ML20217B192

Summary of ACRS Planning & Procedures Subcommitte 971105 Meeting in Rockville,Md Re Conduct of ACRS Business

ML20217B192
Person / Time
Issue date:	11/06/1997
From:	Advisory Committee on Reactor Safeguards
To:	Advisory Committee on Reactor Safeguards
Shared Package
ML20217B198	List: ML20217B192 ML20217B201
References
ACRS-3079, NACNUCLE-3079, NUDOCS 9803250432
Download: ML20217B192 (5)

Text

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R. L. Seale, Chairman November 17, 1997 November 6, 1997_

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SUMMARY

/ MINUTES OF THE ACRS PLANNING AND PROCEDURES SUBCOMMITTEE MEETING NOVEMBER 5, 1997 The ACRS Subcommittee on Planning and Procedures held a meeting on November 5, 1997, in Room 2B1, Two White Flint North Building, Rockville, Maryland.

The purpose of the meeting was to discuss matters related to the conduct of ACRS business.

The meeting was convened at 12:37 P.M. and adjourned at 1:45 P.M.

ATTENDEES R. L. Seale, Chairman D. A. Powers T. S. Kress ACRS Staff J. T. Larkins, ACRS Executive Director S. Duraiswamy C. Harris R. Summers 1)

NEW MEMBERS (Open)

As discussed during the October 1997 ACRS meeting, the Commission has been provided with nominations to fill one of the ACRS vacancies in the area of thermal hydraulics and computational fluid dynamics.

The Commission has not yet reached a decision.

Qualified candidates are being sought for the other vacancy in the area of plant operations.

Cne potential candidate will be interviewed during this full Committee meeting.

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INTERNATIONAL MEETINGS (Open)

~The ACRS Executive Director has had several discussions with Dr. Birkhofer concerning our response to the Japanese invi-

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tation for a Quadripartite Meeting ir Japan during the latter part of January 1998.

We agreed that it would be dI f difficult to have a meeting at this time, since there were still questions concerning the agenda that need to be resolved (i.e., the RSK disagrees with tis current agenda,

/ffoj and we have suggested that the agenda include a discussion on the use of PRA in regulatory decisionseking).

A January 1998 meeting date would not allow sufficient time to prepare

papers and distribute them prior to the meeting.

Dr.

Birkhofer plans to raise this issue with the Japanese and suggest we postpone the meeting until June or September 1998.

After receipt of the German letter, we would send a letter to the Japanese endorsing the German suggestion.

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1 have not yet received a copy of the German letter.

In response to the Committees discussion and agreemedt at the. october 1997 full Committee meeting, we still plan to-meet with representatives,of the U.K. reactor safety commit-tee.

We have received suggestions from Dr. D. Powers for an agenda for that meeting.- We will not contact the U.K. about setting _a date or agenda for this bilateral exchange until the date for the Quadripartite meeting is settled.

After completion of its review'of the AP-600,.the Committee might want to consider a meeting with the Chinese reactor

. safety committee, in light of their proposed nuclear power plant construction program and the recent U.S. policy change that allows China to buy U.S.-designed reactors.

RECOMMENDATION The Subcommittee recommends that the exact date of the Quadripartite Meeting be determined as soon as possible. The Subcommittee also recommends that Members provide items for the agenda with the U.K. to Ms. Summers and that the possi-bility of a meeting with the safety committee in China be considered as a long-tera possibility.

3)

DEFENSE-IN-DEPTH (Open)

The ACNW issued a report during its October 21-23, 1997 meeting to the Commission on the application of defense-in-depth principles to the proposed revision of 10 CFR Part 60.

Dr. Apostolakis participated in some of the discussions.

A copy of the ACNW report is attached (pp.1-4).

4)

PRA DISCUSSION WITH COMMISSIONERS DIA2 AND DICUS (Open)

ACRS Members Kress and_Apostolakis were scheduled to meet with Commissioners Dias and Dieus and representatives of other Commissioner offices on October 4, 3997 to discuss the

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use of PRA in regulatory decisionmaking and the ACRS pro-j posal to elevate the Core Damage Freguency to a Safety Goal.

l Because of the unavailability of Dr. Apostolakis, this meeting has been rescheduled for November 12, 1997.

RECOMMENDATION The Subcommittee recommends that the Members participating in these discussions provide a report to the full Committee.

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5)

MFALTH EFFECTE OF LOW LEVRTR OF YONTZING RADTATION (Open)

Commissioner Diaz wrote a letter to_the ACNW (pp.

