ML20082K249
| ML20082K249 | |
| Person / Time | |
|---|---|
| Issue date: | 08/31/1991 |
| From: | NRC ADVISORY COMMITTEE ON NUCLEAR WASTE (ACNW) |
| To: | |
| References | |
| NACNUCLE, NUREG-1423, NUREG-1423-V02, NUREG-1423-V2, NUDOCS 9108290265 | |
| Download: ML20082K249 (98) | |
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AVAILABILITY NOTICE Availabihty of Reference Materials Cited in NRC Pubhcations Most documents cited in NRC pubhcations will be available from one of the following sources:
1.
The NRC Fubhc Document Room, 2120 L Street, NW., Lower Level, Washington, DC 20555 2.
The Supenntendent of Documents U S. Government Printing Office, P.O. Box 37082, Washington, DC 20013-7082 The National Technical Information Service, Springfield, VA 22161 Although the listing that follows represents the majority of documents cited in NRC publica.
tions, it is not intended to be exhaustive.
Referenced documents available for inspection and copying for a fee from thc NRC Pubhc Document Room include NRC :orrespondence and internal NRC memoranda; NRC bulletins, circulars, information notices, nspection and investigation notices: hconsee event reports; vendor reports and correspondence; Commission papers; and applicant and bcensee docu-ments and correspondence.
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p* =m" q,
~' '
NUREG-1423 in.
Volume 2 A Compilation of Reports of Tae Acvisory Committee on Nuc. ear Waste July 1990 - June 1991 U.S. Nuclear Regulatory Commission August 1991 r'w w-7
AUSTRACT This compilation contains 20 reports issued by the Advisory Committee on Nuclear Waste (ACNW) during the third year of its operation.
The reports were submitted to the Chairman, U.
S.
Nuclear Regulatory Commission, or to the Director, Office of Nuclear Material Safety and Safeguards.
All reports prepared by the Committee have been made available to the public through the NRC Public Document Room and the U.
S.
Library of Congress.
iii
PREPACJJ The enclosed reports are the recommendations and comments of the U. S. Nuclear Regulatory Commission's Advisory Committee on Nuclear Waste during the period between July 1,
1990 and June 30, 1991.
NUREG-1423 is published annually.
Volume 1 contains the Commit-tee's recommendations and comments from July 1,
1988 through June 30, 1990, y
AqlfE MEMBERSHIP (JULY 1, 1990-JUNE 30, 1991)
CHAIRMAN:
Dr. Dade W. Moeller, Professor of Engineering in Environmental Health, School of Public Health Harvard University, Boston, Massachusetts VICE CHAIRMAN:
Dr. Martin J.
Steindler, Director, Chemical Technology Division, Argonne National Laboratory, Argonne, Illinois MEMBERS:
Dr. William J.
Hinze, Professor Department of Earth and Atmospheric Sciences 4
Purdue University, West Lafayette, Indiana Dr. Paul W.
Pomeroy Rondout Associates, Incorporated Stone Ridge, New York EXECUTIVE DIRECTOR:
Mr. Raymond F.
Fraley Advisory Committee on Nuclear Waste U.
S. Nuclear Regulatory Commission vii
.. ~ - -
TABLE OF CONTENT 8 ERRR ABSTRACT iii PREFACE v
MEMBERSHIP vil NRC Staff's Approach for Dealing with Uncertainties in Implemonting the EPA HLW
-Standard, August 3, 1990 1
Decommissioning of the Pathfinder Atomic Power Plant, August 3, 1990 5
Decommissioning Reviews for Other Than 10 CFR Part 50 Licensed Facilities, September 6, 1990 9
Revision 1 of Draft Technical Position on Waste Form, September 6, 1990 Il Program Plan for the Advisory Committee on l
Nuclear Waste, September 7, 1990 15 l
Program Plan for the Advisory Committee on Nuclear Waste, December 19, 1990 21 Priority Issues on Radioactive Waste Management, January 29, 1991 27 Stringency of U.
