ML20147F670
| ML20147F670 | |
| Person / Time | |
|---|---|
| Issue date: | 03/21/1997 |
| From: | NRC ADVISORY COMMITTEE ON NUCLEAR WASTE (ACNW) |
| To: | |
| References | |
| NACNUCLE-T-0112, NACNUCLE-T-112, NUDOCS 9703270073 | |
| Download: ML20147F670 (212) | |
Text
Official Transcript c[f ProceedingsbM O NUCLEAR REGULATORY COMMISSION
Title:
Advisory Committee on Nuclear Waste 90th Meeting TRO8 (ACNW)
RETURN ORIGINAL TO BJWHITE M/S T-2E26 Docket Number: (not applicable) 415-713o THANKS!
Location: Rockville, Maryland q
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l Date: Friday, March 21,1997 !
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0:'8 _76 07ru Ul0 0,0 ^^ T T:':8P Work Order No.: NRC-1054 Pages 107-241 D
I NEAL R. GROSS AND CO., INC.
Court Reporters and Transcribers 1323 Rhode Island Avenue, N.W.
75 i,_) Washington, D.C. 20005 I
g (202) 234-4433 $U!hf I s DD ' j h lh $ l~i L, 9703270073 970321 11 !! ' -
O DI8 CLAIMER PUBLIC NOTICE BY THE UNITED STATES NUCLEAR REGULATORY COMMISSION'S ADVISORY COMMITTEE ON NUCLEAR WASTE 1 l
MARCH 21, 1997 I
1 l
l The contents of this trancript. of thn j proceedings of the United States . Nuclear Regulatory i
Commission's Advisory Committe6 on Nuclear Waste on MARCH 21, I
\ 1997, as reported herein, is a record of the discussions }
recorded at the meeting held on the above date. -
This transcript has not been reviewed, corrected f
and edited and it may contain inaccuracies. !
l t
t i
O NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 R110DEISlAND AVENUE,NW (202)234 4434 WASillNOTON, D.C. 20005 (202)234-4433
107 1 UNITED STATES OF AMERICA
,e m 2 NUCLEAR REGULATORY COMMISSION
! \
3 ++ + + +
4 90th MEETING 5 ADVISORY COMMITTEE ON NUCLEAR WASTE (ACNW) 6 + + +++
7 FRIDAY 8 MARCH 21, 1997 9 ++++ +
10 ROCKVILLE, MARYLAND 11 12 The Advisory Committee met at the Nuclear 13 Regulatory Commission, Two White Flint North, Room T2B3,
,en \
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14 11545 Rockville Pike, at 8:30 a.m., Paul W. Pomeroy, 15 Chairman, presiding.
16 17 COMMITTEE MEMBERS:
18 PAUL W. POMEROY CHAIRMAN 19 B. JOHN GARRICK VICE CHAIRMAN 20 WILLIAM J. HINZE MEMBER 21 GEORGE M. HORNBERGER MEMBER l
22 l
23 24 (O r
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108 1 ACNW STAFF PRESENT:
7y 2 MICHELE KELTON Tech. Secretary
( ')
3 RICHARD K. MAJOR 4 HOWARD J. LARSON 5 LYNN DEERING 6 ANDREW C. CAMPBELL 7 RICHARD P. SAVIO 8 CAROL A. HARRIS 9 THERON BROWN l 10 11 ALSO PRESENT: i 12 JANET KOTRA 13 MIKE BELL I \
kj 14 ROBERT JOHNSON 15 TIM McCARTIN l
16 JOHN AUSTIN '
17 BILL REAMER .
8 18 CHRIS McKENNEY ]
19 JOHN KESSLER 20 l
l 21 22 23 24 l 77
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109 l 1 A-G-E-N-D-A
,., 2 Acenda Item Pace t, ,
\ .,_/
3 Opening Remarks 110 4
5 Defense-In-Depth Philosophy 6 John Garrick 111 l l 7 Janet Kotra 112 8
9 BIOMOVS II 10 Chris McKenney 176 11 12 EPRI BIOSPHERE MODELING 13 John Kessler 206 s
7 l ) l
'N.__/ 14 15 16 17 18 19 20 21 22 23 I
24
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110 1 P-R-O-C-E-E-D-I-N-G-S r~N 2 (8:35 a.m.)
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3 CHAIRMAN POMEROY: The meeting will now come 4 to order. This is the second day of the 90th meeting of 5 the Advisory Committee on Nuclear Waste. Portions of 6 today's meeting may be closed to discuss matters, the 7 release of which would constitute a clearly unwarranted 8 invasion of personal privacy.
l 9 Today the committee will first discuss ;
i 10 defense-in-depth as it applies to nuclear waste; second, !
l 11 hear a briefing on the BIOMOVS II project. Following 12 lunch we will prepare for the next meeting with the
, _s 13 Commission and continue the preparation of ACNW reports. l
[ ') l
14 And for planning purposes, we plan to return today at 2:30 15 in the afternoon.
16 Mr. Richard Major, second on my right, is the 17 designated federal official for the initial portion of 18 today's meeting. This meeting is being conducted in 19 accordance with the provisions of the Federal Advisory 20 Committee Act.
21 We have received no written statements from 22 members of the public regarding today's session. Should l 23 anyone wish to address the committee, please make their 24 wishes known to one of the committee staff.
O
(_,) 25 It is requested that each speaker use one of l NEAL R. GROSS l COURT REPORTERS AND TRANSCRIBERS i 1323 RHODE ISLAND AVE., N W.
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111 1
1 1 the microphones, identify himself or herself, and speak l
s 2 with sufficient clarity and volume so that he or she can w
/
3 be readily heard.
1 4 Do any of my colleagues have any opening 5 remarks?
6 If not, I'll turn the meeting over to Dr.
7 Garrick to open our discussion on defense-in-depth.
8 John?
9 VICE CHAIRMAN GARRICK: As most of you know, 10 the concept of defense-in-depth is very much in the fiber 11 of the regulatory process and has been one of the j 12 mainstays in terms of approaches for assuring public 13 safety. And it has also been interpreted and decomposed !
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, 4
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k/ 14 into subsystem requirements on which there's been a lot of l 15 attention and focus throughout the licensing history of ,
16 the agency.
17 What is happening now is that as we kind of 18 transition into a more systems-oriented philosophy as the 19 Agency is pressed to try to interpret just how the 20 regulations ought to be adjusted or modified or changed to 21 accommodate a new era -- an era that embraces the concepts 22 of risk-informed, performance-based regulation -- the 23 whole concept of defense-in-depth has come under some 24 review and even scrutiny.
.p
( ,/ 25 Particularly with regard to the subsystem NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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112 1 requirements, on the basis that the implementation of 2 defense-in-depth, perhaps, has sometimes been more a
/
( ")
3 matter of complying with subsystem requirements than 4 keeping the focus as integrated and systems-oriented as 5 possible. I think this committee is very much in support 6 of the defense-in-depth philosophy.
7 I think this committee also believes that this l
~8 philosophy can accommodate the new thinking and can be a j 9 continuing part of the basic regulatory process. We need l
10 some information to formulate our views on this, and i 11 that's part of the purpose of this discussion this 12 morning; is to get some background on how the concept came 13 into being, and especially some focus on the subsystem
/
t 4 V 14 requirements issue, and give us a basis for offering some 15 advice on our views, at least, as to where we might want i
16 to go from here.
17 So I believe to lead that discussion we're l
18 going to hear from Janet Kotra from the Division of Waste 19 Management, and she's going to be assisted by people that 20 she will introduce.
21 Janet?
22 MS. KOTRA: Good morning. It's a privilege to 23 be here this morning.
24 As you indicated, my purpose here this morning i ,e~,
(O) 25 is to review the history of the Commission's consideration NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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113 l l
1 of the defense-in-depth principle; in particular, the 73 2 aspect of defense-in-depth referred to frequently as the
! )
3 multiple barrier concept as that was translated into 4 subsystem performance criteria in the development of the 5 technical criteria for our rule for geologic disposal at 6 Part 60.
l 7 You've got the first slide up there; a brief 8 cat line of my presentation. I want to say at the outset 9 that I joined the staff of the NRC -- more particularly, 1
1 10 the staff of the ACRW -- as a Fellow about six months j l
11 after the final Part 60 technical criteria were put in )
I 12 place. So in the interest of disclosure I would say I did !
13 not participate in the development of these concepts; k/ 14 although in the course of my career here this topic has 15 been a perennial theme.
16 The value, the Utility, the problems with 17 implementing the subsystem performance criteria sort of 18 animated a lot of things that I personally have worked on.
19 However, because I came in sort of after-the-fact, in 20 order to prepare for this morning's briefing I felt it was 21 incumbent upon me to pump the colleagues that I enjoy 22 working with, who were here at the time.
23 And that's an increasingly smaller group of 24 people as you well know, but I'm really pleased that Mike r~
( ,N) 25 Bell is with us this morning and he is here to answer NEAL R. GROSS !
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114 1 questions from the perspective of a key player on the
,e s 2 staff in developing the subsystem performance criteria and
\
l 3 the overall rule as a whole. That's a polite way of 4 saying that I'll defer hard questions to Mike.
5 In addition, I've attempted to go beyond just l 6 a review of the written record. I think your staff --
7 Lynn Deering's put together a very comprehensive and 8 thorough package documenting the written record that we 9 have on the subsystem performance criteria: what the 10 Commission said and statement of consideration, some of 11 the criticisms that have been received from within the 12 Agency as well as without.
13 In addition, I would have to say I relied
14 heavily on notes and presentation materials left behind by 15 Dan Fehringer before he left to join the staff of the 16 Nuclear Waste Technical Review Board, and really 17 appreciated having that to draw on. That's the polite way 18 of saying that I borrowed shamelessly from him, and my 19 apologies ahead of time.
20 You might note in the outline that I mentioned 21 two decades of criticism and experience. The astute among 22 you might. recognize that the rule hasn't been in place for 23 20 years, but we have been working on the concepts that 24 underlie the rule.
(_,/ 25 The development of the rule took approximately NEAL R. GROSS COURT REPORTERS AND TRANSCR:BERS 1323 RHODE ISLAND AVE., N W.
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115 1
1 four to five years if you take into account the thinking i
i l (~S 2 that went into it. The initial proposal, or the ANPR, was l N.Y i 3 published in 1980, and I'll get into a little bit more 4 detail about that history and how the thinking evolved.
5 At the last, I will touch briefly on where 1
6 staff intends to go in terms of considering options for 7 future revisions, but the point of my talk this morning is 8 basically to review the bidding on how we got to the 9 regulations we have on the books today.
10 As Dr. Garrick alluded to, the defense-in-11 depth concept is really part of the bedrock of NRC's 12 regulatory philosophy. It assures safety through the
,_s 13 selection, hopefully judicial selection, of multiple,
< s
(\ ') 14 independent barriers. I 15 In the case of reactors where we have applied 16 this philosophy from the outset, those barriers are l
17 familiar to many of you, many of you moreso than I: the 18 fuel cladding, the coolant system pressure boundary, the l
l I
19 containment -- and some people expand that to include 20 siting criteria, emergency planning, operations 21 requirements and so forth. That there are multiple layers J l
22 that ensure safety. )
23 In addition, that requirement for multiple 24 barriers is coupled with requirements for redundancy; that r~' l l (_,}/ 25 you don't want to have one single failure that will l
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116 1 threaten the integrity of those all-important barriers.
7x 2 As I said earlier, this philosophy and i >
C/ 3 approach has been the basis for NRC's deterministic 4 regulatory framework for nuclear reactors and other 5 facilities that we license. It is fundamentally a 6 technique that we've used to manage uncertainty.
7 And traditionally, the reliance on the 8 independence and redundancy of these multiple barriers has 9 served as a very important and useful surrogate for a 10 detailed, quantitative assessment of barrier reliability, 11 especially at the beginning, at the outset, when you're 12 developing criteria for a facility or an industry or a 13 process that you don't have a great deal of experience and
,- 3
\ ') 14 data with. You have to have a way to manage that 15 uncertainty.
16 And that has been the approach that this i
17 Agency has historically taken. In the past, 18 traditionally, there's been little accommodation for the 19 relative likelihood of the events that threatened barrier 20 integrity, oftentimes for legitimate reasons.
21 We really didn't have a good handle on what 22 the relative likelihood was and the barrier integrity --
l 23 according to a strict application of defense-in-depth --
24 would require that you ensure that integrity for likely r~"x
( ,) 25 and reasonably unlikely events with pretty much the same NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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117 1 level of rigor.
rs 2 Clearly, that approach is inherently
( )
3 conservative. The result has been, I think -- most people i
4 agree -- a high level of safety but a very uneven level of l
5 conservatism. Over the years we have evolved in our 6 appreciation and use of probabilistic risk assessment l 7 techniques in this Agency and have gained very important 8 insights into the performance of operating facilities.
9 And there's an inherent tension between a 10 probabilistic risk assessment approach and a defense-in-11 depth deterministic approach. In probabilistic risk 12 assessment I've heard it said that conservatism, unlike in 13 the deterministic approach where more conservatism is j t i
(_/ 14 believed to give you more safety, additional conservatism 15 or unwarranted conservatism in a probabilistic approach is 16 not more safe; it's wrong.
17 And so these techniques can complement each 18 other; in fact the Commission has directed the staff and 19 the entire Agency to expand the use of probabilistic 20 techniques that complement our traditional defense-in-21 depth philosophy and to support and extend the safety that 22 it has provided through defense-in-depth.
23 The next slide. When you move to application 24 of defense-in-depth -- particularly in the late '70s --
?y
( , ) 25 you're applying this concept to a unique, one-of-a-kind, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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i 118 l l
1 first -of-a-kind, facility. Now, that being said, before
,, - - 2 the repository is closed you have a facility that is
(/ _
3 really not, for the purposes of this discussion, that 1
4 unlike any other operating facility that NRC has 5 regulated.
6 And a comparable approach that is used for j 7 other facilities is as appropriate, necessary, it relies 8 on conservatism of design, diversity of design, 9 comprehensive quality assurance requirements, radiation -
l 10 safety programs, procedures, and emergency planning.
1 11 And many of you may recall that not too long 12 ago the Commission revised its regulations in Part 60 for i i
13 the preclosure phase of repository operations -- the DBE
(~'s '
'/
' 14 Rule as it is sometimes called -- to bring that approach 15 in line with what we do for Part 72 licensees, and to a 16 lesser extent, the approach we use for other operating l
17 facilities in the reactor arena.
18 Now, when you move to postclosure performance 19 you have a somewhat different situation and you have to 20 account for the differences between determining repository 21 safety over the long haul, and the requirements that you 22 would feel comfortable with for an operating facility that 23 has active safety systems.
24 Postclosure performance relies exclusively on
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( ,) 25 passive systems. As we all recall, the National Academy '
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119 1 of Sciences has said, you don't have a basis in science 7s 2 for relying on active controls beyond about a hundred i \
~
3 years -- and I'll touch on that a little bit later. And 4 so therefore, in the development of appropriate criteria 5 for such a facility, you have a somewhat different 6 approach than you can use. !
4 7 You don't have the same armamentarium that you 8 have available to you for an operating facility with a 9 relatively short lifetime. No long timeframes from the I
10 get-go. We have known we would require probabilistic ;
l 11 consideration of the relative likelihood of the threats to ,
l 12 the various barriers in a repository system. j 13 You can, certainly, identify multiple, diverse k-- 14 barriers in the repository system. In fact, you can parse 15 it very, very fine or you can speak in terms of large 16 barrier systems. And so that is certainly no different 17 from any other facility that we would regulate. However, 18 the performance of those barriers in this environment 19 really cannot be said in the strictest sense, to be either 20 independent or redundant. And I'll say more about that in 21 a little bit.
22 As I said, the application of the defense-in-23 depth principle evolved over time, and really, the theme 24 of my talk is to kind of show you how the initial thinking
(_j) 25 developed and how it evolved through the completion of NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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120 1 final technical criteria at Part 60.
2 The need to specify quantitative limits for
\pl 3 individual barriers was a fundamental issue in this 4 rulemaking. It received extensive public comment at every 5 stage, there were numerous public Commission meetings with 6 very detailed discussions between the Commissioners and 7 the staff. And the final rule really, truly reflected a 8 Commission evaluation and decision.
9 And I think it'a important that all these 10 years later, we understand what the basis for that 11 decision was as we contemplate revisions to the approached 12 use of Part 60.
13 And if I can take you back now to the late
/,
(/ 14 '70s, about 1978, when the Agency was very new and we knew 15 under the Atomic Enargy Act that we had authority for 16 licensing geologic disposal. The concept of what we were 17 going to be licensing was somewhat different than it is 18 today.
19 At the time, the waste was expected to be 20 reprocessed weste. At that time the hazard associated 21 with that disposal was anticipated to be a 1000-year 22 problem, and only saturated sites were being envisioned in 23 most of these discussions. Expectations were that the 24 primary reliance for isolation would be vested in the p)
(, 25 geologic setting itself.
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121 1 There was a tremendous amount of confidence l
2 that if selected properly, a good site could pretty much 3 carry the whole load; that there would be minimal waste 4 packaging, enough to get it from wherever it was 5 reprocessed to wherever it was disposed of.
6 And the value of the waste form itself -- the 7 durability of the glass or ceramic -- was discussed, and 8 many people felt that it wasn't really all that important l
9 that it be all that durable. Because again, a great deal I 10 of confidence was placed on the value of the geologic j l
11 setting.
12 This changed fundamentally -- as I understand 13 it in reviewing notes and talking to people -- in
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\/ 14 approximately 1979. The exact reason for this I gather is 15 primary speculation. Several things happened about this 16 timeframe. In late 1978 the inter-Agency Review Group 17 Report was issued that placed an important -- emphasized 18 the importance of multiple barriers.
19 There was a major change in NRC staff from the 20 Division Director on down. There was an influx of new 21 faces; many of them are still here today. This is 22 speculation on my part. I think you all recognize the 23 date as TMI and that was kind of like the initiation of 24 this Agency of some major soul-searching that went on for 7
( ,/ 25 a very long time in terms of our role as a regulator.
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122 l 1 And how that affected this process I don't 73 2 have any direct evidence, but I can only surmise that it i
(' ~ ~ ')
3 certainly affected our thinking as we moved to develop 4 criteria for geologic disposal.
5 The change in philosophy -- and if you could 6 put the previous slide on for just a second -- I neglected 7 to mention that initially in thinking about it, it was l 8 assumed that whatever regulations we came up with would be 9 kind of tailored to and reflect whatever repository design 10 the DOE were to come up.
11 That changed in 1979 and the focus then became 12 that the design should satisfy specific and well-13 articulated regulatory objectives. It put a higher
-J 14 premium on the fact that the regulator should establish 15 these objectives and these designers should design a 16 repository or facility to comply with those.
17 MEMBER HINZE: Janet, if I may interrupt?
18 You've mentioned an inter-Agency report that dealt with 19 multiple barriers. Could you tell us a little bit about 20 that report? What are the Agencies involved?
21 MS. KOTRA: It was a -- I think it was a 22 Presidential inter-Agency. Mike, could you come to the l 23 microphone and just enlighten us on that? You loaned your 24 copy to me a couple of days ago.
(~%
( ,) 25 MR. BELL: Michael Bell, the NRC staff.
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123 1 During the Carter Administration, President Carter set up fy 2 an inter-Agency task force in the late '60s, that had i t V
3 representatives from NRC, DOE, USGS, EPA -- a variety of 4 other federal agencies.
5 At this time, you might recall in the early 6 '70s -- it was the AEC still back in those days -- was 7 pursuing a repository in Kansas in salt; they had 8 conducted Project Salt Vault. The experiments lived up to 9 AEC's expectations and they wanted to pursue that site as 10 a national repository.
11 When difficulties were found with the site it 12 became known that large quantities of drilling fluid for 13 oil wells had been lost in the formation and such, and so i,, )
14 that project was abandoned. And beginning in the early 15 '700, I think it was 1972, retrievable surface storage was 16 the national policy.
17 And when the Carter Administration came in 18 basically there was a decision that we needed to get back 19 to a way forward for geologic disposal, and you know, 20 retrievable surface storage was only an interim thing and 21 eventually we would have to dispose of the waste.
22 So the inter-Agency task force was set up. As 23 I mentioned earlier, it had essentially all the Agencies l 24 that are involved today because by that time the AEC had
,a
, ( ,) 25 split into ERDA and then NRC was here.
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124 1 And that was really the recommendation -- two
,r w 2 major recommendations as far as geologic disposal, came 3 out of that. Look for multiple sites and different 4 geologic media so that you can, in parallel, have 5 different choices and, you know, reach a point where you 6 can select the preferred medium - the site in a preferred 7 medium.
8 And don't just rely on the geology because of 9 the surprises that you may find. Like in the Lyons 10 situation. You know, the multiple barrier approach is 11 really, first a recommendation of this inter-Agency task 12 force that then got embraced by the NRC when we developed 13 Part 60.
t
/ T 2 14 MEMBER HINZE: We may wish to beg, borrow, nr 15 steal your copy to make a copy of that so we can have a 16 look at it.
17 MR. BELL: Yes.
18 MEMBER HINZE: That would be very fine if you 19 could provide it.
20 MR. BELL: Sure.
21 MEMBER HINZE: Great. Thank you, Janet.
22 MS. KOTRA: At this point, at least as the 23 Agency was initially embarking on developing draft 24 criteria, they considered -- well, I think the last time o \
i
( ,!
25 they considered in a serious way, true redundancy in the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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125 1 sense that we mean it in another context -- and that would g~) 2 be that you would achieve 1000-year containment which was, i /
v 3 you know, the duration of your hazard.
4 Or as how they anticipated it in those days:
5 a 1000-year containment by your waste form plus your ,
1 6 canister; 1000-year containment by your overall engineered ,
7 barrier system; and 1000-year containment by your geologic 8 setting.
9 At this point I just want to digress a little 10 bit and talk about the development of thinking that went 11 into preparing a rulemaking package. The primary goal or 12 purposes of establishing -- or applying this multiple 13 barrier concept, was to compensate for major sources of 7_
f
) ,
14 uncertainty in the prediction of overall performance. ;
15 That the multiple barriers were, by ascribing 16 criteria or developing criteria for these individual 17 barriers, the idea was that you would compensate for the 18 major sources for uncertainly in the overall prediction of 19 the repository performance.
20 And in this timeframe, three distinct 21 alternatives were considered: a single, overall 22 performance standard -- namely, the EPA standards which 23 were anticipated but by no means were anywhere close to 24 being proposed at that point; minimum performance
(_,/ 25 standards for the major barrier systems; as well as NEAL R. GROSS l COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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126 i
1 performance with the EPA standard.
l 73 2 And also in the developmental process --
i t
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3 although I don't think this got a lot of public visibility 4 in the various statements of consideration -- was a third 5 alternative which was a traditional, very prescriptive 6 deterministic approach where you would establish precise 7 numerical criteria for individual attributes; things as 8 detailed as the peak wall temperature of the canister, for 9 example.
10 The single, overall performance standard 11 approach certainly had its proponents. It was a single 12 figure of merit; it afforded maximum flexibility for the 13 designer; it would allow tradeoffs among system i
p ,
\~2 14 components. However, within NRC at that time it was not 15 viewed as practical for regulatory purposes.
16 And recognize that this sprung primarily, at 17 least in my view of the history, because of the very 18 limited confidence that the staff felt it could place at 19 that time, on the probabilistic techniques that were used 20 to predict repository performance.
I 21 Performance assessment as we know it today was l 22 in its infancy at that time, and to compensate for l
23 uncertainty, the NRC staff articulated, in its rationale 24 for the development of these various options and selection
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(),
25 of a preferred option, that the regulator would have to l NEAL R. GROSS l COURT REPORTERS AND TRANSCRIBERS l 1323 RHODE ISLAND AVE., N W.
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127 i l
l 1 impose significantly greater conservatism than may be 1
73 2 warranted, on either the overall performance measure or
( )
s~/
3 the method of evaluation, or both. I 4 A second alternative, which was to establish i 1
5 minimum performance standards for the major barriers in ,
6 addition to the overall standard -- this was thought to 7 reduce relative contributions of each subsystem to overall 8 uncertainty.
9 Now, we look at that statement today and you l
10 go, well the uncertainty is going to be the uncertainty. I 11 How does imposing some arbitrary or justified criteria -- I l
12 how is that going to change the absolute uncertainty?
13 I think the focus here was largely driven by
(N 1 I k'-
14 the concern about confining the waste during the period of 15 peak heat load so that you would be evaluating performance 16 in the geologic medium in a much more tractable modeling I l
l 17 environment. I think that's what they were trying to 18 address by statements such as these. l l
19 I think we have a somewhat different I 20 perspective today on what actually reduces uncertainty and 21 what is really a tradeoff in terms of ease of modeling, 22 tractability of calculations and so forth.
