ML20217J888
| ML20217J888 | |
| Person / Time | |
|---|---|
| Issue date: | 03/30/1998 |
| From: | NRC COMMISSION (OCM) |
| To: | |
| References | |
| REF-10CFR9.7 NUDOCS 9804070048 | |
| Download: ML20217J888 (76) | |
Text
ORG4A_
p UNITED STATES OF AMERICA q
[h gy NUCLEAR REGULATORY COMMISSION
Title:
BRIEFING BY NUCLEAR WASTE TECHNICAL REVIEW BOARD (NWTRB)
PUBLIC MEETING Location:
Rockville, Maryland Date:
Monday, March 30,1998 Pages:
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DISCLAIMER This is an unofficial transcript of a meeting of the United States Nuclear Regulatory Commission held on March 30, 1998, in the Commission's office at One White Flint North, Rockville, Maryland.
The meeting was open to public attendance and observation.
This transcript has not been reviewed, corrected or edited, and it may contain.
inaccuracies.
The transcript is intended solely for general informational purposes.
As provided by 10 CFR 9.103, it is not part.of the formal or infornal record of decision of the matters discussed.
Expressions of opinion in this transcript do not necessarily reflect final determination or beliefs.
No pleading or other paper may be filed with the Commission in any proceeding as the result of, or addressed to, any statement or argument contained herein, except as i
the Commission may authorize.
1 1
UNITED STATES OF AMERICA 2
NUCLEAR REGULATORY COMMISSION 3
4 BRIEFING BY 5
NUCLEAR WASTE TECHNICAL REVIEW BOARD (NWTRB) 6 7
PUBLIC MEETING 8
9 Nuclear Regulatory Commission 10 One White Flint North 11 Rockville, Maryland 12 13 Monday, March 30, 1998 14 15 The Commission met in open session, pursuant to 16 notice, at 2:00 p.m., Shirley A. Jackson, Chairman, 17 presiding.
18 19 COMMISSIONERS PRESENT:
20 SHIRLEY A. JACKSON, Chairman of the Commission 21 GRETA J. DICUS, Commissioner 22 NILS J. DIAZ, Commissioner 23 EDWARD McGAFFIGAN, JR., Commissioner 24 25 ANN RILEY & ASSOCIATES, LTD.
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1 STAFF PRESENT AND PRESENTERS SEATED AT THE COMMISSION TABLE:
2 JOHN C. HOYLE, Secretary of the Commission 3:
KAREN D.
CYR, General Counsel 4
JARED L.
COHON, Chairman, NWTRB 5
DEBRA S. KNOPMAN, Member, NWTRB 6
RICHARD R.
PARIZEK, Member, NWTRB 7
8 9
10 11 12 13 14 15 16 17 18
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21 22 1
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24 25 ANN RILEY & ASSOCIATES, LTD.
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-1 PROCEEDINGS 2
[2:00 p.m.]
3 CHAIRMAN JACKSON:
Good afternoon, ladies and 4
gentlemen.
This afternoon, the Commission is pleased to 5
welcome Drs. Jared Cohon, Debra Knopman, and Richard 6
Parizek, from the U.S. Nuclear Waste Technical Review Board.
7 The Board members will brief the Commission on the 8
status of their evaluation of the technical and scientific 9
aspects of DOE's work at the Yucca Mountain repository.
10 The Commission is very pleased to have the three 11 of you here.
12 It has been nearly two years, namely July 30th of 13 1996, since the Technical Review Board last briefed the 14 Commission about the Board's activities and its perspective 15 on the Department of Energy's program to manage high level 16 radioactive waste.
17 Much has changed in that period.
I recognize that 18 the makeup of the Board itself has changed considerably in 19 the last couple of years, but the makeup of the Commission 20 itself is different, and that this will be the first 21 briefing that Commissioners McGaffigan and Diaz will have 22 had with the Nuclear Waste Technical Review Board, and all 23 of us have been looking forward to it.
24 So since the last briefing, DOE has completed the 25 25-foot diameter tunnel into Yucca Mountain and DOE ANN RILEY & ASSOCIATES, LTD.
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continues to prepare a viability assessment for determining 2
the technical suitability of the_ Yucca Mountain site.
3 Here at the NRC, the staff is developing 4
site-specific regulations for Yucca Mountain and continues 5-to conduct pre-application review activities of the DOE 6
program.
7 As we are all aware, Congress currently is 8
considering legislation that could significantly alter the 9
existing high level radioactive waste program.
It is clear 10 that that program has been and continues to be in a state of 11 flux.
12 The Commission believes, therefore, that this 13 briefing is very timely is particularly interested in 14 receiving the views of the Nuclear Waste Technical Review 15 Board on the state of DOE's civilian radioactive waste 16 management program.
17 So unless my colleagues have any comments, Dr.
18 Cohon, please proceed.
19 MR. COHON:
Thank you, Chairman Jackson, 20 Commissioners.
It is a pleasure for us to be here today.
21 As you heard, my name is Jared Cohon.
I'm the 22 Chairman of the Nuclear Waste Technical Review Board.
All 23 of our members serve part-time and most of us have other 24 full-time jobs, our day jobs, as it were.
In my case, I'm 25 President of Carnegie-Mellon University and my area of ANN RILEY & ASSOCIATES, LTD.
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_ technical expertise is environmental water resource systems 2
- analysis, 3
Accompanying me are two other Board members who 4
will make part of our presentation today.
Dr. Debra Knopman 5
is Director of the Center for Innovation in the Environment 6
of the Progressive Policy Institute here in Washington.
Her 7
expertise is in hydrology, environmental and natural 8
resources policy, systems analysis, and public 9
administration.
10 Dr. Richard Parizek is a Professor of Geology and 11 Geo-Environmental Engineering at the Pennsylvania State 12 University.
His expertise is in hydrology and environmental 13 geology.
14 We will pretty much stay to the remarks that we 15 submitted to you in advance, but we may stray from them from 16 time to time, if you will permit us to do so.
We do so in 17 the name of time, in order to save plenty of time for 18 discussion.
i 19 As you noted, Chairman Jackson, it's been some i
20 time since we briefed the Commission and had the opportunity
]
21 to meet with you.
In light of that, I'd like to take a 22 moment just to acquaint the Commissioners with who the Board 23 is.
24 We were created by Congress in the 1987 amendments 25 to the Nuclear Waste Policy Act.
We were charged with 1
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'l evaluating the technical and scientific aspects of DOE's 2
high level nuclear waste management program.
This includes 3
site characterization activities at Yucca Mountain and 4
activities relating to the packaging and transport of high 5
level radioactive waste and spent nuclear fuel.
6 The Board is an independent agency within the 7
Federal Government.
We are not part of the DOE or any other 8
agency.
9 The Board is authorized to have 11 members, who 10 are nominated by the National ~ Academy of Sciences and 11 appointed by the President.
I have served as a member since 12 1995 and became the Board's third chairman last year.
13 Drs. Knopman and Parizek were two of eight new 14 members appointed to the Board last year.
With this many 15 new members joining the Board, as Chairman Jackson noted,-
16 we've had a very busy year playing catch-up and, I will tell 17 you, it's been a lot of fun.
This is a very active, dynamic 18 group, a very sharp group of members that we have.
19 Today in our prepared remarks, as indicated in-the 20 slide, which I hope will appear -- this is a test.
21-
[ Slide.]
22 MR. COHON:
As you can see, we want to emphasize 23 certain things, things that we view as key developments 24 during 1997, which will be the year that we focus on.
25 We will also briefly discuss our views of the ANN RILEY & ASSOCIATES, LTD.
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upcoming viability assessment, which we expect to be the 2
focus of much of the Board's activities throughout 1998.
3 Our presentation draws heavily on the Board's 1997 4
summary report, which we hoped would have been delivered to 5
you before now.
Unfortunately, final editing and printing 6
of the report have taken more time than we expected, but you 7
should be receiving the report within the next few days.
8 As I mentioned, we look forward to some collegial 9
discussion with the Commission at the conclusion of our 10 remarks.
11 Let me turn now to the viability assessment, which 12 the Chairman noted in her introduction.
As you know, the 13 DOE is required to provide to the Presidant and Congress a 14 viability assessment, or VA, as we_will refer to it, of the 15 Yucca Mountain site, no later than September 30 of this 16 year.
17 The VAs include the four elements shown on the 18 slide, the repository and waste package design.
I want to 19 emphasize that's both for the repository and the waste 20 package.
Total system performance assessment; a plan and a 21 cost estimate for the remaining work required to complete a 22 license application; and, an estimate of the cost of 23 constructing and operating the repository in accordance with 24 the design concept.
25 Much of the Board's activity during 1997 involved ANN RILEY & ASSOCIATES, LTD.
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preparation to review the VA, which, in light of the. Board's 2
. mission, will focus on design and performance assessment, 3
the technical issues.
4 In 1998, we will continue our preparation and we 5
look forward to reviewing the VA later this year.
6 Let me summarize for you the Board's current views 7
on the four components of the VA.
8 First of all, design.
The Board believes that the 9
design activity of the Yucca Mountain project saw several 10 major accomplishments during 1997.
They include refinement 11 of the designs for repository surface and underground 12 facilities and for the waste package, further integration of 13 spent fuel owned by the DOE into disposal plans, continuing 14 studies of criticality control issues, and improved 15 integration of engineering and performance assessment.
16 There are, however, continuing needs to adopt a 17 more robust engineered barrier system and to thoroughly 18 explore different integrated repository and waste package 19 designs that may offer the promise of better performance, 20 lower costs, reduced uncertainty, or simpler operations.
21 Let me emphasize here, we are not criticizing the 22 design that DOE has developed.
We're simply emphasizing the 23 importance of looking at alternatives.
24 With regard to reposicory surface facilities, 25 these facilities would be located on an 80-acre site at the ANN RILEY & ASSOCIATES, LTD.
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repository's north portal and would consist of more than 15 2
structures and a small rail yard.
These facilities would 3
receive waste and package that waste for disposal.
4 Except for the final closure welds and inspections 5
of the waste packages, the Board considers all of the 6
technology of the repository surface facilities to be 7
commercially demonstrated and available.
8 However, the Board does have some remaining 9
concerns about the design basis, including questions about 10 the assumed peak in placement rate, which may be 11 unrealistically high; the possibility of transferring some 12 waste packaging operations to nuclear power plant sites, 13 with potential cost savings; and, the potential benefits of 14 using multi-purpose canisters as part of the overall waste 15 management system.
16 These concerns are discussed in more detail in the 17 Board's 1997 summary report, which the Commission will be 18 receiving shortly.
19 Let me turn now to the repository underground 20 facilities.
You will see on the monitors a schematic 21 drawing of the proposed repository.
Let me take you through 22 this very quickly, just to acquaint, especially the new 23 Commissioners, with the envisioned layout.
24 First, you see the repository footprint itself.
1 25 That's it.
Excellent.
Also shown is the main access, which ANN RILEY & ASSOCIATES, LTD.
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-is the same thing as the exploratory studies facility that 2
the arrow is following right now.
This is the tunnel that 3
the Chairman referred to before, the 25-foot diameter tunnel 4
that was dug, that was completed just about one year ago.
5 This facility, the exploratory studies facility, 6
has been the crucial experimental facility for providing 7
data about the mountain at the level of the repository and, 8
in addition, as I said, it will serve as the main access, 9
one of the main access points to the repository.
10 Also shown in this diagram is the proposed ECRB 11 or, as the Board has referred to it in the past, the 12 east-west drift.
That proposed tunnel is intended to 13 actually go through rock similar to the repository block 14 itself to gain firsthand access to the environment in which 15 the waste would be placed if this repository opens.
16 DOE is now finalizing plans and starting, I 17 believe, the construction of that tunnel.
18 Finally, let me just point out the surface 19 facilities referred to earlier, shown at the north portal, 20 the beginning of the ESF.
21 By the way, this whole area is approximately 300 22 meters below the surface of the mountain.
23 Let me point out, also, that the current concept 24 is that the emplacement drifts -- that's an emplacement 25 drift.
The idea is that as these are dug, they would be ANN RILEY & ASSOCIATES, LTD.
