ML19332C287

Forwards Commission Paper Discussing Implementation of EPA Stds for Disposal of High Level Radwaste.Paper Will Be Topic of Commission Briefing on 891121

ML19332C287
Person / Time
Issue date:	11/17/1989
From:	Bernero R NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
To:	Coons W NUCLEAR WASTE TECHNICAL REVIEW BOARD
References
REF-WM-1 NUDOCS 8911270101
Download: ML19332C287 (2)

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BISHOT LETTER

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'4 Dr. William W. Coons.

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Dear Dr. Coons:

Enclosed is a recent U.S.. Nuclear Regulatory Connission staff paper discussing of high-level radioactive' waste. Please distribute copier. ef this paaer to any ".

l implementation'of= the Environmental Protection Agency's standards for disposal

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Board menbers who are interested.in this subject. As you eay know, tiis' peper l

7 wiil be the topic of a Commission briefing on November 21, 1989. The Commission meeting will be open to the public, if you or any Board members'should wish.to attend.

I would be interested in any reactions you or' the Board members have to the

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centent of the enclosed paper.

Sincerely, 6

Rnod) lukut kl. Berneio Robert M. Bernero, Director Office of Nuclear Material Safety I

and. Safeguards

Enclosure:

SECY.89-319 d +ed October 17, 1989 m

DISTRIBUTION' Central Files R. E. Browning B. J. Youngblood J. Bunting LSS J. t.inehan R. Ballard On-Site Reps CNWRA

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Dr.' Sidney J. S. Parry MOV 171989

Nuclear Waste Technical Review Board 1111 18th Street, N.W., Suite 801-Washington D.C.

20036

Dear Dr. Parry:

Enclosed is a recent U.S.. Nuclear Regulatoay Commission staff paper discussing implementa1 ton of the Environmental. Protection Agency's standards for disposal; of high-level radioactive. waste. Please distribute copies.of this paper to any

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B3ard members who are interested in this subject.. As you may know, this paper will be the topic of a Commission briefing on November 21, 1989..The Commission

- meeting will be open to the public, if you or any Board members should wish to attend.

I would be= interested in any reactions you or the Board members have to the e

content of the enclosed paper.

Sincerely,

($4000) kDett M Bernero Robert M. Bernero, Director Office of Nuclear Material. Safety and Safeguards

Enclosure:

SECY-89-319, dated October 17, 1989 DISTRIBUTION:-

Central Files R. E. Browning B. J. Youngblood J. Bunting LSS J. Linehan R. Bailard On-Site Reps

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Nonorable Nunzio J. Palladino Chaimen U. 5. Nuclear Regulatory Comission Washington, D. C.

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Dear Dr. Palladino:

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$UBJECT:

ACR$ Com ENTS ON EPA STANDARD 5 FOR HIGN-LEVEL RAD!0ACT!VE WASTE l

O!$POSAL During its 303rd meeting July 11-13. Igel the Advisory Committee on Reactor Safeguards discussed the proposed "Environme,ntal Radiation Protection Standards for Renagement and Disposal of Spent Nuclear Fuel. Nigh-Level and Transuranic

'Radioact' ve. Wastes" (40 CFR 1g1), being developed by the U. 5. Enviremental Protection Agency-(EPA).

This was also the subject of a meetin i

Management subcommittee on June 18.:1985, during which discuss'g of our Weste ons were held with staff members from both the EPA &nd the NRC. 'The Comittee also had the benefit of the documents referenced.

Although we noted a number of questions relating to the proposed standards, a key issue. pertains to the application of probabilistic conditions on the proposed radionuclide release limits.

In this regard, we wish to call atten-tion to a particular recommendation made by the Nigh-Level Radioactive Weste

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Disposal Subcommittee of the EPA Science Advisory Soard, namely:

'We recomend that. use of a quantitative probabilistic condition on the modified Table 2 release limits be made dependent on EPA's ability to provide convincing evidence that such a condition-is practical to meet and will not lead to serious impediments. legal or otherwise, to the licensing i

of high-level-weste geologic repositories.

If such evidence cannot be l

provided we recommend that EPA adopt qualitative criteria, such as those suggested by the NRC." (Reference 2)

It is our understanding that the NRC Staff has concurred with the proposed EPA l

l-standards, including the use of a probabilistic approach on radionuclide release limits.

In view of the importance of the ability of the NRC to deter-eine compliance with the EPA standards in licensing a high-level weste repost-tory, we recessend that the Comission assure itself that the NRC Staff is correct in endorsing this approach.

We believe that demonstration of such compliance will be extremely difficult and that the proposed standards are unduly restrictive.

t Dr. David Okrent. ACR5 member, and Ors. Konrad Kravskopf and Frank Parker. ACR$

consultants, who participated in the ACR$ discussions on this matter, were

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i Honorable Nunzio J. Palladino July 17, 1985 i

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also involved in the review conducted by the EPA Science Advisory Board of an l

earlier version of the proposed standards.

Sincerely.

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h David A. Ward Chaiman l

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References:

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grA working Draft No. 6 -- Final 40 CFR 191. " Environmental Radiation Protection Standards for Management and Disposal of Spent Nuclear' Fuel.

Nigh-Level and Transuranic Radioactive Wastes.' dated June ll. 1985 2.

Letter from H. E. Collier Subcosmittee Chaiman, to W. D. Ruckelshaus.

EPAAdministrator,datedfebruary 17.-1984 forwarding. " Report on the.

' Review of Proposed Environmental Standards for the Management and Disp (osal

+

of spent Nuclear Fuel. High-Level end Transuranic Radioactive Wastes 40 CFR 191)" by the Nigh-Level Radioactive Waste Disposal Subcasmittee.

Science Advisery Board. EPA. dated January 1984 3.

SECY-84-320 for the Commissioners from W. J. Dircks. E00.

Subject:

NRC Staff Comments to Environmental Pretection Agency (IPA) on the Scunce Advisory Board Report on Proposed EPA Standard for Management and Disposal

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of Spent Nuclear Fuel. High-Level and Transuranic Weste (40 CFR Part 191).

dated August 9. 1964 4.

Letter from J. S. Davis. NRC Staff, to EPA.

Subject:

Response to EPA's i

request for comments on their proposed environmental standards for management and disposal of spent nuclear-fuel, high-level end transuranic radioactive wastes, dated May 10,1983 5.

Letter from N. J. Palladino Chairman. NRC. to L. Verstandig. Acting Administrator. EPA

Subject:

Commission's concerns about sections of the proposed standards that deal with means of implementation, dated May 11 1983 9

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MEMORANDUM FOR:

R. F. Fraleyr. Executive Director Advisory Comittee on Reactor Safeguards FROM:

Robert E. Browning. Director Division of Waste Management i

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SUBJECT:

NRC STAFF VIEWS ON IMPLEMENTATION OF THE EPA HLW STANDARDS i

Your memorandum of July 29. 1985 to William J. Dircks forwarded the ACRS l

coments on the EPA standards for disposal of high-level radioactive wastes.

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1 would like to provide you with additional information regarding the staff's views on EPA's standards and on implementation of those standards by the NRC.

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l The ACRS's concerns are capsulized in the following paragraph from David A.

Ward's July 17. 1985 memorandum to Chairman Palladino:

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It is our understanding that the NRC Staff has concurred with the i

proposed EPA standards. including the use of a probabilistic approach on radionuclide release limits.

In view of the importance of the ability of the NRC to determine compliance with the EPA standards in licensing a high-level weste repository, we recommend that the Comission assure i

itself that the NRC Staff is correct in endorsing this approach. We believe that demonstration of such compliance will be extremely difficult and that the proposed standards are unduly restrictive.

The NRC staff recognizes that use of numerical probabilities by EPA represents a novel approach for setting environmental standards. NRC coments on the j

proposed standards stated 'The numerical probabilities in (the proposed standards) would require a degree of precision which is unlikely to be achievable in evaluating a real waste disposal system."