S.
Environmental Protection Agency High-Level Radioactive Waste Repository j
Standards,-January 29, 1991 31 Guidance on Limits on Tsses and Risks to L
Individual Members of the Population, l
January-29, 1991 35 Regulation of Mixed Wastes, February 28, 1991 41 l
l Comments on 10 CFR Part 60.113, Subsystem Requirements, March 1, 1991 49 l
iX
TABLE OF CONTENTS (CONT'D)
Paqo Staff Technical Position on Regulatory Considerations in the Design and Construction of the Exploratory Shaft Facility, March 26, 1991 53 Individual and Collective Dose Limits and Radionuclide Release Limits, April 29, 1991 55 Consideration of Human Intrusion in the Licensing of a High-Level Waste Repository, April 29, 1991 61 Program Plan for the Advisory Committee on Nuclear Waste, April 29, 1991 75 Alternative Approach to the Probabilistic Section of the Containment Requirements in 40 CFR Part 191 ("The Three-Bucket Approach"),
May 30, 1991 81 Review of Regulatory Guides on Revised 10 CFR Part 20, May 30, 1991 85 Review of Draft SECY Paper on Dealing with Uncertainties, May 30, 1991 87 Comments Regarding 10 CFR Part 61 Proposed Revisions Related to Groundwater Protection, June 27, 1991 89 Response to Questions Accompanying Working Dratt #3 of the EPA Standards, June 27, 1991 91 INDEX.
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UNITED STATES
,o NUCLEAR REGULATORY COMMISSION h
ADVISOHY COMMITTEE ON NUCLI AH WASTE WASHINGTON, O C. 2026
/
August 3, 1990 Mr. Robert M.
Bernero, Director Office of Nuclear Material Safety and Safeguards U.S. Nuclear Regulatory Commission Washington, D.C.
20555
Dear Mr. Bernero:
SUBJECT:
NRC STAFF'S APPROACH FOR DEALING WITH UNCERTAINTIES IN IMPLEMENTING Tile EPA HLW STANDARD During the 22nd meeting of the Advisory Committee on Nuclear Waste, July 30-31, 1990, we met with the NRC staff to review and comment on the subject draft SECY paper (Reference 1).
Th.4s draft was prepared by the staff in response to a request by the Commission for a "... summary on the staff's current approach to dealing with uncertainties / methodologies in implementing the EPA probabilistic standard so as to avoid [as) many of the controvercial aspects as possible."
We believe, for the reasons given below, that the staff'n approach is not adequate.
Wo include in this letter cpecific comments on the draft paper and also provide our comments on other aspects of the staff's role in implementing the EPA Standards.
1.
The draft paper describes two parts to the finding of compliance with the EPA Standards.
One part deals with the standard of performance and the other with confidence that the standard of performance has been met.
The staff has failed, however, to provide an adequate approach for dealing with residual uncertainties that will be encountered in completing this finding.
Much of the paper concerns methods for reducing and managing uncertainties related to 10 CFR Part 60 and the potential activities of DOE, but the staff appears to have neglected to develop an adequate approach for dealing with uncertainties inherent in 40 CFR Part 191.
2.
The paper acknowledges, albeit in conditional terms, the need for expert judgment, but provides no insight on how the staff will apply this judgment or develop an approach for selecting from among conflicting but apparently equally supported opinions.
We believe that expert judgment will be required 1
Mr. Robert M.
Bernero 2
August 3, 1990 regardless of the specific form of the final EPA Standards, and thus, the approach to the use of expert judgment in a robust manner is crucial to the quality of the licensing determinations.
The transcript of the 22nd ACNW meeting contains the details of our discussion with the staf f concerning conflicting expert opinions.
Our conclusion is that it may not be appropriate to treat discrepancies in expert opinions by using weighted averages unless this process has been carefully analyzed and the limitations of its application to both technology and licensing matters are well defined.