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filled with waste and as filled, they would be closed off 2
with doors. limiting human access to them.
3 Let me turn now to the waste package.
The 4
referenced waste package design is a double-shelled 5
cylinder, nearly two meters in outside diameter and five 6
meters long, with a two-centimeter-thick inner shell of 7
corrosion-resistant alloy C-22 and a ten-centimeter-thick 8
outer shell of carbon steel, a corrosion allowance material.
9 The waste package will be emplaced on its side on 10 pedestals in the emplacement drifts.
Data obtained from the 11 exploratory studies facilities, which you just saw on the 12 slide before, within the last two years, clearly show that 13 the repository will be wetter than thought as recently as 14 just three years ago.
15 This discovery has triggered examination of 16 enhancements to the existing design.
Examples of such 17 enhancements are drip shields that keep water off the 18 packages and backfill.
The Board is particularly interested 19 in seeing studies of additional design options that might 20 include smaller shielded waste packages, a waste package 21 design using two corrosion-resistant materials rather than a 22 corrosion-resistant and corrosion-allowance material, and 23 ventilation of the repository tunnels.
24 The DOE is actively identifying and evaluating 25 enhancements to the reference design.
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that are added to or changed in the design without altering 2
the fundamental nature of the design itself.
We recommend 3
that the descriptions and approximate cost of enhancements 4
be included in the VA and that their effects on long-term 5
repository performance be included in the TSPA VA 6
sensitivity studies.
7 I am pleased now to turn the presentation over to 8
my colleague, Dr. Knopman.
9 MS, KNOPMAN:
Let me pick up the second element of 10 the viability assessment, which is the total system 11 performance assessment, or TSPA.
TSPA is the principal, but 12 not the only method of evaluating the ability of the 13 proposed repository to contain and isolate waste.
It is, of 14 course, important that we also look at solid conceptual 15 models, good data, field work, and use the TSPA, 16 particularly the sensitivity analyses, as a way'to gain 17 insight into the uncert:ainties of this program.
18 TSPA is essentially a predictive computational 19 model of repository performance over time.
DOE is charged 20 with carrying out a performance assessment that emphasizes 21 the probable behavior of the proposed repository.
22 This past year, DOE has devoted significance and 23 laudable effort to achieving the goal of a credible TSPA.
24 The emphasis on probable behaviors resulted in a division of 25 TSPA into two parts, a base case calculation and a series of
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sensitivity tests.
2 The base case concentrates on probable or expected
)
3 performance and the sensitivity studies concentrate on what 4
if scenarios for alternative parameters and design features 5
and various disruptive events, such as volcanic activity and 6
t 7
Extensive workshops have increased the interaction 8
within the program and have given the DOE substantial expert 9
input from outside the program.
These expert elicitations 10 have brought together field and laboratory scientists, 11 modelers, performance assessment experts from within the 12 program on many important topics.
13 Some of these workshops primarily from outside the 14 Yucca Mountain project have helped to better define the 15 conceptual and parameter uncertainty of the elements that go 16 into TSPA.
17 DOE also took an important step in 1997 by forming 18 an external TSPA peer review panel to delve into important 19 aspects of the TSPA VA.
The Board is very encouraged by the 20 strong and independent comments being provided by the TSPA 21 peer review panel.
22 Let me turn to the third element of VA, which is 23 the plan and cost estinates for license application.
24 The Board is going to focus its review on this 25 particular element, on the plans for an estimated cost of ANN RILEY & ASSOCIATES, LTD.
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. technical activities supporting a license application.
In 2
particular, the Board believes the data-from the new ECRB 3
program, I still want to call it the east-west crossing, and 4
other studies, among other planned studies, are vital for 5
the Secretary of Energy's decision on the suitability of 6
Yucca Mountain.
7 This decision precedes submittal of a license 8
application to the NRC.
There are many other ongoing 9
technical activities; for example, long-term corrosion test 10 program, there is what is called drift scale thermal tests, 11.
and some other additional hydrological tests and wells, and
.12 in the exploratory studies facility, that also must continue 13 to support licensing.
14 The Board is going to want to insure that those 15 activities are included in the license application plan and 16 cost estimates.
17 The fourth and final element of the VA is the
-18 repository cost estimate.
Because the Board's purview is 19 technical, we will confine our review largely to those 20 aspects of the cost estimate that involve technology 21 development.
22 For example, the Board would be interested in 23 techniques, allowances, contingencies used in the cost 24-estimate to reflect the costs of technology development and 25 to reflect current technical or engineering uncertainties.
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Another cost issue that the Board will explore is 2
how potential enhancements to the repository design that are 3
not part of the reference design case are handled.
The 4
Board was very pleased to learn that an independent review 5'
.of the cost estimate for the mined geologic disposal system 6
will be performed for the VA by a major U.S. engineering 7
construction firm.
8 It is important that the DOE clearly define for 9
the cost estimate reviewer the construction process and the 10 contracting basis that will be used to construct the 11 repository.
12 Let me turn now to a very brief discussion about 13 regulations, standards, and the environmental impact 14 statement.
15 During 1997, the Board reviewed and commented on 16 two aspects of the regulatory requirements for a geologic 17 repository; siting guidelines and DOE's interim performance 18 measure.
i 19 With regard to the siting guidelines, in April of 20 last year, the Board submitted comments on DOE's draft 21 revisions of its siting guidelines.
That's 10 CFR 960.
In 22 the draft revisions, the determination of whether the Yucca 23-Mountain site is suitable for development a repository would 24 depend no longer on several individual criteria.
- Instead, 25 DOE's draft suggested that a suitability determination would ANN RILEY & ASSOCIATES, LTD.
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be based solely on whether the repository system's both 2
natural and engineered barriers can meet a post-closure t
3 risk-based standard that will be specified by EPA.
4 In the draft revisions, DOE proposed using the 5
TSPA methodology to support this determination.
In effect, 6
the former multiple criteria standard would be integrated 7
and subrumed into a single performance standard.
8 In the Board's April letter, it indicated that the 9
proposed revisions were, in fact, a step in the right 10 direction, in our view, but the letter also expressed some 11 concern that the revised guidelines might be perceived as 12 changing the rules in the middle of the game and 13 strengthening the fears of some that performance assessment 14 may be manipulated to support any conclusion that's desired.
15 To deal with that concern, the Board offered 16 several suggestions for strengthening the proposed 17 revisions.
One, preserve the principle of defense-in-depth; 18 two, require that a repository system complies robustly with 19 the standard; three, specify the level of confidence that 20 must be reached before making a site suitability 21 determination; four, make performance assessments 22 transparent; and, five, use a public process to decide 23 whether the Yucca Mountain site is suitable.
24 With regard to DOE's interim performance measure, 25 the second regulatory issue that the Board commended on, in ANN RILEY & ASSOCIATES, LTD.
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the absence of environmental standards from EPA, the DOE has 2
developed its own interim performance measure, and this is i
3 for DOE's own use in guiding its technical program and
{
4 communicating with others about the potential performance of 5
the repository at Yucca Mountain.
6 The interim performance measure will be discarded 7
if and when EPA sets standards for Yucca Mountain.
The DOE 8
did follow the recommendations and at least take into 9
account the recommendations of the National Research 10 Council's '95 report, referred to as the technical basis for 11 Yucca Mountain standards.
12 The DOE's interim performance measure emphasizes 13 protection of individuals living within the vicinity of 14 Yucca Mountain; specifically, the annual dose to an average.
15 individual in a critical group living 20 kilometers from the 16 repository, not to exceed 25 millirems per year for 10,000 17 years.
18 Both the form of this performance measure and its 19 level of safety are similar to many other existing radiation 20 protection standards.
With one exception, from the Board's 21 point of view, this interim performance measure seems 22 appropriate for DOE's use.
The exception is the inclusion 23 of children from the definition of the critical group.
24 The Board recommended that the DOE should estimate
{
25 the disclosed likely variation in doses for alternative I
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candidate critical groups, characterized by different 2
locations, ages and lifestyles.
In particular, the Board 3
suggested the potential doses to children should be compared 4
with doses to adults within each candidate critical group.
5 I'll now turn to the environmental impact 6
statement.
Assuming that the site is determined to be 7
suitable, the DOE plans for the Secretary of Energy to 8
recommend to the President in the year 2001 that the 9
President approve Yucca Mountain as a site for a repository, 10 and that recommendation must be accompanied by an EIS.
11 Many of you know that much of the work on the EIS 12 was deferred in 1996, a response to reduced appropriations.
13 In 1997, DOE resumed work on the EIS in earnest.
14 The DOE's EIS contractor mobilized staff, 15 familiarized them with the project, as necessary, and began 16 to assemble and analyze the data.
17 In 1998, the Board will be devoting some of its 18 time to understanding the organization and content of the 19 EIS.
In particular, the Board believes the selection and 20 characterization of the no-action alternative is critical to 21 the technical success of the EIS process.
Indeed, the 22 delineation of each of the alternative actions is critical 23 to the EIS.
24 The Board strongly endorses development of 25 alternative repository and waste package designs and ANN RILEY & ASSOCIATES, LTD, Court Reporters 1250 I Street, N.W.,
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believes that the EIS process is an appropriate venue for 2
exploring these alternatives.
-- 3 Let me next turn to transportation.
During 1997, 4
the Board reviewed the transportation of spent nuclear fuel.
5 The Board's review concentrated on Federal regulations 1
6 governing the transportation of spent fuel, analyses of the 7
risks of transportation, and transportation practices and 8
experiences.
9 The Board reached three conclusions, which I will-10 just quickly highlight for you now.
The Board continues to 11 believe that the risks associated with transporting spent 12 fuel are low based on current experience.
However, if there 13 is a large increase in the scale and operational complexity, 14 as might occur when spent fuel is shipped to a repository or
~15 an interim storage' facility, a heightened safety program 16 will be needed to maintain a good safety record.
i 17 The existing capability to transport spent fuel in 18 the U.S.
Is small and much preparatory work needs to be done 19 before fuel can be transported in large quantities.
More 20 transportation casks with larger capacities are needed.
21 The transportation infrastructure at some sites 22 will need to be upgraded to allow moving heavy loads and 23 substantial institutional planning is needed.
24 Finally, the third conclusion of the Board with 25 regard to transportation is that certain measures, such as ANN RILEY & ASSOCIATES, LTD.
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the use of' dedicated trains and full-scale testing of casks, 2
may enhance the perceived level of safety.
Because the 3
risks of transporting spent fuel are low based on current 4
experience, it is unclear whether such measures would be 5
justified solely for risk reduction, but they may increase 6
confidence in the safety performance of the transportation 7
system.
8 MR. COHON:
Dr. Parizek will now continue.
9 MR. PARIZEK:
Chairman Jackson, it's an honor to 10 address the Commission.
I am on the Board for one year and 11 I think perhaps the new Commissioners struggle with catching 12 up to speed on very complicated technical issues, so we 13 share some common anxiety in this regard.
14 But I've been watching the progress of the Yucca l
15 Mountain project for a number of years and, off the record, 16 there has been a considerable effort made in the last 17 several years and the whole program has ramped up, resulting 18 in some very exciting technical findings.
19 The completion of the exploratory studies facility 20 being one point.
I think many of you may have seen a film 21 of the breaking out of the tunnel, boring machine, last 22 April, that would be on the 25th of April.
That's about a 23 five-mile long tunnel and about 26 feet in diameter, and it q
24 took achievement to complete that goal.
25 As anticipated by the Board, the excavation of ANN RILEY & ASSOCIATES, LTD.
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this tunnel provided a wealth of anticipated and 2
unanticipated data on the geological and hydrological 3
character of Yucca Mountain.
It was a very valuable 4
learning opportunity for the Yucca Mountain project in 5
performing contractor oversight, managing construction, and 6
understanding the value of seeking independent counsel from 7
construction industry experts.
8 Some of the lessons learned are listed below, one 9
being the type of construction. contract is important.
10 Underground construction worldwide uses competitive 11 processes, normally including fixed-price contracts.
12 Cost-plus contracts, such as used by DOE for the ESF, have 13 no known precedent in underground construction and probably 14 little, if_any, incentive for efficient or cost-effective 15 construction.