In discussions following publication of the proposed standards, the NRC staff explained to EPA the difficulties foreseen in trying to implement a standard containing numerical probabilities. As a result of these discussions. EPA has added a new paragraph to Section Igi.13 of the standards which reads as follows:

3

" Performance assessments need not provide complete assurance that the requirements of 191.13(a) will be met. Because of the long time period involved and the nature of the events and processes of interest, ther6 will inevitably be substantial uncertainties in projecting disposal system performance.

Proof of the future performance of a disposal system is not to be had in the ordinary sense of the word in situations that h

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Instead, what is required is a reasonable expectation, on the basis of the recore before the implementing agency, that compliance with 191.13(a) will be achieved."

The staff considers that this wording (which conforms closely to 560.101(a)(2) of the Commission's regulations) sets reasonable bounds on the degree of assurance required for estimates of the likelihood and consequences of potentially disruptive events and processes. The Commission will not need to place sole reliance on probabilistic analyses when evaluating repository safety but, rather, will have considerable opportunity to employ its more traditional analytical and engineering methods. The staff considers that the specific performance objectives of 10 CFR Part 60, the detailed siting and other qualitative criteria of 10 CFR Parts 60 and 960, and the, technical positions under development by the NRC staff will help assure that the appropriate balance is struck between use of traditional analytical and engineering methods and probabilistic analyses in msking licensing findings.

Although the staff continues to believe that the probabilistic nature of the

' standards will pose a significant' challenge, the staff considers' that tho' standards, in the current form, can be implemented in a licensing review. '

I hope that this information proves helpful in explaining the staff's views regarding implementation of the EPA standards by the NRC.

Manum on Robert E. Browning. Director Division of Waste Management n/

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Honorable Nunzio J. Palladino Chairman l

U. S. Nuclear Regulatory Comission I

Washington, D. C.

20555

SUBJECT:

ADDITIONAL ACR$ COMMENTS ON THE EPA STANDARDS FOR A HIGH LEVEL RADI0ACT!vE WASTE REPOSITORY During its 306th meeting, October 10-12, 1985, the Advisory Committee on l

Reactor Safeguards met with you and the other Commissioners to offer comments regarding the Environmental Protection Agency (EPA) Standards i

for a High-Level Radioactive Waste (HLW) Repository, which was the subject of our report to you dated July 17, 1985.

In response to the request made during this meeting, we are pleased to submit the following i

additional coments on the EPA standards which were published as a final.

rule on September 19, 1985.

These standards will apply to the facili-ties being proposed by the Department of Energy and must be met in the associated licensing review conducted by the NRC.

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Our purpose in writing you at this time is to highlight the fact that

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the standards being promulgated by the EPA are unreasonably restrictive and contain serious deficiencies.

This will undoubtedly introduce unnecessary obstacles into the licensing process for an NLW repository, I

with only minimal benefit to the public health and safety. Our justifi-cations for these coments are outlined below.

Development of these standards has been under way within the EPA since

't December 1976.

During this period, the ACRS and its Subcomittee on waste management were briefed periodically by EPA representatives, and at each such meeting coments and suggestions were discussed on an inforinal basis. In early 1983 the EPA submitted the then-current draft of the proposed standards to its Science Advisory Board (SA8) for review.

Detailed coments by the High-level Radioactive Waste Disposal l

Subconnittee of the SA8 included the following:

The Subcommittee recomended "that the release limits specified in the proposed standards be increased by a factor of ten, thereby causing a related tenfold relaxation of the proposed soci-etal objective (population risk of cancer)."

The Subcomittee recomended "that use of a quantitative probabi-listic condition on the... -elease limits be made dependent on EPA's ability to provide convincing evidence that such a condition is practical to meet and will riot lead to serious impediments, l

legal or otherwise, to the licensing of high-level-waste geologic

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i Honorable Nunzio J. Palladino October 16,1985 repositories.

If such evidence cannot be provided, we recomend I

that EPA adopt qualitative criteria, such as those suggested by the J

NRC."

Of particular concern to the SA8 Subcomittee, in terms of meeting the conditions of the standards, was the fact that containment requirements 1

should be such that the cumulative releases of radionuclides from a i

repository to.the accessible environment for 10,000 years af ter dis-posal, from all significant processes and events that may affect the g

disposal system, shall:

"have a likelihood of less than one chance in 10 of exceeding" the quantities (given in an accompanying Table); and i

"have a likelihood of less than one chance in 1,000 of. exceeding ten times" these same quantities.

l The SAB Subcommittee also recommended specific changes in the probabi,

listic aspects of the draft standards to help make it more practical for an applicant to make a case that the quantitative probabilistic criteria had been met.

Although the wording in the standards includes the statement that "perfor1 nance assessments need not provide complete. assurance" that thew requirements will be met, there remains the basic fact that the st0~

a dards, as published, are far too restrictive.

In our opinion, the i

establishment of overly restrictive standards, relieved by leniency in their implementation, is not an appropriate approach.

The proper approach would have been to develop reasonable standards that could have been more definitively enforced.

The problems cited above were but a few of those observed and comented upon by the SAB Subcomittee.

Additional problems in Working Draft No.

6 of the EPA standards were discussed with an EPA representative during a meeting of the ACRS Subcomittee on weste management on Jiine 18 and 19, 1985. These included the following:

The standards, as published, do not appear to be internally consis-tent.

Although the latest data were used for estimating the biological effects M various radionuclides, the associated dose limits for individual body organs were not based on appropriate risk criteria.

' The health risks associated with the release Ifmits specified in the standards are much lower (by factors of a thousand or more) than the risks considered acceptable by the EPA for other environ-mental stresses, such as hazardous toxic chemicals.

The overly restrictive standards may result in the rejection of some sites proposed for an HLW repository that otherwise might be acceptable.

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i Honorable Nunzio J. Palladino October 16, 1985 At. indicated above, the standards will definitely complicate the processas, both technical and legal of demonstrating that a given site is acceptable.

We realize that both the NRC Staff and the DOE Staff have accepted the EPA standards.

Although we can understand, to'some degree, the desires i

of both staffs to complete this step, we are troubled by the serious deficiencies that exist in the standards.

The compromises that have.

.l been made' at this stage will lead to extended delays and an uncertain i

outcome in the licensing process for an NLW repository, with only slight i

benefit to the public health and safety.

Although the ACR$ could undertake a more detailed review and critique of the EPA standards, we believe that the SAS Subcommittee has already done this in a professional manner. A copy of the Executive Sumary of their report is attached for your information.

We hope this letter is helpful.

Although-we realize that the EPA standards have been published, we believe that they contain such serious i

deficiencies that the NRC should take prompt action to voice these con ~*

I cerns.

Sincerely, David A. Ward Chairman l

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Attachment:

L Section !!, " Executive $isunary" of Report on l

the review of Proposed Environmental Standards E

for the Management and Disposal of Spent Nuclear Fuel, High-Level and Transuranic Radioactive Wastes (40 CFR 191) by the SA8, EPA, dated January 1984

References:

1.

Letter frori Herman E. Collier, Jr., Chairman, EPA Nigh-Level Radio-active Waste Disposal Subcommittee, to Mr. William D. Ruckelshaus, Administrator EPA, dated February 17, 1984 transmitting Report on the review of Propos6d Environmental Standards for the Management and Disposal of Spent Nuclear Fuel, High-Level and Transuranic Radioactive Wastes by the High-Level Radioactive Waste Disposal Subcomittee, Science Advisory Board, EPA, dated Janaury 1984 2.

SECY-84-320. "NRC Staff Coments to EPA on the SA8 Report on Pro-posed EPA Standard for Managemcznt and Disposal of Spent Nuclear

' Fuel, High-Level and Transuranic Waste (40 CFR Pa-t 191) " dated August 9, 1984, including Working Draft No. 8. Final 40 CFR 191, Subchapter F - Radiation Protection Programs, dated July 19, 1985

-c Honorable Nunzio J. Palladino October 16, 1985 i

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SECY-85-272, " Report on the EPA's Environmental Standards for High-level Radioactive Waste Disposal," dated August 11, 1985 4

Memorandum from R. E. 8rowning Director, Division of Watste 3

Management, to R. F. Fraley, ACR$.