5) con-carning its. letter dated July 10, 1996 (pp. 6-8) on the Health Effects of Low Levels of-Ionizing Radiation, and commissioner Dieus also raised this issue in'her meeting with the ACNW-en October 21, 1997..Both Commissioners asked

-the ACNW.to devote additional attention to this-issue.

The ACNW plans to hold a Working Group meeting during its Decem-i ber 16-18,;1997 meeting, probably on the 16th.

ACRS members may wish to attend and participate in joint discussions.-

RECOMMENDATTON The Subcommittee recommends that Members interested in attending the ACNW meeting on this subject notify Ms. Sum-mers,.so that relevant documentation can be provided to them in advance of the meeting.

6)

LAcFMDA FOR THR AERE RETRFAT (Open)

Assuming the ACRS moves forward with plans for_a retreat in

-January 1998, we need to discuss an agenda this month and finalize the agenda at the December 1997 meeting.

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meeting site has been changed to Bolger Center in Potomac, MD.

RECOMMENDATION The Subcommittee recommands that a draft agenda for the retreat be prepared at this meeting and that a final agenda be submitted for approval at the December meeting.

7)

.FT.FOTTON OF AERE OFFICERS FOR CY 1998 (Open)

The Bylaws-prescribe that the ACRS elect the Chairman and Vice-Chairman for the ACRS and Member-at-Large for the Planning and Procedures subcommittee at the December meet-ing.

Anyone not wishing to be considered for any of these positions should notify the Executive Director of the ACRS in writing at least two weeks prior to the election (on or

.before November 21,.1997).

Please review the Bylaws con-

' corning the election of officers.

RECOMMENDATION

'.The Subcommittee recommends that Members not wishing to be considered;for any of these positions prepare a brief note uso stating and give it-to the Executive Director by the end of this_ meeting.

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AP600 DESIGN REVIEW (Open)

The ACRS Executive Director recently concurred in a proposed commission paper from the NRC staff on the AP600 schedule.

The paper notes that the ACRS could complete its review of the AP600 design at the July 1998 meeting, subject to re-caipt of an FSER'on May 1, 1998, and assuming that signifi-cant open items are resolved.

Otherwise, it would most likely be completed at the September 1998 Full Committee meeting.

The staff apparently plans to issue the FSER in

May 1998, even if there are open items, and the anticipation at the staff J svel is that there will be at least "a few" open items.

The ACRS has, in the past, completed its review with some open items remaining to be resolved.

A proposed letter from Dr. Larkins to Mr. Roe, NRR, outlining the proposed schedule for ACRS review of the AP600 design is attached (pp. 9-12).

9)

TIME SPENT AT ACRS MEETTNCS IN FY 1997/ ANTICIPATED WORKLOAD FOR 1998 (Open)

A summary of the time spent during ACRS meetings in FY 1997 is attached (pp. 13-2,1).

A majority of the Committees time i

(45%) was spent in preparing reports and letters.

Also attached is a list of anticipated Subcommittee meeting days for 1998 (pp. 22-29).

Based on the currently available information, about 49 days of Subcommittee meetings are anticipated for 1998.

4 RECOMMENDATION The Subcommittee recognizes that the committee has made progress in its efforts to reduce the time spent on ACRS reports and recommends that the Committee continue efforts to enhance its efficiency.

10)

STRATEGIC PLANNING (Open)

A draft survey of ACRS stakeholders has been prepared for Committee review and approval (pp. 30-35).

The commission has requested ACRS and ACNW to obtain input from the NRC staff and others as one of the ways to measure committee performance.

Other performance measures will be developed as required to demonstrate achievement of the Operating Plan i

objectives.

RECOMMENDATION The Subcommittee recommends that Members be given a copy of

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5-the survey at the beginning of the November full Committee-meeting and that Members give any comments on the survey to Ms. Summers by the end of the meeting.

11)

MEMBERS' ISSUES'(Open)

Copies of Dr. Powers' facsimiles on the linear no-threshold theory, plant performance assessment, media reporting of ACRS reports, and silicone foam containment penetration seals are attached (pp. 36-41).

RECOMMENDATION The Subcommittee recommends that the ACRS staff keep track of media reporting on ACRS as one of its performance maa-sures.

12)

ACRS ANNUAL HOLIDAY PARTY (Open)

The ACRS has traditionally sponsored an annual Christmas party for_ Members and Staff and more recently has included the commission in the affair.

The Committee needs to decide on whether or not it would like to sponsor this affair this year.

The cost for the affair will be the same as last year.