16 Secondly, the contractor knows how to manage risks 17 associated with equipment design and performance.
So 18 design, procurement, and disposal of construction equipment, 19 including tunnel boring machines, are normally left to the 20 construction contractor.
21 Specifications for such as the hydraulic spill 22 mitigation, dust control and safety requirements can be 23 defined and enforced without telling the contractor how to 24 accomplish those objectives.
1 25 Industry expertise is important and accessible.
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In 1995, they experienced several difficulties in excavating 2
the ESP.
DOE, in conjunction with the contractor, 3
established a consulting board.
This was largely through 4
roof falls and broken rock conditions which made the startup 5
of the tunnel difficult.
6
~This Board was very effective in achieving 7
improvements and the DOE is commended for involving outside 8
expert consultants.
9 Large diameter tunnels are more expensive and 10 time-consuming'to construct than smaller diameter tunnels.
11 The design for Yucca Mountain repository includes large, a 12 7.6 meter diameter tunneling, for service tunnels and 13 exhaust drift.
Smaller tunnels would be affected much less 14 by the highly fractured nature of the rock.
You would have 15 less risk for rock falls and require less support, and it 16 would be much more constructable than the large proposed 17 tunnel.
18 So there have been some strong views by the Board 19 on these issues.
20 The east-west tunnel is something the Board.had 21
. recommended the importance of doing some years back.
The 22 Board previously recommended this excavation at an elevation 23 at the repository level parallel to an emplacement drift, 24 and DOE decided to place the exploratory tunnel facility 25 above it and on a diagonal to it, in order to maximize ANN RILEY & ASSOCIATES, LTD.
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23 information with different rock units to be penetrated by 1
2 the tunnel and also to provide an opportunity for doing 3
experiments above the experimental tunnel facility that's 4
already there.
5 The principal focus of this tunnel would be to 6
obtain data to reduce the uncertainty of the 7
hydro-geological environmental within the repository.
The 8
DOE has accepted this recommendation in general, but has 9
expanded the scope, which is known as the enhanced 10 characterization of repository block program, which consists 11 of the tunnel and two bore holes to be drilled from the 12 surface and all excavations, including three alcoves off the 13 tunnel, will be completed by about January 1, 1999.
14 The next slide would be helpful in showing where 15 the present ESF is located.
You see in the diagram it's 16 east-west orientation and you see the north ramp, comes to 17 the point of the little round circle, having gone through 18 the Ghost Dance Fault, and then that turns southerly and 19 continues south parallel to the Ghost Dance Fault, before 20 breaking back out to the mountain on the southern ramp, 21 which you saw, I guess, the film, Breskout, pictures.
22 Above it, you'll notice the east-west tunnel rises 23 up above and continues in a southwesterly direction, J
24 penetrating the Solitario Canyon Fault on the west of the 25 block.
Again, there's the importance of knowing what the ANN RILEY & ASSOCIATES, LTD.
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rock conditions and the hydrologic conditions are like in 2
that repository environmental, because the original idea of 3
maybe you would use the block to the east of the Ghost Dance 4
Fault is not currently in the planning, as we understand it.
5 Notice that the emplacement drifts, the black line 6
is located well below the east-west tunnel.
The purpose 7
here would be to give DOE a chance to do experiments, 8
percolation type testing, to perhaps force water flow 9
between the east-west crossing in the tunnel to understand 10 better how water moves in the mountain.
11 So what we have then is this block, which, without 12 this tunnel, you wouldn't have any idea about the faults.
13 You don't see them at the surface, but if they're there, you 14 need to know about this and this is one way to learn about 15 it.
16 The Board supports a decision by DOE to excavate 17 the east-west tunnel expeditiously, although the 18 hydrological testing may not start until 1999, observations 19 and mapping and limited data on chlorine-36, which would i
20 indicate possible flow paths for water moving through the i
21 mountain, and available -- would be available ahead of the 22 VA.
I 23 This is important because the chlorine-36 is the 24 main indication of fast water flow through portions of the 25 mountain that you're familiar with.
1 l
1 1
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The thermal testing program is also in an 2
important stage right now.
One of the primary functions of 3
the ESF is to provide access to the strait in which the 1
repository is to be located and to conduct thermal testing, 4
5 especially the effects of repository heat on movement of 6
water within highly fractured and unsaturated rock.
7 The data from the thermal testing will be useful 8
for validating the various hypotheses and assumptions used 9
in developing performance models in the current repository 10 design.
11 Two tests are being conducted in ESF, a 12 single-heater test and a drift scale test.
The single-heater test has been in a cool-down phase since May 13 14 1997 and all testing was to be completed by the end of 15 January 1998.
Post-test analyses within this portion of the 16 ESF are planned and the information should be available for 17 incorporation in the viability assessment.
18 And the single-heater test is placed in the block 19 of rock surrounded by essentially tunnels on several sides, 20 and, again, it's a limited period and a limited heat source.
21 The drift scale test, on the other hand, is 22 located in a about a 156-foot long test area and it's 23 equipped with heaters that simulate the thermal conditions 24 of a waste package in a repository.
On December 3,
- 1997, 25 the heaters were turned on and data collection was begun ANN RILEY & ASSOCIATES, LTD.
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from sensors in the surrounding rock mass.
There are 2
thousands of measurement opportunities that are being taken 3
and will continue to be taken through the duration of the 4
experiment.
5 The heating phase is planned to last approximately 6
four years, with normally four years for cooling afterward.
7 The DOE is to be really complime.sted and commended on 8
implementing this extensive. and important thermal testing 9
facility.
It was ahead of schedule and required a 10 considerable effort.
11 The large block test is an additional thermal test 12 being conducted on the surface near Yucca Mountain, 13 unexcavated outcrop of welded tuft.
It was designed to 14 promote formation of reflux or heat pipe zones, as heat is 15 applied to the bottom of a large block of fractured rock.
16 The heat pipe is more or less the concept by which water '
17 flow returns back through a boiling zone as a water 18 condensing somewhere up above in an emplacement drift.
19 Water mobilizes as vapor and then is expected to 20 be driven out of the pores of the rock and to flow upward, 21 where it will condense in cooler regions of the rock.
The 22 condensate then will return as reflux to the above-boiling 23 zone.
24 On February 28, 1997, the heaters were turned on 25 and the test was nearing completion at the end of 1997.
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Our major concern would be what happens when 2
radionuclides might actually reach the water table.
In late 3
1997, the Board visited Yucca Mountain and nearby Amergosa 4
Valley for field observations about the flow of ground water 5
between Yucca Mountain and the Amergosa Valley region, how 6
ground water conditions varied in the past as the climate 7
varied and how radionuclides -- radioactive material was 8
released to ground water might in the future enter the human 9
biosphere through seeps or springs or withdrawal through 10 wells.
11 Estimates of the concentrations of radioactive 12 materials entering the environmental south of Yucca Mountain 13 repository will be highly uncertain.
14 The saturated zone is highly fractured and faulted 15 and caused ground water flow to be channelized or there's a 16 chance of having sort of like a fast-path type of flow 17 rather than kind of a diffuse mechanism of flow.
So we 18 would have this chance of having these more transmissive 19 zones.
20 Within these zones, ground water movement will be 21 faster than the. average ground water flow rate through the 22 saturated zone and retardation of radionuclides may be less 23 than average, mixing of ground water-containing 24 radionuclides and the radionuclide-free ground waters within 25 the saturated zone will dilute radionuclide concentrations, ANN RILEY & ASSOCIATES, LTD.
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but demonstrating the degree to which mixing would occur in 2
a channelized flow system may prove very difficult.
3 An important and perhaps greater source of 4
dilution may be mixing at a well head or a spring, where 5
ground water leaves an aquifer and enters the biosphere.
6 This depends on the specifics of the well withdrawal.
7 Dilution by flow and transport in the sattrated zone is 8
difficult to quantify because of its significance in 9
determining the relevant importance of different factors 10 affecting dilution and an early definition of well 11 withdrawal scenarios could provide an important focus for 12 studies at Yucca Mountain.
13 The fate of radionuclides after the end of the 14 biosphere and as they enter food chains and potentially 15 cause radiation doses to humans must be projected.
The use 16 of generic data and models of the transfer of radionuclides 17 through the food chains may cause large uncertainties in 18 estimating radiation doses, perhaps as much as three or four 19 ordere of magnitude.
20 Part of this is the specific nature of conditions 21 at the site.
With that climate, it may make the pickup of 22-radionuclides different than what might appear in the 23 standard data tables that support this.
24 Thank you.
25 MR. COHON:
Thank you, Dr. Parizek.
I have one ANN RILEY & ASSOCIATES, LTD.
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last issue that I would like to cover in our prepared 2
statement, and that is the use of experts from outside of 3
the DOE, an important topic, we think, and one that we know 4
that the NRC has focused on in the past.
5 The DOE is to be commended, as you heard already, 6
especially from Dr. Knopman, in their stepped-up and 7
effective use of experts from outside of DOE.
8 They have two very important standing panels that 9
they have used extensively; the TSPA peer review panel, 10 which has been very active recently, and the mine geologic 11 disposal system consulting board, which has been very 12 effective, first, in the completion of the ESF and, more 13 recently, in planning for the ECRB.
14 In addition, the DOE has become more active and 15 very extensively so in the last two or three years in the 16 use of experts who are not part of one of these existing 17 panels, but from whom opinions are sought in a formal 18 process.
19 This seems to have worked very well.
We, the 20 Board, consider this to be an important activity for DOE, 21 especially in areas where there is great uncertainty, which 22 is to say much of what they're working on in Yucca Mountain, 23 and before all of the relevant data can be in hand, which is 24 also much of what they're working on at Yucca Mountain.
25 Some notable examples of successful application of ANN RILEY & ASSOCIATES, LTD.
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successful use of outside experts are in estimating seismic 2
and volcanic hazards, unsaturated zone and saturated zone 3
flow, and waste package degradation.
4 The Board has pointed out and I want to emphasize 5
today that there are continuing issues that the DOE must 6
deal with in the use of these outside experts.
In 7
particular, we remain concerned about those situations where 8
there are very few experts and those experts sharply 9
disagree.
This is a difficult problem, certainly not unique 10 to DOE's use of experts or, of course, to Yucca Mountain, 11 but nevertheless a problem that must be dealt with if their 12 information is to be used effectively.
13 Let me conclude by saying that, as I said at tMe 14 beginning, this has been a very busy and eventful year, both 15 for the Board and for the program at DOE, and, if anything, 16 the future seems even more eventful, as we look forward.
17 As we know, the VA will be issued later this year, 18 a time when the Board will be expected to comment, and that 19 will be a key milestone as DOE moves to siteability 20 determination approximately in the year 2001 and all that 21 comes after that.
22 That concludes our remarks.
We look forward to 23 your questions.
Thank you, Chairman.
24 CHAIRMAN JACKSON:
Thank you.
Let me begin by 25 asking you a couple of questions and I'm going to wade right ANN RILEY & ASSOCIATES, LTD.
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in to a couple of quasi-controversial topics.
2 Given what you talked about vis-a-vis the 3
possibility or likelihood of channelized flow, with possibly 4
limiting dilution and retardation, possible dilution as the 5
water is withdrawn, perhaps via well, does the Board have a 6
view on what that might -- whether that necessitates having 7
a separate ground water protection standard?
8 MR. COHON:
You did say you wanted to get right to 9
controversial issues.
l 10 CHAIRMAN JACKSON:
Right.
11 MR. COHON:
And congratulations, Chairman Jackson, 12 you did just that.
Do either of my colleagues want to take 13 this one to start?
14 MS. KNOPMAN:
Why don't you start?
15 MR. COHON:
Now we know it's controversial.
They 16 refused.
17 Indeed, this a very sensitive topic, sensitive in 18 the sense of having big impact on the estimates for probable 19 doses.
As the Chairman pointed out, there are two key ways 20 in which dilution may occur.
One is in the saturated zone 21 that is below the water table after the waste migrates to 22 that point and then when the water is withdrawn.
Dr.
23 Parizek referred to these, as well.
24 On the first point, while we have heard what we 25
~have listened to the experts say, and this was a case where ANN RILEY & ASSOCIATES, LTD.