Subject:

NRC Staff Views on Implementation of the EPA HLW Standards, dated September 11, 1985 l

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EPA HIGH-LEVEL WASTE STANDARDS ISSUES ARE THE EPA STANDARDS OVERLY CONSERVATIVE, ESPECIALLY j

COMPARED WITH STANDARDS IN OTHER AREAS?

l CAN THE PROSA81LISTIC FEATURES OF THE STANDARDS BE IMPLEMENTED 1N A FORMAL LICENSING REVlEW7 l

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SUMMARY

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NRC WAS INTENSELY INVOLVED FOR NINE YEARS IN REVIEWING THE DEVELOPMENT OF THE EPA HIGH-LEVEL WASTE STANDARDS.

INDEPENDENT NRC STUDIES HAVE SHOWN THE STANDARDS TO BE s

ACHIEVABLE.

EPA SIGNIFiCANTLY MODIFlED THE STANDARDS TO ALLOW QUALIT JUDGMENTS--IN LICENSING REVIEWS.

AS NOTED lN SECY-85-272, EPA HAS BEEN RESPONSIVE TO NRC'S CONCERNS REGARDING THE ABILITY TO.lMPLEMENT THE STANDARDS.

SINCE SECY-85-272, NO NEW ISSUES HAVE ARISEN WHICH WOULD ALTER THE CONCLUSIONS OF THAT PAPER.

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WHO HAS REVIEWED THE STANDARDS NRC-- ' REVIEWED THROUGHOUT EPA'S DEVELOPMENT.

COMMISSION

)E REVIEWED AND REVISED STAFF COMMENTS ON PROPOSED STANDARDS.

DOC -- INTERACTED WITH EPA, PARALLEL TO THE NRC'S REVIEWS.

i STATES AND TRIBES -- INTENSE SCRUTINY FOLLOWING PUBLICATION OF PROPOSED STANDARDS.

i OMB -- SIGNIFICANT SCRUTINY OF THE PROPOSED STANDARDS PRIOR TO PUBLICATION.

LESS INVOLVEMENT PRIOR TO FINAL PUBLICATION.

i EPA SCIENCE ADVISORY BOARD -

SUBCOMMITTEE WAS FORMED TO REVIEW PROPOSED STANDARDS.

SAB REPORT REVIEWED BY NRC STAFF, AND COMMENTS FORWARDED TO COMMISSION (SECY-84-320).

ACRS -- ACRS AND ITS WASTE MANAGEMENT SUBCOMMITTEE PERIODICALLY BRIEFED ON STANDARDS.

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BASES FOR NRC STAFF POSITIONS l

CONSERVATISM g

- EPA HAS LEGAL RESPONSIBILITY TO DETERMINE ALLOWABLE LEVEL OF HEALTH EFFECTS.

- NRC STAFF CONSIDERS STANDARDS TO BE ACHIEVABLE BASED ON NUREG/CR-3235.

- STANDARDS CAN BE VIEWED AS A QUANTIFICATION OF "AS LOW AS REASONABLY ACHIEVABLE," GIVEN CURRENT UNCERTAINTIES.

PROBASILISTIC FEATURES

- NRC STAFF PROPOSED WORDING TO PERMIT QUALITATIVE LICENSING FINDINGS WHERE NECESSARY.

EPA INCORPORATED WORDING IN STANDARDS.

WORDING IS NOT VIEWED AS COMPENSATION FOR CXCESS CONSERVATISM IN THE STANDARDS.

EPA ~ RULE CONFORMS TO COMMISSION'S DISTINCTION BETWEEN QUANTITATIVE PERFORMANCE STANDARDS AND QUALITATIVE STATEMENTS REGARDING LEVELS OF CONFIDENCE (48 FR 28204).

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MEMORANDUM FOR:

Samuel J. Chilk, Secretary M e! k..... f P

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Lando W. Zech, Jr.

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SUBJECT:

SECY 85-272 JX s 7,

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I have reviewed and carefully considered the ACR3' advice that thCEPR------- -

standards, in the opinion of the ACR$ are " unreasonably restrictive and I

contain serious deficiencies" together with their conclusion that the standards "will undoubtedly introduce unnecessary obstacles into the i

licensing process."

I have also considered the DOE and EPA statements in support of the standards and their conclusion that the standards are reasonable and achievable.

The NRC staff has concluded that the EPA standards are reasonable, achievable and flexible enough that they can,be implemented.

In view of the conflicting advice provided to the coussission 0GC has provided options which the Commission may exercise and concl,uded that since "the ACR$ concerns [are] governed by the policy and technical issues we have described rather than any strictly legal considerations, we maks no recomunendation on how the Cosssission should proceed, other than that it should not act without hearing"from the NRC staff and fully assessing all the factors we have described.

The staff has responded to the Cossnission L

at the October 21, 1985 public meeting and addressed the ACR$ concerns.

The staff has advised the Commission that the staff, as well as 00E and EPA, do not agree with the ACR5 that the standards are overly restrictive and contain serious deficiencies.

The staff stated that they believed, as did 00E and EPA that the standards were flexible enough and could be l

executed.

With all due respect to the advice of the ACRS, I reaffirm my approval of SECY-85-272 in support of the D0E, EPA and staff reconsnendation.

However, I suggest that the stcff be directed to address the ACR$' concerns when developing the package conforming Part 60 to the EPA standards.

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understand they may do this by defining the basis for their assurance that adequate flexibility exists in the standards for them to be implemented, l

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Chairman Palladino Comunissioner Roberts

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November 14, 1985 l

i Honorable Nunzio J. Palladino Chaiman D'1 A U. S. Nuclear Regulatory Comission

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SUBJECT:

ADDITIONAL ACRS COP 9 TENTS ON EPA STANDARDS FOR A HIGH-LEVEL i

RADI0 ACTIVE WASTE REPOSITORY I

During its 307th meeting, November 7-9, 1985, the Ady,isory Comunittee on Reactor Safeguards met with members of the NRC Staff and the Environ-mental Protection Agency (EPA) for additional discussions on the nature and implementation of the EPA Standards for a High-Level Radioactive Waste (HLW) Repository.

This was also the subject of a meeting of thi NRC Comissioners with the ACRS on October 10, 1985; of a meeting of the NRC Comissioners with representatives of the NRC Staff, the Department of Energy (DOE). EPA, and the ACRS on October 21, 1985; and of a com-bined meeting of our subcomittees on Weste Management and Metal Com-ponents on October 24-25, 1985.

In addition, we reported to you on this subject in our letters of July 17, 1985 and October 16, 1985.

As a result of these meetings and associateo discussions, we offer the following additional coments.

i 1.

It is generally recognized that there is essentially no prospect that compliance with the EPA Standards can ever be demonstrated by j

actual observations.

Determination of compliance will have to be based on the results of calculations-using some agreed-upon set of release scenarios, environmental transport models, and their i

underlying assumptions.

As stated in our letter of October 16, 1985, we believe that this has the potential for introducing i

obstacles in the licensing process, and it.was for this reason that we recomended in our letter of July 17, 1985, that the Comission assure itself that the Staff's endorsement of this approach was correct.

+

2.

We continue to believe that the EPA Standards contain deficiencies and inconsistencier, e.g., that the dose limits for single organs are not risk-based, and that different dose limits are being applied to NRC-licensed HLW facilities than to similar 00E facil-ities. Although we understand that time constraints did not permit the EPA Staff to correct these deficier.cies, they nonetheless exist.

In addition, there are errors in the recomended methods for the analysis and interpretation of data collected in the evaluation of the performance of a repository.

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Honorable Nunzio J. Palladino November 14. 1985 i

l-l' The NRC Staff is proposing an approach that may prove successful.

However, we have no confidence that it will succeed.

Our basic concern continues to be whether a fomal detemination can be made that a -

licensee is complying with the EPA Standards.

To help resolve this problem, we encourage the NRC Staff to accelerate their efforts to i

develop analytical methods based on both deteministic and probabilistic i

approaches, and we recomend that a consensus be sought on these methods l

as they are developed.