RECOMMENDATION The Subcommittee recommends that the Christmas party be held on December 4, 1997, and that Members make their contribu-tions before the and of this meeting to Tanya Winfrey.

Commissioners will be invited.

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' UNITED STATES O

NUCLEAR REGULATORY COMMISSION g*-

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October 31,19g7 l

The Honorable Shirley Ann Jackson Chairman U.S. Nuclear Regulatory Commission Washington, DC 20555-0001

SUBJECT:

RECMENDATIONS REGARDING THE IMPLEMENTATION OF THE DEFENSE-IN DEPTH CONCEPT IN THE REVISED 10 CFR PART 60 This letter communicates the recommendations of the Advisory Committee on Nuclear Waste (ACNW) for adopting a mvised approach to the existing subsystem perfo.wance criteria in 10 CFR Part 60, " Disposal of High-Level Radioactive Wastes in Geologic Repositories," to implement the defensein-depth (DID) concept.

RECOMMENDATIONS 1.

The Committee endorses the concept of defense in depth, including institutions! as well as structural aspects. In particular, we recognize the benefit of multiple barriers of protection.

The Committee recommends that sound principles be set forth guiding the implementation of the concept of defense in depth. The Committee, however, does not endorse the establishment of rule-based subsystem requirements as exist in 10 CFR Part 60.

We believe that guidance will depend to a large extent on proper construction of a performance assessment (PA) to expose the role of design elements, operational elements, and multiple barriers, including interdependency of the multiple barriers. The regulations should be clear on how the DID concept should be implemented. The Department of Energy

. (DOE) (or any future license applicant) should be directed to fumish documentation that ahows how the DID concept has been implemented in meeting the overall performance goal.

2.

. The Committee recommends that NRC performance assessment procedures be structured so that the effectiveness of individual barriers can be identified explicitly in the total system performance.

The PA should clearly expose the effectiveness and mis of selected individual barriers such as the engineered systems and the natural geological setting. The assessment of individual barriers should include a quantification of the uncertainties involved.and the inter-relationships among barriers. The Committee believes that there are methods for quantifying the role of individual engineered barriers and the containment capability of the natural setting.

To achieve the capability to assess the effectiveness of individual barriers, both geological

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I p-2 and engineered, it may be necessary to modify the analysis methods, including the PA models, and to enhance the database to reveal the performance ofindividual barriers. The Committee also believes that exposure of the public to a PA process that is sufficiently transparent could lead to improved public confidence in the ability of the repository to isolate waste effectively.

This letteris one in a series ofletters to the Commission conveying the ACNWs views on aspects of the NRC staffs strelegy for revising 10 CFR Ps 160. Previous letters on the staffs strategy for revising 10 CFR Part 60 include " Issues and NRC Activities Associated with the National Research Counds Report, Todinical Bases for Yucca Mountain Standards,'" February 9,1996; " Time Span for Compiiance of the Proposed High Level Waste Repository at Yucca Mountain, Nevada," June 7,1996; and the

• Reference Biosphere and Critical Group issues and Their Application to the Proposed HLW Repository at Yucca Mountain, Nevada," April 3,1997. Our recommendations are formulated.on the basis of presentations made to the Committee during the 90th,91st,92nd, and 93rd meetings by the NRC staff, the DOE staff and its contractors, the State of Nevada, the National Research Council, and representatives from industry, as well as on the basis of the Commission's I

policy on risk-informed, performance-based regulation.

The Nuclear Waste Policy Act of 1982, as amended, mandates NRC to develop technical criteria for HLW disposal that are consistent with the Environmental Protection Agency (EPA) generic standards and provide for a system of multiple barriers. The Energy Policy Act of 1992 mandates that NRC conform its regulation to the final EPA standards for Yucca Mountain, the latter of which are to be based on and consistent with recommendations made by the National Academy of Sciences' Committee on Technical Bases for Yucca Mountain Standards (TBYMS). As directed by the Commission, the NRC staff is currently pursuing development of site specific regulations for Yucca Mountain to implement the forthcoming EPA site specific standards for Yucca Mountain.

In this letter, the concept of DID refers to the methods of design, construction, and operation of a geological repository for HLW in ways that aim to ensure safety in the face of considerable uncertaintyin our knowledge of various processes. The implementation of DID in the repository context entails an analysis that exposes the contribution of each design element, each process (or set of processes) in the natural geological setting, and each operational technique to the safety of i

the repository. The DID concept includes (but is not identical to) the notion of multip;e barriers th.t act to isolate the waste. One of the majorissues regarding regulation within the DID framework is whether and how prescriptive requirements (so called subsystem requirements) should be placed on classes of these barriers. As discussed below, the Committee believes that the adoption of a risk-infonned approach eliminates the need for prescriptive subsystem requirements for Yucca Mountain.