23 It was also asserted at the time that barriers l
24 could be selected, if they were selected properly, which
( ,) 25 would act " independently". And I put that in quotes l NEAL R. GROSS l COURT REPORTERS AND TRANSCRIBERS i 1323 RHODE ISLAND AVE., N W.
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i
4 128 1 intentionally because I think we appreciate the fact that
,s 2 in a repository setting nothing truly acts independently -
\
3 - or redundantly for that matter.
4 But that was again, advanced as a pro for this 5 particular option. In addition, it was felt that by 6 defining in a general sense for the large barrier systems, 7 specific performance criteria, that this would provide 8 some guidance or input to DOE's design process; nevermind 9 that even at this stage DOE was saying, we don't want this l
10 guidance -- the staff felt that this was an advantage by 11 identifying subsystem performance criteria.
l 12 And still, that they felt that this would 13 still retain large measure of design flexibility for the p
\ m/ #
14 designer. Because you weren't prescribing specific 15 engineering values; you were talking about large 16 subsystems, and within those large subsystems the designer 17 would have maximum flexibility to do what he or she felt 18 was appropriate.
19 Lastly, the final option, the very 20 prescriptive, deterministic approach would provide precise 21 and clear guidance to the designers regarding the o
22 licensing requirements. It vas thought that you could be 23 intentionally conservative for particular barriers or 24 particular subsystems of barriers, that could directly I f'% b
( ,) 25 compensate for those areas of uncertainty that you were !
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129 1 worried about.
73 2 Keep in mind that this reflects the still,
- i '
'J l 3 very predominant philosophy of the deterministic approach; !
i 4 that more conservatism meant more safety. So if you had ]
I 5 concerns about a particular part of the package or of the l 6 waste form or of the overall engineered barrier, you could I
7 reach out for a more conservative criteria to compensate 8 for what you thought was an area of large uncertainty.
9 It was clearly the most restrictive of design 10 flexibility. It had NRC presuming a designer role. This l 1
11 was clearly a downside as well. And I think probably the i 12 most important downside that was articulated at the time 13 was that you'd have to set these criteria based on the
\
(
\J -
14 knowledge you had at the time, and you wouldn't have the l l
l 15 advantage of learning from site characterization, design, 16 and construction experience, which was going to take place 17 over a very protracted period of time.
l 18 And even then, it could be expected to 19 generate a lot of important information that might render 20 the criteria that you would select in the late '70s, early
! 21 '80s, less appropriate than you might have thought at the 22 time.
23 In addition, there was thought given to, okay, 24 how do you select what are the primary barriers? The
('
(_j 25 Agency, in addition to the normal notice and comment NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE IS' AND AVE., N W.
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130 1 rulemaking process, also convened workshops and solicited
,fS 2 input on how you define these barriers.
(v !
3 And while there was some variation among the 4 input that was received, by-and-large it kind of fell into 5 three areas. That you should have a waste package that 6 confines the waste, as I said earlier, during the period 1
1 7 where specific activity of waste is very high and the 8 heat-induced perturbations in the natural system would be 9 large -- it would make moceling flow very difficult. ]
10 The overall engineered system -- which would l 11 of curse, contain the waste package but would go well i
12 beyond it -- would limit the release rate or source term
,_ 13 to the geologic setting, and that the geologic system
( )
'-' '/ 14 itself should minimize release of the remaining inventory j 15 once the other two barriers had failed, and that would 16 ensure that the environmental standards are met.
17 Now, I have frequently heard that the former 18 Director of NMSS, Mr. Bernero, summarized these three 19 considerations in a much simpler form. Which is basically 20 that, you know, waste shouldn't leak for a long time, and 21 when it does leak it should leak very slowly, and once it 22 has leaked from the engineered system it should take a 23 very long time to move through the geologic setting to a 24 point where people could be exposed.
,.m
(_,) 25 And it was this general sense of long NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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131 1 containment, slow leakage, slow migration to the biosphere fs 2 that would provide that additional level of reasonable
( )
R/
3 assurance that the Commission will need in order to assure 4 itself that the overall performance objective, the EPA 5 standard has been complied with. j 1
6 Now, a considerable amount of the thinking 7 that I just articulated was in place by the time an 8 Advance Notice of Proposed Rulemaking was issued in 1980.
9 By this time, the disposal concepts have changed. l l
10 Reprocessing was no longer considered feasible !
l l
11 for commercial fuel; that disposal spent fuel would be 12 what we would be dealing with. And it was recognized by I l
13 this point that the hazard was going to persist a lot
?
'/
)
14 longer than 1000 years, and it was thought to be around 15 10,000 years or longer.
16 The philosophy that the staff was clearly 17 coalescing around was the second option, which you 18 recognize is the one that we have today in the 19 regulations; that you would have multiple barriers with 20 minimum performance requirements that would provide that 21 needed assurance I just talked about.
22 The specific performance objectives that were 23 articulated in the Advance Notice of Proposed Rulemaking 24 was 1,000-year containment by the waste package; 1,000-() 25 year containment by the underground facility; 10 4 annual l NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
l WASHINGTON, D C. 20005-3701 l (202) 234-4433 (202) 234-4433
133 l l
l 1 release rate of the inventcry remaining at 1,000 years; j
,3 2 and a 1,000-year radionuclide travel time through the l
( ) !
~
3 geologic medium.
l 4 Also at this point there were no EPA standards l 5 developed. The staff was aware that EPA was probably 6 expected to produce standards that would be in the form of l l
7 a release limit. So there was continuous interaction with i 1
8 EPA as they were going down the road to developing their I
9 own environmental standards. And we had a pretty good l 10 feel, even at this point, that it would take the form of 11 release limits.
l 12 However, I mentioned that the lack of nexus -- l l
l 13 which is a term that emerges later in this story -- was l I
/~'s s
! l ks' 14 intentional. That there was a lack of correlation with l 15 whatever EPA standards would be issued, and it was on 16 purpose. It was believed that these subsystem performance 17 criteria could act in a complementary fashion to provide 18 that reasonable assurance.
19 So even though there was extensive comments 20 that the subsystem performance criteria were not needed 21 even in 1980, the staff believed that they were, and that 22 the fact that they did not tract directly to some yet 23 unarticulated EPA standard was just fine; that that was a 24 good thing.
j
( , 25 In 1981 the thinking had matured still further v
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133 1 and the staff continued to favor the use of quantitative
,s 2 performance requirements for the primary barriers. And
( )
~#
3 this was despite heavy comment that these were not 4 necessary; that they were unduly restrictive; that there 5 was only overall performance that counted. I mean, this 6 was done, you know, intentionally in the face of fairly 7 severe criticism, even at the Advance Notice of Proposed 8 Rulemaking stage.
9 At this point it was decided by the Commission 10 to not even consider the third option I had articulated 11 earlier; that the prescriptive deterministic approach had 12 too many disadvantages. And so in the Notice'for Proposed 13 Rulemaking in 1981 comment was solicited on two
- p i
' -) 14 approaches: the overall system approach and the 15 prescription of minimum performance criteria.
l 16 Now, I will draw your attention to the fact l 17 that between the advance notice of proposed rulemaking and 18 the proposed rule, there was some significant changes.
( 19 Most importantly was that the radionuclide travel time 20 criteria for the performance of the geologic setting had 21 changed to 1000-year pre-emplacement groundwater travel l 22 time criteria.
l 23 This was a big change. The decision was taken 24 because it was thought to be a simpler measure than p)
(_, 25 radionuclide transport time; that it would decouple the NEAL R. GROSS COURT REPORTERS AND TRANSCRlBERS 1323 RHODE ISLAND AVE., N W.
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134 1 determination from very complex chemistry that the staff j i
73 2 believed would introduce perhaps, an unacceptable level of
() 3 uncertainty; and that this would be a simpler measure 1 1
4 based upon routine techniques that could be easily 5 applied. ;
i 6 That's not my purpose there today, to debate l 7 the selection of the individual criteria or the numerical 8 values that were selected, but just to kind of give you a 9 flavor for the thinking that led to them as they exist 10 today. l l
11 Again,no correlation of EPA standards, and 12 this was the focus of intense criticism. And between the 13 proposed rule and the final rule, the staff embarked upon p d r
'/- 14 a study kind of after the fact to kind of determine if 15 there was a relationship between complying with the 16 substantive performance criteria, and what did that gain 17 you in terms of meeting the overall perforinance objective.
18 And this was based on, I believe, about the 19 19th draft or iteration of EPA standards that we had 20 available at the time. And I'll say a little bit more 21 abut that.
22 Between the proposed rule and the final rule, 23 the Nuclear Waste Policy Act of 1982 was passed very near 24 the end of the year. It directed EPA to promulgate g)
\ ,
25 environmental standards for deep disposal of high-level NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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135 1 waste. It recognized that NRC was very well on the way to l rx 2 its own implementing regulations and explicitly allowed N -}
3 for NRC to publish its final criteria in advance of an EPA 4 standard with the caveat that NRC should later conform 5 those implementing regulations to not be inconsistent with 6 whatever EPA came out with.
7 And it also mandated that NRC technical 8 criteria "shall provide for the use of a system of 9 multiple barriers in the design of the repository". And 10 the staff for quite a long time, in terms of with that 11 direction, to be an endorsement of the quantitative 12 subsystem approach that it had been entertaining for a p_ 13 number of years at this point.
l t
'- Finally, in 198 --
14 15 CHAIRMAN POMEROY: Janet, were there active 16 presentations to Congressional Aides and so forth, by the e
17 staff in the course of this?
18 MS. KOTRA: I understand that there was but 19 Mike, I think you can give a better answer to that than I 20 can.
21 MR. BELL: My recollection is that in fact, 1 22 there were several occasions where, you know, Commission 23 officials testified before Congress of hearings on the i
24 legislation and supported provisions like having the l 1
(-
(_,/ 25 multiple barrier requirement in the legislation.
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136 1 CHAIRMAN POMEROY: Okay, thank you.
, ~s 2 MS. KOTRA: But because of the intense
( )
~
3 criticism that had been received at both the ANPR and the 4 NPR stage, the staff endeavored to provide some measure of 5 flexibility in implementing those subsystem performance 6 criteria, and in the final rule -- the final rule 7 reflected that with explicit revisions for alternative 8 criteria where justified.
9 The final standard prescribed minimum 10 performance criteria, as I said. There was again some 11 chance. The substantially complete containment provision 12 -- it was intended and was crafted as a range rather than 13 as a single value of 1,000 years, to reflect the fact that
%/ 14 depending upon decisions made by the designer, that 15 thermal period the staff was most concerned about could 16 vary.
17 And so the prescription for a minimal 18 substantially complete containment time was allowed to 19 var" between 300 to 1,000 years. Now, this became a 20 s c t. of mischief later on which most of you are aware 21 of, and I'll touch on briefly.
22 But this was a change from the original 23 proposal which was for a minimum period of 1,000 years 24 with explicit language in the proposed rule tha stated
( ,) 25 that this was a minimum and the expectation was that the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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137 1 package should last. as long as possible, but for a minimum 73 2 period of at least 1,000 years.
l ( )
'~'
l 3 That was changed to accommodate differences l
l 4 because the concern was to contain it during that period l 5 of high thermal load, and not necessarily to pin it to a 1
6 particular number. The 10 4 annual release rate was pretty 7 much as it had been proposed, and the 1,000-year pre-I
( 8 emplacement groundwater travel time was also retained from 9 the proposal.
10 It did permit NRC specification or approval of 11 alternatives. And the staff and the Commission believe 12 that this was a very important change; that it allowed the l 13 necessary flexibility to meet the criticisms that had been I
\_/' 14 fairly intense during the rulemaking process.
l 15 Also coincident with the publication of the 16 final rule was the publication of NUREG-0804. I believe 17 sections of that have been made available to you. Which 18 showed that the subsystem basically produced the outcome 19 of the study to look at the correlation between meeting 20 the subsystem objectives and the overall standard.
l 21 And the finding was depending upon who was 22 characterizing it. Demonstrated that yes, they did i
23 contribute but _nat they were neither necessary or 24 sufficient to ensure compliance with the overall
/~~T
( ,) 25 performance objective. It was kind of a -- it wasn't a NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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138 l 1
1 definitive finding. It was kind of in the middle range. j 73 2 Yes, you have slightly higher likelihood of i )
~
3 meeting the EPA standard for individual subsystems, but by I i
4 no means was it a guarantee. Again, this reflected the i 5 fact that there was no clear, technical connection between 6 the EPA standards and the subsystem performance criteria.
7 This is the only page of quotes I'll inflict i
8 upon you, but I picked two from the statement of 9 consideration for the final rule that I think are very l l
10 important to keep in mind because the Commission was quite 11 emphatic in the language in the statement of j 12 consideration.
13 That "if the Commission were simply to adopt ;
N' 14 the EPA standard as the sole measure of performance, it 15 would have failed to convey in any meaningful way, the 16 degree of confidence which it expects must be achieved in 17 order to be able to make the required licensing 18 decisions".
19 That's a pretty strong statement; the second 20 one also. It is not ambiguous. "The Commission firmly 21 believes that the performance of the engineered and 22 natural barriers must each make a definite contribution in 23 order for the commission to be able to conclude that the 24 EPA standard will be met."
/~N
( ,) 25 Just an aside here on a couple of points. For NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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1 139 1 one, this flat statement reflected concerns that evolved g3 2 over the course of the rulemaking. Initially, you may
(\_-)
3 recall as I stated, there was concern that DOE was going 4 to place undue reliance on the site; that all the eggs 5 would go in the site basket and not enough attention would 6 be paid to the engineered systems.
7 As we went through the rulemaking process 8 there was another set of concerns that were emerging as 9 the siting guidelines were being developed, as people were i
10 getting a little bit more concerned about specific sites 11 being selected.
12 There was a growing concern that was being 13 articulated in the public and in other sectors; that they
/,_ ,
i' ,) 14 didn't want DOE to be compensating for a bad site with 15 engineering; that engineering shouldn't be allowed to make 16 an unacceptable site, acceptable.
17 So you had the tension between these to 18 concerns. So there was enormous pressure I think -- and 19 this is speculation on my part -- felt by the Commission 20 and the staff, to ensure that neither extreme came to 21 pass.
22 I'll offer my own opinion at this point -- and l
l 23 it is only my own opinion -- is that I think the staff 24 right now is going to embark on working very hard to
/~m\
\s,/ 25 develop creative ways to address the first concern. That l
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140 1 there may be more than one way to convey in a meaningful
,e ws 2 way, the degree of confidence that the Commission will N) 3 have; that the overall performance objective is achievec, 4 that substantive performance criteria may be one way, but 5 there may be other ways to acquire that degree of I
6 confidence. l 1
7 I would also venture my personal opinion that l I
8 it is very unlikely that the Commission staff or the 9 Commission will turn away from the notion of a significant 10 contribution from both the engineers and the natural 1
11 barriers. That's just too fundamental to an assurance of !
I 12 safety. And I'll offer that and let's move on. l
,_ 13 At the time that the final rule was put in 14 place it was recognized that these criteria had been 15 developed almost exclusively with the anticipation of 16 saturated sites and it was recognized that they may l
17 require some adjustments to accommodate unsaturated sites.
18 So it's not long after the final rule was promulgated the 19 proposed rule went out, and in 1985 final amendments were 20 published to expand the technical criteria of Part 60 to l
l 21 include the unsaturated zone.
l 22 This rulemaking reaffirmed the view that the 23 standard of performance for the natural barrier should be 24 independent -- again, this sense that I think most of us
( ,)
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141 1 which is that you could really have a geologic setting
! 2 that is independent of the interactions between the 73
\' ')
~
3 natural barrier and the engineered barrier.
4 It at the time asserted that the emphasis on 5 pre-waste-emplacement conditions provides a higher 6 confidence of this. Clearly, they were reaching for an 7 independent measure for the geologic setting, but the 8 problem with that is, is that -- the ultimate criteria is, 9 does the site and the geologic setting together -- the 10 site plus the engineered barriers -- get you to the 11 overall performance objective?
12 And that is going to be post-emplacement 13 performance of the geologic setting, not pre-emplacement I \
kJ 14 performance of the geologic setting. So there was a 15 fundamental disconnect there.
16 It did underscore the commission option to 17 approve or specify some other travel time on a case-by-18 case basis pursuant to the provision at 113 (b) , and the 19 bottom line was that pre-emplacement groundwater travel 20 time was retained as a generic criteria to be applied both 21 at unsaturated as well as saturated sites.
22 Although it was explicitly recognized that it l 23 could be determined with much less precision in an 24 unsaturated environment than it would be in a saturated
[^T
(,) 25 environment.
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l
142 1 As I've said all along, and certainly after 73 2 the regulations were final, there were excessive i
'~'
)
3 criticisms of the subsystem performance criteria. This is I
4 news to no or.e.
5 All throughout the development of the 6 regulations there was a preference expressed for an 7 overall systems approach, that only the overall j 8 performance counts and critics -- the National Academy of 9 Sciences and others after the fact, also echoed this 10 concern that there may have been a lack of technical basis 11 for the individual values that were selected -- Nuclear 12 Waste Technical Review Board, the National Academy of l
13 Sciences and others -- that individual criteria mat not be !
rx 6 4
1
\) - 14 meaningful measures of the individual barrier performance.
15 Critics, of course including DOE but others, 16 that this was unduly restrictive of DOE's flexibility. I 17 think the National Academy weighed in here in 1990 on 18 this. The specific wording of performance objectives was 19 unclear and subject to conflicting interpretations.
20 This has continued to cause a great deal of 21 difficulty; that not only have we been arguing the concept 22 -- though the validity of the concept of having 23 substantive performance criteria -- the actual wording of 24 the criteria that have been selected have been i
(_) 25 misinterpreted, have been argued about, and continued to NEAl. R. GROSS l
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143 ;
1 be argued about to this day.
,s 2 You may recognize the oxt two as originating
^( i 1 t
3 and being highlighted by Commissioner Curtis: that there i l
4 was a lack of a nexus between the subsystem criteria and 5 the EPA standard, and that this opportunity for 6 flexibility af forded by 60.113 (b) was really illusory.
7 That when push came to shove at the time of j 8 licensing, nc Commission would politically be able to 9 articulate some other criteria; that it would be viewed as 10 tailoring the regulations to meet the vicissitudes of an 11 adequate site or an adequate application and that it was l 12 just a non-starter. That it may on paper appear to be an 13 opportunity for flexibility, but it in fact, would never kJ 14 be used.
15 Lastly, you may also recognize the last one 16 there as probably one of the most recent articulated by 17 the National Academy of Sciences in its 1995 Report on 18 Technical Basis for Yucca Mountain Standards where they 19 spoke directly to the NRC and said that the use of 20 subsystem performance criteria could lead to suboptimal 21 performance.
22 Just as an example of some of the things that 23 the staff has had to exert itself to deal with some of 24 these criticism, in July of 1990 the staff felt compelled i,
) 25 to issue a staff position 60-001 -- was intended to NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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144 1 clarify the meaning of the substantially complete
,e ss 2 containment requirement.
( ,
w/
3 Now, after the change that we discussed ;
4 earlier where, instead of having a single value of 1,000 5 years a range was instead adopted, there was what appeared 6 to be a fairly widespread misunderstanding of what that 7 precise language meant.
8 And DOE was concerned and others were 9 concerned that this appears to place a cap on the waste 10 package lifetime; that it would limit credit for the 11 engineered barrier performance. Again, a kind of a siren 12 song of unduly restricting DOE's flexibility and in a {
l 13 significant way, de-emphasizing the importance of i /~ s
\ )
'/ 14 engineered barriers.
l l
l 15 Now, after having gone through a fairly 1
l 16 thorough review of the rulemaking record in preparing this 17 talk, I can say that this was just flat untrue; it was 18 really not justified in terms of the intent of the 19 Commission. Clearly, the intent of the Commission was not l
20 to do any of this. It was not to say that the waste l
l l 21 packages had to, by regulation, fail at 1,000 years; that l
22 this was somehow a cap that couldn't get any credit in 23 assessing overall performance beyond 1,000 years.
24 I don't think you can honestly read the
(_) 25 rulemaking record and reach that conclusion. However, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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145 1 precise reading of just the regulatory language itself is e" 2 ambiguous; that's certainly true. And the staff position
]
s 3 was issued to clarify that it is a minimum performance l l
4 requirement, it does not limit waste package lifetime, nor I 5 does it limit the credit that can be taken for the waste 6 package if it were redesigned to provide containment for l 7 longer than 1,000 years.
8 But c.his is again, the type of problem that 1
9 the staff ran into in terms of trying to explain itself l
10 and what the criteria did and did not accomplish. A great l
11 deal of experience has been accrued within the NRC, within :
1 12 DOE, in the technical community-at-large, since we first j
,_s 13 started down this road in the late '70s.
14 As I've clearly suggested and as you all know, 15 the implementation of individual subsystem requirements 16 has been problematic. There has been ambiguity in both 17 the technical basis and the wording of the requirements 18 that has given rise to regulatory and technical 19 uncertainty.
20 On the plus side, we have gained enormously in 21 experience with actual system performance analysis. NRC 22 staff's own total system performance assessment, DOE's 23 experience, provides a great deal more assurance that the 24 repository performance will be understood and will be
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146 1 at the time we started down this road in the late '70s.
,s 2 We now have a specific site to look at and
/
)
<J 3 site-specific data that were not available at the time, 4 and we know we will have a site-specific environmental 5 standard that will allow for the specification of site-6 specific processes and more focused analysis on the 7 performance of the specific site in question.
8 We also have a great deal more sophistication 9 in conducting sensitivity studies and uncertainty analysis 10 of individual components and barriers, and it's possible 11 that this may provide a more manageable approach to 12 providing reasonable assurance than simply subsystem 13 performance criteria themselves. And I'm sure you'll be
/, .
I /
'/ 14 hearing more about this in the future.
15 What I've done here -- and this is strictly my 16 attempt to kind of lay out what the universe of 17 possibilities might be as the staff endeavors to create 18 options for consideration -- it is not the options. I put 19 this together for this presentation and it's certainly not 20 meant to be comprehensive.
l 1
- 21 In fact, I can tell you right now that there 22 is -- the full universe is not bounded by this list 23 because clearly you'll notice that the prescriptive option 24 that was considered back in the early '80s is missing. I
(,,) 25 think the reason that I didn't even bother to put that on NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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l 147 ,
1 1 here is that I don't think anybody is considering 73 2 seriously, that option. l
( ) ,
3 But between what we have now and the status 1 4 quo of total system performance objective only, I think 5 there's a range of possibilities. You could have 6 standards, quantitative standards for both the overall 7 system, namely the EPA standards, and quantitative NRC i I
8 regulations with a rigorous nexus between the two.
I 9 You could have a standard for overall 10 performance and have only a qualitative requirement that I
11 there's a substantial and a demonstrable contribution from i
12 multiple barriers, and we could identify specifically what l i
i 13 those barriers should be. l
(-
14 Within the multiple barrier options you could 15 in principle, require total redundancy: 1,000-year, 1000-l 16 year, 1,000-year, 10,000-year, 10,000-year, 10,000-year I
17 and so forth. You could say that the geologic setting 18 must provide isolation for the performance period 19 specified by EPA and that engineered barriers would then 20 provide supplements to that in some manner.
21 You might consider quantitative partial 22 redundancy. How that would work I don't know. These are 1
Dan 23 just kind of ideas that I kind of threw up here.
24 Fehringer had also articulated informally, some of these r's
(_,) 25 concepts before he left.
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l 148 l
l 1 Like I said, this is not meant to be the list )
1 ;
r~s 2 that the staff will consider. It's just that in order to l( -
)
3 kind of chart out that area between an overall systems 4 approach and what we have now, and to come up with 5 credible options, these are some of the things we might j I
6 have to consider. l I
1 7 How will we consider them and on what kind of I 8 a timeframe? We will be reconsidering our approach to i
9 multiple barriers and subsystem performance criteria as 10 part of our overall strategy to anticipate revising Part !
l 11 60 pursuant to the Energy Policy Act.
1 12 We've known for over a decade now that we are l
13 going to have to conform our regulations to some EPA
,/ \ l
\x-14 standard. That EPA standard has changed a great deal and 1
i 15 we still don't have a proposal, let alone a final ,
16 standard. Buc we do know that there will be changes to l
l 17 Part 60 and that we are trying to anticipate how we would 18 approach that responsibility in a very limited timeframe 19 that the statute allows.
20 That strategy is currently under development 21 and as Margaret Federline told you yesterday, the staff 22 expects to forward an Options Paper to the Commission for :
l 23 consideration in late summer and of course as we develop 24 that paper we will certainly be seeking the input of this
(~N
(,) 25 committee to help sharpen our thinking and to focus the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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149 1 options that we will present to the Commission.