3.
The staff has included strategies in the paper such as rule-makings to 10 CFR Part 60 to reduce uncertainties.
While it is possible to narrow the technical and regulatory topics so that only fully determinable variables remain to be considered in the licensing process, we believe this tactic is neither likely to be successful nor is it appropriate.
The description offered by the staff does not allow insight into the scope or the schedule that the staff strategy would call for, in part because existing ru]emaking topics are not in an advanced stage of development.
The status and description of rulemaking previously proposed to support the conclusion that the EPA Standards are workable are cast into question as is the ability to bring uncertainties into concert with the use of the HLW probabilistic standards.
4.
We were unable to discern the relationship between the draft paper and the content of the related strategy document prepared by the NRC staff (Reference 2).
We concluded that an integrated overall strategy and a strategy for devising methods for demonstrating compliance with the EPA Standards are necessary and we urge the staff to develop such an integrated approach for delineation of methods that would demonstrate such compliance.
Such an integrated strategy should also address the connection between those activities to be carried out by DOE in response to uncertainties related to 10 CFR Part 60 and the NRC staff activities related to demonstration, by DOE, of compliance with 40 CFR Part 191.
5.
The current reevaluation of the EPA Standards, which may include a reformulation of its probabilistic requirements, mandates a
reexamination of assumptions about its implementability that were made a number of years ago.
This requires prompt attention to the development of a coherent strategy for dealing with the various uncertainties that arise in performance assessment.
The staff should be urged to undertake such a developinent without delay, 2
1
y, Mr. Robert M.
Bernero 3
August 3, 1990 0
We conclude that the draft paper should be modified by the staff to include a coherent strategy outline that explicitly addresses the implementation of the EPA Standards and consideration of the associated uncertainties.
The modifications should include exposition of the bases on which the strategies are developed, their application to regulatory and technical uncertainties, and a more deliberate oiscussion of how expert judgment would be applied, evaluated and justified.
Sincerely, k
Dade W.
Moeller Chairman
References:
1.
Staff's Approach for Dealing With Uncertainties in Implementing the EPA HLW Standards (WITS 8900236), draft SECY paper, undated.
2.
SECY-90-207, First Update of the Regulatory Strategy and Schedules for the High-Level Waste Repository Program, dated June 7,
- 1990, cc:
M.
Federline, OCM/KC M. Weber, OCM/KC S.
Bilhorn, OCM/KR J.
Kotra, OCM/JC K.
Dragonetto, OCM/JC R.
MacDougall, OCM/FR H. Thompson, EDO R.
Browning, NMSS A.
Eiss, NMSS D.
Fehringer, NMSS 3
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UNITED STATES
-I f
p, NUCLEAR REGULATORY COMMISSION e
ADVISORY COMMITTEE ON NUCLE AR WASTE l~
WASHINGTON. D C. 20566
/
- sees August 3, 1990 q
The Honorable Kenneth M.
Carr Chairman U.S.
Nuclear Regulatory Commission Washington, D.C.
20555
Dear Chairman Carr:
SUBJECT:
DECOMMISSIONING OF THE PATHFINDER ATOMIC POWER PuANT During our 22nd meeting, July 30-31, 1990, the Advisory Committee on Nuclear Waste met with the NRC staff to review plans for the decommissioning of the Pathfinder plant.
The Committee had previously - commented on this subject in our letter to you on October la, 1989.
Documents utilized in our latest review included the Safety Evaluation Report (SER) and the Environmental Assessment prepared by the NRC staff.
This was the first application for decommissioning of a nuclear power' plant that was handled by the Division of Low-Level Waste Management and Decommissioning.- This being the case, this is an excellent opportunity for the staff to reevaluate their generic technical-guidance for the review and approval of similar applications in the future, as well as-procedures for inspection of the decommissioned facilities.
