository rocks. There is little, if any, relevant experience to draw on for predicting the long-term effects of repository heating and subsequent cooling on drift stability. The DOE is evaluating altemative repository designs that might be appropriate as the basis for a license application, and the reference repository design presented in the VA is expected to change as the alternatives are considered. The Board strongly urges that analyses of alternatives should not be limited to " enhancements" to the reference design but should give serious consideration to true alternatives to the reference design, including a design that limits waste package surface temperatures., ' Ieng-Term Scientific Studies. [ If Yucca Mountain is found suitable and construction of a repository is authorized, the i e. 9-Board believes there will be a need for a long-term science program to reduce uncertainties about the performance of engineered baniers and the interactions between the repository and natural processes. An important goal of these studies should be identification of unknown failure modes or unexpected evolution of natural processes that could adversely affect the performance of the major barriers of the repository. Thus, thse studies may be more extensive than the performance confirination activities now anticip.ted for a repository. For example,if the waste package design continues to rely strongly on corrosion-resistant metals protected from corrosion by a passive layer, long-term scientific studies need to be carried out to improve the basic understanding of the processes that could affect the passive layer. Long-term studies of the natural barriers'also will be needed, primarily to verify projections of water movement within the unsaturated and saturated zones near the repository For a high-temperature repository design, furiamental studies of coupled thermal-hydrologic and thermal-geochemical processes will be needed. For a low-temperature design, a less extensive program of monitoring in situ water movement tr9y be adequate. Whether the long-r s D N300VI

e term scientiDc studies are a decade-long program or much longer will depend in part on how the repository design evolves. There is no doubt, however, that a program of some sort will be needed to increase confidence in estimates of long-term repository performance. Postclosure Safety Case The ultimate goal of the studies at Yucca Mountain is to demonstrate that a repository at the site can safely isolate wastes from the human environment. The DOE proposes to demonstrate safe waste isolation through a five-part postclosure safety case consisting of the following. assessment of expected postclosure performance (i.e. TSPA) e design margin and defense-in-depth e consideration of dismptive processes and events e insights from natural and man-made analogs e a performance confinnation plan. e The Board bHiev- +.at thh.mposed strategy is an appropriate way to evaluate a Yucca .omponent, especially defense-in-depth and the Mountain repository, p /2

a es significant additional development. Multiple lines of performance-confirmati evidence will provide a more, symcing demonstration of repository safety than will any individual component of the safety case. TSPA, including sensitivity and uncertainty analyse the appropriate core analytical tool of the safety case. TSPA is the analytical technique together relevant information about the performance of the repository system, determin features or parameters could strongly influence performance, and estimates the uncertaint projections of performance. TSPA hss its limits, however, and the DOE will need to aggressively pursue the other four components of the safety case.

Judging how realistic the " bottom-line" TSPA estimates of; repository performance the VA is difficult. In fact, a DOE presentation to the Board at its most recent meeting stated that the VA's performance assessment (TSPA-VA) cannot be used to do the following. Assess compliance with regulatory criteria. Show defense-in-depth for the design of the repository system. 1 Assess the importance of small design changes. Determine the suitability of the overall repository system. B'ecause of a generallack of data to support critical assumptions in the mathematical models, some of the assumptions in the TSPA-VA are likely to be overly corservative and oth may be nonconservative. Nurnerous examples are presented in the recent report of peer review panel. Assessing the realism (or, at least, verifying the conservatism) of projections of repository performance is an important goal of the additional studi Board. The Board does not believe, however, that relying solely on TSPA to demonstrate repository safety will ever be possible. For that reason, the othe,r four components o postclosure safety strategy should be developed aggressively as complements to T i 6 DJF300VI

s implicit or explicit sixth component of the safety strategy also sh'ould be considered: designing the waste packages and the mpository to minimize uncertainties in projected irpository performance. Conclusion The VA concludes, "... Yucca Mountain remains a promising site for a geologic repository and... work should proceed to support a decision in 2001 on whether to recommend the site to the President for development as a repository." The Board agrees that Yucca Mountali, continues to merit study as the candidate site for a permanent geologic repository and that work should proceed to support a decision on whether to recommend the site to the President for development. The 2001 date anticipated for this decision is very ambitious and much work l remains to be compk. 4 At a minimum, progress on the work identified by the Board in its f November 1998 report and by the DOE in volume 4 of the VA will be required to support a technically defensible decision. The Board supports continuing focused studies of both natural 1 and engineered barriers at Yucca Mountain to attain a defense-in-depth repository design and to I increase confidence in predictions of repository performance. 1 This concludes our pmpared remarks and we will be happy to try to answer any questions f you may have. l l l l l l l 1 l I 7 DJF300VI l