We also encourage the NRC Staff to use rule-i making as a mechanism for implementing these methods, and we support the i

approaches being developed by the NRC Staff to utilize cutside experts to help identify relevant issues and infomation needs.

Additional coments by ACR$ Members Harold W. Lewis and Dade W. Moeller are presented below.

Sincerely.

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M O.aQ David A. Ward Chatman Additional Coments by ACR$ Member Harold W. Lewis It is worth repeating and extending the statement in the ACR$ letters of July 17,1985 and October 16, 1985, that the EPA Standards are too i

stringent.

All these problems of compliance detemination derive from the fact that the EPA risk limits are far below any reasonable 11keli-hood of detection.

It is that that drives the dependence on models and' calculations.

I know of no rational basis (though recognize the political constraints) for a standard involving one-tenth of a fatality per year for ten thousand years, beginning in a few hundred years.

If one uses cost / ben-efit saalysis with any reasonable estimate of the benefit of the repost-tory; if one uses reasonable discounting of future costs against current benefits, a procedure understood by all surviving businesses and nations; if one compares with the risk or even the radioactive effluents from coal burning, the only viable alternative to nuclear powers if one compares with cosmic rays or other natural radiation; however one makes the comparison, these are unreasonably stringent standards.

I recognize that they are the product of EPA, and the result of a necessary political process, but think that the NRC should develop regulatory procedures in such a way as to make the best of a bad set of standards by moving the assessment of the risk in the direction of realism.

To add the usual regulatory conservatism to the implementation of standards which are already too stringent would not be in the na-tional interest.

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i i-i Honorable Nunzio J. Palladino November 14, 1985 I know of no risk issue (perhaps excepting UFOS) in which the discrep-ancy between perceived risk and actual risk is so high.

That seems to be what has put us in this position, but it is still the responsibility of. scientific advisors to remain rational and to deal with real risk That is extraordinarily small here.

l l

Additional Remarks by ACR$ Member Dade W. Moeller L

I recognize that many of the issues etsociated with the EPA Standards i

are controversial and subject to a range of interpretations.

A primary example is the estimation of the average anneal societal risk to an individual as a consequence of the operation of an HLW repository l

constructed and operated in accord with the EPA Standards.

Dependin the number of people assumed to be exposed, one can " demonstrate" g on that the Standards are either comparable to the risks associated with some other existing radiation standards, or that the risks are several orders of magnitude lower.

Since, at the present time, there appear to be no acceptable guides for use by Federal agencies in making risk estimates for radionuclide sources that have the potential for exposing large.

numbers of people at extremely low dose rates over long periods of time, I would-encourage the NRC to request that the coemitte. on Interagency Radiation Research and Policy Coordination (CIRRpt) undertake to develop such guides.

I understand that the CIRRpC would be receptive to such a request.

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UNITED STAft$

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NUCLEAR REGULATORY COMMISSION eks g

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November 20,1985 wp b Docket N{nogue M1 Pro.

opmes op tus

,'g "M" ;;;r MEMORANDUM FOR: Samuel J. Chilk, Secretary rion; y ',c; FROM:

Frederick M. Bernthal E

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$UBJECT:

REAFFIRMATION OF V0TE ON $ECY-85-272 I 2 Tfr..... J 1

Upon extensive examination of the ACRS objections to the EPA standard (including their most recent conenents presented in a letter of 11/14/85) and i

of the analysis of evilable Conunission options presented by 00C, I reaffim sy approval of SECY-85-272.

l The ACR$ has cricized the EPA standard on the grounds that

1. it is overly stringent, mandating a level of protectibn that is far in excess of that provided by other existing environmental standards, and 1

2. implementation of the standard by NRC in licensihg a repository i

will be difficult if not impossible.

1 My review of the O estion suggests that the momentary confusion over the EPA standard arose from imprecise wording oh the part of EPA and Staff in attempting to explain the origin of the cumulative probability distribution i

function of repository release upon which the interpretation of 40 CFR 191 is l

based. Nevertheless, I continue to have reservations, both as to the application of the EPA standard, and as to the reasonableness and consistency of the standard when viewed in light of other societal risks (cf. comunents of ACR$ Members Dade Moeller and Hal Lewis).

Se that as it may, the Nuclear Weste Policy Act clearly assigns to the EPA I

the responsibility for establishing the environmental standard. Given that our staff has repeatedly asserted that the standards as published can be implemented, there appears to be little basis on which to challenge a pblicy i

decision that is, strictly speaking, that of EPA.

But I agree with the suggestion of ACR$ Member, Dr. Dade Moeller that the l

Conunission request the Comunittee on Interagency Radiation Research and Policy Coordination (CIRRPC) to develop guidelines for use by Federal agencies that would fnster consistency in the risk estimates and risk management of low doses of radiation.

I also agree with Conunissioner Zech and the Chaiman that any remaining ACRS concerns should be' addressed to the fullest extent possible in the rulemeking that will be necessary to conform Part 60 to the EPA standard.

In particular, care should be taken to avoid any ambiguity in the application of probabilistic conditions placed on the post-closure containment requirements.

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t The application of these conditions should not impose any further conservatism on an alreaQ highly conservative standard.

l' It-is unfortunate that the ACR$ coments on the EPA standards were made available at a time when Comission options to act without seriously delaying i

the repository pmram had, for the most part, been foreclosed. I would hope that in future rev'ows of MRC activities under the WPA the ACR$ could be i

involved at an earlier stage so that valuable technical advice and input could be used to timely and best adysntage by the Counisssion.

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Chatruen Palladino Comissioner Roberts Comissioner Asselstine Commissioner Zech OGC OPE E00 i

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i te.....i october 17. 1989

-(Notation Vote) ster-in-31, j

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The Commissioners i

From:

James M. Taylor f

Acting Executive Director l

for Operations

Subject:

IMPLEMENTATION OF THE U. S. ENVIR0letENTAL PROTECTION v

AGENCY'S HIGH-LEVEL WASTE DISPOSAL STANDARDS

Purpose:

In response to Staff Requirements Memoranda,M890711A of

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July 21 and MB907268 of August 8, 1989, this paper informs the Commission of:

(1) the status of the U. S. Environ-eental Protection Agency's (EPA's) high-level waste (HLW) disposal standards development; (2) the U. S. Nuclear i

Regulatory Commission (NRC) staff's reevaluation of its e

views on implementation of probabilistic standards; and (3) i the status of the staff's reevaluation of the use of such quantitative standards by development of procedures and rules that are, needed for fap1ementing the standards.

l To request Commission approval of staff plans to pursue a continuing evaluation of the EPA standards by way of rulemakings and interactions with EPA's staff.

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EPA, pursuant to the provisions of the Nuclear Waste Policy Act of 1982 (Pub. L.97-425), is responsible for development of environmental radiation protection standards for disposal of NLW.

NRC is-responsible for licensing the disposal repository, but its licensing judgment must be

{

based on compliance with the EPA standards.

EPA promulgated its standards in 1985, but the standards were vacated in 1987 by the U. 5. Court of Appeals.

They are expected to be reissued for public comment in late 1989, and some parts-of the standards are expected to remain unchanged from those promulgated earlier.

Specifically, the probabilistic nature of the " containment requirements" section, which was initially opposed by the Commission, is expected to.be retained..The staff's reevaluation of its views on implementation of probabilistic standards in a HLW repository licensing review and the basis for the staff's CONTACT:

Daniel Fehringer, 2t55 492-0426 l

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The Commissioners -

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I views arg presented in this paper.

This paper also t

discusses U.S. Department of Energy's (DOE's) plans for esmonstrating compliance with the standards and the NRC staff's plans for rulemakings related to implementation of i

the standaros.

+

Sefere EPA issues revised standards for public comment, the staff will provide the commission an evaluation of the technical basis free which the revised standards were derived, and any comments the staff considers should be provided to EPA before publication of those standards.

RKknemnd:

MLW (including spent nuclear fuel) is highly radiotoxic and i

will remain hazardous for thousands of years.

Projecting the performance of the natural and man-made components of a-repository over such a long time will involve uncertainties that spy be unprecedented "n engineering and risk l

assesament practice.