,e m 2 Thank you for your attention, and I'm ready
( l w.-
3 and Tim McCartin from the staff, Robert Johnson, and Mike i
4 Bell are also here with me to answer those questions that 5 I may not be particularly adept at.
6 VICE CHAIRMAN GAJtRICK: Thanks, Janet. That I 7 was an excellent overview of the history of this whole 8 process. And it certainly has created a large number of 9 questions swirling around in my head. But let me look to 10 my colleagues and see if they can't kick off the question 11 session.
12 Bill?
l 13 MEMBER HINZE: Well, I want to join John in
/ ,
(' ') 14 saying that I think you did a great job; not only in the 15 comprehensive but also in the detail in which you have i 1
16 developed these ideas.
17 One of the things that I recall is that the 18 Center was the lead on SRA -- statutory regulatory 19 analysis -- in which they were looking at, among other 20 things, the ambiguities in 60. Do you see any -- in your 21 preparation for this presentation -- did you look at that 22 document in terms of any evidence of identifying the i 23 ambiguities that are existing in 60, and any 24 recommendations for alleviating these?
p
(,/ 25 MS. KOTRA: I confess, in preparation for this NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS l
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150 l l
1 particular preparation, no, I did not. I have read that I
(~T 2 document in the past. I am not as familiar with it as
- 4 i/-
3 members of the technical staff who have worked to respond 4 to those and those -- many of those uncertainties found 5 their way over time, into the KTIs that we have been 6 pursuing for some time.
7 The subsystem performance criteria were the 8 source of a number -- I can't tell you exactly how many --
9 regulatory and technical uncertainties that were 10 identified in that document. Tim, Robert, you want to 11 address that in more detail?
12 MEMBER HINZE: I might add that my impression, l
,_ 13 which may be totally incorrect, is that that SRA was --
I I
'~# 14 can I say aborted -- before it came to complete fruition.
15 Is that correct? Do we have the full record on the SRA 16 that's available to the committee?
17 MR. JOHNSON: Robert Johnson.
18 I'll try to answer two of your questions. The 19 last one on whether SRA was aborted -- I think the initial 20 part of SRA that identified regulatory uncertainties was 21 completed and documented as far as what the uncertainties, 22 the regulatory uncertainties, were.
! 23 The second part of SRA that principally 24 operated on developing the license application review plan
/*~
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l 151 l
1 reduction. l l
1 2 To answer your first question, the regulatory
\_/ !
3 uncertainties, you know, regarding the subsystem -- if I l 4 can just recollect without having read it for a while --
5 my recollection is that for the most part the regulatory 6 uncertainties that were identified in SRA, you know, with 7 the Center and support from the staff, kint of looking at 8 areas that we are talking about in subsystem.
9 Collected a lot of, you know, the thinking 10 about the concerns that Janet has, you know, recounted 11 this morning, and documented those. Concerns that were, l
12 you know, just have been with us for some time. So I 13 don't believe -- unless the technical staff, you know,
(,_)
'- 14 have some other examples -- that there was anything new 15 there. j l
16 It was trying to systematically go through the 17 regulation -- all the parts of the regulation -- and see 18 where uncertainties were. For these particular 19 requirements, those uncertainties were well known and it 20 was a matter of documenting them and then eventually 21 resolving them.
22 So that part of SRA, to answer your second 23 question again, wasn't aborted. It was the -- the 24 resolution of these uncertainties depended on rulemaking -
,m
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I 152 !
1 1 to pass yet.
l fs 2 MS. KOTRA: I will offer, Dr. Hinze, from my e i 3 own experience. At the time that that document was being 4 developed and the part dealing with regulatory 5 uncertainties was issued, I was on the staff of 6 Commissioner Curtis who had some fairly strong feelings 7 about this issue. l 1
1 8 And I recall that his position which did not l 9 prevail in the Commission, was that as each of these was 10 identified, you know, rulemaking should be initiated to 11 fix it at the time rather than deferring it to a later 12 point in time.
13 The position of the staff and of his fellows i /
N/ 14 on the Commission was that we knew we had this conforming l 15 rulemaking, we'd proposed a conforming rulemaking, had to 16 withdraw it or put it aside when the EPA standard was 17 remanded. !
18 That the idea was this was going to be 19 imminent; that we would be embarking on this immediately, 20 and that rather than go through this very painful process 21 of rulemaking multiple times, each time a new regulatory 22 uncertainty or an old regulatory uncertainty was ,
i l 23 identified and highlighted, that it would be best to do it 24 as part of the overall package.
) 25 But as you know, that overall package has not
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l
153 1"yet come to pass. But there was thinking, even as early
,g 2 as the early '90s, that perhaps some effort should be made O 3 to effort that. That was taken up, not in an official 4 way, but it was certainly discussed a lot, as I recall.
5 MEMBER HINZE: Well, we have the chance now.
6 MS. KOTRA: Tim?
7 MR. McCARTIN: Just one quick thing. In the 8 staff work for looking to revisions to the rule, we do 9 have the Center helping us out and we are incorporating 10 all the information and knowledge gained in the SRA as we 11 look at how should we revise the rule -- obviously for.
12 Initially, the initial thrust is for the 13 individual dose standard, but there's these other things
,s I
\') 14 that are hanging there that we are using.
15 MEMBER HINZE: I think the committee should 16 revisit the SRA, and I suspect there are a lot of goodies 17 in there, at least in terms of integrating some of the i 18 thoughts on these uncertainties.
1 19 MR. McCARTIN: We've summarized -- we've had l l
20 the Center summarize some of the things with respect to 21 the rule that we can provide you.
22 MEMBER HINZE: That would be excellent. l 23 Thanks. Very good. I'll just take another quick 24 question. Janet, presumably, regardless of the outcome of n
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154 1
1 here, with this effort. l l
1 2 That bill calls for interim storage, as you
-')
LJ 3 well know, and I'm wondering, in your review of the 4 history of this whole process, whether you think the fact l
5 that interim storage is going to become a factor here, 6 perhaps leading them to geological disposal, but in any l 1
7 way impact upon the requirements for the multiple j 8 barriers. ;
9 Is that off-the-wall enough?
10 MS. KOTRA: It's out there.
11 MEMBER HINZE: Well, one of the things that --
12 VICE CHAIRMAN GARRICK: Why don't you try 13 again?
/,)
14 MEMBER HINZE: I was trying to leave you a lot 15 of latitude to expand. At one point in time the country 16 had strictly surface storage, as you pointed out, and then 17 went to geological disposal and the identification then of 18 the need for multiple barriers. l 19 The engineered barriers are one way to express 20 it -- at least as that they complement the geological and 21 natural barriers -- and do so particular.l.y in the shorter 22 timeframe, j 23 MS. KOTRA: Recognizing that's a relative 24 term.
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155 1 that reason, because that's not a very specific time
(~~x 2 period. I'm wondering, if as you looked at this material, N-] l 3 if you felt that the surface storage of the waste for a j 4 period of time -- obviously during the time of maximum 5 thermal pulse -- is in any way a factor in thinking about 6 the multiple barriers?
7 I'm trying to think of what does interim 8 storage provide in any -- does this impact in any way, j 9 upon our thinking about multiple barriers?
10 MS. KOTRA: Okay, now that you've sharpened it 11 up a little bit there I think that helps me to answer the l 12 question. I think what you're reaching for is, you have
,_s 13 storage for a long enough period of time to significantly
/ i 14 impact the heat load -- and the source term to some l
15 extent?
16 MEMBER HINZE: Exactly.
17 MS. KOTRA: Yes, it certainly does. It 18 doesn't -- the way you first phrased the question, that 19 somehow that it itself would provide a barrier of sorts.
20 MEMBER HINZE: Well, I was trying to leave you 21 a lot of latitude, okay?
22 MS. KOTRA: Yes, okay. As I now understand 23 your concern, it certainly would have an impact on that 24 period of substantially complete containment, consistent f~M k_, 25 with the concern that was articulated at the time that the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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156 i 1 multiple barriers were identified and the specific value
,g
, 2 of that range -- you know, 300 to 1,000 years. ,
('~') 3 How big an impact it has, I guess I'd be 1
4 qualified on because clearly the intent -- reaching back 5 to the '81 timeframe -- the package should persist for as 6 long as possible. That there was no intent that, you ;
i 7 know, that it would vanish at some point in time.
8 We recognize that at some point there will not 9 be containment, there will not be an engineered system. .
I 10 But that doesn't relieve the developer from, you know, 11 within constraints, which include among other factors, i 12 cost, but certainly not limited to it -- would want to 13 design a package and an engineered system that would
[, )
/ 14 preserve isolation as long as possible.
15 In terms of setting a criteria tied to that j l
16 heat flow and initial fission product source term, clearly 17 old waste is going to be less of a problem than fresh 18 spent fuel.
19 Did that answer it?
20 MEMBER HINZE: Sure you did. And I was trying 21 to get at, is there anything new in terms of our rules and 22 regulations that we should consider as we move ahead in l
l 23 revising Part 60?
24 MS. KOTRA: In our rules and regulations?
,m
( ,) 25 MEMBER HINZE: Well, if Senate Bill 104 goes i NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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157 1 through in terms of interim storage and how long that 7s 2 might be and so forth.
3 MS. KOTRA: Well, most importantly, I see it 4 in 104, is that it would prescribe the overall system 5 objective in a different way than is currently envisioned.
6 And it would put some constraint over what NRC could 7 consider in evaluating compliance with that overall 8 performance objective.
9 I guess I would have to say that that's very l l
10 fluid right now and that we'll have to deal with that when 11 we have -- we've been responding now for a year and a half 12 to various versions of this legislation. And we've 13 commented on -- John, did you want to add something?
O i
14 John Austin?
15 MR. AUSTIN: Yes, John Austin, NRC staff.
l 16 Interim storage could be a component of an 17 integrated waste management system, and the Commission has 1
18 supported various pieces of legislation which would have 19 an integrated approach to the disposition of spent fuel.
20 However, in the waste confidence proceeding, l l
21 the Commission stated that it had confidence that there 22 would be a solution to the high-level waste problem within 23 the first quarter of the next century. So we're talking 24 like, a 25-year period at most, for which there should be r3 (j 25 a repository. And second, the Commission has also said NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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158 1 that interim storage should not be at the sacrifice of the
,s 2 ultimate solution, the repository itself.
( )
\_/
3 So I think a 25-year period is not that 4 significant in terms of heat load, so it should not be --
5 yes, the storage issue should not, as far as I can see, be 6 a factor in setting criteria for a repository.
7 MEMBER HINZE: Thanks. That summarized it 8 very nicely.
9 VICE CHAIRMAN GARRICK: George?
10 MEMBER HORNBERGER: Janet, you mentioned at 1
l 11 the start the idea that people see a tension between a PRA l
12 and a deterministic, defense-in-depth approach. I think l 13 that some people, perhaps the staff, might see this as a i $
\ s# 14 creative tension; others might see it as an 1 i
15 irreconcilable, incompatibility.
16 I was just curious, as you move forward to 17 consider your options from you know, A to Zed, of how you 18 think that probabilistic assessment techniques would weave 19 into the subsystem requirement issue?
20 MS. KOTRA: Let me take that in several steps.
21 I emphasized throughout my presentation that growing 22 confidence in the validity and the utility of 23 probabilistic assessment techniques has been a very 24 important change from the time we started to develop these p)
(_, 25 criteria and where we are today.
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159 1 I think in the technical community at large,
,ew 2 there is a much greater confidence in the power of these (v) 3 techniques. I'd offer my own opinion that that confidence 4 has not been effectively communicated to the community 5 beyond the technical community to the public-at-large and 6 to other decision-makers as effectively as it might be.
7 But it certainly is very real. I think you 8 expressed it very well: a constructive tension. That 9 there are -- there can be complementary approaches as 10 opposed to irreconcilably opposed approaches.
11 We have been directed by the Commission's PRA 12 policy statement to view it in just such a way; to extend 13 the defense-in-depth approach, to complement the defense-
,r3 k/'1 14 in-depth approach, to acquire the insights that 15 probabilistic safety assessment can afford. But to not in 16 any way, abandon the defense-in-depth approach.
17 John or Tim, did you want to add to that? I 18 think that -- the most truthful answer I can give you is, 19 I don't know yet how that's going to be interwoven, how we 20 surmount that natural tension to come up with a solution 21 that satisfies both philosophies. That's its challenge.
22 VICE CHAIRMAN GARRICK: Paul?
23 CHAIRMAN POMEROY: Janet, a quick question and 24 then one other one. The quick question: back at the time g
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160 j 1 groundwater transport, I understand your explanation of 2 why that happened, but I wonder if there is any j
%) j 3 documentation of some of the thoughts or the criticisms ;
1 l
4 that came in at the time that we might look at -- that I S might look at, anyway?
6 MS. KOTRA: The appendices to the proposed 7 rule package -- I believe it's Appendix J -- was the l 1
8 rationale for the subsystem performance criteria. That's 1
9 a little hard to find if you use the internal NUDOCS l 10 retrieval system because that one of the ten appendices I 11 was not originally included in the record. I found this .
I 12 out a few weeks ago.
i 13 It is in the system, however, but to ease your )
(~ ;\ i i ;
14 review of it I'd be more than happy to provide copies to 15 the committee if you'd like to see that document. I think 16 it's a very useful one and it discussed -- Jeff, you're 1
7 nodding your head in agreement.
18 I think that's where you will find 19 specifically articulated, the concerns about how little we 20 knew about the complex chemistry and why the decision-21 makers in the staff at the time believed that the emphasis 22 should be placed on pre-emplacement as a simpler, easy, 23 shortened and simple measure of geologic performance.
24 We know that that's really not the case from
(~
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161 1 advanced at the time, and I think that's the document
-- 2 you'd want to look at.
'V 3 CHAIRMAN POMEROY: Great. I really would like 4 to get a copy of that, Janet. I'd appreciate it greatly 5 if I could.
6 MS. KOTRA: Sure.
7 CHAIRMAN POMEROY: As you pointed out, 8 Commissioner Curtis articulated two points that you 9 quoted, but the second one is one I wanted to dwell on 10 just for a minute. Namely, that any flexibility you write 11 into -- that was written into the current standard --
12 current regulation, rather -- is rather illusory because 13 of the political concern.
/~ ~N i i d 14 MS. KOTRA: That was his opinion, yes. l 1
15 CHAIRMAN POMEROY: Yes. What I'm wondering 16 about is if that's true -- and I personally believe it is 17 -- how can we give the flexibility to the NRC that I think 18 it needs, if indeed they can't exercise it, as we get l 19 closer and closer? And now we're certainly six years 20 closer than --
l 21 MS. KOTRA: Right. We like to think we are.
i 22 CHAIRMAN POMEROY: Yes, perhaps " closer" was 23 the wrong word.
24 MS. KOTRA: I apologize; that was a little l
O I think we do have -- in all seriousness, I C) 25 cynical.
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162 1 think we do have reason to believe that we have more fx 2 flexibility than we had before. Recall that when Part 60 i i LJ 3 was put in place we still were thinking about nine sites.
4 It was clearly a generic rule reflecting a generic ,
i 5 standard; that it was supposed to cover all possible 6 sites, all possible media, etc. l l
7 It was recognized even at that time, that once ,
l 8 you actually got about the business of characterizing real 9 sites with real geologic media, that ycu would have 10 additional information.that would illuminate your 11 consideration of what is a good figure of merit.
12 And I will draw your attention -- I can't 13 quote it chapter and verse although after all these years
/ T
l 14 I should be able to -- that specifically with regard to I 15 groundwater travel time, not the other two, but ;
16 specifically with groundwater travel time, in the criteria 17 itself it says something to the effect, or other measure 18 as the Commission deems appropriate. I'm paraphrasing 19 very loosely.
20 And that's in addition to the tract or -- poor 21 choice of words -- the alternative option in 113 03) . So 22 it was recognized even then that there was some degree of 23 uncertain'./ about how good a figure of merit this might 24 be. And it allowed the Commission, both in the criteria
/~
(_N) 25 itself to specify some other criteria, or to specify under NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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163 1 113 (b) , some different, quantitative value for that gy 2 criteria.
)
3 So I think we now have a situation where we 4 have a site-specific standard, we will be developing 5 regulations that have to implement a site-specific 6 standard, and clearly we will be exploring means to do 7 that in the context of a generic rule or through some 8 other mechanism. But we will have to -- we will ,
9 explicitly have to take into account site-specific factors 10 -- free up a mountain -- that we could not have envisioned 11 at the time.
12 So I think we are better off. Now, how much 13 better off I'm not really free to speculate on that.
r~T,
'% - 14 CHAIRMAN POMEROY: Right. The last question 15 really is one that perhaps I should address to somebody 16 else, but the intention here is ultimately to go ahead and i 17 develop a revised Part 60, eventually?
18 MS. KOTRA: That's correct.
19 CHAIRMAN POMEROY: Whether it's Part 60 or 20 some other --
21 MS. KOTRA: Well, to revise our regulations to 22 conform to an EPA standard.
23 CHAIRMAN POMEROY: Yes. If we don't have an 24 EPA standard, what happens?
,- y
(_) 25 MS. KOTRA: Well, that's a tough one.
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164 1 CHAIRMAN POMEROY: I am perhaps -- you know,
,N 2 I'm --
t \
]
3 MS. KOTRA: I notice that Bill Reamer from the 4 Office of General Counsel is here. Could you help us out 5 in this regard? Because under the law right now, as it 6 exists right now, Energy Policy Act, Nuclear Waste Policy 7 Act, we are on the hoof to conform to and implement, an 8 EPA standard.
9 MR. REAMER: Bill Reamer, Office of General 10 Counsel. Mr. Pomeroy, I don't know the answer to that.
11 If there's no EPA standard then what do we conform to?
12 There's nothing to conform to. But I guess for planning 7
13 purposes the staff is going forward in the expectation f ;
\# 14 that there will be an EPA standard. So that's the 15 planning assumption.
16 CHAIRMAN POMEROY: Okay. Thank you, Bill.
1 17 MEMBER HINZE: Could I go back to your second j l
18 question and state what's rather obvious? And that is 19 that as you have pointed out, Janet, having a site-l 20 specific regulation makes it somewhat easier. In the same l l
l 21 --
l 22 MS. KOTRA: A site-specific standard? l I
23 MEMBER HINZE: Standard, right. Is going to !
24 make it somewhat easier and also because you have all this (n,) 25 information now on Yucca Mountain and your designing this NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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165 1 for Yucca Mountain and so forth.
r's 2 But it also makes it more difficult, too, and ,
N,) l 3 it makes it more difficult because any relaxation, any 4 perceived relaxation of the current 60 is going to be met 5 with a lot of opposition, I would think, by many parties.
1 6 So changes, of course, will have to be extremely well l 7 verified, justified, and not be perceived -- to do 8 everything possible to destroy the perception that there 9 is a relaxation in the regulations of 60.
10 MS. KOTRA: I don't dispute for a moment what 11 you say is absolutely correct. I guess my problem with it 12 is that it's absolutely impossible for me as a technical
,_ 13 person to turn .ay back on close to 20 years of experience,
'- 14 that has -- not just with regard to the site-specific 15 nature of the problem, but with regard to our generic 16 techniques.
17 We have improved our ability to analyze this 18 situation, significantly, and to ignore that in setting 19 criteria, I think is unforgivable. That being said, 20 you're absolutely right. We have to justify whatever 21 criteria we put forth, and if they differ from the ones we 22 felt were justified in 1983 the Commission is duty-bound 23 to explain itself, and explain itself with technically-24 sound arguments.
in)
(_/ 25 MEMBER HINZE: That's why the history and the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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166 1 philosophy behind this that you have given us today is so fy 2 very important. It's really the cornerstone on which we
- i
%I 3 build, I think.
4 VICE CHAIRMAN GARRICK: Yes. And I wanted to 5 pick up on one of those technical items. In your very 6 good historical perspective, one of the things that seems 7 to me to be an important underpin of the whole defense-in- l l
8 depth philosophy, is something you had as a bullet in your ]
1 1
9 slide on page 3, defense-in-depth concepts labeled, 10 Provides Means to Manage Uncertainty.
11 To me, that's a very logical and solid basis 12 for the whole concept. But having said that and thinking i i
13 a little bit about the question that George asked about l
'- ' 14 the role of PRA, it seems to me that some opportunities 15 really jump out at you as to what that role might be.
16 And in particular, the whole idea of the )
l 17 probabilistic thought process of course, is to quantify 18 uncertainty. And so the question that I would think a lot 19 of people would be asking is, if we are in a position to 20 quantify the uncertainty of the various lines of defense, 21 then are we not setting the stage for a scientifically-22 based mechanism of tradeoffs between barriers?
l l
23 It seems that this is something that you'll 24 probably be pushed on quite hard if indeed, there's
(~
(_,T/ 25 genuineness in: a) it being scientifically based, and b) l NEAL R. GROSS I COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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167 1 it being an attempt, a genuine attempt to try to bring in 2 a systems perspective.
((w) v 3 My own belief in this is that you can have ;
4 your cake and eat it, too. I think that the best analogy 5 of this -- and you mentioned it -- is in the reactor game.
6 I think that maybe the biggest contribution of the whole 7 risk process has been in the calibration and 8 quantification of the effectiveness of lines of defense.
9 We had very little notion of how much worth we 10 could assign to a mitigation system, or how much worth we 11 could assign to the primary system, or how much worth we i l
12 could assign to the containment system -- even the !
13 passive components of the containment system.
i )
\/ 14 We had very little sense of what that was 15 before we started really homing in on trying to quantify 16 the uncertainties associated with their respective 17 effectiveness. We now know a lot on a plant-specific 18 basis, about how good those systems are.
19 So I hope that whatever direction this goes --
20 and also what has come out of that is some movement, not 21 as much as a lot of people would like to see, but some 22 movement in the ability to do tradeoffs between different 23 lines of defense.
24 So it seems to me that number one, the great (3
() ,
25 opportunity here is to quantify what those lines of NEAL R. GROSS l
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168 1 defense are and see what responsible we really are; see if 7x 2 we're spending ten times as much resources on a line of l
)
v 3 defense that's only one percent of the value.
4 So I just wanted you to comment if you could, 5 at that level as to whether or not you think that the )
6 approach here will include the business of trying to l 7 quantify and calibrate the effectiveness of the different 8 barriers. And two, will that provide regulatory l 9 opportunities. regulatory-based opportunities for some 10 tredeoffs?
11 Now, there's some things you said that are 12 very disturbing. This issue of, the matter of i 13 independence and redundance. I could take that to the ;
e's
( I
\ 14 limit and say, you have no -- you only have one line of 15 defense.
16 If you can't somehow get resolution between 17 these barriers in terms of independence and redundancy, 18 then in fact, you don't have in the limit, multiple 19 barriers. You just essentially have one barrier and the 20 logic seems to fall apart at that level.
21 But anyway, let me just come back to the 22 question of systems analysis concepts, and in particular, 23 probabilistic concepts in the whole issue of lines of 24 defense.
7_.
() 25 MS. KOTRA: Well, I tried to hint at that when NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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169 1 I talked about the value of much-improved ability to do r3 2 sensitivity analysis and to do the kind of calibration
)
3 you're mentioning. But I'd like to turn it over to Tim. l 1
4 I have some thoughts on it after he finishes, but I would 5 let Tim answer your question initially.
6 MR. McCARTIN: Okay, yes, Tim McCartin, NRC 7 staff. Obviously the application of subsystem 8 requirements we've thought a lot about and how best to 1
9 implement them. And I think where you're headed is that, it at least when we see a lot of the difficulties with the l
l 11 subsystem requirements is, how do I close them out, how do 12 I demonstrate meeting or not meeting, complying with those I 13 requirements?
I )
\ 14 One way to do that that I think we're thinking 15 about in terms of the rule is, clearly in doing a 16 performance assessment I'll be looking at container 17 lifetime, the release rate from the engineered system, and 18 the travel time from there.
19 If you, in the course of doing your 20 performance assessment you now demonstrate the 21 contribution in what those values are, is one way of 22 meeting -- or at least demonstrating what subsystems, how 23 they're contributing to overall performance, etc.
24 Now whether you put an actual numerical value n \
l
() 25 on, do I have to have 1,000 years -- that's a different NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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1 170 ,
i 1 issue. But I think one way to do it is, we are looking at
,rg 2 -- you're looking at the subsystems in your total system N.)
3 performance. 1 4 VICE CHAIRMAN GARRICK: Yes. Now Tim, the 1
i 5 point there is -- part of the point is that you're going 6 to discover that the uncertainty is very different between ;
7 the barriers. And therefore it would suggest, if one of 8 the underpins of the defense-in-depth concept is the l 1
l 9 management of uncertainty, it would suggest that there 10 ought to be some basis for the subsystem requirements 11 therefore being different.
1 12 Somehow, the arbitrariness of those 13 requirements has got to be, it seems to be, diminished in
(,,_s)
\ ~
14 favor of a real connection, a real tie with the underpins j 1
1S and the philosophy of the concept in the first place.
16 That's part of the point.
17 That's just something to sort of telegraph a 18 little bit, of a thought or two of opportunities of 19 incorporating the systems ideas with the subsystem 20 requirement process.