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DOE appealed to outside experts and they had superb people, 2
by the way, on their expert panel.
Where the experts felt
.3 there was considerable uncertainty about the effect of 4
dilution in the saturated zone, that, if anything, they felt 5
it was more probable that significance dilution would not 6
occur.
Channelization would occur, as you said.
7 That we should expect the plume to stay fairly 8
much intact rather than spreading out greatly.
That's their 9
expectation.
10 Dilution at a well head offers -- could be very 11' large.
I guess the big difficulty here is whether one can 12 count on that.
It is possible to sink a well and take water 13 just from one strata and, therefore, get no dilution, no 14 significance dilution.
That may be a low probability event, 15 but it's possible.
I think the key question, of course, 16 will be, as the Chairman put it, what the standard says.
17 Now, colleagues, do you want to expand or subtract 18 from what I said?
19 MS. KNOPMAN:
No.
You did an excellent job.
I 20 would just add that in thinking about these different well 21 withdrawal scenarios, you could get the substantially 22 different result if you were, say, looking at a well field 23 rather than an individual well and you were looking at total 24 pumping rate from a well field, let's say a water company, 25 and then the mixing of all those waters prior to delivery to ANN RILEY & ASSOCIATES, LTD.
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the population.
2 That would produce a different, substantially 3
different dilution than what would get from looking simply 4
at single-well withdrawals that either may intercept 5
multiple layers, in which case you could get substantial 6
dilution, or a single layer at a direct hit rate into the 7
center line of a plume.
8 So there is tremendous variation within the well 9
withdrawal scenarios from the kind of result that you might 10
-- the kind of dose that you might be delivering to the 11 population.
12 MR. PARIZEK:
I have a feeling that the ground 13 water is a part of a system and even if you didn't want to 14 take any credit for the ground water system by saying 15 nothing can be released to the water table below the site, 16 you lose some sense of reality.
17 Materials in time do reach the water table.
There 18 can be some forgiveness there.
There are faults and there 19 are fracture zones, but not all of the rock mass is 20 necessarily that way and a certain amount of the flow paths 21 from the unsaturated zone reach the rock mass behow and 22 there would be a tie-up or hold-back of some portion of the 23 water.
24 The question-is what percentage of that would be 25 in the dif fuse part of the system a.nd what portion in the ANN RILEY & ASSOCIATES, LTD.
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fast-path part.
- l 2
So the idea is that there would be some
- 3 retardation.
There is bound to be some' diffusion and matrix 4
diffusion from the fracture. zones and fault zones, and there 1
5
-could be' benefit.
6 There is also alluvium, which is present to the 7
south of-the site, the exact location of where the saturated 8
zone alluvium versus bedrock occurs.
It's not too well 9
.known.
It's an area generally of data deficiency.
But 10 alluvium would give us a slowing down of the flow rates, 11 much higher chance for retardation than might be possible in-12 the fractured rock.
So'there's benefits to be received 13 there.
14 On the other hand, to say that you will base all 15 of it on dilution to protect the human health, maybe at that
,16 point, if dilution of the well head is_your last part of the 17 calculation perhaps, you hit some credit, but it makes a 18 difference whether there's one well or groups of wells or a 19 large well field.
That's a future that may be a little bit 20 hard to characterize.
21 So I say you should give some credit to the ground 22 water system.
More can be learned about the ground water 23 system and more is underway to be learned about it by some
'24 of the deep drilling that's being planned, is underway at 25 the Yucca Mountain site.
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CHAIRMAN JACKSON:
Are you looking at or do you 2
feel that DOE needs to look at, for lack of a better
.3 terminology, whether it makes any sense to talk about 4
institutionally controlled use in design?
5 MR. COHON:
Institutional control of the water, is 6
that what you're talking about?
7 CHAIRMAN JACKSON:
Let me make sure I make myself 8
clear.
Just as you talk about engineered barriers, you 9
raised -- you said the key question is what the standard 10 says, but leading up to that, can one count on dilution at 11 the well head and there is one way one could answer that 12 within the context of -- or try to answer it probably using 13 expert opinion or judgment.
14 There is one way one can try to get at that 15 vis-A-vis coming at some best estimate of what the natural 16 environmental would allow or suggest and to what extent one 17 could make some predictive statement down the line.
18 The second part of it that this flows into, but 19 not unlike the whole issue of engineered barriers is to what 20 extent can one -- or does it make sense to talk along that 21 line, design in institutional controls?
Because if you're 22 talking looking down the line, the issue of institutional 23 controls in terms of organized society is something that you 24 can't talk about.
25 MR. COHON:
Right.
Chairman Jackson, I remember ANN RILEY & ASSOCIATES, LTD.
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. vividly appearing at the House hearing on the legislation, 2
on a panel with you, and a member of the committee asked the 3
question that was not unlike this, though he was looking in 4
the future.
5 He was talking about human intrusion into the 6
repository, which has always been a very difficult issue to 7
deal with.
And what I said then, which I'm not sure if it 8
came back to haunt me or not, but it still might, was that 9
based on the study by the other NRC, that we basically 10 considered those kinds of issues not tractable or not 11 ponderable, things that were beyond us.
12 Now, I wonder if the issue the Chairman has raised 13 would fall under that.
Can one say with any confidence that 14 if water is developed a thousand years from now, it will be 15 managed by a water company managing a whole well field and, 16 therefore, getting maximum benefit from doing that, if there 17 is any contamination.
I don't know.
18 MS. KNOPMAN:
The Board is agnostic at this point 19 as to whether well withdrawal is the appropriate one to use 20 in the regulatory context.
Our concern is the predictive 21 capability of the models that might be used as a basis for 22 making any fu'rther predictions about the dilution at the 23 well head and right now the models, saturated zone modeling 24 effort is -- also pardon the pun -- in flux and is not at a 25
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capability.
2 So that's where our concern is right now as to how 3
to improve that capability.
4 CHAIRMAN JACKSON:
Because I think you hit it on a 5
few sentences ago, and that is, you know, what is 6
appropriate or what do you need to decide what is-7.
appropriate in a regulatory context, because that's kind of 8
where the rubber meets the road for us.
9 Let me go on and ask controversial question area 10 number two.
I.had a question for you which went like this; 11 to what extent is the DOE program focused on the most 12 important issues related to the overall performance of the 13 repository?
And, of course, so as to have full disclosure, 14 you mentioned things like the various thermal tests and, 15 related to that, hydrologic studies.
16 In fact, I've just happened in the past couple of 17 months to be out and I've looked at the large block path 18 heater, the drift heated test and so forth.
19 But the real question becomes -- we, of course, 20 have this -- and I don't mean for you to give a definitive i
21 answer.
I'm more interested in where your thinking is 22 going.
23 Were you surprised by the article in Scien'ce and 24 what it suggests about the volcanism and to what extent do 25 you feel DOE is giving attention in that area and has your ANN RILEY & ASSOCIATES, LTD.
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opinion in that regard changed vis-A-vis the recent Science 2
Journal article?
3 MR. COHON:
Let me say, first of all, as a general 4
matter, that I believe the program right now is much more 5
focused and effectively so than it was just two years ago 6
and much, much more than it was five years ago, as it should 7
be.
8 I think DOE deserves a lot of credit for having 9
been able to go from basically a science program to 10 something really focused on the question, is this site 11 suitable.
I think we need to keep that in mind.
12 As a Board, we have been asking ourselves just 13 this question, Chairman Jackson; that is, how much more 14 should the program be focused, recognizing that if the 15 program sticks to schedule, there's really very little time 16 left between now and the point where they are likely to 17 recommend to the President that the site be found suitable, 18 and then come to you to apply for a license.
19 In light of that, the DOE needs to be very 20 efficient and use its very limited resources in the most 21 efficient and effective way possible.
22 We are, within the Board and working with DOE, 23 trying to develop our own understanding of what that might 24 be, how much more focused can the program become, and the 25 key here, of course, is identifying the key uncertainties ANN RILEY & ASSOCIATES, LTD.
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that will remain after VA and to focus resources on 2
resolving those uncertainties that can be resolved or can be 3
reduced.
Resolving them is probably too strong a word, but 4
can be significantly reduced between VA in the time that 5
suitability is determined.
6 We are not surprised to here about -- we are not 7
surprised by the Science article.
We've been aware of that 8
research for some time and have been tracking it.
We may be 9
a little more surprised by the press reports of the Science 10 article, which is, of course, a different matter.
11 CHAIRMAN JACKSON:
Come work with us.
You get a 12 lot of press reports.
13 MR. COHON:
That's right.
Now, I don't have the 14 exact date, but I believe^that there is a meeting coming up 15 in the next month or so.
Does someone know, offhand?
16 MS. KNOPMAN:
Seismic hazard assessment.
17 MR. COHON:
I'm sorry.
But there is a meeting 18 coming up where this will be looked at more carefully.
19 In particular, understanding the uncertainties 20 associated with the data itself that's reported on in 21 Science and then trying to understand what the implications j
22 of that might be for seismicity or other activity.
23 MS. KNOPMAN:
Can I just add a little bit to that?
24 CHAIRMAN JACKSON:
Please.
25 MS. KNOPMAN:
This is an area of the seismic and ANN RILEY & ASSOCIATES, LTD.
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volcanic hazards where DOE did seek out outside experts and 2
it's been -- that group has been meeting for quite some time 3
and, in fact, probably did better at coming to closure than 4
some of the other groups.
So I don't think this was a 5
surprise to the program.
6 You raised the question about what's important 7
here and how does -- is the program focusing on what's 8
important, and the Board, just to give you a flavor of where 9
the Board's thinking is.
10 When you get right down to it, what we're talking 11
-- what we're most interested in is what the near-field 12 environmental is for those waste packages, and that means 13 understanding the water, water flow in and out, and what's 14 happening in terms of the conditions in which the canisters 15 are going to be. subjected.
16 I think the program has, because of the use of the 17 outside experts, there is actually a specific panel, expert 18 elicitation panel that's been convened specifically on the 19 near-field environmental and I think the department is
)
20 getting to that focus and that's also, I think, one of the 21 indicators of how TSPA can be used productively to get 22 through sensitivity analyses, to get to the heart of what's 23 really driving the system.
24 So I think they're getting there.
25 MR. PARIZEK:
I would say the same.
DOE has ANN RILEY & ASSOCIATES, LTD.
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received a lot of recommendations for the need of follow-up 2
studies to reduce uncertainty in time for, say, an LA and 3
this list comes from the expert station panels, it comes 4
from the NRC through the interaction that you have with DOE, 5
and it also comes from the Board.
6 The key thing is not to let those programs die 7
just because it looks like a shopping list for more science.
8 And if you had asked the program ten years ago what was a 9
good list, it would have been a long list.
Today it's a 10 much more focused list, but it's an urgent list.
11 And to come before a Commission with a license 12 application, I maintain you have to have good science and 13 good engineering to justify your recommendations.
14 Otherwise, you will perhaps deny and there will be delays in 15 the program and credibility shrinks.
16 I think it's quite urgent to make sure we track 17 the remaining the studies that must be conducted, make sure 18 that they are conducted, and funding is provided to see this 19 through.
Congress has cut the program, but you can't cut it 20 very much more before the science may drop.
And this has to 21 do with material science, the new areas that are being 22 talked about.
23 There is a short period of record there.
Judges 24 often feel insecure about our record, but we have analogs, 25 natural analogs to draw from.
The materials people maybe ANN RILEY & ASSOCIATES, LTD.
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lack some of that same sort of thing.
So this 2
experimentation has to be done on the corrosion processes 3
and better understand that whole thing, because we put a lot 4
of faith on a robust barrier, the engineered barrier, but we
.5 got to make sure it's going to work.
6 So I think keep the science alive and the 7
engineering work going right to the LA deadline.
8 CHAIRMAN JACKSON:
I'll make a comment in lieu of 9
a question.
I remember when I visited Yucca Mountain two 10 years ago and then, of course, I've visited again more 11 recently, there was a concern here on the science and the 12 issue is how do you keep the focus in the right technical 13 areas, but integrating them so it's not just a giant, 14 multi-part research program as opposed to one that has the 15 appropriate program integration, driving to understanding 16 the features most important to repository operation and 17 safety.