1. g UNITED STATES 8

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SUBJECT:

WASTE (ACNW) AND NUCLEAR WASTE TECHNICAL REVIEW BOARD (NWTRB) The ACNW is t^,heduled to meet with the NRC Commissioners between 9:00 - 10:00 a.m. on Wednesday, March 17,1999 to discuss the ACNWs review of the Department of Energy's Viability Assessment. INTRODUCTION - Chainnan Shirley Ann Jackson 9:00 9:05 a.m. PRESENTATIONS - Advisory Committee on Nuclear waste (Presenters listed under each topic)* 1. Overview and Performance Assessment issues 9:05 - 9:20 a.m. - 8. John Garrick, ACNW 9:20 9:35 a.m. 2. Natural System and Repository Design issues - Charles Fairhurst, ACNW 9:35 9:50 a.m 3. Engineered Barrier System issues - Raymond G.Wymer, ACNW 9:50- 10:00 a.m.

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.') + l Moving Beyond 1 the Yucca Mountain Viability Assessment: Preliminary Views Dr. Debra S. Knopman, Member Dr. Daniel B. Bullen, Member U.S Nuclear Waste Technical Review Board presentation to the U.S. Nuclear Regulatory Commission March 17,1999 Rockville, Maryland

l n 1 i i Chairman Jackson, Commissioners, ladies, and gentlemen, good morning. It is a pleasure to be here today. My name is Debra Knopman and I am a member of the U.S. Nuclear Waste Technical Review Board. All Board members serve part-time, and most of us have other full-time jobs. I am director of the Center for Innovation and the Environment of the Progressive Foundation in Washington, D.C. My technical expertise is in hydrology, environmental e.nd l natural resources policy, systems analysis, and public administration. With me today is another Board member, Dr. Daniel Bullen, who is' director of the Nuclear Reactor Laboratory and associate professor of mechanical engineering at Iowa State University in Ames, Iowa. His - technical expertise includes performance assessment modeling of radioactive waste disposal facilities and materials performance in radiological and severe service environments. Our Chairman, Dr. Jared Cohon, would have liked to be here today to make this presentation, but he is out of the country on university business. Dr. Cohon sends his regrets. 1 Let me begin by briefly summarizing who we are and what we do. The Nuclear Waste Technical Review Board was created by Congress in the 1987 amer dments to the Nuclear Waste Policy Act and is charged with evaluating the technical and scientific aspects of the Department of Energy's (DOE's) high-level nuclear waste management program. This includes site-characterization activities at Yucca Mountain and activities relating to the packaging and transport of high-level radioactive waste and spent nuclear fuel. The Board is an independent agency within the federal government, not part of the DOE or any other agency. The Board has eleven members who are nominated by the National Academy of Sciences and appointed by the President. Dr. Bullen and I have served as members of the Board since January,1997, Introduction Today, you asked the Board to provide its views on the viability assessment (VA) of the Yucca Mountain site that was published recently by the DOE. We are pleased to do so, but we must preface our remarks by noting that the Board's review of the document is on-going and the preliminary views we present today may evolve as our review continues. As you know, the purposes of the VA are to summarize the scientific information that has been collected at the site over the past 15 years, present the conceptual design of a repository and waste packages that might be suitable for the site, estimate how well such a repository would isolate wastes from the human environment, identify the additional studies (and their costs) needed to evaluate the suitability of the site and prepare a license application, and estimate the overall cost of disposing of waste at the site. The VA is an evaluation of progress on site characterization at Yucca Mountain and provides the technical basis for deciding whether to continue studying the site. The VA is not, and was not intended to be, a determination of whether the Yucca Mountain site is suitable for development as a permanent geologic repository. The suitability decision, projected for 2001, allows for the completion of further site studies, repository design work, and analyses of repository system performance. So far, neither the Board's review of the VA nor its other reviews of the program has identified any features or processes that would , itomatically disqualify the site. i mrmvi i