-This guidance would be particularly helpful -in ensuring uniformity in handling such applications.
Because of the low power and limited operating lifetime of this Plant, the associated decommissioning operations cannot be con-sidered comparable to those anticipated for a major nuclear power plant.
The same is-true for the recent decommissioning of the Shippingport Atomic Power Station.
Nonetheless, both of these operations, and the cleanup activities at Three Mile Island, Unit 2, are providing information, guidance and data that will be useful for the future.
To this end, we encourage the NRC staff to keep abreast of such activities and to collect and digest the lessons learned.
The stated exposure rate to be attained in decontaminating the buildings and equipment surfaces at the-Pathfinder plant is less than 5 pR/hr, which is comparable to less than 45 mR/yr (assuming continuous exposure).
Because this dose rate will be confined to 5
i The Honorable Kenneth M.
Carr 2
August 3, 1990 a secured area (with only plant workers having access), we believe it is acceptable.
Nonetheless, care should be taken, using realistic exposure scenarios, to ensure that this approach is compatible with the recently issued Policy Statement on Below Regulatory Concern.
Included in such an assessment should be a consideration of the half-lives of the principal radionuclides involved.
We believe that the SER provides inadequate attention to the generation, retention, and analysis of liquid wastes.
The SER does not appear to accurately reflect the attention directed to this problem by the licensee.
One item that needs to be given greater consideration relative to the potential environmental impacts of the decommissioning operations is groundwater contamination.
Specific steps that should be taken include documenting existing groundwater contamination levels and vstablishing sufficient wells to monitor the possible migration of radionuclides down the hydrologic gradient to other areas.
A careful assessment also needs to be made of the potential for transport of radionuclides by groundwater.
Airborne tedionuclide releases to the environment which are anticipated during the decommissioning operations are expected to be well within NRC regulatory limits.
The licensee, however, had not established a means to provido a written record of such releases.
We concur with the NRC staff that the licensee should be required to measure, evaluate and report such teleases.
In our letter to you on October 18, 1989, we offered recommenda-
-tions on five topics that we believed should be given specific attention by the NRC staff in its review of plans for decommis-sioning the Pathfinder Atomic Plant.
Each of these topics has been addressed.
Because of the low radionuclide levels and radiation dose rates involved, there could be a tendency for the licensee (and/or its contractor) to become " relaxed" in their approach to this project.
For this reason, we urge that the NRC staff closely monitor the decommissioning to assure that standard operating procedures, including good health physics practices, are observed throughout the operation.
6
1 The Honorable Kenneth M.
Carr 3
August 3, 1990 Based on our review, and with due consideration to the advice given
- above, we concur with the NRC staff that this phase of the decommissioning of the Pathfinder Atomic Power Plant can be conducted without undue risk to the public health and safety.
Sincerely,
'~ '
0-f if Dade W.
Moeller chairman 1<e f erences :
1.
Safety Evaluation Peport on Proposed Final Decommissioning of the Fuel Handling Building and Reactor Building at the Pathfinder Generating Plant," License No. 22-08799-02, Docket No. 30-05004, June 1990 2.
Environmental Assessment of Proposed Final Decommissioning of the Fuel Handling Building and Reactor Building at the Pathfinder Generating Plant," License No. 22-08799-02, Docket No. 30-05004, June 1990 7
h UNITED STATES 7
'o NUCLEAR REGULATORY COMMISSION
.E ADVISORY COMMITTEE ON NUCLE AR WASTE WASHINGTON, D C. 20666 o%
/
September 6, 1990 The Honorable Kenneth M.
Carr Chairman U.S.
Nuclear Regulatory Commission Washington, D.C.
20555
Dear Chairman Carr:
SUBJECT:
DECOMMISSIONING REVIEWS FOR OTHER THAN 10 CFR PART 50 LICENSED FACILITIES During its 23rd meeting, August 29-30, 1990, the Advisory Committee on Nuclear Waste discussed the ongoing reviews by the NRC staff of decommissioning plans and activities for other than 10 CFR Part 50 licensed facilities.