18 And so the question -- so I assume that that's 19 something that the Board keeps a focus on.
20 So let me just ask one last question and then I'm 21 going to turn it over to my colleagues.
22 I note that the Board has urged DOE to consider 23 including alternative design concepts into the viability 24 assessment, and you mentioned that in your remarks.
25 The question is, do you know if the DOE is doing ANN RILEY & ASSOCIATES, LTD.
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.s 1
this and what level of detail are you really looking to see 2
in the viability assessment with respect to this?
3 MR. COHON:
We believe they are.
Well, we know 4
t h e y a r,.t.
They are looking at alternative designs.
We do 5
not believe that they need to be looked at in great detail 6
or developed in great detail for the VA.
In fact, it 7
probably is not a good idea, given the limited time and 8
limited resources, and they do need to develop the reference 9
design, the base case as fully as possible.
.10 Our strong recommendation that they consider 11 alternatives is so that thinking about the limited time that 12 remains after VA, if we stick to cchedule, we fear that the 13 program might be get locked into a particular design and 14 find it difficult to think outside of the box of that 15 particular design.
16 That's why we have been pushing alternatives so 17 hard.
18 CHAIRMAN JACKSON:
All right.
19 MR. COHON:
There are also EIS implications 20 potentially as well.
21 CHAIRMAN JACKSON:
That's right.
Commissioner 22 Dicus.
23 COMMISSIONER DICUS:
You mentioned the TSPA peer 24 review panel that DOE formed last year and I think you 25 mentioned that you were encouraged by the rather strong ANN RILEY & ASSOCIATES, LTD.
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1 independent comments that were coming from that panel.
2 Could you characterize those just a little bit 3
more, particularly more significant comments regarding the 4
TSPA?
5 MS. KNOPMAN:
As you know, the TSPA is a -- takes 6
results that have been generated from fairly complex 7
physical models, mathematical models representing physical 8
processes, and so the TSPA modeling process is but another 9
level of abstraction from the underlying mathematical 10 modeling.
And there is a lot that can -- there is a lot 11 going on there, a lot of assumptions embedded in that.
12 The concern of the peer review group has been as 13 it has been for the Board, is how much -- by the time you 14 get to TSPA, results have been grounded in reality, with 15 real data and some kind of field experience to really back 16 that up.
17 So the peer review panel, the TSPA peer review 18 panel went into some depth about concerns of lack of data
- 9 and justification for using certain model forms in TSPA.
20 I don't know if you want to elaborate on that.
Il MR. PARIZEK:
It continues, I think, with Chairman 22 Jackson's comment about the focus.
I think when you run a 23-TSPA and sees what seems to drive a system, the so-called 24 sensitivity analysis part of the what-ifs part, you begin j
25 seeing what are the critical portions of the system that ANN RILEY & ASSOCIATES, LTD.
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need further work, like the climate effects.
2 Clearly, that's a driving variable.
So one has to 3
deal with that-HIf corrosion is one, you've got to deal 4
with that.
So whatever the outcome of this next_go-around 5-is that's issued this fall, you will have a clearer picture 6
of where the study needs are.
7-The question is can you fill the gaps in the time 8
period between then and LA.
In terms of like-reaching the 9
ground water modeling, there are vast areas of areas south 10 of Yucca Mountain with no well control.
As a result, it is 11 somewhat speculative exactly what rocks are -- hydrological 12 conditions occur there.
i 13 And then the question is how much credit would you 14 want to assign to the ground water rule anyhow.
Maybe you 15 can get a lot more credit out of a canister and'say go with 16 the canister part.
But all of these pieces have to somehow L
17 f't'together and I think when you're running the TSPA, you 18 begin finding out how much credit you can get for each part 19 of it as we understand at this point in time.
20 CHAIRMAN' JACKSON:
So you're' thinking of the TSPA 21 itself as a manager.
22 MR. PARIZEK:
Yes, it is.
It's a question of 23
'whether the managers now use it that way, which was your 24 question.
The program seems to have gotten more focused in 25 recent years than it used to be in terms of grabbing onto ANN RILEY & ASSOCIATES, LTD.
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critical parts of the story, as I see it.
2 Again, maybe I've missed the point, but TSPA is an 3
education to all of us and you can't tell what the outcome 4
is going to be until you finally run it and then it has 5
uncertainties with it.
So what we want is to make sure we 6
can shore up all of the areas where you don't feel 7
comfortable, make sure the next go-around is going to be as 8
thorough and complete as it can be.
9 A lot has been learned at Yucca Mountain since the 10 early da'rs of that program and, again, there is ramping up 11 at a rapid rate.
There is very good information coming in 12 that we wouldn't have had only a few years ago, part of it 13 with the tunnels, part of it with experiments that are 14 coming to maturity.
15 COMMISSIONER DICUS:
Let me ask you a process 16 question, too.
Given the fact that the Board has 11 members 17 and you have somewhat similar and also maybe differing 18 expertise, but how -- it's sort of a question about how you 19 arrive at your decisions, but more importantly, how have you 20 handled divergent opinions and how will those come forward?
21 MR. COHON:
Well, it's not a very pretty sight, 22 Commissioner Dicus.
23 COMMISSIONER DICUS:
Like sausage being made.
24 MR. COHON:
That's right.
I didn't say that, but 25 you did.
We -- the Board works hard to attain consensus on i
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all major issues, all major positions that the Board adopts 2
and before we communicate that to DOE.
3 We will vote on occasion, vote for our record, 4
which is to say the public record, but generally we are able 5
to reach consensus, and that means a lot of compromise and 6
discussion about wording and positions about things.
7 Our meetings can get long.
They are usually not 8
very contentious.
It's quite a remarkable collection of 9
people.
They are very, very good at working together and 10 seeking that common ground.
11 I think, based on some recent meetings we've had 12 which could have been very contentious given the issues we 13 were discussing, that the Board -- the individual members 14 enjoy interacting with each other very much and realize that 15 they learn a great deal from that.
16 Let me correct one possible misconception.
You 17 happen to be looking at the three people with some water in 18 their backgrounds.
The other eight members don't.
So, in 19 fact, we're quite diverse in our backgrounds and what we 20 bring to the Board, and that helps, as well.
So we learn a 21 great deal from each other because they are experts in 22 something I'm not, and we listen carefully to each other, 23 learn, and then generally arrive at consensus.
24 So far, so good.
25 MR. PARIZEK:
Could I add a remark?
And that's ANN RILEY & ASSOCIATES, LTD.
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the role of the staff.
It is a very dedicated, very 2
competent staff that keeps an awful lot of this history 3
going for us, because as new members coming in, there is no q
4 way you can get up to speed on all these activities.
All
)
I 5
the expert panel meetings, usually three of them for each l
6 panel, many panels, you can't monitor those activities and I
7 keep track of the literature and so on.
i
\\
8 So the staff brings an awful lot to the table to 9
help get us into an understanding of the issues.
That 10 doesn't mean that we buy off on that, but at least it sets 11 it up for us in a way that we're not having to start from 12 ground zero and trying to invent all of this material 13 ourselves.
14 With that, it would be almost impossible because 15 we all have other full-time jobs and there's not enough of 16 us to get this job done, the Commission knows the problem of 17 having a limited number of. people with a big assignment.
18 MR. COHON:
Just to pick up on one thing that Dr.
19 Parizek just said, because it will help understanding our 20 process.
He made reference to panels.
The Board organized 21
-- organizes itself into five panels, each with five Board 22 members on it, and these are panels that are devoted to 23 specific aspects of the repository problems.
24 Those panels generally take on the leadership on 25 particular issues and do the work outside of our Board ANN RILEY & ASSOCIATES, LTD.
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meetings and then inform the rest of the Board members when 2
we come back together.
3 CHAIRMAN JACKSON:
Commissioner Diaz.
4 COMMISSIONER DIAZ:
I'd like to say that I have 5
maintained a very open mind on the issues of Yucca Mountain 6
by staying ignorant about it and for having a very wide 7
gradient between ignorance and expertise when we get to 8
doing stuff.
9 But I was listening to you and was interested in 10 the drift between science and application and, of course, 11 science never ends and sometimes we like to keep it going.
12 But scientific applications have to end and, in this case, 13 there are some particular date lines and deadlines that have 14 to apply and then closure to the VA is important and closure 15 to the LA is important.
16 Thinking on the terms that scientific 17 applications, engineering and technology and they have to be 18 closed, do you see any show-stoppers for actually preventing 19 this repository to becoming reality?
20 MR. COHON:
No.
I don't believe the Board has 21 seen any show-stoppers.
22 COMMISSIONER DIAZ:
All right.
Going back now and 23 retreating to the fact that I am more of an engineer than 24 anything else, going back to the engineered barriers, I was 25 particularly interested in the Board interest in the ANN RILEY & ASSOCIATES, LTD.
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engineered barriers.
2 There are essentially three issues; small waste 3
packages, waste packages with two corrosion-resistant, And 4
ventilation of the repository tunnel.
I was having a 5
problem fitting these things together.
6 When you actually make sma]ler packages, you 7
increase the surface significantly, which gives you an 8
additional potential corrosion problem, snd, of course, it 9
increases cost.
10 It'might be better and easier to handle, but it's
-11 certainly an issue.
I don't see how it combines by putting 12 two corrosion-resistant materials in the package because if 13 you tried to make them smaller, then that becomes more of a 14 problem.
You are actually increasing the actual cost of it.
15 Of course, I guess ventilation of the tunnel is 16 because you're trying to get humidity out of it?
17 MR. COHON:
Exactly right.
18 COMMISSIONER DIAZ:
But that also increases some 19 of the other issues that are -- and I'm very ignorant about 20 this, but you know we always worried when things have higher 21 temperature and places with higher temperatures tend to 22 carry materials away to the lower temperatures.
23 I was wondering whether isolation was part of the 24 design.
So I was having a little problem in '. coking at the 25 three of them interacting together, especially looking at ANN RILEY & ASSOCIATES, LTD.
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closure, resources, and the conditions that were to be 2
specified.
3 MR. COHON:
You should come and spend some time 4
with the Board.
We would enjoy it very much.
This is 5
exactly the kind of thing we hope that DOE will take on.
6 COMMISSIONER DIAZ:
I see.
7 MR. COHON:
And the key is to view the system as a 8
system.
Now, in this case, these three alternatives that we 9
identified that you picked up on are distinct from each 10 other.
We're not saying smaller packages and two 11 corrosion-resistant and ventilation.
These are just three 12 separate, but if you did them all, obviously, interacting, 13 things one might try.
14 Your analysis of each is very good.
But let me 15 put out one thing that might help you because you're new to 16 Yucca Mountain and we're happy for you being new to Yucca 17 Mountain.
18 The whole idea, water is the big issue, as you 19 heard and as you know.
Water is the big issue because of 20 the impact on the waste packages.
So the argument for 21 ventilation is to keep the tunnels and emplacement drifts as 22 dry as possible for as long as possible, so as to the reduce 23 the probability of corrosion.
That's the whole argument.
24 So it's the life of the package which is driving 25 this and that's related to water.
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COMMISSIONER DIAZ:
But I have a problem, and I'm 2
not a water expert, but every time you remove water, you're 3
actually increasing some process in looking at pressure and 4
now you're decreasing the pressure, so you're attracting 5
more water, if the water is getting there.
6 Sometimes what we'd want to do is we'd want to 7
keep the concentration high.
I don't know --
8 MR. COHON.:
This is the key point that I want to 9
make.
There is an assumption -- not an assumption.
There 10 is -- the way we understand the problem, and that's the big 11 we, not just the Board, is that the y thing is keeping 12 those packages intact as long as possible.
13 So the issue is not -- during the first part of 14-the life of this repository, the issue is not so much 15 migration of waste away from the tunnels, but rather keeping 16 those packages intact because if they're intact, you don't 17 have anything to worry about.
18 So that's the idea.
That's what drives it all.
19 So we're not so worried early on about gradients that are 20 created because we're assuming that the packages will be 21 intact and, therefore, nothing is going to be moving -- no 22 waste will be moving out of the drifts anyhow.