( General Views on ue VA The VA is the mo3t significant milestone thus far in the characterization and evaluation of the Yucca Mountain site. Many pans of the VA present cutting-edge scientific analysis in a comprehensible fonnat. The Board commends the DOE for the successful completion of this assessment. In assembling the VA, the DOE integrated large amounts of data and analyses, established a preliminary repository design, and set priorities for work to be completed before decisions are made about site recommendation and licensing. The process ofintegration has had the salutary effect of focusing the objectives of the scientific investigations. In particular, the VA highlighted the close connections between the repository design and the priority list of key uncertainties about the natural system. For example, such site characteristics as the movement of water and vapor at temperatures above boiling and the effect of high temperatures on rock stability are important only because of the VA's high-temperature repository design. In a low-temperature (below boiling point) design, these uncertainties would be less significant and might not need to be resolved for making a suitability determination. The Board concurs with the DOE that the VA is simply a " snapshot" of current knowledge about the site that the U.S; Congress can use to make an informed decision on whether to continue to fund studies of the site. Today, we will discuss the Board's general views on the site and on the design of a repository for the site, based on our review of the VA. The Board concludes that Yucca Mountain continues to merit study as the candidate site for a permanent geologic repository and that work should proceed to support a decision on whether to recommend the site to the President for repository development. The 2001 date anticipated for this decision is very ambitious and much work remains to be completci At a minimum, significant progress on the work identified by the Board in its November 1998 report and by the DOE in volume 4 of the VA will be required to support a technically defensible decision. The Board suppons continuing focused studies of both natural and engineered barriers at Yucca Mountain to attain a defense-in-depth repository design and to increase confidence in predictions of repository performance. Uncertainties in Repository Performance In November 1998, the Board issued a report outlining its views on future research needed to address uncertainties about the performance of the repository system, including both the engineered and the natural barriers. The Board concluded in that report that although there are conomic and technical limits to reducing uncenainties about the performance of the proposed e repository system, some key uncertainties can be reduced further over the next few years through a focused research effort. The Board realizes that there always will be uncertainty about the performance of a repository far into the future and that eliminating all uncertainty is not possible or necessary. However, the Board believes that identifying important sources of uncenainty, estimating the magnitude of those uncertainties, reducing critical uncertainties, and evaluating the effects of residual uncenainties on expected repository performance are essential for supporting a technically defensible site-suitability decision and license application. nmoovi

o V . p, t-s) o The Doard noies that the VA relies heavily in some cases on the formal elicitation of expert judgment. This was necessary and extremely useful, given the lack of field and laboratory data in certain areas and the equivocal nature of some of the data in other areas. However, as the experts themselves pointed out, expert judgment should not be used as a substitute for data that can be obtained directly from site, laboratory, and other investigations. In the Board's view, I every reasonable effort should be made to minimize uncertainty through repository and waste l package design. Additional data then can be sought to address uncertainties, rather than relying so heavily on expert judgment to support decisions about the suitability of the site and a possible license application. After reviewing the VA, the Board concludes that a significant amount of additional l scientific and engineering work will be needed to increase confidence in a site-suitability decision and license application. Alternative repository designs should be evaluated that have the potential to reduce uncertainties in projected repository performance, thereby reducing the scope of additional necessary scientific study. Regardless of the design adopted, however, long-term scientific studies will be needed to establish a solid foundation for projecting repository performance thousands of years into the future. Let me discuss the Board's views in more detail. Additional Scientific and Engineering Work is Needed The DOE has spent many years (and many dollars) studying the Yucca Mountain site and designing the engineered components of a repository system compatible with the site. These efforts have produced a large amount of data, but significant uncertainties remain about the ability of the VA reference design to safely isolate radioactive wastes. In part, this is a problem inherent in extrapolating repository performance for thousands of years from data acquired over a much shorter period (years to decades). Uncertainties also are associated with specific characteristics of the Yucca Mountain site, especially the difficulty in predicting the nature of water movement through the fractured unsaturated rocks of the mountain and the possible entry of water into repository tunnels and its contact with waste packages. Uncertainties likely would be exacerbated by the high _ temperatures o t e re erence repos ory es gn, w c may reduce tunnel stability, enhance waste fh f it di hi h package corrosion, and perturb water movement in ways that are difficult to predict. Predicting the performance of the waste packages, which play a crucial role in the performance of the VA reference repository design, is a critical area that needs more study. Candidate waste package materials rely on the presence of a thin passive layer to protect the underlying metal from the oxidizing environment that will be present in a Yucca Mountain repository. Improving the basic understanding oflong-term passivity is essential because, at l' present, there seem to be no documented natural or man-made analogs that can be used to demonstrate whether this mode of protection would persist over the desired period of time. Research also should be continued on the susceptibility of the passive layer to known modes of corrosion, especially potentially catastrophic failure modes, such as stress-corrosion cracking. The Board believes that the scientific and engineering work completed to date, as extensive as it is, should be supplemented to improve the technical foundation for evaluating the suitability of the site or preparing a license application. The Board agrees with a DOE-commissioned peer DJF300VI 3