21 MS. KOTRA: If I may, I think that -- it's 22 very fair to say that at the time those particular values 23 were selected -- in this document that I'm promising to 24 make available to Dr. Pomeroy and make available to the
/N
\
'(_/ e5 committee -- goes into fairly extensive detail on how NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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171 1 those decisions were made.
2 But I think it's very clear that there wasn't 7x
() 3 a great deal of technical analysis about the relative 4 uncertainty of these various barriers supporting that 5 selection. It was done at a time when the experience with 6 this beast and how it would perform and how we could 7 project it to perform, was limited.
8 I think that is one of the things that has 9 changed a lot. But I think you've also -- and I'm really 10 stepping into an area that is beyond my expertise -- but 11 to the extent that I'm familiar with this debate in the 12 reactor arena -- and it's a very live one even now --
13 about now do you apply a probabilistic perspective to what (p_ )
' 14 is basically a deterministic regulatory framework?
15 Everybody's comfortable with saying ah, with 16 this new insight I've gotten from PRA we now have 17 identified a new vulnerability that we did not see before, 18 that would not have emerged from the deterministic 19 approach, and we can more safety by -- and we can get 20 better bang for our regulatory buck by focusing in this 21 area.
22 The converse, on the other hand, of looking at 23 a deterministic framework that has been in place for some 24 time and saying hey, we're investing a great deal over f~'\
(,)i f
25 here in something that doesn't buy you quantitative, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE _, N W.
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172 1 incremental increases in safety, and the getting from that
.7
, 2 to justifying a relaxation or even a perceived relaxation,
- s i /
3 is more than just a technical problem.
4 And that gets back to the ability of this 5 Agency and the technical community-at-large, to 6 communicate its confidence in the analytical techniques 7 and tools we have available now. Because if that 8 communication is not effective, then it is going to be 9 perceived as an unacceptable relaxation of regulatory 10 rigor and standards.
11 VICE CHAI.RMAN GARRICK: Bill?
12 MEMBER HINZE: Janet, I know this was beyond 13 your assignment, if you will, but have you in your reviews i
\
14 on this come up with any interesting information about how 15 this problem is handled on the international scene in 16 other countries?
17 MS. KOTRA: I haven't really thought about it 18 in the context of this particular presentation. I think l I
19 that we've got a lot to learn and share in the 20 international environment and we certainly participate in 21 international activities with counterparts in other i
22 countries. l l
23 I think the big difference that we keep 24 running into -- in my limited experience in this area with j n
() 25 OECD, NEA, working groups and the like -- is the licensing l
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173 l
1 litigative environment in which we have to do our i 1
73 2 technical work. That puts constraints and forces us to be l v
3 a lot more explicit than --
4 MEMBER HINZE: Prescriptive. I 5 MS. KOTRA: And in some cases that translates 6 into prescriptiveness. And so many times there a sort of 7 a wistful nature when I hear of the experiences and the 8 challenges that the Europeans face, for example, because 9 they do not necessarily, at least at this point in time, 10 do not face the kind of hurdles that we know we have to 11 dea. with.
I 12 But I'll be happy to think about that
]
13 question.
p ,_
- i
- 14 MEMBER HINZE: I'd appreciate it. I 15 VICE CHAIRMAN GARRICK: We're trying to get to j l
16 a break but I think George has one.
17 MEMBER HORNBERGER: I'll try to be quick.
18 Actually, it was a follow-on to John's question. But let 19 me try to phrase it in a somewhat specific way. My 20 question is how one tries to build flexibility into this 21 whole arrangement.
22 And if for example, analysis points to, let's 23 say neptunium and technetium being the real things that 24 drive the overall system performance assessment, it could
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174 1 lifetime and a 1,000-year groundwater travel time, don't
,r-] 2 contribute very much.
- /
q/
3 Again, I think it's on John's questions about 4 tradeoffs. Do you see in your evolving analysis, trying 5 to build a flexibility into the regulation to handle such 6 potential eventualities?
7 MS. KOTRA: I think we will definitely be l l
8 considering, among those alternatives, the value of the 9 quantitative subsystem performance criteria to handle just 10 such a case. But Tim, if you want to comment on that in 11 terms of -- I mean, that would lead you toward, at most, a 12 qualitative requirement of contributions of multiple i 13 barriers, l\ /
i 14 But Tim? i 15 MR. McCARTIN: Yes, I mean, the exact 16 numerical value, I mean value, what Janet's saying, going 17 to a qualitative -- there has to be some contribution from 18 different parts of the system which is, I think, she 19 mentioned before. The Commission is very strong on that; 20 that we would be very uncomfortable putting waste in a 21 paper bag down in any repository, and I think somewhere we 22 want to see some contribution.
23 And although you're right, that with a 24 sufficient groundwater travel time there's a lot of short-r's
( ,)
25 lived stuff that dies off that you never see. However, l
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175 1 one can't -- but look at the inventory of some of the
,e~3 2 short-lived stuff that goes down there and see that a i i v
3 significant decay in inventory occurs over, you know, a 4 relatively short period of time. Some very, very hot 5 stuff that just -- just in a general sense you want to see 6 it stay there.
7 And so I think, as Janet pointed out, we want 8 some engineering that we can rely on. Exactly how far you i 1
9 go is - .
10 VICE CHAIRMAN GARRICK: Okay. Thanks again, 11 Janet, that was an excellent overview and I think Mr. i 12 Chairman, I'll turn it back to you.
,s 13 CHAIRMAN POMEROY: Thank you, John. Yes, I'd I 14 just like to thank you, Janet, and also all your 15 colleagues for taking the time and making the effort to 16 come down and give us this very important briefing. Thank 17 you.
18 MS. KOTRA: My pleasure.
19 CHAIRMAN POMEROY: We'11 now take a 13 minute 20 break by that clock, and be back here at 20 minutes after 21 10.
22 (Whereupon, the foregoing matter went off l 23 the record at 10:12 a.m. and went back on 24 the record at 10:27 a.m.)
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176 l
1 order. We'll now proceed with the next agenda item, and i
7w 2 Dr. Garrick is the lead member for that item, so John?
l (x_-) 3 VICE CHAIRMAN GARRICK: Thanks, Paul. By the l
1 4 amount of time it's taken this committee to prepare a l 5 letter on the reference biosphere, I have to conclude that 6 this is an awfully important subject. And indeed it is, 7 and I think we are going to hear some interesting 8 discussions today between Chris McKenney of the staff and 9 John Kessler of EPRI. i l
10 So I think that with that, we'll get right I 11 into it.
12 Chris?
13 MR. McKENNEY: Thank you. My name is Chris f)
- 14 McKenney. I'm with the Division of Waste Management and I i 1
15 was requested to do a summary of what has been done on the l
16 international level by the BIOMOVS group on particularly l 17 reference biosphere and some on critical group.
18 BIOMOVS II is an international study known as 19 the Biospheric Model Validation Study. It was majorly 20 funded by five different international organizations and 21 was supported by, up to I think, 17 when it ended in 22 October.
23 The first phase of the program was from 1986 l
24 to 1990, and the second phase which just ended in October i ,s k ,, 25 was fror.i 1991 to 1996. And it's mainly on refocusing on 1
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177 1 what was discussed in the second phase of the program.
f
-w 2 The objectives of the BIOMOVS II were to test V
3 the accuracy of the predictions of environmental 4 assessment models and to explain the differences in model 5 predictions due to model structure. Which is like having 4
6 a steady-state model versus a dynamic model, or having a 7 very detailed groundwater system versus a very simplified 8 groundwater system -- which when you look at a lot of the ,
i 9 overall models, sometimes you have major difference in 10 that.
l 11 There is also the differences in modeling )
12 assumptions between the users, and the differences in 13 input data or the use of the input data. They also wanted (K/
14 to recommend priorities of future research to improve the 15 accuracy of model predictions. And one of those is the 16 reference biosphere methodology.
17 The BIOMOVS was in a numerous number of 18 working groups. They had not only the two that I'll 19 mainly talk about today -- the reference biospheres 20 working group and the complementary studies -- but they 21 also had quite a few that were focused on validation 22 attempts such as the use of post-Chernobyl data on special 23 radionuclides which were improving modeling attempts over 24 previously conservative models, and also doing risk fm
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178 1 uncertainty ar' validation issues.
,S 2 The complementary studies was a modeling
\ ;
v 3 exercise to investigate and explain the differences 4 between the contemporary biosphere models that existed in 5 1990, 1991. And there were ten participants from around 6 the world, and the site that was used as the example was 7 an inland, temperate, Central European valley -- actually 8 it was in Switzerland.
9 The two radionuclides of concern were iodine 10 129 and neptunium 237. To try to look at more of the 11 models than the data, they used a very extensive database 22 between the two. The modeling exercise used a defined 13 source release to a groundwater aquifer, and then you were I
esi
' w/
14 supposed to analyze for various concentrations in the 15 environment or doses to humans.
16 Two of the more important conclusions from the 17 program were that they were -- the maximum, total, annual 18 individual dose summed over all pathways was relatively 19 robust between the models. Now, the timing may be 20 slightly different but the value was relatively robust.
21 The parameter uncertainty was much more 22 important than representational uncertainty, and that was i
l 23 mainly that the differences between the models sometimes 24 wasn't as important as the values they used for the data.
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(
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l l
179 1 that had been developed from a previous study, the
, -'s 2 complementary studies that existed in BIOMOVS. They found i
v )
3 out that when you try to do these comparisons it's 4 sometimes very difficult to find out what processes each 5 person is modeling, and find out exactly what sort of 6 biosphere are they modeling in.
7 And so as part of BIOMOVS II the group decided 8 to create a method to create a detailed conceptual model 9 of the features, events, and processes that would exist 10 and their interactions, in the biosphere to be assessed.
Il Now, originally it was thought that they were 12 going to be able to develop actually a reference 13 biosphere, but with all the different groups in the wor 3d, i
14 and it was better decided that there is no one reference 15 biosphere; that there is more of a methodology to follow 16 to be complete, but every site has its own appropriate 17 reference biosphere -- or biospheres, if you consider long 18 timeframes.
19 MEMBER HORNBERGER: Chris, what does reference 20 mean then, as an adjective?
21 MR. McKENNEY: It's more of -- for your 22 analysis you are saying that this is your biosphere. It l
23 is the base case, it is -- it's not necessarily exactly 24 ,che reality, but it's -- you're establishing the entire
,r \
(,) 25 biosphere and saying, from every event and process, from NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE IS',AND AVE., N W.
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180 1 how much does it rain, how much do you irrigate, how do
,r'S 2 people act in the area -- everything, for the biosphere to LY 3 try to be complete and concise.
4 And so once you get that done you now have a 5 reference on what your biosphere is and how you came about 6 it.
7 Now, one of the benefits of this process is 8 that it improves the transparency of how did the people 9 establish the reference biosphere, how did they make their 10 assumptions? Because the entire process is a 11 documentational auditing trail of: why did you include 12 this, why didn't you not include this, why was each of
,_s 13 these decisions made?
~
I )
14 Which is very helpful when you start asking, 15 well, the Swiss do it this way and they got a result of 16 this. Why did we not get a result like that? Which 17 always come up. I mean, in any type of modeling exercise 18 that's always, well they modeled it and they came up with 19 a different result; why are we different?
20 If you have a documentation of why you made 21 all the assumptions and you're making them while you're 22 doing the modeling rather than afterwards, it's much more l
! 23 transparent.
24 Now, the methodology is an interaction between p
(_) 25 the basis system description which would be: what site do NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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181 1 you have, what type of disposal is this; and the 2 international list of every feature, event and process
%./
3 that people could think of.
4 We use those and, why are you modeling the 5 site; the assessment context. What are you trying to get 6 out of it? Are you trying to get a dose to a total 7 release or a dose to the individual, to construct a 8 conceptual model of the reference biosphere, the site, the 9 releases.
10 Now, the reference biosphere methodology 11 mainly focused on this box in BIOMOVS II which was, how to 12 construct a conceptual model. And the whole methodology 13 really, goes through these internal steps of screening,
( )
\ -
14 identification with FEPs, and the relations and setting up 15 a relational of: how do the FEPs relate to each other, 16 how does each feature relate to another one? Or how do l 17 different processes in the environment interact with each 18 other?
19 And to try to conceptualize this process in a 20 method so that people could try to understand where you
- 21 were discussing, they used this, what is called the rock 1
l 22 matrix interface -- sorry, rock engineering system 23 interaction matrix -- lot of words there. And that 24 identifies the importance of each of the FEPs and
,/m
( ,) 25 interactions between the components.
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182 1 Now, this one is actually from the EPRI report 7s 2 because it was really nice, because it was a lot less
\
^
3 cluttered than some of the other ones. But you have a 4 center line of big, general features. Such as just the 5 sediments, the variable saturated zone, surface or 6 atmosphere flora. All those are just on this diagonal.
7 And you start to look through and figure out 8 how does each one interact with other ones? And using a 9 clockwise system. Like, how does the variable saturated 10 zone deal with the sediments? You have in this box the 11 conversion bank collapse, or if you have variable 12 saturated zone relating the permanent saturated zone you 13 have percolation.
i )
1/ 14 And then conversely, then you have on the 15 other side, some other results like the atmosphere, does 16 dose to the critical group through direct exposure in 17 7.11?
18 So you have a way to draw arrows of how does 19 each of these on the diagonal interact with another one?
20 And what you want a result in is: 1) you have described 21 how each one interacts and your decisions on why they 22 interact this way, and 2) that each of these interactions 23 can be covered by at least one feature event and processes 24 that you will describe in either your model or -- at least g
(_) 25 your conceptual model.
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183 1 Now, as can be guessed it's definitely an 1
7- 2 iterative process because when you originally begin with L) 3 this program your matrix is never this uncluttered. I 4 mean, you've got nearly every box filled with something or 5 some decision-making, and you start then to get more and !
6 more site-specific and say that these processes aren't 7 existent at this site, and these will be -- are important j 8 enough to be continued.
9 Also, it uses the generic FEP list as a 10 starting point that's been developed so that people can 11 say that they weren't -- that it isn't all of a -- that 12 you didn't think up all of them yourself so you're i 13 excluding things because you don't want to model them.
'-- 14 You're also referencing -- you're geing to go 15 through the entire FEP list of the generic one and say, 16 why did you not model this and why you didn't model that, 17 as part of the steps.
18 It uses a critical group approach in that the 19 people, the dose in human activities you're looking at is, 20 you're trying to find which group is going to receive the 21 highest exposure. Which may not always be as simple as a 22 lot of people like to say, because if you have multiple l 23 different pathways that they could be exposed through 24 different geosphere transport pathways, different x ,)
25 activities could result in quite different doses.
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184 1 Which is, for operational facilities, one of
,w 2 the best examples is Selafield in Britain with its 3 releases of liquid low-level waste to the Irish Sea.
4 Which was, at first the fisherman were assumed to be the 5 highest doses, but when they actually did the -- out and 6 did experiments and measurements it was a couple of small 7 villages on the Welsh -- of Welsh that used seaweed as the 8 basis for breads. And they were actually getting the 9 highest exposures.
10 CHAIRMAN POMEROY: Chris, on that, did each 11 participant use their own definition of critical group?
12 MR. McKENNEY: No, there's been -- while they 13 haven't actually -- this is one of the areas that hasn't
(' ) 14 been fully detailed yet; that's part of the improvements.
15 They essentially use one but the time allowances for 16 working on this project were such they didn't focus on 17 that at this stage.
18 And they just, in the document on the 19 technical report on it, they discussed whatever country 20 uses currently. And one of the improvements in that l
21 program that I was going to discuss at the end of the 22 program, which is the IAEA's new program, BIOMASS, which 23 is a follow-on to BIOMOVS -- is to actually come out with 24 defining criteria of, how do you define a critical group,
(_) 25 how do you select one when you're dealing with a NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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185 1 hypothetical group and long time periods?
,r's 2 And which is, as everybody knows, is quite
.)
3 difficult and is a problem that everybody has. I mean, 4 we've also worked on discussions in ICRP -- with ICRP also 5 -- NRC has been working on this topic because it's very 6 important to us and it's very much in, not only our high-1 7 level waste program but our low-level waste and 8 decommissioning areas.
9 CHAIRMAN POMEROY: Okay, fine.
10 MR. McKENNEY: And I just want to state that i 11 EPRI, as John Kessler will discuss a little later, came 12 out with a reference biosphere that they did on Yucca ,
,,. 13 Mountain using this process. Now, they didn't completely
( ) i 14 at first, use the rest, but they used various different !
15 approaches to look at all of the interactions.
16 Now, as I just talked about, there are 17 improvements and future work, because when you get done 18 with a project you always want to find out where you can 19 have future work. That there's a -- mainly it's focused 20 on the testing and the augmenting of the methodology as it 21 was discussed in BIOMOVS II, in their technical report.
22 Three of the areas that they wanted to test 23 for, or augment -- and mainly the first two are an l
i 24 augmentation -- are that -- one is, how did you define the t,,
(ji 25 critical group, and two -- which is another area which was NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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186 1 discussed from the other areas on primary uncertainty --
,s 2 how do you select appropriate databases, especially when a LJ 3 lot of your material that you have is based on a national 4 scale or an international level of ranges of parameters?
5 And how do you select the appropriate values for a fully 6 referenced biosphere?
7 And they also wanted to augment the system on, I l
8 when you have climate change as part of your model, that l 1
9 you have timeframes of the right -- of that long in your 10 analysis, how do you account for the transition period, 11 how do you change your model to incorporate the i 12 transitions?
13 They also wanted to identify the parameter for
( )
\/ 14 relevant features, events, and processes if they could.
1 15 And they wanted to actually take it even further and l
16 actually list input data as much as possible.
17 And that there should be a continued l 18 maintenance of the biosphere FEP list which is, if someone 1
19 comes up with an event that isn't on the list now, they l
20 want to keep on adding to it, so the list is as inclusive l
l l 21 as possible, of everything people thought of or found to l
22 be an event in process that's relevant.
23 Well, to do that they need another program 24 because BIOMOVS II was out. And so in October -- actually n
(_,) 25 previous to that, but October was the first meeting of a NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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I l 187 1 new program called BIOMASS. Now this one is being
, e3 2 supported by the International Atomic Energy Agency where t ;
3 the other one wasn't previously.
4 It is still funded by quite a few countries, 5 along with being funded by IAEA. And it is on the 6 biosphere modeling assessment methods, developed both out l 7 of BIOMOVS II and the VAMP programs that had been ;
l 8 previously done. j 9 And there are three areas of focus to this !
10 program which is the radioactive waste disposal area, 11 which is mainly focused on implementation and augmentation 12 of the reference biosphere methodology, including in the l 13 long term, a test of the entire methodology by doing a .
/m 1
\ -)
- 14 case study and creation of a reference biosphere.
i 15 Including going back to the -- where they had 16 previously focused on this area, they want to take it in 17 this test, all the way through to come up with, in their 18 case study, an assessment tool. They want to see how to 19 convert this to mathematical description and come out with 20 an assessment tool, because currently it's only been 21 discussed in more of developing the conceptual model.
22 The second theme of BIOMASS is environmental 23 releases. And it has two areas in this which is: dose 24 reconstruction calculations and environmental remediation.
- () 25 Both of these are more of model benchmarking and NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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188 ,
I 1 validation attempts.
2 The dose reconstruction they currently are
!y) f-w/
l 3 looking at is the iodine releases from Hanford. And the 4 environmental remediation is a radium site in -- Denmark, 5 Paul? Belgium.
6 And the third theme which is more of -- is 7 continuation to the smaller areas of focus that people 8 wish to discuss is on biospheric process and it's usually 9 focused on specific areas of -- or specific events and 10 processes of transport to the environment.
I 11 Such as tritium which is, they're continually 12 trying to improve the models from the conservative values 13 that they used in the '70s, of assuming that it was always I
('%g l
\ !
\/ 14 at steady-state in the environment.
15 And for many of the European countries there 16 was an interest in developing forests and fruit tree 17 modeling. Forest being the use of contaminated forest 18 products, or fruit tree which is more short-term, tree 19 models -- for stuff like Belarus and other areas that were 20 contaminated by Chernobyl. And where do you need to 21 actually focus your remediation if you -- is it a problem?
22 Now, Theme 1 is the area that we're most 23 interested in -- the NRC is currently. And this is the 24 timeline for it, and as you can see the first two topics
(_) 25 which are the principles for the definition of NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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I l
189 i 1
1 hypothetical critical groups and how do you -- and the j
,f- ~3 2 principles for application of data to assessment models --
Li 3 are both fairly short-term. They're only a year-and-a-4 half until a final report.
1 5 And those, the first four are apparently now j 6 underway, and we're just about to where the little cross 7 is, which is our first semi-annual meeting in Oxford in 1
8 three weeks; at which point we'll start working on the l 9 drafts of trying to develop -- or they will as NRC is an i
10 observer in the process.
11 But the augmentation is meant to be -- occur 12 first, and then as can be seen, there's then 13 implementation down below of actually trying to do the
/ ;
) 14 entire reference biosphere methodology, including model 15 development.
16 Now, one of the big questions is, what is the 17 NRC related to this international work? We've been 18 observers in BIOMOVS II since approximately 1994, mainly 19 because of the interest with the NAS recommendations to go 20 to a dose standard.
21 We are now observers in the BIOMASS program, 22 Theme 1, and we have used simple reference biosphere and 23 critical group approaches. We have not gone to the f 24 process of doing the reference biosphere methodology yet.
I i
o 1
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190 1 considering its use.
(~T 2 But we used the overall concept when we were
\ -
)
3 in discussions with EPA last year in support of their 4 standard. NRC supports the use of the reference biosphere 5 and critical group in waste disposal and decommissioning 6 activities. It's not just for high-level waste. We view 7 it as important for all realms.
8 And we're currently considering the 9 international approach in reference biosphere methodology 10 and the selection criteria, especially the upcoming ones 11 for how to determine a critical group for use in NRC 12 activities.
,_ 13 And we have not yet applied the actual
( '
)
14 reference biosphere methodology to Yucca Mountain in a 15 full-out results, but we have done different things on 16 looking at site specific habits and possible exposure 17 pathways in various ways, but we just haven't rigorously 18 done the reference biosphere methodology.
19 VICE CHAIRMAN CARRICK: Okay.
20 Questions? George?
21 MEMBER HORNBERGER: Chris, this is sort of a 22 general question to help in my continuing education. If I i
23 have a student who wants to measure, say, concentration of 24 a volatile organic using a gas chromatograph, I understand ry
! A
(_/ 25 how one would determine accuracy with the use of l NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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l 191 1 standards, and I also understand the difference between l
,f 3 2 accuracy and precision.
3 L_J 3 I noticed in, I think your second slide, it 1
4 used the word accuracy twice with regard to the objectives 5 of BIOMOVS II.
l 6 MR. McKENNEY: Right. l l
l 7 MEMBER HORNBERGER: And I'm just curious -
8 whether this has a well-articulated meaning in this 9 context, or whether it's a fuzzier concept than I'm used 10 to. )
l 11 MR. McKENNEY: It can actually be in both 12 ways, depending on what you're talking about. In a lot of 13 areas that they are doing with respect to specific model
> e
\l 14 involvement -- when they're not talking waste management -
15 - they're talking just biospheric processes where they can 16 actually do some model validations.
17 Because the timeframes are of the appropriate 18 nature, they were looking for actual accuracy of -- like 19 some of their lysimeter studies were -- they had a 20 contaminated water source and they had plants growing 21 above it, and they were doing model comparisons of trying
)
22 to model exactly the radionuclide concentrations in the 23 soil and in the plant over time, because the data and 24 everything else -- they were trying for accuracy in that.
(% >
25 The same thing with the post-Chernobyl ones
()
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192 1 where they were -- they knew the contaminated ground
<3 2 sources, they knew over time from studies, how the ponds -
( )
~J 3 - the cooling ponds and stuff -- changed in radioactivity.
4 And they were trying to model that change based off 5 washoff and other things in the area.
6 So in the limited -- in quite a few of the 7 limited studies they were actually looking for the same 8 accuracy, but when you're talking total pathway, long term 9 in the future accuracy, it's more the fuzzy concept of 10 trying to be able to explain how you got to the process.
11 Because what we're doing for future analysis 12 is not a piediction; it's a tool for the decision- aker to 13 make a decision. It's not a prediction of actual doses, i )
\/ 14 VICE CHAIRMAN GARRICK: Chris, one of the 15 things that occurs to me about this -- and I'm learning as 16 George is -- is that the biosphere modeling is, depending 17 on the circumstances, a highly constrained model. If you 18 look at, on the one hand you have the source term which l 19 could be the radionuclide flux at the geosphere-biosphere l
20 interface.
l 21 On the other hand, you have the critical group 22 which could specify the biological uptake.