The challenge facing NRC and EPA is i

. to develop a regulatory approach that will accommodate these uncertainties.

Such a regulatory approach should i

allow licensing decisions to bei reached on acceptance of e

suitable sites and designs and rejection of unsuitable i

ones, while avoiding reliance on overly conservative i

l approaches that wou'd excessively increase disposal costs or might elleinste suitable repositories from

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consideretten.

I In the late 1970's, EPA began development of environmenta!

l radiation protection standards for disposal of HLW.

As the benchmark for overall repository systes safety, those i

standards address:

(1) the time period after disposal for which repository performance must be projected (at least 10,000 years); (2) the conditions for which performance is to be assessed (both expected performance and performance following reasonably foreseeable disruptive processes and events); and (3) the maximum allowable contaminetton of g eundseters, doses to individuals, and population impacts.

"he standarts reflect an unprecedented societal concern over the perceived long-term hazards of HLW, and an apparent societal willingness to best the cost of impismenting the safest disposal technology that is reasonably achievable.

1 I-On December 29, 1982, EPA published its proposed standards (40 CFR Part 191, 47 FR 58196) and solicited public comment l

on them.

Of particular note was the probabilistic nature of the standards, which endorsed a non-linear, inverse

+

relationship between the allowable size of a release and the likelihood that a release would occur.

NRC's comments 1

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The Cammissioners i (dated May 10 and 11, 1983) objected to the probabilistic nature of the standards, stating, in part, that "[t]he numerical probabilities in (the standardsl would require a degree of precision which is unlikely to be achievable in evaluating a real waste disposal system." The NRC comment went on to explain that "... identification of the relevant processes and events affecting a particular site will require considerable judgment and will not be amenable to j

accurate quantification, by statistical analysis, of their probability of occurrence."

l EPA retained its numerical standard, but in response to NRC's comments EPA added wording to the final standards which was i

virtually identical to the wording of Section 101 of 10 CFR Part 60.

This text recognized the long time involved and the

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associated substantial uncertainties in projecting HLW repository performance, and emphasized that a " reasonable akpectation," rather than absolute proof, is to be the test of compliance with the standard.

In an additional attempt to provide flexibility for implementation of the standards, EPA also provided that quantitative predicticns of releases from a repository were to be incorporated into an overall probability distribution only "to the extent practicable." This phrase appears to I

l allow at least some additional discretion for NAC to incorporate qualitative considerations into its decision-making, rather than placing sole reliance on numerical

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projections of repository performance.,

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1 Sased on these changes in EPA's standards, the NRC staff withdrew its objection to the standards.

In SECY-85-272, dated October,1985, the staff inforseed the Commission that "[a]1though the statf continues to believe that the probabilistic nature of the standards will pose a signifi-cant challenge, the staff considers that the standards, in l

the current form, can be implemented in a licensing l

review." The Commission did not disagree with the staff's assessment and, on September 19, 1985, EPA promulgated final environmental radiation protection standards for disposal of HLW (50 FR 38066).

The final standards (40 CFR Part 191) included provisions for (1). groundwater protection; (2) individual protection; and (3)' total release of radioactive material to the environment for 10,000 years after waste disposal.

The latter requirement, the " containment requirements," retained its probabilistic format, imposing more restrictive release limits for relatively likely releases than for those less likely to occur.

Included in the containment requirements was the

^^

l The Cassissioners qualifying woredng referred to previously, recognizing the j

need fo? non guantitative censiderations when evaluating r

compliance with the probabilistic standarcs.

The-j requirements for groundwater and individual protection were such less encompassing, being limited to "undicturbed

-l performance" for only the first 1,000 years after waste i

disposal.

A 1987 Federal court decision remanded these standards for further consideration by EPA.

The basis for the romand 1

involved the procedures used to issue the groundwater and individual protection requirements and inconsistencies between those requirements and other EPA standards.

The l

probabilistic containment requirements were not found to be defective.

A recent internal EPA (working) <traft of the revised EPA standards indicates that most, but not all, changes unoer consideration are related to the court i

decision, and that the probabilistic portion of the l

standards is likely to be retained largely unchanged.1

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1 epa's peniling revision and reissuance of its NLW standards has provided an opportunity for the NRC staff to reexamine its earlier views on implementation of those standards.

In i

particular, the additional experience acquired by the staff since 1905 in probabilistic risk assessments for power

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plants and application of NRC's safety goals will be drawn

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l on to determine whether the staff still retains its i

confidence that probabilistic standards can be implemented in an NRC licensing review.

Discussion:

EPA developed its standards by evaluating the performance of several hypothetical repositories and by considering the costs and benefits associated with alternatives such as improved engineered barriers.

In describing the standards, epa stated that "... the Agency (EPA) has been able to develop standards for the management and disposal of these

't westes that are both reasonably achievable - with little, if any, effort beyond that already planned for commercial westes - and that limit risks to levels that the Agency i

believes are clearly acceptably small" (50FR38070, September it. 1985).

EPA's standards are thus more a generic quantification of "as low as reasonably achievable" t

(ALARA) than a safety limit based solely on consideration of acceptable levels of risk.

A second working draft is expected later this fall.

The staff plans to 3

provide specific written comments to EPA on the second working draft.

The staff will infore the Commission of any problems and the staff's recou-eendations for resolving them prior to providing the comments to EPA.

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The probabilistic portion of the EPA HLW standards was derived so that population impacts would be restricted to 1000 premature cancer deaths over 10.000 years for s repository inventory of 100,000 metric tonnes of spent fuel (the approximate inventory to be generated by all currently operating power plants in the U.S.).

This average 3

population risk (10-1/yr) is intermediate between the population risk typically posed by a single commercial nuclear power plant (10.a/yr) and that represented by all commercial nuclear power plants in the U.S. (100/yr). - Thus, although the standards represent something of a generic quantification of ALARA, the level of impacts allowed by the standatds does not appear to be significantly differe '

i from that currently presented by operating nuclear power plants.

Housver, it is important to recognize that the achievability of this risk level by a real repository has not yet been tested by analysis and thua achievability by a real l

repository is uncertain.

00E's current efforts in developing performance assessment captbilities for the civilian i

repository program may previde significant insights, ?s will 00E's experience in4Jeveloping performance assessments for the proposed repositr,ry for defense transuranic wastes.

i.e., the Weste Isolatirn Pilot Plant (WIPP).

The EPA nas

~

proposed that the DOE publish the performance assessments for WIPP in a supplement to the Environmental Impa:t Statement for that facility, where all can see and comment on it.

An effort by a tcan of staff from the Offices of Nuclear i

Material Safety and Safeguards and Nuclear Regulatory i

Research to conduct preliminary analyses of repository performance will be a further step in answering this question.

Meanwhile, the staff intends to give substantial attention to the proposed revisions of the EPA HLW standards.

Prior to pubitcation of EPA's revised standards, i

the staff will provide'the Commission an evaluation of the technical basis from which those standards were derived, and any comments the staff considers should be provided to EPA before public comments are requested.

The Nature of the problem

'i Differing views on implementation of the EPA HLW standards ultimately derive from different perceptions of the statistical rigor required for estimates of the probabilities of potential'y disruptive events such as fault movement, volcanic activity and climate change.

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The Commissioners '

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A rigorous application of EPA's numerical standards would require estimates of the probabilities of potentially 1

disruptive events that are derived from a statistical data j

base of previous occurrences of those events at the repository site.

Some of the events of interest may be relatively rare compared to the length of.the geologic-i record for a repository site. A recent National Research Council reporta dealing with probacilistic seismic hazard analysis noted that the relatively short historical record i

of seismic activity requires reliance on other techniques when projecting seismic activity for thousands of years l

into the future.

horeover, some potential events may not even be evidenced in the geologic record (e.g., human-initiated events).

Therefore, a rigorous application of j

the EPA standards would lead to the cenclusion that the j

standards :annot be implemented in a licensing review.

?

Indeed, this interpretation was exactly NRC's view of the i

standards when EPA proposed them for public comment in 1982.