In response to your request, we are pleased to provide the following comments on this matter.
As you know, we recently met with the NRC staff to discuss plans for its review of the decommissioning of the Pathfinder Atomic Power Plant.
This experience confirmed that such operations, whether they pertain to nuclear power plants or otr. types of NRC licensed facilities, involve a wide range of topics and activities of interest to this Committee.
These include the types and quantities of radioactive wastes produced and possible e "ps for reducing their volumes, as well as steps that might be taken to reduce or avoid the generation of wastes that fall into the mixed waste category.
Also of interest are the development of permissible limits for the release of decommissioned facilities for unrestricted use and relevant applications of the recently issued BRC Policy Statement.
Because we believe we can assist in resolving these issues, we look forward to working with the staff on these matters.
If you concur, we would plan over the next few years to join with the NRC staf f in examining and resolving key issues at a few sites, selected from among the approximately 40 that have thus far been identified.
Although experience to date indicates that the problems at each site are different, one of our goals will be to highlight key technical issues and to assist the staff in addressing them on a generic basis.
9
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The Honorable Kenneth M.
Carr 2
September 6, 1990 Our discussions with the NRC staff, and information presented in SECY-90-121 (Reference), indicate that certain factors should be kept in mind as this program develops.
Listed below are three that were brought to our attention by the NRC staff and with which we concur:
1.
Through its current cleanup program, the U.S.
Department of Energy is gaining considerable expertise in this area.
Every effort should be made to ensure that the related technology is transferred for use by the NRC and its licensees.
2.
The NRC staff needs to keep ' abreast of, and to develop a capability for processing, the latest environmental transport and dose evaluation models applicable to assessments of decommissioned facilities.
Although it is relatively easy to establish a dose limit for permitting such facilities to be released for public use, the determination of whether a given facility meets the dose rate criteria is much more difficult.
This involves not only the application of the previously mentioned models but also the development of procedures for conducting followup surveys of the decommissioned facilities.
3.
In order to make such determinations, the NRC needs to obtain guidance on a
variety of
- factors, including acceptable contamination limits for decommissioned facilities and/or sites.
In this regard, the staff should keep abreast of relevant developments within the National Council on Radiation Protection _and Measurements, the American National Standards Institute, and the Interagency Task Force chaired by EPA that we understand is addressing this subject.
We trust this responds to your request, and we look forward to working with the NRC staff as it establishes plans for regulating the decommissioning of these types of facilities.
Sincerely,
~
i Dade W.
Moeller Chairman
Reference:
SECY-90-121 dated March 29, 1990 for the Commissioners from James M.
- Taylor, Executive Director for Operations,
Subject:
Site Decontamination Management Program i
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UNITED STATES y
NUCLEAR REGULATORY COMMISSION S
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.f ADVl80nv COMMITit C ON NUCit AR WAbit WASHINGTON. D C N46
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Scptember 6, 1990 The lionorable Kenneth M.
Carr Chairman U.S.
Nuclour Regulatory Commission Washington, D.C.
20555 Dear Chairman Carr
SUBJECT:
REVISION 1 OF DRAFT TECll!!ICAL POSITION Oil WASTE FORM During its 23rd meeting on August 29 and 30, 1990, the Advisory Committee on Nuclear Waste (ACHW) reviewed a draft version of Rovision 1 of the Technical Position on Wasto Form, prepared by NRC's Division of Low-Lovel Wanto Management and Decommissioning.
Tho Committee also had the benefit of discussion with the NRC staff on this matter.
The revisic,n represents a significant expansion of the previous document on this same subject and reflects many of the points that were called to the attention of the NRC staff during previous ACNW and ACRS subcommittee mootings.