23 MR. McKENNEY: Right.
24 VICE CHAIRMAN GARRICK: And then you have the (y
( ,) 25 very long times. It sort of raises the question of, what NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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193 1 does it matter? Why not go to extremely simple models?
fm 2 MR. McKENNEY: Sometimes you actually result I
)
3 in that by going through this, where you can start going 4 through and saying that these are processes that could 5 occur in the environment, but aren't as important as this 6 or they can be bottled in a much more simple way by 7 modeling, making this assumption.
8 The reference biosphere methodology doesn't I 9 mean that you come up with a complex model. It means that 10 you've gone through the steps and determined what's going 11 to be in your model. You've gone through and made it 12 transparent to say, these are what we have thought of and 13 this is what our conceptual model we're using is -- of the
'/
14 area or the exposure -- then that is why we came up with 1
15 the result we have. l 1
16 VICE CHAIRMAN GARRICK: I guess my point is l l
17 that the extremely long times involved seem to -- they 18 would almost wash out a lot of the FEPs and their impact.
19 MR. McKENNEY: Some of them, yes. I mean, you 20 can -- that is occurring, and that you have to describe.
21 I mean, that is part of the assessment context is the time 22 that you're calculating this for.
23 If you are -- I mean, you could potentially 24 use reference biosphere methodology or approach like that
,ry
) 25 for, if you were developing a licensing of an operating i
- NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS l 1323 RHODE ISLAND AVE., N W (202) 234-4433 WASHINGTON. D C. 20005-3701 (202) 234 4433
194 i site and you wanted to do assessment because, obviously your site's not there and you're doing assessment in the
~}
u/
2 3 short term.
4 It's not necessarily only waste disposal but 5 -- and where some of the shorter term FEPs as you say, 6 would be inconsequential over the long-term, would become 7 more important over the short term.
8 or if you have knowledge that there is going 9 to be -- that you may have pulse releases from a facility 10 where short-term FEPs could result in importance, because i 11 the release of all your material is over a very short i 12 timeframe where that would be important. ,
l 13 VICE CHAIRMAN GARRICK: Yes. Paul? ;
/,,N i
' 14 CHAIRMAN POMEROY: Chris, I just want to turn 15 for a minute to your slide on complementary studies 16 results. I'm always interested in intercomparisons. I 17 guess my first question is, where you say on the report, 18 conclusions, that the maximum total annual individual dose 19 over all pathways appears relatively robust, can you give 20 me a feeling for what you mean by "relatively"? I mean, 21 is this three orders of magnitude or is this a factor of l
22 two?
l 23 MR. McKENNEY: Actually, I didn't make a slide 24 of most of the presentations because they were like, eight
,3
(_) 25 graphs to a page and they were very confusing like that.
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195 I
1 But the thing is that, out of the --
l 2 VICE CHAIRMAN GARRICK: You knew your i
(] l L'J l 3 audience.
1 4 MR. McKENNEY: Out of the ten persist events, 5 and quite a few for the robust, of the peak dose, nine out 6 of the ten would be within a factor of about two or three.
7 Because they had a comprehensive database and they tried 8 to use as many assumptions as possible. There was one 9 that had a very different modeled structure that resulted 10 in general, quite wide variances from the rest of them.
11 But they were all within only -- within a factor of ten of 12 each other.
13 CRAIRMAN POMEROY: Even though they were, for
!7i
~'
i 14 instance, using different definitions for critical groups?
15 MR. McKENNEY: Yes, yes. On what pathway they 16 all were doing it. If you looked on a pathway basis they 17 had quite big differences, but for the way they modeled 18 they all came up to be -- for the groundwater release they 19 were having quite similar results in the overall pathways :
20 analysis.
21 CHAIRMAN POMEROY: And then you said I think, 22 that the timing was different, though, and I wanted to get 23 a feeling for that, in terms of -- I assume you mean the ;
1 24 time and peak dose? j l
()\
(m 25 MR. McKENNEY: Time and peak dose, right. And HEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS l 1323 RHODE ol AND AVE., N W.
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196 1 also the rate of dose increasing over time. I mean, of 2 the -- how wide the peak is or the shape of the peak was (fu/ w) 3 different, but the actual value was similar. It was 4 mainly that yes, they are having different timeframe.
5 They had -- the time and peak dose was different.
1 6 It was not the -- I mean, not orders of I 7 magnitude since the analysis was only over 10,000 years, 8 but that it was, you know, relatively the same time. But )
9 the time-dependent doses were different, but the peak 10 doses were similar. 1 11 CHAIRMAN POMEROY: And I guess when you're l
12 saying that the parametric uncertainty was more important j l
13 than the representational uncertainty, you're talking --
> i
J 14 representational uncertainty is --
15 MR. McKENNEY: How do they get exposed, how do 16 you model the biosphere, how do you -- I mean, are you i 17 assuming that the aquifer is well mixed at all times or 18 are you assuming that there's five or six different boxes 19 of mixing rates of your aquifer?
20 Those are representations -- were results of 21 the -- much less uncertainty to the overall dose when they 22 did their uncertainty analysis than just the parameters l
23 that they had available, and especially like food uptake 24 and other values which unfortunately, are more on an (3
(_,) 25 international basis, and the ranges are very large, and NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS
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197 1 the parameters themselves became very important. ,
~x 2 CHAIRMAN POMEROY: That's all within that l l } l L/ ,
3 factor of two --
4 MR. McKENNEY: No, no. The factor of ten when j l
5 the robustness was -- is more of -- that would be l
6 basically their expected doses. All their expected doses 7 were within a factor. Now, each participant had quite a !
8 large range -- I can remember exactly what it was. But j l
9 when you look at what caused the uncertainty for each l 10 participant --
11 CHAIRMAN POMEROY: Ah, okay.
12 MR. McKENNEY: -- then the representational l
13 uncertainty wasn't as important as the primary
\/ 14 uncertainty.
15 CHAIRMAN POMEROY: Thank you.
16 VICE CHAIRMAN GARRICK: Bill?
17 MEMBER HINZE: I realize that the FEPs give 18 you a considerable degree of flexibility, but I'm 19 wondering if the generic basis of this from 20 decommissioning to high-level waste imposes any 21 limitations to the results of the study? We've heard this 22 morning about the advantages of having site-specific 23 regulations.
24 We're dealing here with methodologies that are
(.
meant to cover really a broad swath. And I'm wondering,
() 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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198 1 in your observations about the progress of this, what 73 2 kinds of limitations are imposed upon this as a result of N J'-
3 this broad, generic approach?
4 MR. McKENNEY: Right. The FEP list itself is 5 generic, but what your process is supposed to be is to 6 result in a site-specific FEF list. You want to have a l
7 generic FEP list that is inclusive of everything.
8 I mean, it has -- if you look at it, it's not 9 only for inland sites, it's also got a whole range of 1
10 things for coastal sites that would be -- I mean, for if i
11 you're doing the Yucca Mountain one, that whole range of i 12 FEPs is just wiped out because you just -- you described, 13 since it's near a site those aren't appropriate.
/~
\
N 'j 14 But the one from personal opinion is that, at 15 times it can get a little too detailed, that you can be 16 spending time on this, on FEPs that probably would be 17 inconsequential, before we finally explain them and decide 18 not to use them. But that could be a case.
19 It is also quite an extensive and thorough 20 review where, for a lot of our decommissioning sites and 21 other sites, we may not need that level of thoroughness or 22 thnt level of certainty in what the -- on actually these 23 parameters and how things move through environment, 24 because of the levels of risk and other things that we've o) s 25 discussed.
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1 199 1 1
l 1 I mean, 10,000 different people doing this l
gS 2 would be, you know, 7,000 different sites would not be
(/ 4 3 worth the -- in cost of money, probably, than the risk !
i I
i
! 4 that most of these sights actually pose because they are - l l
l 5 - so for decommissioning its limitation is that it's very ,
1 6 work-intensive and it can be very expensive to go through.
I 7 And so it's more for -- you have more, and i
8 sites that need good justification -- you're trying to do 9 a conservative but realistic -- a cautious but reasonable 10 assessment of the risk at the site rather than a 11 conservative value. And so you wish to put forth effort
! 12 in describing the biosphere as succinctly, or the critical
,_ 13 group as succinctly as possible, to provide it as being i
14 reasonable rather than highly conservative.
15 MEMBER HINZE: If I may ask the question, if 16 this whole exercise is useful, why is the NRC not a person 17 that is supporting this?
18 MR. McKENNEY: We've been observers for the 19 past while and we've been providing data -- that's 20 actually right there. We one, haven't decided how much to 21 use of the actual reference specs, we haven't decided how 22 to -- we haven't made decision on the full extent of the 23 use of reference biosphere methodology as itself in NRC 24 activities.
A t \
(,) 25 But we have made a determination that we would
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200 1 like to use reference biospheres and critical groups -- of ;
e'N 2 the concepts, in decommissioning and low-level waste and
\ )
x_ _/
3 high-level waste. But we are an active observer, to put 4 it succinctly. We may not be the ones creating the 5 documents but we are actively looking over the drafts and 6 looking -- and in the discussions.
7 VICE CHAIRMAN GARRICK: Of course, in the 8 context of the BIOMASS program you have U.S. financial 9 support through IAEA, right?
10 MR. McKENNEY: Theme 1 unfortunately, is the 11 one area that is not supported in fully, is it --
12 MR. KESSLER: IAEA is a co-sponsor --
-- 13 MR. McKENNEY: John Kessler, i )
14 MR. KESSLER: -- is the primary --
15 MR. McKENNEY: Could you get to a mike?
16 MR. KESSLER: IAEA is the lead organization.
17 There are co-sponsors on the steering committee for Theme 18 1. But IAEA is definitely participating and co-funding.
19 VICE CHAIRMAN GARRICK: For the record, that 20 was John Kessler.
21 MEMBER HINZE: Let me ask the question. If 22 the NRC were a participant, could the results be made more l
23 valuable to the NRC?
24 MR. McKENNEY: I m not too certain on how much i
7x \
(,,! 25 there would be to any one particular site. There could be 1
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201 l 1 insights that we could develop. I mean, we're not a l
,3 2 complete observer in this. I put it as an observer since
! J .
<.: 1 3 we're not one of the prime writers of this. We do work l l
l 4 quite heavily with this. And we are also in other areas, 5 like ICRP, working in waste management to try to -- Tim?
6 MR. McCARTIN: Yes. We are observing and as 7 you know, I mean, BIOMOVS was going up for quite a while.
8 It's only recently that the specter of an individual dose 9 calculation -- some of these things have come to play. As 10 with everything, we need to weigh the priorities and 11 budget-wise, you know, right now we're observing as things 12 go on as we do work with our standard. Could we re-13 evaluate and look at things? Possibly, but right now r~S
- )
~
14 things are pretty tight, as you know.
15 VICE CHAIRMAN GARRICK: This whole dialogue 16 reminds me of the farmer Senator from California, Senator 17 " " kawa, when he was asked about what we should do about 18 the Panama Canal, he said -- his response was, well I 19 think we should keep it; we stole it fair and square.
20 MEMBER HINZE: Would you do that slowly so I 21 can copy?
22 (Laughter.)
23 MEMBER HORNBERGER: John?
24 VICE CHAIRMAN GARRICK: Yes, go ahead.
7-~.
( ,,/ 25 MEMBER HORNBERGER: Geosphere, biosphere, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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i
l 202 l
1 critical group. Are the definitions of these things, do
- 2 they make them independent? And if so, is the definition
( )
'O on the basis of a separation at physical space, or is an 3
4 operational definition? And what confused me is you 1
5 mentioned that the biosphere you were talking about I 6 included an aquifer. ]
7 MR. McKENNEY: Well, that's actually one of 8 the things -- is that the biosphere is not fully defined 9 now. The critical group is part of the biosphere, by 10 definition, but also it affects the biosphere that you 11 select, or the events and processes in the biosphere.
12 There was unfortunately, not a -- there is not 13 unfortunately a clear-cut line. Some people in the
/,,s
( i
' 14 complementary studies area put the water bearing aquifer 15 that the critical group used into the biosphere 16 calculation. And some other groups used that as --
17 considered that as part of the geosphere.
18 And so again, you're working with the l
19 individual definitions of, unfortunately, of that 20 interface, which is -- l 21 VICE CHAIRMAN GARRICK: We know it's a 22 problem. We searched through your documents looking for 23 those definitions. Paul, you had a question?
24 CHAIRMAN POMEROY: Yes, I just had a quick (o),
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1
203 1 I'd like to pursue just for a second the last statement on 2 your slide, Chris. Namely, we haven't yet applied 7-~3
('~' /
3 reference biosphere methodology to Yucca Mountain.
4 I guess my question is: could we if we wanted 5 to, Tim, if -- how would it help us over the kind of thing 6 we're doing now, and do you see the development of the, 7 under BIOMASS, the principles for selecting critical 8 groups and so forth, being useful when they come out 9 sometime after the end of this year? Presumably at the 10 termination for the final report. A lot of questions.
11 MR. McCARTIN: Yes, yes. Well, I mean, the 12 short answer is yes, and let me say something. Chris, you 13 can, you know, when I'm done, correct anything, any
/ 1 i /
'/ 14 misstatements.
15 But certainly within our deliberations on how 16 we're going to deal with the rule, we have already gone 17 down the path of looking at things to do with the 18 reference biosphere and the critical group. Clearly, 19 we're already doing that.
20 We are aware of the FEPs list. Part of our, 21 say -- we're not overly concerned with the FEP list that 22 has everything. We're not that worried right now in terms 23 of, are we complete for Yucca Mountain? We've been 24 looking at Yucca Mountain long enough; we feel we have a
/N And as Chris pointed
() 25 pretty good handle of what is there.
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204 1 out, well, they've got things for a coastal site, they p 2 have -- you know, it's universally applicable worldwide.
3 Well, we're pretty familiar with Yucca 4 Mountain and so some of those things that, are we -- in 5 terms of the completeness, have you considered everything, 6 I guess going through that FEP list very diligently, you !
i 7 could answer that question.
8 To date we have not gone through that. We 9 feel Yucca Mountain -- we're familiar enough that we think !
10 there aren't -- we know the big issues, and so that's one 11 reason we haven't done things, but we certainly are ,
1 12 looking at what they're doing.
l
, 13 We have a lot to do to justify, certainly the i
( )
14 selection of a critical group at Yucca Mountain, and we're l 15 certainly very interested in what's going on in that area 16 to see, is it supportive of what we're doing and maybe we 17 have to alter our approach, but we have to -- we have a 18 pretty tight time schedule and so we're moving forward 19 with what we -- with an approach for critical group 20 reference biosphere.
21 CHAIRMAN PCMEROY: Let me ask you just a quick 22 question on that. Do you think this is a worthwhile 23 expenditure of resources, to be involved? You wov.id have 24 to chink that, otherwise you wouldn't be doing it, but I'm
,m
! i
() 25 going to ask you to evaluate that.
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[
205 1 MR. McCARTIN: Well, certainly in terms of rg 2 being an observer it makes a lot of sense, and I know, boy i $
'v' 3 --
4 CHAIRMAN POMEROY: Over reading the final 5 reports when they come in?
6 MR. McCARTIN: Yes, yes. And I know we 7 probably -- that's what I'm trying to think. And maybe 8 John Kessler can remember the date, but the last two years 9 have been a blur for me, I think. And I think it was 10 about a year ago there was a BIOMASS meeting and we 11 presented some of our initial thinkings with respect to 12 critical group, reference biosphere to them.
13 Chris and I attended that and I think hearing i7~;
\ '/ the feedback and getting some information there is very 14 15 useful. This is pretty much uncharted waters for us to I
16 try to define these things, and hearing other countries 17 that have been trying to deal with it for longer -- gee, 18 does this make sense, do you think this is detendable --
19 that is useful.
20 So I believe it's been a good experience, 21 because other countries have been dealing with the dose 22 based standard for quite a bit more.
l 23 CHAIRMAN POMEROY: Thank you.
24 VICE CHAIRMAN GARRICK: Any other questions?
,e]
(_.) 25 Okay, Chris, thank you very much.
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206 1 MR. McKENNEY: Thank you.
,, 2 VICE CHAIRMAN GARRICK: I guess now we're
( )
w/
3 going to hear from John Kessler from EPRI.
4 MR. KESSLER: Thank you very much for inviting 5 me, and thanks Chris, for helping me make my presentation 6 shorter. I noticed that we have some of the exact same 7 viewgraphs, so that will make my life a lot easier.
8 Yes, I'm here today to talk about what we've 9 done with EPRI funding on biosphere modeling and dose 10 assessment for Yucca Mountain, and at the end I also 11 wanted to talk about BIOMASS and spend some time talking 12 about what I think will be happening in the critical i
13 groups task group within BIOMASS. l
\# 14 I think this one is pretty self-evident.
15 Yucca Mountain regulations are likely to require dose 16 assessments. Obviously we don't know yet but we're 17 operating under that assumption. Certainly the NAS 18 committee recommended an individual health risk criterion 19 that can convert to dose criterion as acceptable to the 20 NAS. Proposed legislations got it, therefore biosphere 21 modeling is going to be required.
22 We recognized that along with everybody else 23 quite a few years ago, and that's when I got involved 24 directly in BIOMOVS at that time, when it was just -- the
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207 1 standard and we bloody well better know what we're doing 73 2 with biosphere when that day arrives.
i i L.s
3 Obviously there's a lot of things you do when 4 you do mcdel development. I should say a few oft 5 forgotten biosphere model criteria among others.
6 It's got to be appropriate for the particular 7 assessment. I'll probably emphasize this more than Chris G did; this whole idea of assessment context. That is one 9 of the main things that will be occupied in BIOMASS; that 10 is, what is your endpoint?
11 Okay, well we all like to chink about 12 individual dose criterion, but timeframe is part of an I 13 assessment context, the level of conservatism or best l' i
\ '#
14 estimate which we use the terms " cautious" and equitable l l
15 in the final BIOMOVS report.
16 All of those get wound up into assessment 17 context, and if you don't develop a model and a whole
- 18 l aporoach that's appropriate for that assessment, you may 19 be not operating under an optimal situation there.
j 20 Obviously, the criteria have to be l
l 23 transparent, you have to understand what things are in --
i l 22 or, the model must be transparent; you've got to 23 understand what's in it, why they're there, and how they 24 got there.
(_,/ 25 It also has to be sufficiently comple" : hat NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1023 RHODE ISt.AND AVE N W.
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208 1 is, all the necessary pieces are included. And an s
s 2 internationally accepted approach in developing it would Ir \
'~ ')
3 be helpful.
4 VICE CHAIRMAN GARRICK: By the way, I should 1
5 have mentioned that John is Chair of the critical group's l
6 task group of the BIOMASS projects. '
i 7 MR. KESSLER: Thank you, John. In the just-l 8 completed report that I believe the committee has -- and 9 if any of the rest of you would like it that don't, please 10 give me your card and I'd be happy to give you a copy --
11 we did try to develop an example approach of developing a I
12 biosphere model using the BICMOVS II, which I'll talk j 13 about.
/ \
- 14 Although I wrote part of the report, 15 QuantiSci, Ltd. was certainly the heavy lifter in terms of 16 putting that report together for me.
17 Well, as Chris has already greased the skids, 18 EPRI -- we didn't have to re-invent the wheel. BIOMOVS II 19 reference biosphere's working group -- which I'll probably 20 skip into RBWG lingo -- developed this generic approach 21 that Chris has already walked you through. So it was 22 based on international input and consensus and provides 23 general guidance and tools.
24 But we wanted to see if we could implement
() 25 that general guidance and apply it to Yucca Mountain. So NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS i
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1
209 1 the reference biosphere working group provided this (3 2 reference approach that is not a reference biosphere.
v 3 Chris has already explained that to you; that they 4 provided that referenced approach.
5 What I have to say and what, I believe most of i
6 what Chris referred to is in this final BIOMOVS II I I
7 Technical Report. I have one copy here but again, you can 8 get copies of that from Quantisci, Ltd., and I'm sure l
l 9 Chris has got copies that he could provide for you, too. ;
1 10 Yes, here it is again. I'll try to emphasize 11 a few additional things. Thanks Chris, for saving me some 12 time. We start with these three things: international )
1 13 FEP list is what's provided, either by BIOMOVS II -- j
(,,) i 14 there's lots of other FEP lists out there. Assessment l 15 context is center.
16 We have to have a model, even a conceptual 17 model that takes into account the details of what the j 18 assessment context is. W a+'s your time period, what 19 level of conservatism are ysu interested in, what's your 20 risk basis? Whatever you like. That all gets wrapped up I
t l 21 into assessment context. We really have to define what 1
22 that means.
23 We all tend to run around in our heads 24 assuming a certain -- what we call an assessment context.
(
'V 25 That critical groups is the right way to go, because that NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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210 1 implies a certain -- you're trying to go for those extrema 2 in distributions of potential doses. That's all part of
~')
'%.,/
3 an assessment context we run around with in our head.
4 We'd better well write that down so we can be consistent.
5 A basic system description is really, what are 6 the details of your own particular site? In this case, 7 Yucca Mountain. We're going to meld all these together in 8 a qualitative -- in a way to come up with these conceptual 9 models that Chris talked about.
10 And you use these international FEP lists, il like Chris has already talked about, to exclude FEPs that 12 you can document. And then you go on through and develop
,_ 13 your mathematical description, your assessment tool.
('~ )
14 I am going to emphasize the FEP-making process 15 because I think it is important. Even if we may think we 16 know what all the FEPs are -- we may very well know --
17 we're still going to have to show that to other people.
I 18 So they've got to be identified systematically.
19 It's important to understand the FEP 20 relationships. It is going to be important for the 21 regulator to see what is included and what is excluded.
22 If it's done intelligently you can use this 23 FEP list to obviously: list the FEPs; show the linkages 24 between the related FEPs in some sort of clear way;
,a
\
t
't,/ 25 document your choices of FEPs that have been included and NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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211 1 excluded -- which I think is just as important; and
,s 2 document the models and the parameter values shown.
!%.)) 3 If you can do all that in one FEP list I think 4 that goes a long way to providing clarity as to what 5 you're eventually going to put in your model and why you .
l l
6 put it there and how you put it there.
7 What's our interest in FEP lists? There's a 8 lot of different ways out there of representing FEPs and 9 their relationships. We wanted to look for an approach 10 that can make Yucca Mountain-specific FEPs; that was 11 reasonably simple to understand, as any FEP list-making ;
12 process can possibly be; and documents the decisions made 13 that generate the FEP list, t j k' 14 We chose a method that finally was an end- l 15 product of BIOMOVS II and their FEP-making process. It ;
1 16 started way back in BIOMOVS Phase I that Chris mentioned.
17 It really started with sort of an ad-hoc FEP-making I
18 process. They just sat around the table and said gee, 19 what FEPs can we think of? You know, what processes are 20 there; what features are there?
21 Then they started organizing them by category.
22 They had a few linkages identified and that's as far as 23 BIOMOVS I went. Then the international FEP list was born.
24 They had provided a detailed example similar to conditions g)
(, 25 in Switzerland, as Chris already talked to you about.
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212 1 More recently they adopted this RES c3 2 interaction matrix approach, which I think is really slick i'!
3 -- or as slick as any FEP-niaking process can be. I'll try i
4 to explain again a little bit quickly. I I
5 Here's that FEP interaction matrix. Here's i
6 the leading diagonal element. These are really the 7 features that Chris talked about. But what we want to do l 8 is capture somehow visually, so that we can understand 1
9 what are all the processes and how are they linked? l l
10 So I'm going to put a process in here that is, l
11 how does A affect B7 Down here I'm going to put a new l 12 process that, how does B affect A? And that way I can at !
l 13 least at the first level of making FEPs, get them down in l
/"'N t I l
k/ 14 some sort of conceptual way and put them there for 15 everybody to see.
16 Okay, Chris put one up there. I'm going to 17 show you the big, beautiful, international FEP list that 18 was provided in the final BIOMOVS reference biosphere's l
l 19 working group report. There it is. I will quickly go l 20 through in a minute, these main features that Chris talked l
l 21 about.
22 But the idea is, yes, it looks pretty -- it 23 looks like there's a lot there, and yes there is. And Tim 24 is absolutely right, as is Chris, that a lot of them are
( ,/ 25 not applicable to Yucca Mountain, but you start from NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE IS!.AND AVE., N.W.
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1 1
213 l i
1 somewhere. It's always nice to have an international list
.r ~\ 2 that you can say, yes, at least we thought about as many )
('~' )
3 things as people in the world have thought about.
4 And yes, most of you can very quickly 5 eliminate -- there's where I disagree with Chris; I don't i 6 think it takes much resources to eliminate a whole bunch I 1
7 of these. I 8 But the idea is, is that -- well, let's pick i
l 9 one here. The effect of sediments on dose to the critical l l
10 group. Well, that's external and direct contamination.
11 The effect of human activities on surface soil. Well :
1 12 obviously, there's agriculture, pollution, forestry, i
13 construction, irrigation, and so on. Underneath all of l
('w-) 14 these FEPs you can have a detailed --
15 MEMBER HINZE: Is mining included there? In !
16 the human activities?