) ( review panel which found that two types of additional data are needed to improve the credibility of the total system performance assessment part of the VA (TSPA-VA): (1) fundamental data that are essential to the development and implementation of the models and (2) data sets designed to i challenge conceptual models and test the coupled models used in the TSPA-VA. There are substantial uncertainties about the performance of a repository based on the VA reference design that can be resolved only by considering alternative repository and waste package designs and by collecting additional scientific data. In volume 4 of the VA, the DOE has identified and set priorities for a suite of additional studies to produce information needed for repository licensing, assuming that the site is determined to be suitable for development as a repository. The planned studies include data collection, analysis, and engineering design, as appropriate, for the three major bamers discussed by the Board in its November 1998 repon (unsaturated zone, engineered barrier system, and saturated zone). Among the most important are geologic, geochemical, and hydrologic studies, including those planned for the east-west cross drift. These studies are aimed at understanding the magnitude and distribution of seepage into the repository under present conditions and under past conditions when the climate was very different. They include systematic analysis of the rock samples being collected, especially for chlorine-36 and other indic*or kotopes: flow and seepage tests at different locations along the drift; moisture-monitoring activities; tests in the iithophysal zones that would host the majority of wa e packages; and studies of the Solitario Canyon fault, the active fault bounding the reposito- .at also may serve as a main conduit for percolating water. Of equal l importance are studies r supporting projections of the performance of the engineered barrier system, which,in the \\ reference design, plays a critical role in isolating radioactive wastes for tens of thousands of years. The studies identified by the DOE in volume 4 of the VA appear to be appronriate in the sense that they are technically feasible and are likely to produce useful information that will improve the understanding oflong-term repository performance. There is no guarantee, however, that completion of these studies will lead to successful development of a repository at the site. The studies could show the site to be unsuitable, or they could raise new questions requiring further study. On the basis of current information, however, the Board is pleased that volume 4 identifies an appropriate suite of studies to be pursued in the years ahead. The Board is concerned that some of the planned studies identified in volume 4 of the VA may be deferred because funds are not available to carry them out in a timely manner. Deferring scientific and engineering studies will delay the assembly of a more credible technical basis to support the site recommendation anticipated in 2001 and,if the site is found suitable, a license 1 application in 2002. For the current VA repository design, a credible basis does not yet exist. Alternative Repository Design High temperatures in the VA repository design cause large uncertainties about how the site would behave both before and after repository closure. The Board believes that a repository design with lower waste package surface temperatures merits further detailed analyses. Such a design has the potential to reduce uncertainty, simplify the analytical bases required for site recommendation, and make licensing easier. Combined with improved waste package shielding, the design also DJDOOV! 4