23 COMMISSIONER DIAZ:
Water will be moving in.
24 That's why we got three. water experts today.
25 MR. COHON:
That's the whole purpose of these-ANN RILEY & ASSOCIATES, LTD.
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thermal tests.
Do you want to say something about that?
2 MR. PARIZEK:
The whole idea of of a hot waste 3
package if you go with a hot repository is it boils the 4
water out and does so for a prolonged period of time.
Part 5
of the problem is where does the water go you boil out.
6 It's going to condense somewhere and will want to come back 1
7 to haunt you, perhaps right back in some of the emplacement 8'
drifts.
9 So as an example, getting on with the engineering 10 decision, if you can't decide and the experiments can't be 11 run long enough to know what happens to this refluxed water, 12 the choice'might be to consider an alternative design, as 13 suggested by the Board, have a cold repository, in which 14 case you don't have to deal with this reflecting issue.
15 Maybe you won't solve that problem, but, 16 nevertheless, right now, if you go into Yucca Mountain, you 17 never did see a drop of water falling in one you any place.
18 That doesn't mean it might not be doing that, because you 19 have the chlorine-36 data showing that somewhere in the last 20 50 years water got to those depths, but the fact that it's 21 ventilated means that it keeps it dry.
22 Under the present environment, you could sit in 23 there and not rust yourself, I suppose, for some number of 24 years.
We haven't had as much time as possible into the 25 future, when the canister hasn't yet been asked to do ANN RILEY & ASSOCIATES, LTD.
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anything.
It's sitting there waiting for the first arrival 2
of water, sometime in the distant future.
3 And the moisture would be driven out because of 4
the heat source that the warmer packages or the hot packages 5
bring into the mountain.
6 So that was part of the idea of the ventilation 7
concept.
Again, if it doesn't calculate out to be suitable, 8
you might drop it from the thinking.
But right now it would 9-buy time for canisters, and that's part of the game -- get 10 the longest life you can out of your waste package before it 11 has to finally resist a corrosion problem.
12 CHAIRMAN JACKSON:
Thank you.
Commissioner 13 McGaffigan.
14 COMMISSIONER McGAFFIGAN:
I'm going to go back to 15 the Chairman's first line of questioning just for a little 16 bit. On page 7 of your statement, there was a -- you talked 17 about them being on the right track with their siting 18 guidelines and meeting a post-closure risk-based standard, 19 but then you put some provisos in and one was that you 20 require the repository system complies robustly with the 21 standard.
22 Can you define the adverb " robustly?"
23 MS. KNOPMAN:
We're working on that.
24 COMMISSIONER McGAl'FIGAN:
I mean, I can turn a 25 25-millirem standard into a.25 millirem standard as ANN RILEY & ASSOCIATES, LTD.
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robustly,fthat means a factor of a hundred, or does robustly 2
mean a factor of 20 percent.
In order of magnitude, do you 3
know what robustly means?
4 MR. COHON:
No.
We have not quantified it and I 5
don't know that it's quantifiable until the standard is 6
quantified and we have an understanding, in a quantitative 7
sense, of the uncertainties surrounding it.
8 COMMISSIONER McGAFFIGAN:
That's the great 9
let's stay on that thought.
At the moment, they're working, 10 as you say later on that page,. on a 25 millirem all pathways 11 standard, which is to an average member of a critical group,
{
12 and I think ICRP recently suggested 30, but 30 and 25 are 13 essentially equivalent, especially if we're dealing with 14 adverbs like robustly.
15 But if you hypothesize -- I don't know how much 16 the group is familiar with WIPP and whether you've looked at
]
17 the WIPP situation, but at WIPP, the EPA has a standard that 18 includes a ground water MCL standard and it's been salt and 19 it's been stable for 250 million years and it's probably 1
20 going to be stable for 250 million more.
So WIPP will pass 21 whatever standard is imposed, I suspect.
4 22 But have you done any thinking about an MCL 23 standard which, using the current MCLs, which are not 24 risk-based and which go as low as.06 millirem for 25 strontium-90, et cetera, have you looked at whether Yucca ANN RILEY & ASSOCIATES, LTD.
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Mountain could possibly pass robustly a standard that 2
included ground water MCLs?
q i
3 MR. COHON:
No.
We talk about this all the time, 4
but it's -- I'm not sure -- well, I better be careful about 5
going too far with this.
What I'm about to say is one 6
person's view.
I am not speaking for the Board here, but 7
1/11th of the Board.
8 I think it's really too soon to say whether Yucca 9
Mountain could meet a ground water standard robustly, even 10 without a definition of the word robust, and I say that 11 because we're still trying to understand what the 12 uncertainties are.
I think we now know what the key 13 uncertainties are; that is, where they will come from.
14 But I don't think we know yet -- I don't know yet, 15 maybe DOE knows now, how big those are.
16 COMMISSIONER McGAFFIGAN:
That's my next question.
17 Later, on page 12, you say those uncertainties could be 18 three to four orders of magnitude.
19 MR. COHON:
Yes.
20 COMMISSIONER McGAFFIGAN:
So if I'm now dealing 21 with something -- and let's say we' e going to be robustly 22 trying to meet a standard and conservative with 23 defense-in-depth is another principle.
And I add all that 24 up, I may now have a.001 millirem standard for ground 25 water.
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De facto, can Yucca Mountain -- can a non-salt 2
formation meet-that sort of standard?
3 MR. COHON:
Time will tell.
Do I think salt is 4
more robust?
Yes.
Do I think WIPP is more robust?
Yes.
~
5 But that's with still not mature knowledge about Yucca G
Mountain.
We still have a way to go.
I don't think we'll 7
know at VA, again, one person's opinion.
8 COMMISSIONER McGAFFIGAN:
Could DOE even do the 9
calculations required at this point, given that they've been 10 focused on the 25 millirem all pathways standard in time for 11 VA, if EPA were to propound a standard not dissimilar from 12 WIPP's standard?
13 MR. COHON:
Could DOE do the calculations?
14 COMMISSIONER McGAFFIGAN:
Could they do the 15 calculations?
16 MR. COHON:
Sure.
17 COMMISSIONER McGAFFIGAN:
With dealing with all 18 these uncertainties?
19 MR. COHON:
Yes.
TSPA could do that now, j
i 20 MS. KNOPMAN:
You need to show them uncertainty.
)
21 MR. COHON:
Exactly right.
They key thing would 22 be what the uncertainty related with that, what that
)
23 demonstration would be.
That's where we come back to 24 robustly.
That's why we used the word.
We know it's vague, 25 but we think it captures the key point here.
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I think the Board feels confident that you could 2
show the repository to meet a standard of the sort that we 3
expect will come out, but the key question will be the 4
uncertainty surrounding that, the uncertainty surrounding 5
the probability with which the standard will be met.
If I 6
said that right.
7 MR. PARIZEK:
Could I have a clarification of 8
whether you're saying at the repository, below the 9
footprint?
10 COMMISSIONER McGAFFIGAN:
I'll take 20 kilometers.
11 At the repository, at the footprint, I would assume it's 12 absolutely hopeless.
13 MR. PARIZEK:
I didn't know where your fence, 14 because certainly WIPP is not a good example for us to be 15 emulating.
You've got the Bell Canyon, which has got a 16 brine that nobody wants to drink and it's got two dolomites, 17 which have salty water right above the repository.
Nobody 18
'really almost wants to drink.
Some people say they have 19 used that water.
So that's a little bit different; the 20 water could be there, but nobody drinking it.
21 Your question is whether you could get anything to 22 those aquifers, even if you could.
23 MR. COHON:
It will depend very much on what 24 happens in the saturated zone and what assumptions are made 25 about dilution in pumping, as Chairman Jackson was d
1 ANN RILEY & ASSOCIATES, LTD.
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suggesting.
2.
MS. KNOPMAN:
If I can just put my two cents in 3
here.
Where the Board has put its effort is in wrestling 4
with the question of technical defensibility, so that when 5
DOE comes forward with an estimate of whether or not it can 6
meet a proposed standard, has it done so with a set of 7
assumptions and data and a scientific community consensus 8
behind it, that it is a credible assessment, even with 9
uncertainties attached, but, nonetheless, credible.
10 So this is the tough part of figuring out whether 11 these many models that have been developed do have some 12 bearing on reality.
Sure, they can show something.
It's a 13 question of whether they're showing what we think is 14 actually going to happen there, and that's where the Board 15 wants comfort is in understanding that those modeling 16 representations are a good -- are our best shot at that 17 representation of the system.
18 CHAIRMAN JACKSON:
So perhaps in this context you 19 would replace robustly with credibly.
20 MS. KNOPMAN:
Yes, until we figure out what robust j
21 means.
/
22 CHAIRMAN JACKSON:
Right.
23 MR. COHON:
I'm very glad that Dr. Knopman said
]
24 what she did.
Let me just paraphrase it or expand upon it a i
25 little bit.
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or even comment on what level of uncertainty is acceptable 2
or not, but rather to comment on the methods and the data 3
used to arrive at those estimates of uncertainty.
4 Thanks for pointing that out.
5 COMMISSIONER McGAFFIGAN:
Let me just ask.
Have 6
you all taken a position with regard to what a reasonable 7
standard is?
8 MR. COHON:
No.
9 COMMISSIONER McGAFFIGAN:
You have not.
10 MR. COHON:
No.
11 CHAIRMAN JACKSON:
Commissioner Diaz.
12 COMMISSIONER DIAZ:
Just a quick thing on the same 13 point, I believe.
What happens if the uncertainty with any 14 one of the methods is as large as, say, the basic quantity 15 that you're trying to measure, what do you do?
16 MS. KNOPMAN:
That's a social decision.
17 CHAIRMAN JACKSON:
And actually that comes more to 18 the Commission.
19 MR. COHON:
Exactly right 20 COMMISSIONER DIAZ:
So you are going to be trying 21 to separate this thing so we can actually see what it is.
22 Thank you.
23 CHAIRMAN JACKSON:
Because, in fact, that was what 24 my basic point was going to be, that in the end, the 25 definition of robustly and credibly, et cetera, actually is ANN RILEY & ASSOCIATES, LTD.
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a policy, a policy' decision, and it's one that's going to 2
end up coming to the Commission.
3 Well, thank you very much, Dr. Cohon, Dr. Knopman 4
and Dr. Parizek.
This was an excellent session and you've 5
raised many of the same issues that the NRC itself has been 6
concerned with, obviously, vis-a-vis the high level 7
radioactive waste program.
8 If you'd like to make any comment on our own focus 9
on the key technical issues, I'm happy to hear it, but I'm 10 not asking you those questions.
11 I think hearing from you on a more regular basis 12 as we can move through this pre-licensing phase, 13 particularly with the viability assessment, et cetera, 14 coming through.
15 Given that, the Commission truly appreciates your 16 taking the time to come and present and talk with us today.
17 There have been a number of key developments in that program 18 that have occurred over the last few years and we look 19 forward to continuing to hear from you.
20 Unless there are any further comments, we are 21 adjourned.
22
[Whereupon, at 3:25 p.m.,
the public meeting was 23 concluded.]
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CERTIFICATE This is to certify that the attached description of a meeting of the U.S. Nuclear Regulatory Commission entitled:
TITLE OF MEETING:
BRIEFING'BY NUCLEAR WASTE TECHNICAL REVIEW BOARD (NWTRB)
PUBLIC MEETING l
PLACE OF MEETING:
Rockville, Maryland 1
DATE OF MEETING:
Monday, March 30, 1998 was held as herein appears, is a true and accurate record of the meeting, and that this is the original transcript thereof taken stenographically by me, thereafter reduced to typewriting by me or under the direction of the court reporting company hO@
Transcriber:
y Reporter:
Mike Paulus I
The Department of Energy's Civilian Radioactive Waste Management Program:
An Independent Perspective l
Dr. Jared L. Cohon, Chairman Dr. Debra S, Knopman, Member Dr. Richard R. Parizek, Member U.S. Nuclear Waste Technical Review Board presentation to the U. S. Nuclear Regulatory Commission March 30,1998 Rockville, Maryland jic037v3
s introduction Chairman Jackson, Commissioners, ladies, and gentlemen, good afternoon. It is a pleasure to be here today. My name is Jared Cohon, and I am Chairman of the U.S. Nuclear Waste Technical Review Board. All Board members serve part-time, and most of us have other full-timejobs. I am president of Carnegie Mellon University and my area cf technical expertise
~ is environmental and water resource systems analysis. Accompanying me are two other Board members who will make part of our presentation today. Dr. Debra Knopman is director of the Center for Innovation and the Environment of the Progressive Foundation in Washington, D.C.