17 MR. KESSLER: Mining is in there somewhere.
l 18 I've got dredging and removal -- remember, mining is --
19 do you consider mining to be part of the biosphere or part 20 of the geosphere? And again, it probably depends on the 21 kind of mining activity it is. I think they've used the I
22 word " excavation" in there in terms of mining to just get 23 the idea that it's part of the biosphere.
24 Okay, the RES matrix approach. Here's those
/^N q,) 25 leading diagonal elements. I'll walk through them a NEAL R. GROSS COURT REPORTERS AND TRANSCR;BERS 1323 RHODE ISLAND AVE., N W.
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214 1 little bit in more detail in a minute. Source term here j 2 for Yucca Mountain -- that's assumed to come from the I fx
! \
'< ._)
3 geosphere and is located at the geosphere/ biosphere i 4 interface. Yes, there is a lot of discussion about how to i 1
1 5 properly define that.
6 I think we have an easier job at Yucca 7 Mountain defining the geosphere/ biosphere interface than a 8 lot of these other sites do that are much more humid.
1 9 Aquifer is next. Surface water, sediments, variably ]
1 10 saturated zone -- which includes the deep soil -- surface l l
11 soil, atmosphere, flora, fauna, human activities, and 12 finally, dose to the critical group. l
[
13 As I mentioned, those off diagonal elements or 7_
l \
'# 14 the interactions between leading diagonal elements. Most 15 of the FEP processes -- all the fun, really -- is in all 16 thoee off diagonal elements.
17 Okay, so what do those leading diagonal 18 elements mean for Yucca Mountain? In terms of source term 19 we've got the flux of radionuclides from the geosphere l 90 into the biosphere; it's assumed abstracted from a well.
l l
l 21 The aquifer is next, or the permanent i
22 saturated zone. It's the unconfined aquifer immediately 23 beneath the unsaturated zone. For the biosphere model 24 it's not considered a big player because we're already
.r s
(_) 25 taking our source term for the aquifer.
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1 215 l l
1 The interaction back between the biosphere and l
l fN 2 the aquifer is not considered important except as a source l i I l s/ \
3 term. And this is just the function of trying to fit an j 4 international approach to Yucca Mountain specifics.
5 We could revise the leading diagonal elements; 6 we chose not to for clarity in our report. But there's 7 nothing sacred about those leading diagonal elements if ,
l 8 there's another set that's more appropriate for Yucca j 9 Mountain. ,
l 10 Surface water is next: rivers, streams, l
11 canals, ditches, lakes, reservoirs, and lagoons. May be 12 relevant for Yucca Mountain if surface ponds and ditches
,_ 13 are assumed, and we want to include those in our model.
i s
\
obviously, we know that there's a few areas of surface 14 15 water now; maybe during a pluvial there will be more. We 16 left them in.
17 Sediment, bed sediments, perhaps only 18 marginally applicable at Yucca Mountain. Obviously, 19 bigger problems for other sites worldwide.
20 Variably saturated zone is the deep soil 21 generally below the root zone, all the way down to the 22 saturated zone. Surface soil includes the root zone soil 23 where all of the real biologic activity occurs, and 24 includes solid soil, soil water, and gases.
n
(_) 25 Flora: all plants, fungi, crops, crop NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE , N W.
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216 1 products; including not just what you eat, but for 2 clothing, wood for furniture, housing materials. Hey, 4
73 <
%_.)
3 it's a complete list.
4 Fauna: all animals -- water and land.
5 Human activities: all relevant activities in 6 the vicinity of the release, including modifications to 7 the environment. That includes: agricultural practices, 8 building practices -- there you go, Bill -- excavation, 9 use of soils for building, etc., hunting, fishing, water 10 usage, more. It's all in human activities.
11 And finally, the dose to the critical group is 12 the radiation exposure pathways for the critical group, 13 linked by all these off diagonal elements, and it's p_
( )
\/ 14 partially defined by the assessment context. You're going 15 to have a different critical group depending on the 16 assessment context you're running with. You may not even 17 call it a critical group for some assessment contexts.
18 okay, after we went through all that, 19 QuantiSci tried to generate the FEP list a couple of 20 different independent ways to make sure that we were being 21 inclusive. What we found was that the RES matrix worked 22 quite well for us. In the report itself they've l
l 23 documented reasons why they excluded whole rafts of the 24 international FEPs, and pared it down to this much smaller n)
(, 25 list.
l l
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217 1 But the idea was, is that we wanted to 2 demonstrate that we could document rationale. It's 73
! ?
v certainly not complete but we wanted to show the process 3
4 of using it to apply to Yucca Mountain.
5 VICE CHAIRMAN GARRICK: And what did they use 6 as their basic source material to prune this down? Was 7 this the DOE's FEPs list?
8 MR. KESSLER: This was the BIOMOVS II 9 reference biosphere's working group's FEP list that was i 1
10 documented -- described in their final report.
11 VICE CHAIRMAN GARRICK: Yes, but I'm talking 1
12 about getting it down to the Yucca Mountain-specific FEPs 13 list. What was your standard, or what was your -- ,
l
(~ N, 14 MR. KESSLER: DOE information, NRC reports, j 15 site visits, documentation from the State that we used.
16 In terms of the documentation, any use of this for a 17 licensing basis would have to be better documented than 18 what we had in our report. That's a given.
19 Again, I want to emphasize, we wanted to 20 demonstrate that this is a workable approach. It's 21 certainly far from a complete approach but we're confident 22 that it seems workable. But that's the kind of 23 information used for this particular demonstration that we 24 have in the EPRI report.
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218 1 though, John -- on the basis of your judgment or
,3
, 2 QuantiSci's judgment, excluded certain factors, is that t i
\_J 3 correct?
4 MR. KESSLER: We applied -- a good chunk of 5 them were subjective criteria. But they're pretty much 6 no-brainers, for lack of a better word. This idea, you i
I 7 know, do you have -- there are things that have to do with 1
8 estuaries or permanent rivers, and you know, you can just !
9 knock them out of hand.
10 We had difficulty with some of the sediments 1 11 because Quantisci was concerned, well, what if you have ,
l 12 irrigation canals and you may have sediments there? For 13 some radionuclides there's a lot -- they will build up in
/, x
! \
\2 14 these sediments and give you a direct exposure, an ,
15 external exposure that can be significant, that they were ;
1 16 aware of.
17 They didn't want to just automatically throw 18 them out until they had more information. When in doubt, 19 we left them in.
20 Okay. So we took the FEP list, we generated a 21 model -- QuantiSci generated a model from it based on the 22 Yucca Mountain-specific RES matrix. We also, when we went 23 into the model phase to generate real numbers we had come 24 up with data.
f (3,) 25 I asked QuantiSci to do a selected data NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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219 ;
1 survey. They did these particular radionuclides because fx 2 we were finding them in our TSPA report to be the dominant t \
(_) 3 radionuclides. And in the report -- which I also think is 4 rather nice -- they have completed this data survey and l 5 selected what they considered best estimate values where 6 they -- best estimate values exist.
7 And again, Chris is absolutely right; there is 8 difficulty when you're trying to select data worldwide.
9 Applying it to Yucca Mountain-specific situations the l
)
I 10 uncertainty ranges can be pretty high, and you'll see l
I 11 those documented in the report.
12 This is an attempt to describe the linkages
,_, 13 that are actually in the model that we used in terms of i I
\
\
14 the RES matrix. The heavy lines represent actual doses or i 15 exposures to the critical group. These thinner lines 16 represent radionualide migration pathways within the 17 biosphere that were directly modeled in the model that was 18 developed from this.
i 19 I throw this out just for fun, but this was l
l 20 the critical group consumption rates that we used. There l
21 they are; you can choose to like them or not, but that's l
l 22 what we came up with.
23 I'd say it's sort of an attempt to pull on 24 board, in the section of our report where we sort of do a
,-~
( ,)
25 survey of what other people have done worldwide, sort of NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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220 1 modified for what we think U.S. consumption patterns are
,/) 2 and put it there.
L.)
3 Obviously, this would require a lot more work 4 to come up with a defensible list, but that's what we put 5 in there.
6 MEMBER HORNBERGER: Is it per capita?
7 MR. KESSLER: Yes.
8 MEMBER HORNBERGER: Five kilograms of liver 9 per year?
10 VICE CHAIRMAN GARRICK: Not you.
11 MR. KESSLER: I made them take the mutton out, 12 okay? Mutton was in there originally, along with offal, 13 which we don't do a lot of. Okay, so the point is, is 73 I )
'~
14 that the model was generated and we came up with a few of 15 these dose conversion factors. I just put them in there 16 for you to take a look at. I will show them in graphical i 17 form here a little bit better in a minute.
18 In addition, we came up with the top three 19 exposure pathways contributing to peak dose for a whole 1
20 raft of nuclides. I put them in your paper here, not i 21 intending to go through them all. But let's just show you 22 technetium-99 and iodine-129. .
1 1
23 Well, look at what the drinking water portion 24 is. Five percent for technetium, 13 percent for iodine.
(D
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l 221 1 for those particular radionuclides. And there's other 73 2 examples in the tables here.
t I
\_./
3 I might stop on neptunium-237 when I get to it 4 -- there we 90. Cow milk wins for neptunium-237, followed 5 by fruit. Drinking water comes in at ten percent of the 6 total dose.
7 MEMBER HORNBERGER: And calves get all of 8 their water out of the well, right?
9 MR. KESSLER: Yes. This is definitely 10 subsistence farming community -- thank you, George, I 11 should have pointed that out. Definitely subsistence 12 farming community. This is sort of the upper end of a 13 critical group. We are assuming all water for all q_
14 activities is derived from that well; that there is no 15 external water. We are not diluting it in any way, shape, 16 or form. This is full strength.
17 Okay, I will show two figures from our recent 18 TSPA analysis that show the difference between including 19 drinking water pathway only in all of these agricultural, 20 critical group type pathways. This is individual dose at 21 five kilometers; drinking water pathway only.
22 And you'll see that again, we have iodine and l 23 technetium dominating here; we've got neptunium here; 24 we've got a few daughters of neptunium and uranium that 7
(_) 25 come out also, but way down here at much lower rates.
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222 1 Now, if I overlay that, the contribution from
<~ 2 all pathways including all the agricultural consumption i~~/
3 pathways, the situation has changed. Again -- and this is 4 something I like to emphasize that I heard come up 5 yesterday in your discussion of your draft letter.
6 This is at five kilometers. We are assuming a 7 full-bore, agricultural subsistence agricultural 8 community, five kilometers downstream. That, in my 9 opinion and from what I've heard Tim imply, is -- I think 10 it's unrealistic and there may be some suggestions that 11 the staff also thinks that's unrealistic. But I want you 12 to be aware of that when you look at these curves, okay.
13 So we're roughly increasing the individual
(
N -/ 14 deses here by an order of magnitude for most nuclides. l 1
15 You'll notice now that neptunium, out here on the long 16 timeframe, is down here. Daughters of neptunium and l 17 uranium actually come out higher because we've introduced 18 these non-drinking water pathways in there. Selenium-79 19 which was never a player in the drinking water pathway 20 only, suddenly shows up.
l 21 I would add that if I were to move what I i
22 thought what would be the proper location for a 23 subsistence agricultural community downstream to where I 24 think it makes sense, in our TSPA report which I believe
/N.
(,) 25 you have copies of, we show roughly an order of magnitude NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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223 1 decrease due to dilution as you move downstream.
fs 2 VICE CHAIRMAN GARRICK: Which one of those is
- \
'\. s ' . .
3 protactinium?
4 MR. KESSLER: Protactinium is --
5 VICE CHAIRMAN GARRICK: That solid line?
6 Solid, thin line?
7 MR. KESSLER: You'll fine it here. Yes, 8 solid, thin line is protactinium.
9 VICE CHAIRMAN GARRICK: Yes, right.
10 MR. KESSLER: And where the -- right here, in 11 the drinking water only. So it goes from here for 12 drinking water only, up to here for the other pathways.
13 So it's not really a fair comparison in the sense that i
\/ ) 14 I've forced an agricultural scenario only five kilometers 15 downstream. But it's the best way to overlay and show you 16 what you get when you add these other exposure pathways.
17 Yes, we do include sections on critical groups 18 --
19 MEMBER HINZE: John, did you do this at other 20 than five kilometers? How sensitive is this to five 21 kilometers? How robust is this?
22 MR. KESSLER: Which answer would you like?
23 MEMBER HINZE: The right one.
24 MR. KESSLER: We looked at earlier studies of,
(~'s
(. ,) 25 right up to the edge of the repository footprint. It was NEAL R. GROSS I COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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224 1 roughly an order of magnitude change there. We did
,,S 2 independent calculations, not within our total system
( )
N _/'
3 performance assessment, out to 15 to 25 kilometers.
4 And what we estimated -- and this was Frank 5 Schwartz doing some calculations for us -- that the 6 dilution between five kilometers and 15 to 25 kilometers, 7 is roughly an order of magnitude factor of 6 to 30, 8 something like that, depending on the assumptions he made 9 for dispersivity, etc.
10 So we're talking about roughly an order of 11 magnitude reduction in peak concentrations between five 12 kilometers and downstream where we think that it would 13 make more sense to have an agricultural community. And
\
' '} 14 this is something that I think that you should be aware 1
15 of. Obviously, these are estimates and data could change, 16 but I notice that there seemed to be a lot of emphasis 17 about position. j 18 And we're not talking orders of magnitude --
1 I
19 at least not in our current estimates -- and I believe not i
20 in DOE's current estimates. We're talking about an order l I
21 of magnitude. So --
22 MEMBER HINZE: Did you make any contour maps ,
i 23 of total dose?
24 MR. KESSLER: No, we did not. We did not.
,m
/ i
(,,/ 25 One of problems is, is that the way we have our TSPA model NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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I 225 l l
1 set up, our saturated zone is represented by the Bullfrog l 1
r- 2 welded unit, and you quickly run out of that unit as you Y)3 run downstream and get into the alluvium, and we can't 3
4 push our model that far; it doesn't make sense. So we did l 5 these offline calculations just to get a handle on 6 dilution. !
7 VICE CHAIRMAN GARRICK: John, on this location 8 question -- just to make the point a little more -- you're 9 suggesting that the location-dependency is not maybe very 10 great --
11 MR. KESSLER: Well, I perceived in your 12 discussion that you were thinking it was huge.
13 VICE CHAIRMAN GARRICK: Well, what I'm getting
(__)
14 at --
15 MR. KESSLER: That's obviously for you to say. l 16 VICE CHAIRMAN GARRICK: Well, what I'm getting 17 at is another reason why it may not be very huge. Because l
18 if you took into account the uncertainties in your l
19 analysis, your uncertainties are probably of the order of 20 an order of magnitude in these results. At least.
I 21 MR. KESSLER: At least. They're higher than 22 that. In fact, I think I presented those results to you 23 at your timeframe hearing. l 24 VICE CHAIRMAN GARRICK: Okay. So if in fact, C'i Q' 25 the location was of an order of magnitude then, it's NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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I 226 1 almost a wash in terms of what we -- in terms of the
,, -~x 2 uncertainties and the results in the first place.
i 1
'% )
3 CHAIRMAN POMEROY: Yes, and just to say 4 though, you need to see some real sensitive calculations - l l
5 -
l l
6 VICE CHAIRMAN GARRICK: That's right.
7 VICE CHAIRMAN GARRICK: -- to know exactly 1
i 8 what you're dealing with. j l
9 MR. KESSLER: Absolutely. I mean, my l
l 10 statements are only as good as what goes into the models; 11 that's very true.
12 VICE CHAIRMAN GARRICK: Yes.
13 CHAIRMAN POMEROY: John, you're not showing j i,_ ')
\/ 14 any dose for these particular radionuclides at less than 15 10,000 years?
16 MR. KESSLER: Correct. Well, I'm showing them 17 below the scale --
18 CHAIRMAN POMEROY: Below the scale.
19 MR. KESSLER: Right. We do -- they're not --
20 I could give you another whole talk obviously, on TSPA 31 approaches --
22 CHAIRMAN POMEROY: Okay, don't --
23 MR. KESSLER: They're not zero, because we 24 allow some early releases from a few containers in our r^T
( ,) 25 model. But they're below that scale.
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i 227 '
1 CHAIRMAN POMEROY: But in general, when do the l
,s 2 releases occur, other than the few?
3 MR. KESSLER: The bulk of our containers start 4 failing between about 20,000 and 50,000 years. That's 5 when the majority of our containers start failing, in that 6 range, in our TSPA model.
l 7 CHAIRMAN POMEROY: Thank you.
8 MR. KESSLER: Okay, critical groups. Begin 9 with the assessment philosophy. This was discussed in the l 10 report. Again, it was echoed in the reference biosphere's I
11 working group report. That there's a big difference l l
12 between assessment philosophies. All of them are 1
1 13 justified on various ways you want to look at risk and
(~'T l
\~/ 14 safety for Yucca Mountain.
15 Arguments were made that both approaches are 16 valid. You just have to choose one and elucidate one as 17 you being to develop regulations and assessments. But 18 it's very important that you elucidate this. What is your 19 assessment philosophy? And then be consistent about it.
20 That's one of the messages that I'd like to leave.
21 If you're going to go with a cautious 22 philosophy we tried to define what that meant in terms of 23 critical groups. And certainly it goes way beyond 24 critical groups, too. Same with equitable. We tried to
(')
( ,) 25 define a basis for those two philosophies, both based on NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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228 1 risk or perceived risk, and what we thought that meant in 7y 2 terms of application to critical groups. .
! l
%_J i
3 Also in the report there's this international 4 survey of guidance and regulations and implementations of 5 critical groups. And in the appendix we've provided an 6 example of the equitable assessment philosophy approach 7 which you heard about from me last June, j 1
8 In a nutshell, I think this was one of the l l
9 curves that was referred to yesterday during your l 10 discussions. A cautious philosophy -- well, let me 1
11 describe the figure. Again, this is a hypothetical l 1
12 figure; not based on data but based on subjective feeling 13 as to what we think the dose distribution is in a j f m.
k'
)
14 population size.
15 We've ordered the dose distribution here where 16 this is individual dose rate averaged over the population l
17 size that you're considering. Where we've successively, 18 as you march out here, each individual you add to this has 19 a lower dose than the one before.
20 So obviously out here when your population 21 size is one, you're talking about the maximally-exposed 22 individual. You may be talking about a critical group in 23 here where if you wanted to include the maximally-exposed 24 individual between here and here, maybe that factor of ten m
,, ) 25 criterion that seems to run around ICRP and was picked up NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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229 1 in the NAS statement as well, f
-w s
2 Equitable philosophy considers more of what's
( )
~.s 3 happening with the average. Both of them are defensible 4 in terms of risk tolerability by societies, but you may 5 want -- if you're going to go with the cautious 6 philosophy, we might want to pick one definition and even 7 one dose limit for that.
8 If you're going to go with an equitable 9 philosophy you may pick a different population size and 10 maybe even a different dose limit for that. There's 11 precedent for that. The Swiss have a dose limit that 12 they, at least say on paper, is flexible depending on the
,_ 13 size of the population that you consider.
! i
'- 14 Given that we're running out of time I'll try j i
15 to go through this quickly. But in this particular table l
16 in the EPRI report we tried to define what we thought a l 17 cautious approach versus an equitable approach meant in 18 setting definitions of critical groups. And how that goes 19 through in terms of establishing criteria in the 20 regulatory side and complying with those criteria on the 21 applicant's side.
22 Okay, I am going to switch gears now and l 23 elaborate a bit more on Chris' discussion of what's 24 happening in BIOMASS, the Theme 1. It's the followup to
[^)\
(_ 25 BIOMOVS II. The purpose is to develop practical NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W
(
l (202) 234-4433 WASHINGTON. D C. 20005-3701 (202) 234-4433
230 l
I 1 approaches to biosphere model development, critical and i
(~x! 2 other indicator groups, use of data in biosphere models.
i w/
3 It's specifically for low-level waste /high-level waste 4 disposal safety assessments. j 5 They talk about solid waste disposal but the ;
i i
6 people involved are all in one of these two camps. And ;
1 7 IAEA is a co-sponsor. i I
8 As Chris mentioned, there are these six task i
9 groups. Critical and other indicator groups is task group i
10 1. Use of data. Assessment contexts happens to be task l 11 group 3. We've all pretty much agreed internally it 12 really should have been task group 1. It really drives 1
7, 13 the show. I
( i
' 14 Everything depends on the assessment context.
15 They have the shortest leash in terms of timeframe; I 16 think Chris showed that on his viewgraph. They've got to 17 be done real soon because they're feeding the rest of us. ;
18 They have to define what are these assessment contexts so 19 that we can go on and do our work in these other task 20 groups.
l 21 And yes, as John Garrick pointed out, I'm 1
22 Chairman of the critical and other indicator groups task 23 group. Biosphere evolution, system descriptions, and 24 model development are all coming down the pike. But the tg
() 25 emphasis is on practical interpretation --
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231 1 MEMBER HINZE: What does evolution mean there?
-~1 2 MR. KESSLER: I'll try to elaborate on what l
\s_-) 3 Chris said. This is looking at really, pluvials, for l
l l
4 example. How does --
5 MEMBER HINZE: Transitions? Is this the l 6 transition --
4 7 MR. KESSLER: Yes, there's discussion as to i l
8 exactly what it's going to cover. Do we just look at 9 alternative fixed biosphere states like, current 1
i 10 conditions pick a pluvial? Are we going to look at the l 11 actual transients between states or not? That is l i
12 undecided at this point as to exactly what they'll get !
l p_
13 into in that particular task group. l I
, g
~' 14 System descriptions are how do you really ]
15 develop those conceptual models? What is it that you need I
16 to describe about the biosphere before you can go on and 17 develop your models?
38 Okay. Critical groups task group plans. I I 19 really intend for us to convert assessment contexts into 20 practical guidance. I want to provide wherever we can, an 21 -- with where we can develop international consensus, I 22 quantitative guidance to critical and other group 23 definitions.
24 We're not going to provide a critical group
,a
(_) 25 and say they eat five kilograms of liver a year. No, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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232 1 we're going to provide: what are the rationales, what are f ~s 2 the bases, how do you conduct surveys, what ara you going
/ \
~
3 to take out of those surveys to do that?
4 An example of potential guidance detail --
5 here's where I need to be careful of getting in the way of 6 IAEA. Nothing's decided yet. These are just to give you 7 an idea of what kinds of things to stay tuned for.
8 I hope that we will come out and say, when do 9 you do local or regional surveys of habits? What do you 10 have to consider? You know, what habits are important in 11 biosphere modeling? For example, if we're going to think 12 about a critical group we may say, choose the 95th 13 percentile of consumption rate for the critical group.
(p_ )
'/
14 Be that specific in our definition, so that at 15 least people have something to hang their hats on when NRC 16 or DOE has to go and define a critical group there's at i
17 least this international guidance out there on how to do a l 18 survey, what to take from it. Although, obviously the l l
19 details of the critical group will be site-specific.
]
20 Other quantitative specifications of cautious 21 but reasonable, because that's the general guidance we l 22 have now. I think a critical group that's cautious but '
23 reasonable -- I don't think that cuts it. We need to be 24 able to say, it's cautious but reasonable. The 95th p
(_,) 25 perceutile of certain consumption behavior from regional l
4 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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233 1 site -- or a local site survey.
,s 2 VICE CHAIRMAN GARRICK: But there would be
! \
%.)
3 nothing to prevent you from using the whole curve?
4 MR. KESSLER: Obviously, I'm speculating on 5 what we will say. There's nothing to prevent you -- in 6 fact, maybe we'll say, use the whole curve. But the point 7 is, is that if you want to come out with specific lists i
8 that you can put in a table of base case values, you know, 9 maybe we will recommend this; I don't know.
1 10 But we're all going to discuss that. l 11 Certainly that's what the Oxford meeting is all for. Air l i
12 these issues. How do we want to approach these things; I 13 what are our topics?
/ \
t )
k' 14 And here's my list of probable critical group l 15 task group topics, based on a survey of which Chris did 16 respond as to what he thought NRC's interests were, and 17 I'm very grateful for that input.
18 For instance, for critical groups which I 19 associate with the cautious assessment philosophy, when 20 are they appropriate to use? In what assessment context 21 is it right to use critical groups? There are other 22 assessment contexts where critical groups are not 23 appropriate.
24 What information is required prior to rN
( ,) 25 specification? Detailed specification recommendations NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE , N W.
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234 1 includes how to maintain the appropriate degree of
,f s 2 conservatism as you go through and specify that. Again as
! /
v 3 Chris mentioned, we like to have at least one illustrative 4 example of actually carrying through this process.