c ~ I could simplify preclosure performance confirmation by enhancing access to the tunnels, thus reducing or eliminating the need for separate performance-confirmation drifts, and permitting direct access to performance-confirmation instmmentation near the waste packages. The following factors influenced the Board's thinking on repository design. Lower temperatures would significantly reduce coupled thermal-hydrologic and thermal-geochemical processes. Maintaining near-field temperatures bel.ow the boiling point of water after repository closure, by ventilation or aging, could reduce uncenainties about the movement of water and associated geochemical processes in the repository's natural barriers. This could increase confidence in the analyses of l repository performance required for a site-suitability determination. For a given environment, chances for degradation of corrosion-resistant waste package materials would be reduced significantly if peak waste package surface temperatures were reduced. High repository temperatures are expected to increase the mechanical degradation of + repository rocks. There is little, if any, relevant experience to draw on for predicting the long-term effects of repository heating and subsequent cooling on drift stability. The DOE is evaluating alternative repository designs that might be appropriate as the basis for a license application, and the reference repository design presented in the VA is expected to change as the altematives are considered. The B.oard strong y urges that analyses of alternatives should not be limited to " enhancements" to the reference de,ign but should give serious consideration to true alternatives to the reference design, includiag a design that limits waste package surface temperatures. Long-Term Scientific Studies If Yucca Mountain is found suitable and construction of a repository is authorized, the Board believes there will be a need for a long-term science program to reduce uncertainties about the performance of engineered barriers and the interactions between the repository and natural processes. An important goal of these studies should be identification of unknown failure modes or unexpected evolution of natural processes that could adversely affect the performance of the major barriers of the repository. Thus, these studies may be more extensive than the performance confirmation activities now anticipated for a repository. For example,if the waste package design continues to rely strongly on corrosion-resistant metals protected from corrosion by a passive layer, l long-term scientific studies need to be carried out to improve the basic understanding of the processes that could affect the passive layer. Long-term studies of the natural barriers also will be needed, primarily to verify L projections of water movement within the unsaturated and saturated zones near the repository. For a high-temperature repository design, fundamental studies of coupled thermal-hydrologic l and thermal-geochemical processes will be needed. For a low-temperature design, a less extensive program of monitoring in situ water movement may be adequate. Whether the long-l i DJF30W1 5

w f term scientific studies are a decade-long program or much longer will depend in part on how the repository design evolves. There is no doubt, however, that a program of some son will be needed to increase confidence in estimates of long-term repository performance. Postclosure Safety Case The ultimate goal of the studies at Yucca Mountain is to demonstrate that a repository at the site can safely isolate wastes from the human environment. The DOE proposes to demonstrate safe waste isolation through a five-part postclosure safety case consisting of the following. assessment of expected postclosure performance (i.e. TSPA) e design margin and defense-in-depth e consideration of disruptive processes and events e insights from natural and man-made analogs e a performance confirmation plan. e The Board believes that this proposed strategy is an appropriate way to evaluate a Yucca Mountain repository, although each component, especially defense-in-depth and the performance-confirmation plan, requires significant additional development. Multiple lines of evidence will provide a more convincing demonstration of repository safety than will any individual component of the safety case. TSPA, including sensitivity and uncenainty analyses, is the appropriate core analytical tool of the safety case. TSPA is the analytical technique that pulls together relevant information about the performance of the repository system, determines which features or parameters could strongly influence performance, and estimates the uncenainties in projections of performance. TSPA has its limits, however, and the DOE will need to aggressively pursue the other four components of the safety case. Judging how realistic the " bottom-line" TSPA estimates of repository performance are in j the VA is difficult. In fact, a DOE presentation to the Board at its most recent meeting stated that the VA's performance assessment (TSPA-VA) cannot be used to do the following. j i i Assess compliance with regulatory criteria. Show defense-in-depth for the design of the repository system. Assess the importance of small design changes. Determine the suitability of the overall repository system. Because of a general lack of data to support critical assumptions in the mathematical models, some of the assumptions in the TSPA-VA are likely to be overly conservative and others may be nonconservative. Numerous examples are presented in the recent report of the TSPA-VA peer review panel. Assessing the realism (or, at least, verifying the conservatism) of TSPA projections of repository performance is an important goal of the additional studies called for by the Board. The Board dees not believe, however, that relying solely on TSPA to demonstrate repository safety will ever be possible. For that reason, the other four components of the postclosure safety strategy should be developed aggressively as complements to TSPA. An DJFMOV! 6

s u I implicit or explicit sixth component of the safety strategy also should be considered: designing the waste packages and the repository to minimize uncertainties in projected repository performance. Conclusion The VA concludes,"... Yucca Mountain remains a promising site for a geologic repository and... work should proceed to support a decision in 2001 on whether to recommend the site to the President for development as a repository." The Board agrees that Yucca Mountain continues to merit study as the candidate site for a permanent geologic repesitory and 3 that work should proceed to support a decision on whether to recommend the site to the President j for development. The 2001 date anticipated for this decision is very ambitious and much work remains to be completed. At a minimum, progress on the work identified by the Board in its November 1998 report and by the DOE in volume 4 of the VA will be required to support a technically defensible decision. The Board supports continuing focused studies of both natural and engineered barriers at Yucca Mountain to at.ain a defense-in-depth repository design and to increase confidence in predictions of repository performance. This concludes our prepared remarks and we will be happy to try to answer any questions you may have. j i I i DJF300VI 7}}

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