~ Her expertise is in hydrology, environmental and natural resources policy, systems analysis, and public administration. Dr. Richard Parizek is a professor of geology md geoenvironmental engineering at The Pennsylvania State University. His expertise is in hydrogeology and environmental geology.
Since we have not met with some of you before,let me Nucisar waste Tecnnical begin by briefly summarizing who we are and what we do. The Renew Board Nuclear Waste Technical Review Board was created by m_
Congress in the 1987 amendments to the Nuclear Waste Policy yagg==oosi Act and is charged with evaluating the technical and scientific a-=.--o nem.-
aspects of the Department of Energy's (DOE's) high-level W '"' * "
nuclear waste management program. This includes site-charac*eization activities at Yucca Mountain and activities relatirs to the packaging and transport of high-level radioactive waste and spent nuclear fuel.
The Board is an independent agency within the federal govemment, not part of the DOE or any other agency. The Board is authorized to have eleven members who are nominated by the National Academy of Sciences and appointed by the President. I have served as a member since 1995 and became the Board's third chairman last year. Drs. Knopman and Parizek were two of eight new members appointed to the Board last year. With this many new members joining the Board at once, we have had a very busy year.
Today, in our prepared remarks, we would like to O*********"**"
emphasize our views oc the key developments of 1997. We will also briefly discuss ocr views of the upcoming viability assessment, which we expect to be the focus of much of the n.em==, s== m. w e. sis Board's activities throughout 1998. Our presentation draws
- L"*'"","",
heavily on the Board's 1997 Summary Report which we hoped would have been delivered to you before now. Unfortunately, final editing and printing of the report have taken more time than expected, but you should be receiving the report within the next few days. At the conclusion of our presentation, we look forward to a collegial discussion
- _of the type we have greatly enjoyed during the Board's previous presentations to the Commission.
I jic037v3 -
1
l Progress in the Viability Assessment As required by the 1997 Energy and Water Development '
components of the Appropriations Act, the Secretary of Energy is to provide to the ViabHity Assessment President and Congress a viability assessment (VA) of the Yucca Mountain site no later than September 30,1998. The w mmm p=*==
VA is to include the following elements:
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- 1. The preliminary design concept for the critical elements for the repository and waste package. (The DOE calls this design the " reference design.")
- 2. A total system performance assessment based on the design concept and the scientific data and r.nalysis available by September 30,1998. It is to describe the probable behavior of the j
repository in the Yucca Mountain geological setting in relation to the overall system performance standards. (This component is referred to as the TSPA-VA.)
- 3. A plan and a cost estimate for the remaining work required to complete a license application.
- 4. An estimate of the cost of constructing and operating the repository in accordance with the design concept.
The Board !,tends to conduct a timely review of the parts of the VA that fall within the Board's purview a' mn as the VA becomes available. Because the Board is a technical body whose members t
,sent scientific and engineering disciplines, our review will concentrate on technical and scient.fic aspects of the VA. Essentially, this means that our review will focus primarily on the design and performance assessment components.
Much of the Board's activity during 1997 involved preparation to review the VA. Board
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meetings during the year focused on performance assessment, hydrology, repository and waste
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package design, and repository operations. In 1998, we will continue our preparation, and we look forward to reviewing the VA later this year. Now, let me summarize for you the Board's current views on the four components of the VA.
Design I
The Board believes that the design area of the Yucca U** *"
Mountain project had several major accomplishments in 1997.
They include refinement of the designs for the repository
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surface and underground facilities and for the waste package;
,*g further integration of spent fuel owned by the U.S. Department
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criticality-control issues; and improved integration of T____
engineering and performance assessment. There also were a
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few shortcomings in the design area in 1997. There are continuing needs to adopt a more robust engineered-barrier system and to thoroughly explore different integrated repository and waste package designs that may offer the promise of better performance, lower cost, reduced uncertainty, or simpler operations.
jic037v3 2
I Repository Surface Facilities The principal repository surface facilities would be located on an 80-acre site at the repository's north portal and would consist of more than 15 structures and a small rallyard.
These facilities would receive waste and package it for disposal. Except for the final closure j
welds and inspections of the waste packages, the Board considers all of the technology of the I
repository surface facilities to be commercially demonstrated and available. However, the Board I
does have some remaining concerns about the design basis, including: (1) questions about the assumed peak emplacement rate, which may be imrealistically high; (2) the possibility of transferring some waste packaging operations to nuclear power plant sites, with potential cost savings; and (3) the potential benefits (e.g., safety, standardization) of using multipurpose canisters as part of the overall waste management system. These concerns are discussed in more detail in the Board's 1997 Summary Report.
Repository UndergroundFacilities This slide shows a plan view of the conceptual repository layout. All underground drifts would have circular
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cross sections. The diameters of the ramps from the surface to the repository, the main drifts around the periphery of the
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repository, and the exhaust drift (which would be located iy %
approximately 10 m underneath the repository) would be 7.6 m,
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and the diameters of the emplacement drifts would be 5.5 m.
w The ramps and most of the east main drift exist now as the E
recently completed exploratory studies facility (ESF). The balance of the main drifts and the exhaust drift would be U (g g
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constructed next, followed by emplacement drifts, starting from u
I the north.
Waste would be emplaced in the drifts, one at a time, starting with the northernmost emplacement drift, and moving to the next drift south after filling a drift. After an emplacement drift is filled, it would be closed off with doors at each end (i.e., where the drift intersects the main drifts on the cast and west sides of the repository), limiting ventilation to insignificant amounts. Human entry into a drift would be prohibited after the first waste package has been emplaced in that drift due to high temperatures and high levels of radiation. Therefore, all operation, maintenance, inspection, testing, etc., in drifts containing waste would be done remotely.
The Board recommends in its 1997 Summary Report that the DOE should develop alternative repository designs as well as enhancements to the teference design. Although it is neither necessary nor appropriate that the alternatives be developed as fully as the reference design at the time the VA is delivered, we believe that including alternative design concepts in the VA could enhance the VA's value and credibility significantly. 'Ihus, we urge the DOE to consider including alternative design concepts in the VA.
jic037v3 3
1 Engineered Barrier System (Waste Package) ne reference waste package design is a double-shelled cylinder nearly 2 m in outside diameter by 5 m long with a 2-cm-thick inner shell of corrosion-resistant alloy C-22 and a 10-l cm-thick outer shell of carbon steel, a corrosion-allowance material. The waste package will be.
l emplaced on its side on pedestals in the emplacement drift.
I Data obtained from the ESF within the last two years clearly show that the repository will f
be wetter than thought as recently as three years ago. This discovery has triggered examination of enhancements to the existing design. Examples of such enhancements are drip shields and backfill. The Board is particularly interested in seeing studies of additional design options that include: (1) smaller, shielded waste packages, (2) a waste package design using two corrosion-resistant materials (CRM) rather than one CRM and one corrosion-allowance material, and (3) l ventilation of the repository tunnels.
The DOE is actively identifying and evaluating enhancements to the reference design.
(Enhancements are features that are added to or changed in a design without altering the fundamental nature of the design itself.) We recommend that the descriptions and approximate costs of enhancements be included in the VA and that their effects on long-term repository performance be included in TSPA-VA sensitivity studies.
Total System Performance Assessment (TSPA)
TSPA is the principal method of evaluating the ability N " *ac' A*****"*"
of the proposed repository (engineered and natural components acting together) to contain and isolate waste. It is essentially a predictive-computational model of repository performance over
. Tseavanois.ainion c icui.non time. The DOE is charged with carrying out a performance
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assessment that emphasizes the probable behavior of the pawa aae mousmia auma -
proposed repository.
The DOE has devoted significant and laudable effort to achieving the goal of developing a credible TSPA. The emphasis on probable behavior has resulted in a division of the TPSA-VA into a base-case calculation and a series of sensitivity tests. The base case concentrates on probable, or expected, performance, and the sensitivity studies concentrate on "What if?" scenarios for alternative input parameters and design features and disruptive events, such as volcanic activity and earthquakes.
Extensive workshops have increased interaction within the program and have given the DOE substantial expert input from outside the program. De workshops brought together field and laboratory scientists, coregoal modelers, and performance-assessment analysts from within the program on many important topics. Some of the workshops involved eliciting expert judgment, primarily from outside the Yucca Mountain project, to better define the conceptual and parameter uncertainty of the important elements that go into the TSPA. De DOE also formed in 1997 an extemal TSPA Peer Review Panel to delve into the important concepts and details of the TSPA-VA. De Board is encouraged by the strong jic037v3 4
, 3 and independent comments being provided by the TSPA peer review panel.
Plan and Cost Estimate for License Application The plan and cost estimate for a license application is the third element of the VA. The Board will focus its review on Ucensing Plan and Cost Estimate the plans for and estimated costs of technical activities supporting a license application. In particular, the Board
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believes that data from the new enhanced characterization of
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the repository block (ECRB) program are vital for the Secretary om= ====== aa r==a d of Energy's decision on the suitability of Yucca Mountain.
Of This decision precedes submittal of a license application to the U.S. Nuclear Regulatory Commission (NRC). Many other
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ongoing technical activities (e.g., the long-term corrosion test program, the drift-scale thermal tests, and hydrological tests in wells and in the ESF) also must continue to support licensing, and the Board wants to ensure that these activities are included in license application plans and cost estimates.
Repository Cost Estimate
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This is the fourth (and final) element of the VA.
Because the Board's purview is technical, we will confine our Rep @t Estwnate review largely to those aspects of the cost estimate that involve
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technology development. For example, the Board is particularly
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interested in techniques, allowances, and contingencies used in
,a"=" Y the cost estimate to reflect the costs of technology development
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(e.g., manufacture of prototype waste packages, development g'** = ca* 8** * **aa==
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and testing of robotic or remote handling systems for remote l
emplacement and monitoring) and to reflect current technical or engineering uncertainties. Another cost issue that the Board will explore is how potential enhancements to the repository design that are not part of the reference design case are handled.
The Board was pleased to learn that an independent review of the cost estimate for the mined geologic disposal system will be performed for the VA by a major U.S. engineering-construction j
firm. It is important that the DOE clearly define for the cost-estimate reviewer the construction process and the contracting basis (e.g., fixed price or cost-plus) that will be used to construct the repository.
i jlc03?v3 5
Regulations, Standards, and the EIS During 1997, the Board reviewed and commented on two aspects of the regulatory requirements for a geologic repository.
- Seng guulelsnes Siting Guidelines 37-a u we.m 1
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.a.~a g g-n,n. ga-On April 15,1997, the Board submitted comments on ooe. w.nm p-t-nc. -.
the DOE's draft revisions of its repository siting guidelines,
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10 CFR 960. In the draft revisions, the determination of whether the Yucca Mountain site is suitable for developing a repository would depend no longer on several individual criteria. Instead, a suitability determination would be based solely on whether the repository system (natural and engineered 3
1 barriers) can meet a postclosure risk-based standard that will be specified by the Environmental Protection Agency (EPA). In the draft revisions, the DOE proposed using the TSPA methodology to support this determination. In effect, the former, multiple-criteria standard would be integrated and subsumed into a single performance standard.
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The Board's April 15,1997, letter indicated that the proposed revisions represent a step in j
the right direction. It expressed concern, however, that the revised guidelines might be perceived as " changing the rules in the middle of the game," strengthening the fears of some that performance assessment may be manipulated to support any conclusion desired. The Board offered several suggestions for strengthening the proposed revisions: (1) preserve the principle of defense-in-depth,(2) require that a repository system complies robustly with a standard,(3) i specify the level of confidence that must be reached before making a site-suitability determination, (4) make performance assessments transparent, and (5) use a public process to decide whether the Yucca Mountain site is suitable.