5 Subsistence farming community we'll certainly 6 address. When should it be used; what are suggested 7 databases for it? Historical since it's not present-day 8 behavior. How do we deal with that issue? If there are 9 statements saying, use the subsistence farming community 10 but base it on present-day behavior, what on earth do we 11 do with that? What's a practical approach to dealing with 12 that?
13 Alternative indicator groups. There's a lot I,_sI
\# 14 of interest in not just looking at a critica. group. For 15 instance, it was mentioned, you may need -- well, let's 16 see, Brian O'Meara from AECL talked about in Canada they 17 needed to look at a lot of different native groups, their 18 particular habits as part of their assessment that they 19 did for their public hearing process. i 20 That was very important for public acceptance l
21 and it was included. Can we, on an international basis, 1
l 22 provide some rules as to how to use those? Which are j 23 appropriate; how to obtain data for those?
24 Implications for other task groups will
('~'\
( ,) And implications for l
i 25 certainly be covered in the reports.
NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE,, N W.
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235 1 compliance assessments as well are things that we hope to 73 2 address in the critical groups task group within BIOMASS j l_.] 1 3 Theme 1. j l
1 4 Okay, to conclude regarding the EPRI report, i 5 at least I think it demonstrated that it's possible to put !
6 in ernational guidance into practical use. It's a good i 1
7 way to list and document biosphere FEPs in an l I
8 understandable and traceable manner. And it also is I l
9 possible to have more than one valid approach to the use l l
10 of critical groupe. And it also provides a useful survey l 11 of data relevant to Yucca Mountain biosphere model.
12 For BIOMASS, BIOMASS Theme 1 will extend l
,_ 13 BIOMOVS II's successes. We're going to develop practical i.
)
14 approaches. There was general guidance that came out of 15 BIOMOVS II; that's great, but let's make it practical now. !
1 16 Concrete, internationally applicable guidance 17 and information. And to add on to the end of that one, I 18 certainly strongly recommend that NRC and DOE should 19 actively participate.,
20 Now, to get to the questions that you were l l
21 asking both Tim and Chris at the end. To me, 22 participation is, do they come to the meetings, do they i 23 provide input to ideas as to what the reports are, do they i
24 review the material they contribute from their to\ 25 perspective? NRC will be doing that, even as an observer C/
NEAL R. GROSS COURT REPOR1ERS AND TRA'4 SCRIBERS 1323 RHODE ISLAND AVE., N W.
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I 236 1 status.
gm3 2 They, like everybody else, are waiting to see
\'~ 'I 3 what we produce, and in that sense, I don't care whether 1 4 they call themselves observers or actual participants; 5 they are providing very useful input that can be used to l 1
6 try to develop international standards. Whether i 7 individual applications are made of it at the end --
8 obviously I hope that they are -- but that remains for 9 every group worldwide to decide whether they want to use 10 them or not.
11 I did throw one little extra viewgraph at the 12 end, just because of the discussions I heard yesterday 13 during your meeting, where again, you were talking about
( ) ,
x' 14 biospheres and changes in biospheres during a pluvial. '
15 And this is just pulled out of one figure out of a -- I 16 think this was a NYREX assessment of how they thought l 17 consumption might change from temperate -- which is what 1
18 they have now -- to more of a tundra or boreal climate, as 19 to how that might affect critical group consumption.
20 And I'll stop there.
l 21 CHAIRMAN POMEROY: George, you're down to one l l
l 22 kilogram a year now.
i 23 VICE CHAIRMAN GARRICK: But it's pig liver.
24 And it doesn't seem to be temperal dependent. John, you
/~'N
( ,) 25 came close to it, but what is DOE's role in all of this?
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237 l 1 MR. KESSLER: They are -- they responded to I
,y 2 our survey. They have even -- they tell me they have even l
! )
~'
3 a bigger budget problem then I think NRC's telling me. At i
4 least Chris manages to get to the meetings no matter what l 5 country they're in. Somehow DOE has walls up around the )
1 6 U.S. borders, and if there's a meeting outside the U.S.
7 they can't get to it.
8 Because I'm Chairing the critical groups task !
9 group you can be assured that I will do what I can to keep i I
10 them in the loop no matter where our meetings are.
11 Obviously that falls short of them actually being there to 12 participate or making the tough decisions at the last 13 minute, but I'm doing what I can to keep the biosphere l
\' / 14 modelers and the TSPA people within DOE well-informed of 15 what's happening, and will certainly provide them drafts 16 of reports.
17 Like I said, they've responded to the survey 18 of, what are you interested in and how do you do things, 19 and I'll continue to do things, at least for the critical 20 groups task group. But they are not active participants 21 because they just don't come to the meetings.
22 VICE CHAIRMAN GARRICK: Interesting. Bill?
23 MEMBER HINZE: No questions.
24 VICE CHAIRMAN GARRICK: Paul? George?
,r y
( ,) 25 MEMBER HORNBERGER: John, in your report, one NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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238 l 1 of the things that interests me is that you did of course j i
7y 2 do this nice bit about the cautious and equitable !
1 3 business, but I'm curious whether people -- you or people 4 internationally -- are possibly thinking in terms of how l l
5 some sort of graduated standard might look, rather than 6 one standard?
7 And it seems to me that we have precedence for 8 that because after all, workers in the nuclear industry 9 have higher dose limits than the general public, as one i 10 example. And it strikes me that one could come up with a l 11 standard that might be reasonable where you'd have a 10-4 12 risk for some small critical group, and a 10-' risk for a ,
l 13 much larger critical group.
/~T !
i <
'/ 14 Have people been thinking in these terms or is ll 15 this just off-base? ;
16 MR. KESSLER: For this group it's off-base in 17 the sense that we are implementors. We do not make 18 policy. We try to interpret policy in practical ways.
19 But one of the things that was a very clear result of 20 BIOMOVS II was, in the report there we said, you've got to 21 make your policy clear, you've got to make your policy 22 consistent, or we don't know what to do with critical 23 grcups or biosphere modeling to be able to put them 24 together and mesh them in a defensible way.
/~'
( ,)s 25 But in terms of this group making policy, no.
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239 1 That's why you'll see this in the EPRI report. We think I
,e's 2 it's an issue simply because, from a risk perspective you
(
w- )
3 can look at it different ways and they all seem reasonable 4 in the sense -- well, they all have a basis, okay? But 5 certainly when it comes down to risk it's a subjective 6 decision in the end.
7 I think that there's precedent out there.
8 We've done -- we're in the middle of doing some work now, 9 seeing how EPA and other regulatory bodies have looked at 10 the effect of population size and when do they regulate 11 and when do they not regulate? In that sense there's some 12 precedent here in the U.S. on that issue.
13 But in terms of international, this is -- at i
)
14 least I don't hang out with the right people. That's 15 being dealt with at the ICRP level. And I know that ICRP-16 46 for example, is being considered to be revised, and 17 I've heard that they're going to be taking that -- at 18 least they're thinking about that issue. Whether they ;
)
19 deal with it, I don't know.
20 MEMBER HINZE: A quick question, if I might.
l l
21 In terms of the timeline on this, if I read the diagram i l
22 that Chris showed us correctly, your committee for 23 example, will not complete its work until somewhere in the l 24 '98 to '99 timeframe?
!y ,) MR. KESSLER: We hope -- I have every
(_/ 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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240 1 intention of having our report done next spring, because I fN 2 know what the deadlines are here in the U.S. And one of
)
(s -
3 the reasons I volunteered for the job is I saw that was --
4 I knew it was an important issue, the timeframe looked 5 like it would work in the sense that I was making the 6 assumption that we would have something to feed to NRC 7 whenever they got something from EPA.
8 I'm hoping that the timing works out so that 9 we have something for NRC to consider, at least from an 10 IAEA-sponsored group, as they try come up with developing 11 some guidance they may be getting from EPA on critical 12 groups.
7s 13 MEMBER HINZE: Are you saying a year from now,
() 14 then?
15 MR. KESSLER: Yes. A year from now we should 16 have a report out.
17 MEMBER HINZE: Thank you.
i 18 VICE CHAIRMAN GARRICK: All right. Thanks 19 very much, John, Chris. You're both excellent time 20 managers. We are through right on time.
21 Mr. Chairman, it's your meeting.
22 CHAIRMAN POMEROY: Thank you, John. And thank 23 you for being on time.
24 The committee will now take a one hour recess l
25 and reconvene at 1 o' clock where at which time we will NEAL R. GROSS COURT REPORTERS AND TRANSCR!BERS 1323 RHODE ISLAND AVE., N W.
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241 I
1 discuss preparing for our next meeting with the !
fx 2 Commission. We will discuss our final version of a i
i y!
3 reference biosphere and critical group letter, and discuss 4 other activities that seem appropriate.
5 We're adjourned until 1 o' clock.
6 (Whereupon, at 12:05 p.m., the 90th Meeting of 7 the Advisory Committee on Nuclear Waste went 8 off the record.)
l 9 l 10 11 ,
l 12 1
13
's _-
14 15 16 17 18 19 20 21 22 23 24 25 NEAL R. GROSS COURT PEPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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r N.3_]
CERTIFICATE This is to certify that the attached proceedings before the United States Nuclear Regulatory Commission in the matter of:
1 Name of Proceeding: 90" ACNW l Docket Number: N/A j l
Place of Proceeding: ROCKVILLE, MARYIAND l
were held as herein appears, and that this is the original transcript thereof for the file of the United States Nuclear Regulatory Commission taken by me and, thereafter reduced to
( \
C typewriting by me or under the direction of the court reporting company, and that the transcript is a true and accurate record of the foregoing proceedings.
?
wAf Ru kORBETT IIT/NER
~
official Reporter Neal R. Gross and Co., Inc.
1 f ~~
Nd I l
NEAL R. GROSS COURT REPORTERS ANDTRANSCRII3ERS 1323 R1 LODE ISLAND AVENUE, NW (202)234-4433 WASil!NOTON,DC 20005 (202)234-4433 j
.- - - - = - - . - .-
O O O N Defense-in-Depth and the Role of Multiple Barriers in the Development of 10 CFR Part 60 Technical Criteria t
L f %
- =*
A BRIEF HISTORICAL PERSPECTIVE presented by:
Janet P. Kotra Performance Assessment & HLW integration Branch Division of Waste Management, NMSS March 21,1997 l
l
- --_-_-_- _ - _ _ _ _ - _ _ _ _ _ _ _ - . __ ._ _ _ _ _ _ _ . _ _ . ..i
O O O .
OUTLINE
- BACKGROUND
- EVOLVING NRC REGULATORY PHILOSOPHY
- 10 CFR PART 60 TECHNICAL CRITERIA
- TWO DECADES OF CRITICISM AND EXPERIENCE
- DEVELOPMENT OF A STRATEGY FOR FUTURE REVISIONS
O O O .
" DEFENSE-IN-DEPTH" CONCEPTS e DEFENSE-IN-DEPTH ASSURES SAFETY THROUGH
- MULTIPLE, INDEPENDENT BARRIERS REDUNDANCY (" SINGLE FAILURE CRITERION")
e BASIS FOR NRC'S DETERMINISTIC REGULATORY FRAMEWORK FOR NUCLEAR REACTORS e PROVIDES MEANS TO MANAGE UNCERTAINTY e TRADITIONALLY, RELIANCE ON INDEPENDENCE AND REDUNDANCY OF BARRIERS HAS SERVED AS A SURROGATE FOR QUANTITATIVE ASSESSMENT OF BARRIER RELIABILITY e LITTLE ACCOMMODATION FOR RELATIVE LIKEllHOOD OF THREATS TO BARRIER INTEGRITY; BARRIER INTEGRITY MUST BE ENSURED FOR LIKELY AND REASONABLY UNLIKELY EVENTS e APPROACH IS INHERENTLY CONSERVATIVE
O O O .
" DEFENSE-IN-DEPTH" FOR GEOLOGIC DISPOSAL OF HLW
- NRC REGULATIONS FOR GEOLOGIC DISPOSAL REPRESENT A UNIQUE APPLICATION OF THIS PHILOSOPHY TO A FIRST-OF-A-KIND FACILITY
- PRE-CLOSURE OPERATIONS COMPARABLE APPROACH TO THAT USED FOR OTHER NRC-LICENSED FACILITIES Conservatism of Design Diversity of Design Comprehensive QA Radiation Safety Programs and Procedures '
O O O .
" DEFENSE-IN-DEPTH" FOR GEOLOGIC DISPOSAL (cont.)
e POST-CLOSURE PERFORMANCE L
MUST ACCOUNT FOR DIFFERENCES BETWEEN A REPOSITORY AND i AN OPERATING FACILITY WITH ACTIVE SAFETY SYSTEMS POST-CLOSURE PERFORMANCE RELIES ON PASSIVE SYSTEMS i
LONG TIME FRAMES REQUIRE PROBABILISTIC CONSIDERATION OF RELATIVE LIKELlHOOD OF THREATS TO LONG-TERM '
PERFORMANCE
- MULTIPLE, DIVERSE BARRIERS CAN BE IDENTIFIED FOR BOTH ENGINEERED SYSTEM AND GEOLOGIC SETTING, HOWEVER, PERFORMANCE OF INDIVIDUAL REPOSITORY BARRIERS CANNOT BE CONSIDERED EITHER INDEPENDENT OR REDUNDANT 5-
NRC APPLICATION OF DEFENSE-IN-DEPTH PHILOSOPHY FOR EVALUATING POST-CLOSURE PERFORMANCE EVOLVED DURING RULEMAKING FOR PART 60 TECHNICAL CRITERIA I
e NEED TO SPECIFY QUANTITATIVE PERFORMANCE CRITERIA FOR ,
INDIVIDUAL BARRIERS WAS FUNDAMENTAL ISSUE e EXTENSIVE PUBLIC COMMENT
- NUMEROUS PUBLIC COMMISSION MEETINGS
- FINAL RULE REFLECTED COMMISSION EVALUATION AND DECISION t
6
O O O EARLY NRC APPROACH TO HLW DISPOSAL circa 1978 ;
i PHILOSOPHY !
REGULATIONS SHOULD REFLECT REPOSITORY DESIGN i DISPOSAL CONCEPT
- REPROCESSED WASTES
- 1,000 YEAR HAZARD
- ONLY SATURATED SITES ENVISIONED EXPECTATIONS OF BARRIER PERFORMANCE
- MAJOR RELIANCE ON GEOLOGIC SETTING FOR ISOLATION
- MINIMAL WASTE PACKAGE CONTAINMENT
- MINIMAL ROLE FOR WASTE FORM DURABILITY 4
O O O NRC STAFF VIEWS CHANGE IN 1979 PHILOSOPHY REPOSITORY DESIGN SHOULD SATISFY REGULATORY OBJECTIVES i I
t REGULATORY STRATEGY FOR BARRIER PERFORMANCE e REPOSITORY SAFETY ACHIEVED VIA THREE-WAY REDUNDANCY 1,000-year Containment by Waste Form plus Canisters 1,000-year Containment by Engineered Barrier System 1,000-year Containment by Geologic Setting i
i r
o o o .l DEVELOPMENT OF REGULATORY APPROACH FOR PART 60 PERFORMANCE OBJECTIVES
- GOAL :
- Compensate for Major Sources of Uncertainty in the Quantitative Prediction of Repository Performance !
- THREE ALTERNATIVES CONSIDERED
- Single Overall Performance Standard (i.e. the EPA Standard) i
- Minimum Performance Standards for Major Barriers as well Conformance with the EPA Standard Prescriptive, Numerical Criteria for Specific Attributes of the System
.g.
O O O
- SINGLE OVERALL PERFORMANCE STANDARD SINGLE FIGURE OF MERIT MAXIMUM FLEXIBILITY FOR DESIGNER PERMITS " TRADE-OFFS" AMONG SYSTEM COMPONENTS <
NOT VIEWED AS PRACTICAL FOR REGULATORY PURPOSES t
LIMITED CONFIDENCE IN THE PROBABILISTIC TECHNIQUES USED TO PREDICT REPOSITORY PERFORMANCE t TO COMPENSATE FOR UNCERTAINTY, REGULATOR WOULD HAVE ;
TO IMPOSE GREATER CONSERVATISM f
iX
O O O e ESTABLISH MINIMUM PERFORMANCE STANDARDS FOR MAJOR BARRIERS IN ADDITION TO OVERALL STANDARD WAS THOUGHT TO REDUCE RELATIVE CONTRIBUTION OF EACH !
SUBSYSTEM TO OVERALL UNCERTAINTY WAS ASSERTED THAT BARRIERS COULD BE SELECTED WHICH ACT " INDEPENDENTLY", THEREBY ENHANCING CONFIDENCE PROVIDES SOME GUIDANCE / INPUT TO DOE DESIGN PROCESS i
RETAINS LARGE MEASURE OF DESIGN FLEXIBILITY l
l e PRESCRIPTIVE, NUMERICAL CRITERIA FOR SPECIFIED SYSTEM ATTRIBUTES PROVIDES CLEAR GUIDANCE TO DESIGNERS RE: LICENSING REQUIREMENTS !
INTENTIONALLY CONSERVATIVE CRITERIA MAY BE SELECTED THAT WILL DIRECTLY COMPENSATE FOR UNCERTAINTY .
MOST RESTRICTIVE OF DESIGN FLEXIBILITY REGULATOR ENCROACHES ON ROLE OF DESIGNER i
- CRITERIA REFLECT EXISTING KNOWLEDGE; CAN'T ACCOMMODATE RESULTS OF FUTURE R&D l
t
O O O SELECTION OF PRIMARY BARRIERS '
- WASTE PACKAGE SHOULD CONFINE WASTE DURING PERIOD WHERE SPECIFIC ACTIVITY OF WASTE IS HIGH AND HEAT INDUCED PERTURBATIONS OF THE NATURAL SYSTEM ARE LARGE; !
- ENGINEERED SYSTEM SHOULD LIMIT RATE OF RELEASE OR SOURCE TERM TO THE GEOLOGIC SYSTEM;
- GEOLOGIC SYSTEM SHOULD MINIMlZE RELEASE OF REMAINING INVENTORY SUCH THAT ENVIRONMENTAL STANDARDS ARE MET
O O O .;
ADVANCE NOTICE OF PROPOSED RULEMAKING IN 1980 1
DISPOSAL CONCEPT -
- NO REPROCESSING; DISPOSAL OF SPENT FUEL
- HAZARD WILL PERSIST FOR 10,000 YEARS AND LONGER PHILOSOPHY
~
MULTIPLE BARRIERS WITH MINIMUM PERFORMANCE REQUIREMENTS TO l PROVIDE NEEDED ASSURANCE THAT EPA STANDARDS ARE MET REGULATORY STRATEGY FOR BARRIER PERFORMANCE i
- SPECIFY PERFORMANCE OBJECTIVES BY RULE 1,000-year Containment by Waste Package 1,000-year Containment by Underground Facility ,
10-5 Annual Release Rate after 1,000 years 1,000-year Radionuclide Travel Time
- EPA STANDARDS NOT YET DEVELOPED; RELEASE LIMITS EXPECTED i
O O O PROPOSED RULE IN 1981 PHILOSOPHY t
CONTINUE TO FAVOR QUANTITATIVE PERFORMANCE REQUIREMENTS FOR PRIMARY BARRIERS REGULATORY STRATEGY FOR BARRIER PERFORMANCE
- SOLICIT COMMENT ON TWO APPROACHES
- 1) Prescribe Single Overall Performance Standard (EPA Standard)
- 2) Prescribe Minimum Performance Criteria for Three Primary Barriers in addition to Overall Performance Standard ;
1,000-year Waste Package Containment 10 4 Annual Release Rate from EBS after 1,000 years '
1,000-year Pre-emplacement Groundwater Travel Time No Correlation with EPA Standards .
t
O O O -
NUCLEAR WASTE POLICY ACT OF 1982 e DIRECTS EPA TO PROMULGATE ENVIRONMENTAL STANDARDS FOR DEEP GEOLOGIC DISPOSAL OF HLW e DIRECTS NRC TO DEVELOP TECHNICAL CRITERIA CONSISTENT WITH -
EPA STANDARDS e MANDATES THAT NRC TECHNICAL CRITERIA
...shall provide for the use of a system of multiple barriers in the design of the repository..."
t
[
i
FINAL RULE IN 1983 PHILOSOPHY
- QUANTITATIVE PERFORMANCE CRITERIA FOR PRIMARY BARRIERS; EXPLICIT PROVISION FOR ALTERNATIVE CRITERIA WHERE JUSTlFIED i I
REGULATORY STRATEGY FOR BARRIER PERFORMANCE -
e PRESCRIBE MINIMUM PERFORMANCE CRITERIA FOR THREE PRIMARY BARRIERS IN ADDITION TO OVERALL PERFORMANCE STANDARD "Substantially Complete" Containment for 300-1,000 years 1
10 4 Annual Release Rate from EBS 1,000-year Pre-emplacement Groundwater Travel Time e
PERMIT NRC SPECIFICATION OR APPROVAL OF ALTERNATIVES t
e NUREG-0804 SHOWS SUBSYSTEM OBJECTIVES CONTRIBUTE BUT ARE NEITHER NECESSARY OR SUFFICIENT TO ENSURE COMPLIANCE WITH EPA STANDARDS l
t
O O O i
THE COMMISSION CONCLUDED: l t
...if the Commission were simply to adopt the EPA standard as the sole measure of performance, it would have failed to convey in any meaningful way the degree of confidence which it expects must be ,
achieved in order for it to be able to make the required licensing decisions." ,
l
...the Commission firmly believes that the performance of the engineered and natural barriers must each make a definite contribution in ;
order for the Commission to be able to conclude that the EPA standard i will be met." I i
i Final Rule, June 21,1983 1 I
l 1985 AMENDMENTS TO PART 60 TECHNICAL CRITERIA FOR THE UNSATURATED ZONE
- REAFFIRMED VIEW THAT STANDARD OF PERFORMANCE FOR THE !
NATURAL BARRIERS IN THE GEOLOGIC SETTING SHOULD BE
... independent of any interaction between these natural barriers and the engineered barriers"
- ASSERTED THAT EMPHASIS ON PRE-WASTE-EMPLACEMENT ,
CONDITIONS PROVIDES ,
i
... higher confidence in the continued isolation capabilities of the natural barriers of the geologic setting over the long term." ;
- RETAINED COMMISSION OPTION TO APPROVE OR SPECIFY SOME
' OTHER PRE-EMPLACEMENT GROUNDWATER TRAVEL TIME (GWTT) l ON A CASE-BY-CASE BASIS PURSUANT TO 9 60.113(b)
WELL AS SATURATED SITES i
EXTENSIVE CRITICISM OF PART 60 SUBSYSTEM CRITERIA Preference Expressed for "OVERALL SYSTEMS" Approach; Only Overall Performance Counts Lack of Technical Bases for Individual Criteria; May not be Meaningful j indicators of Barrier Performance Unduly Restrictive of DOE's Flexibility to Design Barriers to Meet i Site-specific Conditions Specific Wording of Performance Objectives Unclear, Subject to Conflicting Interpretations Lack of Nexus between Subsystem Criteria and EPA Standard Commission Flexibility to Specify Alternatives Illusory; Politically Impossible to implement at Time of Licensing
- May lead to Suboptimal Performance
O O O STAFF POSITION 60-001 (July,1990)
- ISSUED TO CLARIFY MEANING OF 960.113(a)(1)(ii)(A) REQUIREMENT FOR SUBSTANTIALLY COMPLETE CONTAINMENT
- ADDRESSED CONCERNS OF DOE AND OTHERS THAT REQUIREMENT
- Appears to Place a Cap on Waste Package Lifetime
- Appears to Limit Credit for Engineered Barrier Performance
- Unduly Restricts DOE's Flexibility Deemphasizes importance of Engineered Barrier Performance STAFF POSITION CLARIFIED THAT s60.'113(a)(1)(ii)(A)
- Is a Minimum Performance Requirement t Does not limit waste package lifetime, .
Does not limit credit that can be taken.if Waste Package is Designed to Provide Containment > 1,000 years] :
1 i
l i
IMPORTANT EXPERIENCE SINCE RULE ESTABLISHED
- IMPLEMENTATION OF INDIVIDUAL SUBSYSTEM REQUIREMENTS HAS ,
BEEN PROBLEMATIC
- AMBIGUITY IN THE TECHNICAL BASES AND WORDING OF THE SUBSYSTEM REQUIREMENTS HAS GIVEN RISE TO REGULATORY AND TECHNICAL UNCERTAINTY i
- EXTENSIVE EXPERIENCE WITH TOTAL SYSTEM PERFORMANCE ASSESSMENT (NRC STAFF AND DOE) PROVIDES ENHANCED ASSURANCE THAT REPOSITORY PERFORMANCE WILL BE UNDERSTOOD AND ADEQUATELY BOUNDED
- SITE SPECIFIC STANDARD PERMITS SPECIFICATION OF SITE SPECIFIC PROCESSES AND MORE FOCUSSED ANALYSES
- SENSITIVITY STUDIES AND UNCERTAINTY ANALYSES OF INDIVIDUAL ;
REPOSITORY COMPONENTS MAY PROVIDE A MORE MANAGEABLE .