Owing to the importanco to public health and safety that is now proporly attached to the quality of the low-level waste form, we conclude that this technical position, when fully implemented, can serve as a useful guido in the evaluation of wasto forms used in low-Icvol wanto disposal.
Wo believe that the required reporting of mishaps will bo especially useful.
Listed below are several concerns that the Committee has on this subject.
Ilowever, we believe that publication of the Technical Position need not be held up pending resolution of th a e concerns.
To assist in their resolution, we recommend that the NRC staff consider the detailed discussions held during the ACNW meeting of August 29, 1990.
1.
The applicable regulation (10 CFR Part 61) places emphasis on the physical stability of the waste form (Class B and Class C) with the intent that by this means access of water to the warte can be controlled.
There is no requiremont in Part 61 for a specified resistance of the waste form to leaching of radionuclides by ground water.
We believe that an important attributo of the waste form is its behavior related to migration of radionuclides into the environment.
We believe a revision of Pert 61 addressing this point is needed, but 11
1 The Honorable Kenneth M.
Carr 2
September 6, 1990 until that is completed, the Technical Position should be amended to reflect more directly the attent ion that loaching resistance should be given.
The almost exclusive focus of the Technical Position on mechanical integrity of the wasto form and the offect of various phenomena (e.g.,
thermal cycling, radiation, and immersion in wator) on that integrity should be supplemented by requirements that loach resistanco, as measured by a specifiod separate test, should be maintained in parallel with mechanical strength after the wasto is subjected to those phenomena.
2.
The testing requirements cited in the revised Technical Position should be representative of conditione likely to be encountered in a shallow land burial sito.
The primary mobilizing agent is ground water which could be more aggros-sive in enhancing movement of radionuclidos than the distilled water or synthetic sea water now specified in the Technical Position.
We believe that the specific test conditions cited in the Technical Position, now oriented only to structural impact, should be compicmented by additional conditions that relate to the ground water chemistry of tho wasto.
- Further, biodegradation tests should be specified for comentitious wasto matricos using bactoria that are likely to af fect coment as well as the organic component of the waste.
3.
Wo bellove that the provisions for touts of the radiation resistance of waste forms may not be suf ficiently conservative when considering the potential for hydrogen generation in closed spaces.
The HRC staf f is urged to rooxamine this topic-to ensure that slow buildup of hydrogen from water-bearing wastos in scaled containers does not becomo a problem for long-term, safo disposal.
4.
Wo believe that insufficient attention has been given to the testing of aged waste forms.
Many of the matrices, including concrote, that are used to contain vastos continue to chango chemically and physically long af ter their preparation. Owing to the longer term focus (i.e.,
300 years) of the wasto integrity requirement, definition of the behavior of wasto specimens that simulate aged waste forms appears appropriate for inclusion in the Technical Position where such testing appears foanible and reasonably reliable.
S.
The Committoo notes that a part of the regulatory control over low-level wasto disposal is based on Part 20 regulations (10 CFR 20.311).
Wo urge that the NRC staff examine the revisions in Part 20 that affect low-level waste and ensure that the Technical Position and the updated Part 20 are compatible.
6.
The Committoo is aware that the newly developed criteria for compressive strength of acceptable cementitious vaste forms 12 l
The lionorable Kenneth M. Carr 3
September 6, 1990
[500 psi) lacks strong technical justification but was selected to proclude the use of unstable wasto forms. The 11RC staff should include in the Technical Position recognition that the compressivo strength that is initially called for may not be retained by the waste form for its required lifo.
Long-term degradation of compressivo strength to lower levels, but not loss than the approximatoly 60 psi required for other waste forms, may be acceptablo.
Wo hopo you will find those comments uuoful.
Sincoroly, Of '
f Dado W. Moo 11er Chairman
Reference:
U.S.