The DOE's Interirn Performance Measure in the absence of environmental standards from the EPA, the DOE has developed an interim performance measure. The interim performance measure is for the DOE's own use in guiding its technical program and communicating with others about the potential performance of a repository at Yucca Mountain. The interim performance measure will be discarded if and when the EPA sets standards for a repository at Yucca Mountain. In developing the interim performance measure, the DOE took into account the 1995 report of the National Research Council's Committee on Technical Bases for Yucca Mountain Standards.
The DOE's interim performance measure emphasizes protection of individuals living in the vicinity of a Yucca Mountain repository. Specifically, the annual dose to an average individual in a critical group living 20 kilometers from the repository is not to exceed 25 millirems per year for 10,000 years. Both the form of this performance measure and its level of safety are similar to many existing radiation protection standards. With one exception, this interim performance measure seems appropriate for the DOE's use. The exception is the exclusion of children from the definition of the critical group. The Board recommended that the jlc037v3 6
a m
DOE should estimate and disclose the likely variation in doses for alternative candidate critical
_ groups characterized by different locations, ages, and lifestyles. In panicular, potential doses to children should be compared with doses to adults within each candidate critical group.
EnvironmentalImpact Statement Assuming that the site is determined to be suitable, the Environmentalimpact statement DOE plans for the Secretary of Energy to recommend to the President in 2001 that the President approve Yucca Mountain
. Anv==n.n.neman = mv a res.may as a site for a repository. By law, the Secretary's fe's? """*" "* " "*""*"""'"
recommendation must be accompanied by an EIS.
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%" O'""j O" response to reduced appropriations for fiscal year 1996. In 1997, the DOE resumed work on the EIS in earnest. The DOE's EIS contractor, selected in 1996, mobilized staff, familiarized them with the project as necessary, and began to assemble and analyze data for the EIS. In 1998, the Board will be devoting some of its time to understanding the organization and content of the EIS. In particular, the Board believes that the selection and characterization of the "no action" attemative is critical to the technical success of the EIS process, he Board strongly endorses development of alternative repository and waste package designs and believes that the EIS process is an appropriate venue for exploring these altematives.
Transportation During 1997, the Board reviewed the transportation of Dan 8Ponation spent nuclear fuel within the United States. He Board's review concentrated on federal regulations goveming the transportation
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of spent fuel, analyses of the risks of transportation, and gg
==wori==_nihm transponation practices and experiences. The Board reached one a rnove w three conclusions *
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and half-acale lashng of caele, eney enhance the postesved level of aalsty.
The Board continues to believe that the risks associated with transponing spent fuel are low. However,if there is a large increase in the scale and operational complexity, as might occur when spent fuel is shipped to a repository or an interim storage facility, a heightened safety program will be needed to maintain a good safety record, i
The existing capability to transpon spent fuel in the U.S. is small, and much preparatory work needs to be done before fuel can be transponed in large quantities. More transportation casks, with larger capacities, are needed; the transportation infrastructure at some sites needs to be upgraded to allow moving heavy loads; and substantial institutional planning is needed.
Cenain measures, such as use of dedicated trains and full-scale testing of casks, may enhance the perceived level of safety. Because the risks of transporting spent fuel are low,it is unclear whether such measures would be justified solely for risk reduction, but they may increase confidence in the safety performance of the transportation system.
jic037v3 7
)
.d Technical and Scientific Developments Completion of the Exploratory Studies Facility The excavation of the exploratory studies facility (ESP)
Technicai and scientme Develop =nt8 was officially completed on April 25,1997, providing a 7,877-m-long (25,800 ft) tunnel at Yucca Mountain. As anticipated cans==n a exw-==y mue r.ciwy by the Board, the excavation of this tunnel provided a wealth of
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=m dama anticipated and unanticipated data. on the geologic and
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hydrogeologic character of Yucca Mountain and was a very
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valuable learning opportunity for the Yucca Mountain project TCI%.
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in performing contractor oversight, managing construction, and understanding the value of seeking independent counsel from construction industry experts. The following are some of the lessons that can be learned from the construction of the ESF.
The type of construction contract is important. Underground construction worldwide uses competitive processes, normally involving fixed-price contracts. Cost-plus contracts, such as used by the DOE for the ESF, have no known precedent in underground construction and
. provide little, if any, incentive for efficient, cost-effective construction.
Contractors know how to manage the risks associated with equipment design and performance. Design, procurement, and disposal of construction equipment, including tunnel-boring machines, normally are left to the construction contractor. Specifications, such as for hydraulic spill mitigation, dust control, and safety requirements, can be defined and enforced without telling the contractor how to perform.
Industry expertise is important and accessible. In 1995, after experiencing severe difficulties in excavating the ESF, the DOE, in conjunction with its contractor, established a consulting board. This board was very effective in achieving improvements, and the DOE is commended for involving outside expert consultants.
Large-diameter tunnels are more expensive and time consuming to construct than small-diameter tunnels. The design for a Yucca Mountain repository includes large (7.6-m diameter) tunneling for service tunnels and the exhaust drift. Smaller tunnels would be affected much less by the high fracture density of the rock in the repository horizon and would be much more constructible than the large proposed tunnels.
jic037v3 8
East-West (ECRB) Tunnel The Board previously recommended excavation of an Tecnnical and scientdic cast-west exploratory tunnel at the elevation of the repository oevelopments (conto and parallel to the proposed emplacement drifts. The principal c
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focus of this tunnel would be to obtain data to reduce the
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uncertainty of the hydrogeologic environment within the
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repository. The DOE has accepted this recommendation in
. sep,.auc.unc.,i.,no m general, but has expanded the scope to what is known as the
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" enhanced characterization of the repository block"(ECRB) program, which consists of the tunnel and two boreholes, to be drilled from the surface. All excavation, including three alcoves off of the tunnel, will be completed by January 1,1999.
The next slide illustrates conceptually, although not to Locahonof Eam-WedTunnW, scale, the location of the ESF, the cast-west tunnel, the potential
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repository, and some of the more prominent geologic features bN
'E of the site. The Board supports the decision by the DOE to excavate the east-west tunnel expeditiously. Although hydrogeologic testing may not start until 1999, observations, lE, mapping, and limited data on chlorine-36 (36Cl), which would
}p indicate possible fast flow paths for water moving through the mountain, may be available before the scheduled delivery date for the VA, thus providing valuable confirmatory data for the VA.
Thermal Testing at Yucca Mountain One of the primary functions of the ESF is to provide Tecnnicai and scientnic access to the strata in which the repository is to be located to oeveiopments (conre conduct thermal testing, especially the effects of repository heat n,.n,,.n on movement of water within highly fractured, unsaturated
. s. nom,
. -,n rocks. Data from thermal testing will be useful for validating
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,,c the various hypotheses and assumptions used in developing L.ro.= = m compaion performance models and the current repository design. Two tests are being conducted in the ESF, the single-heater test and the drift-scale test.
The " single-heater test" has been in its cool-down phase since May 1997, and all testing was to be completed by the end of January 1998. Post-test analyses within this portion of the ESF are planned, and key information should be available for incorporation into the viability assessment.
The " drift-scale test" is located in a 47.5-m-long (156 ft) test area equipped with heaters that simulate the thermal conditions of waste packages in a repository. On December 3,1997, heaters were tumed on and data collection was begun from sensors in the surrounding rock mass.
jic037v3 9
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The heating phase is planned to last approximately 4 years, with nominally 4 years for cooling afterward. The DOE is to be commended on implementing this extensive and important thermal test facility.
The "large-block test"is an additional thermal test being conducted on the surface near Yucca Mountain on an excavated outcrop of welded tuff. It was designed to promote formation of reflux (heat-pipe) zones as heat is applied to the bottom of a large block of fractured rock.
Water, mobilized as vapor,is expected to be driven out of the pores of the rock and to flow upward where it will condense in cooler regions of the rock. The condensate then will return as ref;ux to the above-boiling zone. On February 28,1997, the heaters were turned on, and the test was nearing completion at the end of 1997.
1 What Happens When Radioactive Waste Reaches the Water Table?
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l Late in 1997, the Board visited Yucca Mountain and wnat Happens when Radioactive nearby Amargosa Valley for field observations about the flow waste Roaches the Water Table?
of groundwater between Yucca Mountain and Amargosa Valley, how groundwater conditions varied in the past as the tect.nnamonanoo**on no climate varied, and how any radioactive materials released to 6%,cco,,,..
the groundwater might, in the future, enter the human biosphere, gg, through seeps, springs, or withdrawal through wells.
c.u wv. une.n-in oo Estimates of the concentrations of radioactive materials entering the environment south of a Yucca Mountain repository will be highly uncertain. The saturated zone is highly fractured and faulted, causing groundwater flow to be " channelized" within the more transmissive zones of fractured rock. Within these zones, groundwater movement will be faster than the average groundwater flow rate through the saturated zone, and retardation of radionuclides may be less than average. Mixing of groundwater containing radionuclides and radionuclide-free groundwater within the saturated zone will dilute radionuclide concentrations, but demonstrating the degree to which mixing would occur in a channelized flow system may prove very difficult.
An important, and perhaps greater, source of dilution may be mixing at a wellhead (or a spring) when groundwater leaves an aquifer and enters the biosphere. This depends on the specifics of the well withdrawal. Dilution by flow and transport in the saturated zone is difficult to quantify. Because of its significance in determining the relative importance of the different I
factors affecting dilution, an early definition of the well-withdrawal scenario could provide an important focus for studies at Yucca Mountain.
The fate of radionuclides after they enter the biosphere and as they enter food chains and potentially cause radiation doses to humans must be projected. The use of generic data in models of the transfer of radionuclides through food chains may cause large uncertainties in estimated radiation doses, perhaps as much as three or four orders of magnitude.
jlc037v3 10 j
O 4
DOE Use of Outside Experts The Yucca Mountain project is receiving valuable advice from two DOE-funded external review groups: the DOE Use of Outside Experts TSPA Peer Review Panel and the Yucca Mountain Site.
Characterization Project Mined Geologic Disposal System
- tw - sw Consulting Board. In the past, the Board has urged the DOB to 6%'""j,,,%.
make greater use of expertise outside of that already found
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within the Yucca Mountain program, and the Board is pleased
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that the DOE is domg so.
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The Board's 1997 Summary Report discusses another type of external input: recent, specially elicited expert judgment. Expert judgment is required when dealing with an inherent uncertainty in scientific understanding or when there is a need to make an assessment before all relevant data can be collected. An example of the latter is the TSPA for the VA. ~ Although informal implicit or explicit expertjudgment from one or more Yucca Mountain scientists has always been used in performance assessment, the recent elicitations are formally structured studies that involve multiple experts, most of whom are from outside the Yucca Mountain program. The topics covered by the expert studies (some of which are not yet complete) include seismic and volcanic hazards, unsaturated-zone flow, waste package degradation, saturated-zone flow and transport, near-field / altered-zone coupled effects, and waste form degradation and radionuclide mobilization. A primary purpose has been to describe the uncertainties associated with particular models and data.
Overall, the clicitations have proven very successful, ne DOE is commended for carrying out these studies and, in particular, for including a substantial number of outside scientists and engineers on the expert panels. Aside from supplying information that can be used directly for performance assessment and design, the elicitations have provided important insights into the program. They include the endorsement or rejection of previously accepted scientific models and design assumptions; the importance, or lack thereof, of different hypotheses; and the need to acquire selected additional data. The challenge to the DOE is to make full and effective use of the experts' input.
In making full and effective use of the expert clicitations, the DOE needs to articulate how it intends to aggregate the views of multiple experts and address the potential problems posed by receiving input on some issues from only a small number of the experts who were asked. This is especially important when there are relatively few experts and they differ sharply
. on meaningful issues. Sufficient information must be presented to trace the effect of an individual expert's judgment on overall conclusions. The DOE needs to explain whether and
- how the views of individual experts will be treated in sensitivity studies for the TSPA-VA, and it also should consider developing guidelines on how it will treat the results of an expert elicitation in the light of new data and analyses.
3 This concludes our prepared presentation. We will be happy to answer any questions you may have, jic037v3 11