APPROACH TO PROVIDING REASONABLE ASSURANCE I
o o o
% l i .
POSSIBLE OPTIONS FOR STAFF CONSIDERATION
- STANDARD FOR OVERALL SYSTEM PERFORMANCE ONLY
- STANDARDS FOR BOTH OVERALL SYSTEM AND SUBSYSTEMS WITH RIGOROUS WEXUS i
- STANDARD FOR OVERALL SYSTEM PERFORMANCE ONLY WITH QUALITATIVE REQUIREMENT FOR SUBSTANTIAL CONTRIBUTION FROM MULTIPLE BARRIERS
- MULTIPLE BARRIER OPTIONS Total Redundancy Engineered Barriers as Supplements ,
Partial Redundancy
,
- STATUS QUO
-2 3-
O O O ;;
t
?
. POTENTIAL REVISION OF MULTIPLE BARRIER APPROACH
- STAFF WILL RECONSIDER ITS APPROACH TO MULTIPLE BARRIERS :
AND SUBSYSTEM PERFORMANCE CRITERIA IN THE CONTEXT OF AN OVERALL STRATEGY FOR REVISIONS TO PART 60 TECHNICAL ,
CRITERIA PURSUANT TO THE ENERGY POLICY ACT OF 1992
- STRATEGY IS CURRENTLY UNDER DEVELOPMENT e STAFF EXPECTS TO FORWARD AN OPTIONS PAPER FOR I COMMISSION CONSIDERATION IN LATE SUMMER 1
t i
O O O
~
. 9!
BIOMOVS ll
SUMMARY
U<g s ,
- =W b -
O
'+n 4hu*
CHRISTEPHER A. MCKENNEY PERFORMANCE ASSESSMENT & HLW INTEGRATION BRANCH DIVISION OF WASTE MANAGEMENT, NMSS PHONE - (301) 415-6663 EMAIL - CAM 1@NRC. GOV l
_ _ _ _ - _ . _ _ _ _ _ - _ _ _ _ _ _ _ . _ _ _ _ _ _ _ _ . _ . _ _________-_________m _m ___._._.____ _ _ _____ - w__. _.__.___-_.________m
BIOMOVS ll BACKGROUND e BIOSPHERIC MODEL VALIDATION STUDY (BIOMOVS) e JOINTLY FUNDED BY FIVE ORGANIZATIONS e THE ATOMIC ENERGY CONTROL BOARD, CANADA; e ATOMIC ENERGY OF CANADA LIMITED; e CENTRO DE INVESTIGACIONES ENERGsTICAS MEDIOAMBIENTALES Y TECHNOL GlCAS, SPAIN e EMPRESA NACIONAL DE RESIDUOS RADIACTIVOS SA, SPAIN
- SWEDISH RADIATION PROTECTION INSTITUTE e FIRST PHASE - 1986-1990 e SECOND PHASE - 1991 -1996 ACNW Breefing - 21 March 1997 O O O -
O O O
~
BIOMOVS 11 OBJECTIVES
- TEST ACCURACY OF THE PREDICTIONS OF ENVIRONMENTAL ASSESSMENT MODELS .
i e EXPLAIN. DIFFERENCES IN MODEL PREDICTIONS DUE TO MODEL STRUCTURE MODELLING ASSUMPTIONS l
INPUT DATA i
e RECOMMEND PRIORITIES FOR FUTURE RESEARCH TO IMPROVE ACCURACY OF MODEL PREDICTIONS :
I l
t i
t ACNW Br efmg - 21 March 1997
i BIOMOVS 11 WORKING GROUPS g Reference : Complementary Biospheres Studies
(
Uranium Use of Post-MillTailings Chernobyl Data Wash-off from Experimental Plots Cooling Pond Atmosphenc Resuspension O
Special Radionuclides Tritium Carbon-14 Uncertainties &
Validation Uncertainty Analysis edeuons User interpretation Model Complexity Lysimeter Data 0
o o o~! -l COMPLEMENTARY STUDIES
- MODELLING EXERCISE TO INVESTIGATE AND EXPLAIN DIFFERENCES EXISTING BETWEEN CONTEMPORARY BIOSPHERE MODELS
- 10 PARTICIPANTS !
- INLAND, TEMPERATE CENTRAL EUROPEAN VALLEY
- RADIONUCLIDES l-129, NP-237 t
- COMMON EXTENSIVE DATABASE
- IMPORTANT CONCLUSIONS
- MAXIMUM TOTAL ANNUAL INDIVIDUAL DOSE OVER ALL !
PATHWAYS APPEARS RELATIVELY ROBUST
- PARAMETRIC UNCERTAINTY MORE IMPORTANT THAN REPRESENTATIONAL UNCERTAINTY !
ACNW Briefing - 21 March 1997 1
REFERENCE BIOSPHERE METHODOLOGY o CREATES DETAILED CONCEPTUAL MODEL OF FEATURES, EVENTS, AND PROCESSES (FEP'S) AND THEIR INTERACTIONS IN THE BIOSPHERE TO BE ASSESSED e IMPROVES " TRANSPARENCY" WITH THE DOCUMENTATION OF INFORMATION OR DECISIONS TO INCLUDE OR EXCLUDE FEP'S e USES ROCK ENGINEERING SYSTEM (RES) INTERACTION MATRIX METHODOLOGY TO IDENTIFY IMPORTANCE OF FEP'S AND lNTERACTIONS BETWEEN COMPONENTS
- ITERATIVE PROCESS e USES INTERNATIONAL GENERIC FEP LIST AS STARTING POINT
- USES CRITICAL GROUP APPROACH e EPRI REPORT " BIOSPHERE MODELING AND DOSE ASSESSMENT FOR YUCCA MOUNTAIN" ACNW Briefing - 21 March 1997 O O O .
1 1
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i i Basic System Assessment International I 2 Description Context FEP List l t
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O O O IMPROVEMENTS / FUTURE WORK :
1 FOR REFERENCE BIOSPHERE METHODOLOGY
- TESTING AND AUGMENTATION OF METHODOLOGY
- PRINCIPLES FOR THE DEFINITION OF THE CRITICAL GROUP i
r e DEFINITION OF CRITERIA FOR CONSTRUCTION OF l APPROPRIATE DATABASES !
- TRANSITIONS BETWEEN CLIMATES
- IDENTIFICATION OF PARAMETERS FOR THE RELEVANT FEP'S e INPUT DATA t
e t
l CONTINUED MAINTENANCE OF THE BIOSPHERE FEP LIST l i
ACNW Breehng - 21 March 1997 I t
l
! _. . _ . _ _ _ . _ . . _ . _ _ _ _ . _ _ _ . _ _ . _ _ _ _ _ _ _ _ _ J
i BIOMASS l
- INTERNATIONAL ATOMIC ENERGY AGENCY PROGRAM l
- BIOSPHERE MODELING AND ASSESSMENT METHODS l
e DEVELOPED OUT OF BOTH BIOMOVS II AND IAEA'S VALIDATION OF ENVIRONMENTAL MODEL PREDICTIONS (VAMP) PROGRAMS ,
- THREE AREAS OF FOCUS
- THEME 1: RADIOACTIVE WASTE DISPOSAL
- IMPLEMENTATION AND AUGMENTATION OF REFERENCE BIOSPHERE METHODOLOGY e THEME 2: ENVIRONMENTAL RELEASES
- DOSE RECONSTRUCTION
- ENVIRONMENTAL REMEDIATION e THEME 3: BIOSPHERIC PROCESSES l
- TRITIUM
- FOREST / FRUIT TREE ACNW Briefing - 21 March 1997 ,l o
I e -- - - - - -
e
NOM o FIGURE 31. THEME 1: RADIOACTIVE WASTE DISPOSAL TASK SCHEDULE A A e
- 4 i
+
4 PRfNC!PLES FOR THE DEFINITION OF 1
MYPOTHCTICAL CRiflCAL GROUPS
- A A O! l
- A A -
COMPLETION i PRINCIPLES FOR TNE APPLICATION OF ,
DATA TO ASSESSMENT MODELS l w
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MODEL DEVELOPMENTS (A B 1
. conceptualmoceis m atnem at cal mode's
- assessment mocess a !
a Climate transitens N atural anacgwes AUGMENTATION Oynamic modelhng of hosphere systems f ffects of future human actions Oct 96 Oct 97 Oct 96 Oct 99 Oct 2000 Oct 2001 PLENARY SESSION d ORAFT 00CUMENTATION h INTERME01 ATE MEETING g FINAL DOCUMENT 9 14 I INTER. NATION AL ATOMIC ENERGY AGENCY (IAEA)
WAGRAMERSTRASSE !. P O BOX 100. A 1400 VIENNA ( AUSTRI A)
Telephone +431206021428 Telex 112645 ATOM A Facsimile +43120 607 DIVISION OF Rant ATION & WASTE SAf ETY WASTE S AFETY SECTION Version 4 Ref ID4096.ne8
NRC INVOLVEMENT AND UTILIZATION
- OBSERVERS IN BIOMOVS ll SINCE 1994 i
e OBSERVERS IN BIOMASS PROGRAM THEME 1 i i e USED REFERENCE BIOSPHERE AND CRITICAL GROUP APPROACH i
IN CALCULATIONS SUPPORTING DISCUSSIONS WITH EPA i e SUPPORT USE OF REFERENCE BIOSPHERE AND CRITICAL GROUP IN WASTE DISPOSAL AND DECOMMISSIONING ,
e CONSIDERING THE INTERNATIONAL APPROACH AND SELECTION l CRITERIA FOR USE IN NRC ACTIVITIES ;
! e HAVE NOT YET APPLIED REFERENCE BIOSPHERE METHODOLOGY TO YUCCA MOUNTAIN i
ACNW Briefmg - 21 March 1997 d G t
, G G G : i i
o o o en:;
Biosphere Modeling and Dose Assessment for Yucca Mountain John H. Kessler Electric Power Research Institute presented to the Advisory Committee on Nuclear Waste 21 March 1997
Yucca Mountain Regulations Likely to Require Dose Assessments NAS TYMS Committee
- individual health risk criterion
- conversion to dose criterion acceptable l Proposed legislation Therefore, biosphere modeling is required O O O -
A Few " Forgotten" Biosphere Model Criteria .
Appropriate for the particular assessment i
Transparent
- understand what things are in it
- understand why they are there 1
- understand how they got there Sufficiently complete '
- all of the necessary pieces are included Internationally accepted approach helpful E
EPRI Report (TR-107190, 1
December 1996)
" Biosphere Modeling and Dose Assessment l for Yucca Mountain" Example approach to developing a Yucca Mountain-specific biosphere model QuantiSci, Ltc.. primary author O O O -
I EPRI did not Have to Reinvent i,
the Wheel
}
l BIOMOVS II Reference Biospheres l Working Group (RBWG) generic approach l chosen i
j - based on international input and consensus l - provides general guidance and tools RBWG provided a reference approach
- - not a " reference" biosphere i
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i TECHNICAL REPORT No. 6 1
i-l l
l Development of a Reference e Biospheres Methodology for i Radioactive Waste Disposa Final Report of t1e Reference Biospheres Working Group of the BIOMOVS ll study
\ J Se atem 3er 1EB O
BIOMOVS - an internationalstudy to test models designed to predict the environmental transfer and bicaccumulation of radionuclides and other trace substances
I B10MOVS 11 s
). TR6 l
l l
Basic System Assessment International Description Context FEP List !
Procedure to Construct ConceptualModels A
Initial Screening Qualitative .
.. Qualitative Aspects "
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relationships S-between FEPs E.
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( s, Figure 2.1: Steps in the Development and Application of a Biosphere Model 7
l o o o i
l FEPs Must be
! Systematically Identified l
i Important to understand FEP relationships
! Important for the regulator to see what is included j If done intelligently, can use a FEP list to l - list the FEPs l
- show the linkages between related FEPs
- document the choices of the FEPs that have been j included (and excluded) l - document the models and parameter values chosen i
EPRI's Interest in FEP Lists i Many different ways of presenting the FEPs and their relationships Looking for an approach that:
- can make Yucca Mountain-specific FEPs ,
- is reasonably simple to understand i
- documents the decisions made that generated the FEP hst i l
i
i EPRI Chose BIOMOVS II RBWG FEP-making Process ,
- Initial BIOMOVS 'I' effort-ad hoc FEPs organized by category ;
some linkages identified International" FEP list i
detailed example similar to conditions in i Switzerland
- More recently, adopted the "RES interaction matrix" approach e o e
_m..~_3m,
~
the context of Rock Engineering Systems Hudson,1992;, i referred to as the RES methodology.
cChodology starts with a top down approach to ensure that m are being covered. In this way, the problem is gradually "I h its constituent parts. The basic device used is the interac main biosphere components, or more generally " things", are ng the leading diagonal of the matrix. The interactions s occur in the off-diagonal terms.
Component Influence A of A on B
.O , ,2 i
Influence Component of B on A B 2,1 2,2 tstrated in the sketch above for a 2 x 2 matrix, together with n for influence direction. As the number of leading diag <
ager, so does the number of interactions. In practical work al elements should be used, leading to (13+13)-13 off-diagone AO7
Biosphere FEP List and RES Interaction Matrix Development Specijic to Yucca Mountain u u o to a t. e a i.. uo in 600BC111Rae Comemanatwn Cememaneann Consarnanation Consommatosi No d be g aa'we in f5 penal B C. free ica dmeddes este==rs latal resseeep rewdise on ce n, rWeseel l
I A3 3 ! t
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rEltALANENT Flew waiw + Fhi n waear .
i h eter transpan Da nmganan Na Nol unenn ter Nce tmean te Lee c6 maner l k.e we.e me.-
S A f t*RA TE D =duie soluie CePdlers nee our evosens enar e, sue wns 2DNT.1 Agesle** Idendwrtel v td=<tiarE** Impatien due te Dnnkerg weia hwnen arrivmen 13 12 13 14 15 le 1: 1h 3,diarge EL'RFACE ^4eson Redwege Flasding 19 1 10 au Aweesis Uptake 0peake W eser euppiv Lpease L nemer WATER Eiwesosi ithrough nver Ddtuneen seemsence ir6e'sen immen nes twue.on b.nh i sedeneni.ewn Dem ng Advemen Erosace Evaporeence Arngaissa Supenmose 4.1 4.4 4.3 e.4 44 4 en 4J 4A 49 4.40 is,.
h ase + seausee Sedunens SEDIMENTS Converesan Carwerten Awonoi. Upsake Enternal Open, Easernal i t,.,m.
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ZONE torineteen esedeel snesesel g3 h2 63 he 63 64 m: un es, e6 w me.
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- .1 .2 7.3 :.4 Th :.6 1J :h *4
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Fenabeeman Cancpv Seamang C orubbenei w anhout heter Redustan et Eseredeen *eind speed ya 9.2 v3 v4 93 v.6 9J 94 9.9 +1 v, t i Cantaminnston Diosurbanan Burrs = vine Escrwhen Enhalanese Cspenapphen FAUNA Depus.derg en inseinan Dnaars Snorurbetosi boundary Femheirs Duect Es semei terrowiry amaanansinon Condshone Eroseen 10.) 40.2 IG.3 10.4 10 3 10.6 10J 10 4 no.9 10.10 10. H intruesen tNew Weiw ewgrocneri heter rscharge Dredgang PoBucon CM Agncuhww PoDuben Baevdang Penrung saarege HUMAN Dependmg en cannedereds Pollutaan Water airedwn Ranrevas ergewer fDeep Pouvrace Fdiraben Steroge burnsg Hussan5 ACTIVITES teundan Recharg e Folkstum Flowmfl Foran rv \ ennisten Mahag Condabcne Tresanrew Treseawnm Gwil Fumnure De.si. rid dr i C.,orerwet*
.t si iL4 IL2 IL3 AL4 113 4 L6 AL7 IL6 IL9 A L10 LL11 DOSE TO CJUT1 CAL CROUP)
Figure 2-1 Generic biosphere RES matrix for an inland groundwater release source term (taken from BIOMOVS II [1995]).
O 2-22
o o o-The RES Matrix Approach Leading Diagonal Elements (LDEs): main features of the system to be modeled
- Source term (assumed to come from the "geosphere" and is located at the "geosphere/ biosphere interface")
- Aquifer
- Surface Water
- Sediments
- Variably Saturated Zone (includes deep soil)
- Surface Soil
- Atmosphere
- Flora
- Fauna
- Human Activities
- Dose to Critical Group
The RES Matrix Approach (continued}
Off Diagonal Elements (ODES):
interactions between the LDEs .
- most of the FEP " processes" lie in the ODES G 9 9
o o o Description of the RES LDEs Source term .
- Flux of radionuclides from the geosphere into the biosphere
- Assumed abstracted from a deep well Aquifer (or Permanent Saturated Zone)
- Unconfined aquifer immediately beneath the unsaturated zone)
- Not a big player for Yucca Mountain biosphere
1 Description of the LDEs (continued) surface water
- Rivers, streams, canals, ditches, lakes, reservoirs, and lagoons
- May be relevant for Yucca Mountain if surface ponds and ditches assumed Sediment
- Bed sediments (perhaps only marginally applicable at YM)
O O O
Description of the LDEs (continued)
- Variably Saturated Zone
- Deep soil generally below the root zone
- All.the way down to the saturated zone Surface Soil
- Root zone soil
- Lots of biological activity including crop growth
- Includes solid soil, soil water and gases Flora
- All plants, fungi, crops, and crop products (e.g., cotton clothing, wood for furniture and housing materials)
- Fauna
- All animals (water and land).
Description of the LDEs (continued) '
Human Activities
- All relevant activities in the vicinity of the release including modifications to the environment:
agricultural practices building practices (excavation, use of soils for building, etc..)
hunting and fishing water usage
- m o re . . . . . . . . . . . . .
Dose to Critical Group
- Radiation exposure pathways for the critical group (linked by ODES)
- Partially defined by the assessment context O O O
.. . . - . ~ . . ._ ~ .- - ~ - . . . . . ~ -- . - - - . - -. - - . - . . _ - - .
i Biosphere FEP List and RES Interaction Matrix Development Specific to Yucca Mountain u 44 a3 J4 ib i7 SOURCE TERA 8 4e Le 14 g to a gg i
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Figure 2-2 BIOMOVS II reference biosphere RES matrix [BIOMOVS II,1995] modified for the Yucca Mountain biosphere. !
1 8 8 4
i ik i
I 2-23 r-I
- .,e
o o o Dose Calculations Based on Yucca Mountain-specific RES matrix Report also includes selected data survey
- I-129, Tc-99, Np-237, Se-79, Pa-231, Pa-233, Th-229 Best estimate" values applicable to Yucca Mountain chosen for model
t i Biosphere Dose Cakulations e
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i Figure 5-2 BIOMOVS II Reference Biosphere RES matrix modified for Yucca Mountain j,j biosphere. No surface water body is assumed. The thin arrows refer to nuclide migration processes; the thick arrows refer to exposure pathways.
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Biosphere Dose Calculations Table 5-8 j f" Critical Group l
Consumption Rates
} Foodstuff Consumption Rate (kg fw y")
{ Cow:
f- Meat 15 l Liver 5 l Milk 100 Pig Meat 15 ll-l Sheep Meat 15 l
Chic ken (3
V Meat 15
} Liver 5
- l. I Eggs 15 1
Grain 60 Root Vegetables 80-lj . Green Vegetables 40 Fruit 46 Water (m' y4 ) 0.6 Soil 0.05 Note: fw fresh weight KD
. . 5-23 i
- . - . ~ . . . . . . . . . . ~ . . . - . . ~ _ . _ _ . _ - - - . - - ~ . . . _ . . . . . - . .
I Biosphere Dose Calculations Table 5 I Dose Conversion Factors for Unit Flux to the Well Flux-to-dose conversion factor (Sv y/mol y) -
I Radionuclide (1) Total Dose Drinking Water Dose i Np-237 1.5E 1.5E Pu-239 6.8E+2 3.1E+0 Pu-240 2.1E+3 1.2E+1 Pu-242 4.8E+1 1.9E-1 Am-243 2.0E+3 8.2E+0 Notes (1)'Ihe contribution to dose from the in-growth of daughters in the biosphere is included in the factor given for the parent.
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idioactive aste disposal. Therefore, strict re latory dose or risk limits (rather t uidance) are in order.
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considers this populauon
, , " Cautious" philosophy considers this population T
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EPRI Report Includes Sections on Critical Groups Begin with " Assessment Philosophy"
- " cautious"
- " equitable" International survey of
- guidance and regulations
- implementations Example of an " equitable" assessment philosophy approach
- average individual in the local population e -
G S
obody w' ever receive anything more the a small dose (or health risk) tr ,
idioactive aste disposal. Therefore, strict rc latory dose or risk limits (rather uidance) are in order.
" Equitable" philosopFy or 7 considers this popul
, , " Cautious" philosophy considers this population T
E E%
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.5 o Ilypothetical Population Size Maximally exposed Ilypothetical individuals with hypothetical - - - -* successively decreasing individual individual dose rates l Figure 3-1 Average individual dose rate as a function of exposed population size for a hypothetical release.
3-5
neguiaoun3 Regulatory issue " Cautious" Approach " Equitable" Approach i
Establishment of Criteria Social perception of Acceptance of need for limits, unacceptable risks leads to but these will be set at very strict regulation. generally higher levels, Adoption of strict (and consistent with upper limits generally relatively low) to risk currently tolerated for !
limits to dose or risk small groups in society. A lower " target" dose / risk,
- . consistent with general i l population averages, will
! also be established, below which further optimization will not typically be required.
Compliance Assessment Acknowledgment of Tendency for more " realistic" (with criteria) assessment uncertainties assessment of potential doses '
leads to preference for based on " representative" l managing such uncertainty members of hypothetical through pessimistic critical groups, and taking assumptions (e.g., account of present day :
" maximally exposed practices.
individual", tails of '
distributions ofintake rates, ;
etc.).
3-13 t
- um i
o o o-BIOMASS " Theme 1" Follow-on to BIOMOVS II
Purpose:
develop " practical" approaches to:
- biosphere model development
- critical and other " indicator" groups
- use of data in biosphere models Specifically for LLW/HLW disposal safety assessments IAEA-cosponsored
BIOMASS " Theme 1" (continued) .
Six Task Groups
- TG1: Critical (and other "incicator") Groups ;
- TG2: Use of data '
- TG3: Assessment contexts '
- TGL: Biosphere evolution ;
- TG5: System descriptions
- TG6: Model development O O O
o o o .
Critical Groups Task Group (CGTG) Plans Convert assessment contexts into practical guidance Quantitative guidance to critical (and other) group definition
- Example of potential guidance detail (not " official")
Do local or regional survey of habits
- consumption, farming, local water use, time outdoors, etc.
Choose 95th percentile of consumption rate for " critical" group Other quantitative specifications of" cautious but reasonable"
Probable CGTG Topics (based on Task Group interests)
Critical groups (" cautious")
f
- when they are appropriate (assessment context)
- information required prior to specification
- detailed specification recommendations includes how to maintain an appropriate degree of conservatism
- at least one illustrative example Subsistence farming community ;
- when it should be used :
- suggested data bases ;
historical since not present day behavior O O O -
o o o! -
Probable CGTG Topics (continued)
Alternative " indicator" groups
- rules for when to use them
- groundrules on which are appropriate how to obtain data Implications for other Task Groups Implications for compliance assessments
Conclusions - EPRI Report EPRI report demonstrated it is possible to
- put international guidance to practical use
- list and document biosphere FEPs in an understandable and traceable manner
- have more than one valid approach to the use of
" critical" groups EPRI report provides a usefui survey of data relevant to Yucca Mountain O O O
i Conclusions - BIOMASS ,
BIOMASS Theme 1 will extend BIOMOVS II successes
- will develop " practical" approaches
- concrete, internationally applicable guidance and information
. - NRC (and DOE) should actively participate i
Critical Groups: Compilation and Analysis ofInformation ;
i Table 3-3 Consumption kgly i
}
temperate tundra / boreal grain 80 0 i root vegetables 80 0 I 4
green vegetables 40 0 5 herbaceous fruit 10 0 '
beef 40 40 .
cow 2 2 milk 150 150 f
pig meat 10 10 pig liver 1 1 chicken 10 10 eggs 10 10 I'
water 600 600 '
freshwater fish 20 51 marine fish 110 229 '
mollusks 7 7 .y crustaceans 18 18 4
seaweed 10 10 1
.j p
. /,
Occupancy, h/y y farmland 8760 8760 2
estuary 2000 2000 j
Breathing / dust j farmland 1.05E4 m'/y 1.05E4 m'/y dust in air SE-8 kg/m' 5E-8 kg m' h
!}:.
The exposure basis for the critical group includes all the above assumptions, which in h !
~
turn relate to the structure assumed for the surface environment at the time of release.
3-29 .i I