EPA retained the numerical standard, but in resp'onse to i

NRC's concerns. EPA added text (previously mentioned), to j

its probabilistic containment requirements, rect,gnizing the uncertainties involved'in rrojecting repository

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performance over long time periods.

Specifically, EPA l

stated that "[p]Poof of the futum performance of a disposal syette is not to be had in the ordinary sense of the word in situations that deal with much shorter time frames.

Instead,'what is required is.a reasonable l

expectation, on the basis of the record before the implementing agency, that compliance... will be achieved."

In Appendix 5 of the standards EPA elaborated on its views on implementation of the standards. There.

l EPA stated:

Determining compliance with [the standards] will also i

L involve predicting the likelihood of events and processes that say disturb the disposal system.

In 1.

making these various predictions, it will be appropriate for the implementing agencies to make use of rather complex computational models, analytical theories, and prevalent expert judgment Mlevant to l

the numerical predictions.

Substantial uncertainties are likely to be encountered in making these a Panel on Seismic Hazard Analysis, Probabilistic Seismic Hazard Analysis.

National Academy Press, Washington, D.C., 1988.

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predictions.

In fset, Jole reliance on these y

numerical predic*.4.3 to detereine compliance may not be appropriate; the implemer. ting agencies may choose to supplement such predictions with qualitative judgments'as well.

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b' This text indicates + hat. EPA did not intend to require that NW repository licensing decisions be based solely en numerical probability estimates.

Rather, EPA recognized that other,'more qualitative considerations, such as the multiple-barrier. defense-in-depth concept--

?

- imbedded.in Part 60, would play a_ major role in evaluating tho' safety of a proposed repository.

Although these-

- statements by EPA characterize the use of non-quantitative' factors;as " supplemental to" the numerical standard.and discuss flexibility in tern of treating uncertainties, the determination that must be made under EPA regulation is that there-is a " reasonable expectation" that repository performance will comply with the numerical standard.. Thus.

while ths language added by EPA'to.the rule and in the

?l Supplementary Information tends to recognize qualitative-L' considerations en acceptable approach to implemer.tation is 3

- still ambiguous-and the governing standard is still'the ababilistic numerical standard.-

hRE iconsino Reevirements Part 60 currently contains language in Section 60,101 i

recognizing that " reasonable assuranco" must have a somewhat different interpretation in r'epository licensing than it'has in,other NRC licensing escisions dealing with such shorter time periods.

However, Part 60 does not now directly address implementation of the EPA standards, because those standards had not yet been developed when Part 60 was published.

After promulgation of the EPA standards in:1985, the NRC published. proposed " conforming amendeonts" to incorporate those standards into NRC's regulations (51 FR 22288, June 19, 1986).

Those proposed 3

amendments, which were withdrawn when the Court of Appeals remanded the. EPA standard,'would have added, to Part 60, text nearly identical to that cited from EPA's Appendix B, previously mentioned.

In addition, a lengthy exposition on implementation of the EPA standards was presented in the Supplementary Information for the proposed amendments.

The conforming amendments were intended to establish, through rulemaking, the regulatory basis to ensure that the EPA standards could be implemented in a workable manner in NRC's licensing process.

As will be discussed later in this paper, the staff anticipates reinitiation of the 9

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conforming amendments rulemaking (and initiation of. one or apre additional implementation rulemakings) when the EPA standards are reissued. The staff believes that the-conduct of these rulemakings can and_will ensure that the i

application'of probabilistic analyses in NRC's' licensing process will remain carefully judgmental, as intended by l

EPA'and NRC.

Probability Estimates As discussed previously, numerical probability estimates i

are not intended to be the sole basis for repository J

licensing decisions.

However, neither er purely qualitative considerations.

In the NRC staff's view,:the EPA standards require a combination of the two types of information to be weighed when evaluating repository safety.

Thus, the question still remains as-to whether probability estimates for very unlikely events can be s

F

.eerived in any meaningful.way.

L The staff view is that probability estimates can be developed that are reasonably defensible -- at least for i

sites.that are not unusually complex or geologically active. -(current-informatton is:not adequate to determine

whether the Yucca Mountain, Nevada site is so geologically complex and active as to preclude meaningful. probability estimates.. This,is a major issue to be resolved as soon as e

l practicable during site characterization.) The basis for this view consists, in part,<of an.important distinction between:the probability.of occurrence'of a potentially disruptive event and the probability that a release of radioactive.netarial'to the accessible environment will

~

occur within the 10,000-year regulatory period addressed by the EPA standards.

The very low probability contained in the standards -- one chance in 1,000, over 10,000 years --

refers to a release to the accessible-environment rather than'the occurrence of an' event that sight lead to the g

W release.

The probabilities of events and releases can be quite different because of three factors, referred to here as the resiliency, geometric, and time factors.

Resiliency factor.

The nature of an NW repository is such that it may be partially or totally resistant'to some types of events.

As an example, vibratory ground action associated with fault movement is likely to be relatively unimportant because for most repository designs there are no components whose integrity is sensitive to vibratory ground action.

Similarly, drilling into a repository during the first 300 to 1000 years, when waste canisters L

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are required to be substantial.ly intact, or drilling into an unsaturated zone repository, may cause little or no release unless the drilling directly strikes a canister.-

1 If a repository site were found with a grounowater travel

- time between the repository and the accessible environment approaching-10,000 years, that site would be resistant to most events other than those that could substantially e

shorten the groundwater travel time.-

The staff anticipates that, for some events, there will be no need for probat"111ty estimates, when it:can be shown that the repository system is resistant to the disruptive effects of the. events.

~

Geometric factor.

Generally, the NRC and EPA regulations presume that a repository would be located within a larger, relatively homogeneous geologic setting. _The geologic

<record of this larger area can provide the basis for' estimating quite small probabilities of occurrence at the repository site.

Consider, for example, a 10 km2-reposi-tory site 1ccated within a 10,000 kn. geologic setting.

a Events distributed randomly within the geologic setting,-

and with a recurrence interval of 10,000 years, would have a probability of occurrence at the repository site of only 10 7 per year.- To the extent.that potentially disruptive.

events can be considered randon, the staff anticipates that L

= this type of geometric consideration will be very signi-ficant in developing probability-estimates.

Time factor.. The time'at which an event is postulated to accur is very important in evaluating its significance.

First, radioactive decay rapidly reduces the radioactive inventory of.same of the shorter-lived constituents of HLW.

For events that disrupt only a very small fraction of a repository (e.g., drilling that strikes a waste canister) releases may not be significant unless the event occurs within the first few hundred years after repository closure.

Second, the time' lapse between the occurrence of an' event and any resulting release may be quite long for a well-designed and sited repository.

If, for example, the time for transport of released waste through the geosphere to the' environment is 9000 years, only those events that occur within the first 1000 years after repository closure would be of regulatory significance in applyirig a 10,000-year standard.

In both cases, the staff expects estimates of event probabilities to be more meaningful over these shorter time periods than they would be for 10,000 years.

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m In summary, three may be a difference of orders of magni-1

= tune-between tne ::robability that an event will occur and t

a the probability that a release will result.

Thus, in' order to' demonstrate that a release has a probability less than 1 cnance in 1,800 over -10,000 years, it might only be

-i necessary to show that the probability of an_ initiating event'is less'than 1 chance in 100,000.per year -- a short enough recurrence interval so that the geologic record should provide useful information.

The predominant staff.

1 view is that meaningful. although not necessarily statistically rigorous, probability estimates can be made Lfor repositaries located at well-chosen. sites -- i.e.,

sites-that,are not unusually complex or geologically active.

In-fact, the ability to develop the required i

probability estimates is a de-facto siting criterion for evaluating how well the site is understood.and thus, how-confident one can be of its future performance as part of a repositary.

As'an example, the staffs of both DOE and-

-NRC have been working te develop' methods'for predicting the-probability of future volcanic activity at the Yucca Mountain, Nevada site, based on studies of the-record.of

past volcanism near the site.