The present form of 10 CFR Par 160 partly implements the DID approach by prescribing performance requirements of particular baniers.' As noted in the Statement of Consideratior's to 10 CFR Part 60, in addition to the natural barrier provided by the geological setting, this multiple barrier approach identifies two engineered barriers: the waste package and the underground facility. The Statement of Considerations notes that the multiple barrier concept is implemented by the performance objectives or requirements, as well as by more detailed siting and design criteria. The Committee

' Paraphrasing the regulation, the performance requirmnants specif) submantially complete wah=aar af wame packages fcr 300 to 1,000 years aAer pennanent closure, release rates o(radionuclides ham the engmeered banier symem less than one pan in 100,000 per year at 1,000 years a$er closure, and a prewaste emplacement groundwater travel time of at leaa 1,000 years.

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recognizes that inclusion of the quantitative subsystem performance requirements in the rule was

. thought to provide additional confidence to compensate for uncartainties associated with predicting the behavior of a repository over thousands of years and for the generallack of experience and confidence in analyzing repository performance.

The Committee supports the NRC's view expressed in the Statement of Considerations to 10 CFR Part 60 that the performance of the engineered portion of the repository and the geological system must each make a definite contribution to waste isolation. The Committee recognizes the need for '

reliance on multiple and diverse barriers as part cf the DID concept. However, we do not endorse the implementation of the DID concept through inclusion of prescriptive subsystem criteria in the revised 10 CFR Part 80.

Cummt thinking, which is supported by much experlanos and empirical evidence in both probabilistic performance assessment and site characterization is that performance-based regulations are much more efficient and effective in protecting health, safety, and the environment than are

" command and-control" approaches. Focusing on quantitative subsystem requirements for the proposed repository at Yucca Mountain would run counter to this thinking because it potentially could force a design that would increase overall risk even though all subsystem requirements were met.

.'A hypothetical example may clarify: a requirement that backfill in the repository be capable of substantially retaining all radienuclides leached from the waste package for 1000 years might be imposed. Such a requirement, which on the surface could be seen as beneficial, might force a design that would diminish significantly the lifetime of the waste canister by changing geochemical conditions in the near field. The outcome could be an increased risk to affec%d populations relative to a repository without backfill. It is this type of potentially adverse effect from subsystem requirements that an overall performance-based regulation would avoid. Consideration of such j

hypothetical examples supports our main conclusion that an overall performance-based regulation in the context of a risk based standard is a superior tool for promoting safety relative to imposed subsystem requirements.

A major problem with the current version of 10 CFR 60.113," Performance of Particular Barriers After Permanent Closure," which prescribes performance of particular barriers, is that it is not clearjust how relevant any subsystem performance requirement is to the overall safety performance of the repository. Furthermore, in the analysis of repository performance, interdependency of barriers makes it difficult to assess precisely the role of individual baniers. For example, the assumed rate of percolation of water through the repository affects the performance of all subsystems. The connection between barrier performance and overall performance is very site-and design specific.

Prescribing individual barrier performance may create a design that is imbalanced in terms of individual barrier effectiveness. Subsystem requirements may also result in very poor designs from an economic standpoint. The ACNWs view is consistent with the TBYMS report, which cautioned against imposing subsystem requirements that may inadvertently result in a suboptimal repository design.

The primacy of an overall performance based regulation does not imply that DOE, as the license applicant for Yucca Mountain, would not have to demonstrate convincingly to the NRC that both the geological system and multiple aspects of the engineered system were effective in providing waste isolation capacity. The NRC should insist that the applicant's PA clearly and quantitatively indicates how e6ch barrier contributes to meeting the overall safety objective. This information-should provide the basis for an informed decision on the license application.

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4 The cpproach that we ricor~nmend offers many advantages over prescriptive subsystem requirements. First, it allows taking maximum advantage of site-and design-specific properties and features. Second, it is a clear example of risk infonned, performance based regulation. The import 6nt contributors to risk can be ranked, thus providing a basis for prioritizing design ch and risk management activities. Third. N clarifies the degree of dependence of overett repos performance on indMdual baniers. In a sense, the safety margins of the various barriers are made more eglicit through quantification.

Sincerely, r

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8. John Garrick Chairman 9

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