These methods have been used to develop numerical estimates of site performance

.The-

- i uncertainties'in the probability estimates reflect technical concerns with the site which must.be resolved before 1Iconsieg, regardless of the stancard which nust be

~

-implemented to evaluate the site, rather than cotecerns with the ability to develop these. numerical values. The NRC 4

staff expressed its views in its comments on DOE's Site Characterization Plan (SCP), and additional discussions-are planned for future meetings with 00E.

It is also possible to interpret the EPA standards to require a more rigorous statistical basis, in analyses incorporating significant conservatises, for licensing.

The only way to produce the required probability estimates would be to have available a site-specific geologic record

~i approaching the age of the earth, and since such lengthy geologic records can seldon'be found, rigid implementation of the EPA standards is likely to prove impossible. 'Also, the principal discussion has focused on geological examples.

However, the EPA standard is not limited to geologic events but an entire spectrum of events that have the reouisite likelihood.

It can be extremely difficult to deal with the tail of a probability distribution of very large events with mean probabilities on the order of 10 7 to 10.s/ year.

In the context of the EPA standard, it may also be difficult to deal with such things as climatic changes caused or affected by human activity over thousands m

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.or years (e.g., greenhouse effect concerns resulting from-increased fossil fuel use in recent decades).

~Where from Here?

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. While the basic principles reflected in the EPA 1985-changes which recognized uncertainties and the'need for t

non quantf fiable technical judgments in assuring repository performance remain valuable and important, additional clarification and guidance is required in order to deal-with these issues.

Specifically, additional clarification and guidance is needed-to c m to grips with how a

non quantifiable technical judgaents 'are to be used in assessing " reasonable expectation" of compliance with'the' governing numerical standaM..The NRC staff has-identified..

1' L

two basic courses-of action availaide to the Commission --

L

'(a)'reaffim its earlier. acceptance of the probabilistic x nature of the. EPA standards provided that clarification of the treatment of key problem areas can be worked out (in this connection the staff will work closely with. EPA to develop werding which could be used in either revised EPA standards or in NRC regulations, as appropriate, to minimiza potential implementation problems and will~ remain alert to developmente that could potentially alter this acceptance) or,-(b) if the standards are now=or subsequently a

judged not to be-implementable, petition EPA to raissue the L

standards in an altered or non probabilistic format.

Combining these two basic courses of action with the prospect of developing implementing amendments to Part 60 has led the staff to identify the.following four alternatives.

l-Alternative 1 ---Current EPA Standards and Part 60.

In this a'tornative, the probabilist'c portion of the EPA standards would be reissued with the same format as in 1985.

The specific wording of the standards and of Part 60 would be revised only as necessary to resolve potential implementation problems and to ensure consistency between the two regulations.

The main advantage of this alter-native is-that a complete set of regulatory standards could be established quickly, providing guidance to DOE for its repository development program.

The main disadvantage of this alternative is that it might leave many c6rtentious issues, such as acceptable methods for estimating the probabilities of disruptive events, to be resolved during a licensing review.

The absence of clarification may make it virtually impossible to resolve difficult licensing issues within the three year statutory time frame.

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p Alternative 2 -- Revised EPA Standards and Current Part 60~

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$evera possible revisions to the EPA standards have been af considered as ways to' sake the standards easier to imple-ment.

These include substitution.of qualitative-terms (likely, unlikely, etc.) for the numerical probabilities in the standards, restating the numerical probabilities-in a f

less precise way (e.g., combining tho' numerical proba-bilities with modifiers such as "on the; order of"), and making the~ standards consequence-based rather than risk-'

based (i.e., completely removing all probabilistic' aspects i

of the standards).

Amendments-of these types might allow more flexibility for implementation of the EPA standards, l

but would be accompanied by significant; uncertainties about i

pc interpretation of the standards.

These greater uncertain ;

L ties raise a different obstacle for the~1icensing process, namely, the lack of a clear standard of' acceptability.

The t

predominant view of.the staff is that the current wording of. the EPA standards represents a reasonable compromise-between the goal of precise statement of the regulatory j,

requirements of the standards and the: desire for-flexibility in implementing the standards.

But, as discussed above, additional clarification-and guidance is-needed to address more clearly how non quantifiable-technical judgment any be used in lieu of or to fulfill

_l the numerical standard.

Since the fundamental -issue is one

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of clarifying the EPA-standard, this should be=the responsibility of EPA, with substantial input from NRC concerning the specific nature of such clarification.

Alternative 3 -- Current or Revised EP'A Stonderds and' Aavised Part 60.

This alternative, which 's currently 4

being pursued by the staff, involves two phases.. First.

the staff will pursue an aggressive interaction with EPA during reissuance of its standards' aimed at identification and resolution of potential implementation problems.

To the extent possible the staff seeks to have EPA expand on-

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r r its interpretation of the EPA standard.

Second, the staff will amend Part 60 before a licensing review so as to resolve, where practicable, any rensining potentially contentious issues on implementation.: The staff currently plans three rulemakings related to implementation of the EPA HLW standards (see SECY-88-285, October 5, 1988).

One will provide the basis for making site-specifit determinations on the potentially disruptive events and a Development of technical positions or regulatory guides, and interlocutory review by a licensing board for resolution of issues., are variations of this alternative.

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1 processes that will need to be considered in developing HLW l

release e:enarios.

It wil1~ revise the current definitions of " anticipated" and " unanticipated" processes and events in Part 60.

The revisions will specify a non probabilistic

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• m method to be used for categorizing processes and events as i

" anticipated" or "unant'af9ated." The staff proposes this'-

method because of its u n that categorization on the basis' of numerical probabili w m inates would be too uncertain 1

to use as the primary basis for preliminary screening of events and processes.

A second rulemaking, referred to as the " conforming 1

amendments," will incorporate directly into Part 60,all the substantive provisions of the EPA standards and will' adopt

.any changes in terminology necessary for conformance

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l between the two regulations. An earlier conforming rulemaking, previously discussed, was terminated when the EPA NW standards were remanded by a-decision of-a Federal Appeals Court.

The amendments currently contemplated will L

serve the same purpose as those previously initiated --

L i.e., to reproduce within"Part 60 all of the substantive requirements of-the. EPA standards and to eliminate any

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differences in. terminology that might otherwise cause p

confusion duri.ng a licensing review.

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As discussed earlier, it is the staff's intention to work closely with EPA during reissuance of-its standards-to reduce or eliminate, to the extent practicable, potential sources of confusion or contention about acceptable means for implementing the EPA standards.

Nevertheless, the staff recognizes that it likely will not be possible for EPA to resolve all issues regarding the standards, and.that an additional initiative by the NRC may be necessary.

Thus, the staff is planning to pursue a third rulemaking, called.the " implementing-amendments," which is now only in i

the initial scoping phase.. Possible topics to be addressed by this rulemaking include:

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1) identification of acceptable methods for validation of the models and computer codes to be used for projecting repository performance;

2) specification of acceptable methods for estimating the likalthood of potentially disruptive processes and events, either generically or on a site-specific basis; I

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f 3) further elaboration, beyond that currently provided in Part 60,= of. the conditions for evaluating potential

- i human-induced disruotions of a repository and of the needi for incorporation of human-initiated releases into an.

j overall-probabilistic distribution of releases from a i

. repository;

- 4) -endorsement of an acceptable method for identify.ing potentially disruptive scenarios for analysis, and specification of criteria for screening out scenarios with low likelihood or consequences; and

5) -elaboration on the meaning of the Section 60,122 requirements for evaluation of " favorable" and "potentially adverse" conditions--- especially the requirement to show

- that a potentially adverse condition does not compromise i

the ability of the geologic repository to meet the performance objectives relating to isolation of the wasta.

7 5

The advantage of this: alternative is that it permits resolution of certain potentially contentious-issues before a licensing review, so:that those. issues will not delay or -

prevent a licensing-decision on repository acceptability.-

l The disadvantage of this alternative is the.significant j

amount of time _ and staff resources required' to develop and promulgate thelnecessary amendments to Part 60.

Since.the i

purpose and effect of these NRC rules is the implementation; of the EPA standards,: EPA endorsement of.such NRC L

' litigation over whether.such NRC rules are consistent with implementation would minimize the potential for protracted 1

NRC's statutory obligation to be consistent with EPA-standards.

Preferably, EPA should clarify its' standards or amplify the Supplementary Information~ accompanying ~its regulation in a manner consistent with the thrust'of NRC's

" implementing regulations."

Altemative 4 -- No EPA Standards and Current or Revised Part 60.

This alternative is included because of the-possihility that EPA sight be significantly delayed in reissuing its standards, or that the standards might again L

be found legally inadequate by a court.

If there should be L

no EPA HW standards in place at the time a repository license application is received, NRC could still carry out its licensing review, relying on Sections 60.31 and 60.41 as the criterion for overall systes performance (no unreasonable risk to public.%alth and safety).

Doing so would, however, inject a significant uncertainty concarning the level of risk that would be considered " unreasonable."

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r To prevent this from occurring, NRC could add to Part 60 a i

more precise criterion for overall system performance. The q

staff does not now favor this alternative, and assumes that

~s the EPA' standards will-be available when they are needed..

The staff will~ monitor EPA's progress in reissuing its standards and,:if significant delays become evident,.will reevaluate the-desirability.of. pursuing this alternative..

The staff will also1 keep abreast of developments regarding implementation of the EPA standards for DOE's WIPP as'part of its continuing evaluation of the ~ standards.'

Evaluation of Alternatives-As previously discussed, the EPA standards already contain s

wording allowing considerable flexibility for imple-mentation. -Alternatives that further increase flexibility suffer from a lack of precision in their statements of the safety levels to be achieved (e.g., replacing numerical probabilities with "likely," "unlikely," or " credible").

Additional flexibility might prove counterproductive because a' licensing review would need to interpret-the meaning of the standards:as well as consider whether compliance with the: standards has-been achieved.. What is-needed.is clartification of.how the flexibility provided by j

some of-the wording in the rule and in;the-Supplementary.

Infornatfon' accompanying the 1985 reviston may be used in.

satisfying the governing numerical standard.

Rather-than-petition EPA for major revisions to the probabilistic format, the staff recossends an aggressive effort to work closely with EPA to identify potential implementation L

problems in the' standards and to develop solutions to l-those problems which can be incorporated by EPA in the i

standards when they are reissued.

To the extent that this L

strategi is successful, the breadth of issues needing NRC l

resolution as discussed in Alternative 3, above, will be minimized.

The EP4 standards also apply to facilities used for disposal of K

transuranic wastes. -- the type of wastes to be emplaced at WIPP -- and DOE must prepare probabilistic analyses to demonstrate compliance of WIPP with 1

the standards.

EPA's comments on a draft Supp'lemental Environmental Iseact Statement ~(EIS) for WIPP urge DOE to publish an additional supplemental EIS or similar compliance document for public review and comment after the planned five year test phase and before initiation of l

l the final disposal phase of operations.

NRC staff review of DOE's L

iterative performance assessments for WIPP, which will be necessary to support the compliance document, could provide additional valuable insights into the implementability of the EPA standards.

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The NRC staff recommends continued pursuit of Alternative 3.-and' approval of this recommendation is requested.

3 00E's Plans

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The SCP for the Yucca Mountain site, recently reviewed by:

-NRC staff, describes in general terms DOE's plans for implementing the EPA ~ standards.

These plans involve identification of potentially disruptive processes and events (several dozen are described in the SCP), grouping a

these into scenarios or " scenario classes," evaluating radionuclide releases to the environment for.each scenario L_

or scenario class,--and combination of the resulting l?

information into a " complementary cumulative distribution-function" (CCDF). for evaluation of compliance with the EPA standards.

DOE's plans correspond weli.with the staff's i

views of the requirements of the EPA standards..It should s

be noted that the Technical Review Board's (TRB)

Subcommittee on Perfomance Assessment is reviewing DOE's plans for implementing the'EEA standards.

f 4

If the Standards Are Not Isolamentable Although EPA considers its standards to be implementable, EPA recognizes that. doubts continue-to remain about implementation of the EPA-standard.

As a result, provisions for development of alternative' standards have been incorporated.

The Federal Recistg text (50 FR 38074, c

September 19,1985) describing the alteinative standards provision, stated:

There are several' areas of uncerteinty the Agency-

[ EPA] is. aware of that might cause suggested modifications-of the standards in the future.

One of these concerns implementation of the containment requirements: for mined geologic repositories.

This will require collection of a great deal of data during site characterization, resolution of the inevitable uncertainties in such information, and adaptation of

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this information into probabilistic risk assessments.

Although the Agency is currently confident that this will be successfully accomplished, such projections over thousands of years to determine compliance with an environmental regulation are unprecedented.

If --

after substantial experience with these analyses is acquired -- disposal systems that clearly provide good isolation cannot reasonably be shown to compiy with the containment requirements, the Agency would

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_ consider whether modifications to [the standards] were-f 4

appropriate.

Any NRC staff position that the EPA standards can be implemented depereds upon the flexibility for NRC to develop _

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. and apply non probabilistic criteria consistent with the Commission's traditional multiple-barrier, defense-in-depth licensing philosophy, and the ability to work with EPA to identify and resolve potential _iasues regarding implementa-tion.

The staff anticipates that this resolution will-consist of modifications to the EPA standards and.NRC.

I rulemakings.

However,-if this stritegy should. fail'to:

l

. rescrive open issues. and if implementation of the-EPA i-standards should prove unworkaile for a rep,ository 4

that otherwise appears suitable:3 EPA appears to be i

p committed to reexamine its standaros e d, presumably.to l --

modify those standards as needed to allow a reasoned' l

licensing decision to be reached.

Application of the p

standards-to WIPP will be an additional test of the standards and'should help to resolve' questions about the

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standards.-independent of a formal NRC licensing review.

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==

Conclusions:==

The predominant view of the staff is~that the technical l

scope of a repository licensing. review will be the same

-l regardless of the.way in which the EPA standards-are formulated.-

If one is to-reevaluate the use of quanti-I tative ' licensing standards for the HLW repository, such a reevaluation cannot be done separately, but'only by a I

thorough evaluation of the procedures..and controls for use of such. standards in the regulatory process..Thus,-it is l'

the further view of theistaff that resolution of implementation concerns.through close1 interaction with EPA-

[

during reissuance of its standards, followed by the:

L technical. development and rulemaking process' described in IL SECY 80-285 is the essential path of such reevaluation.

- i Regarding potential releases-from a repository, the L

fundamental purpose of the licensing review is to answer the questions:

--What can go wrong with a repository?

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--What are the effects on public health and thi environment if these things happen?

--How likely is it that they will occur?

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4 The likelihood of potential repository disruptions must be evaluated in srme manner, and EPA's. approach of combining

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numerical-probabilities with wording allowing substantial reliance oh qualitative considerations appears to be workable in a licensing review. '00E bears the " burden of proof" of compliance with the standards.

If NRC's or-DOE's-experience in attempting to implement EPA's standards demonstrates serious difficulties in implementing-the-standards, EPA appears to be committed to reexamine the standards and to modify thee, as needed, to allow a reasoned licensing decision-to be reached.

NRC staff willl ensure that EPA is promptly informed of any such difficulties based on NRC's experience.

Recommendation:.

That the Comeission approve staff plans to pursue a i

long-tors, ongoing evaluation of the EPA stendards by_way of. its implementing rulemakings and, as' it does -so, to -

maintain close contact with EPA to identify and resolve, L

within the EPA standards, potential implementation issues-to the extent practical.

5 l

Coordination:

The Office of the General Counsel has reviewed this paper and has:no legal. objection.

The Office of Nuclear Regulatory Research has-also reviewed and concurred.in this paper. ; The Advisory Committee on Nuclear Waste j'

~

(ACNW) and its predecessor, the Waste Management Subcomeittee of tht Advisory Committee on-Reactor Safeguards (ACRS) have expressed reservations about the faplementability and about the. stringency of the EPA HLW standards.- Pertinent correspondence is enclosed.

A s M. Tay1 o

ing Executive Director o

for Operations s

Enclosure:

~ACRS:and ACNW Correspondence Related L

,to EPA HLW Standards L

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