11uclear Regulatory Commission Draft Technical Position on Waste Form (Rovision 1) dated June 1990, Prepared by Technical Dranch, Division of Low-Lovel Wasto Management and Decommissioning (Prodocinional) 13
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/aco % gr, UNITED STATES l'
't NUCLEAR REGULATORY COMMISSION
.I ADVISORY COMM111El ON NUCLt AR WASTE o,
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WASHINGTON. D C. M&4 September 7, 1990 The lionorable Kenneth M. Carr Chairman U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Dear Chairman Carrt
SUBJECT:
PROGRAM PIAN FOR Tile ADVISORY COMMITTEE ON NUCLEAR WASTE This is our third response to your memorandum of November 6,
- 1989, in which you requested that the Advisory Committee on Nuclear Waste (ACNW) provide a program plan at four-month intervals.
This plan covers the period September-December 1990.
We hope you will find this a convenient source for anticipating our upcoming activities and for providing feedback on issues on which the Commission wishes us to focus our efforts.
In preparing this program plan, we have considered the list of specific technical issues of particular interest to the Commission, requests of individual Commissioners, the EDO's list of proposed agenda items for the ACRS and the ACNW, the NRC's Five-Year Plan, and items of particular interest and/or concern to the Committee.
The priorities proposed are based on information provided by representatives of NMSS, NRR, RES, and the EDO office, as well as our own interpretation of the subject in relation to our activities as a Committee and our input into the regulatory process.
This program plan is based on the current best estimates of work output by the DOE, EPA, NRC staff, and their consultants and contractors, as well as our own estimates of how to deal with these issues effectively.
In addition to the full Committee meetings
- noted, Working Group meetings will be held an necessary to facilitate full Committee review and action.
There may be some revisions to this plan associated with the completion of NRC staf f, applicant, and/or contractor studies and reviews as well as other schedule problems beyond our control.
Full Committee meeting dates for this period are tentatively scheduled as follows:
24th Meeting - September 19-20, 1990 25th Meeting - October 24-26, 1990 26th Meeting - December 12-14, 1990*
November Meeting cancelled and December meeting dato changes.
15
The lionorable Kenneth M. Carr 2
September 7, 1990 The Committee anticipates considering the topica listed below during this four-month period.
Sectomber 19-20. 1990 e
The Committee will discuss a response to the EPA's request for clarification of the comments made by ACNW which critique the EPA's high-level waste standards.
(Iligh Priority) e The Committee may review the NRC staff's evaluation of the National Academy of Sciences / National Research Council report on
" Rethinking liigh-Level Radioactive Waste Disposal."
(Medium Priority)
The Committee will hear a presentation on EPRI's performance annessment methodology for a llLW repository.
EPRI's report on this work is scheduled for release in October.
(Iligh Priority) e The Committee will define the strategy and schedule for responding to recent requests from Commissioner Curtiss to review technical issues involved in the disposal of mixed waste with an emphasis on the resolution of conflicts between NRC's and EPA's regulations, and to review subsystem requirements within 10 CFR Part 60 to determine their conformance with the EPA high-level waste standards.
(Iligh Priority)
The Committee will review the "Public Comment" version of the Format and Content Guide for High-Level Waste Repository Licensing Applications.
(Madium Priority)
October 24-26, 1990:
The Committee will hear a presentation by the Division of High-Level Waste Management (DHLW) staff on the " Phase I Demonstration of the Nuclear Regulatory Commission's Capability to Conduct a Performance Assessment for a HLW repository."
(High Priority) e The Committee will be briefed on a recent report by Sandia National Laboratories which concluded that there is reasonable confidence that compliance of the WIPP facility with the EPA Standar:N is achievable.
(High Priority)
The C% ittee will hear a presentation on the revision of the NRC staff review plan for DOE Study Plans associated with site I
characterization for the proposed high-level waste repository.
(Medium Priority) 16
The lionorable Kenneth M. Carr 3
September 7,1990 The Committee will hear a briefing and review information on e
Performance Assessment Meth uology for an LLW site by NMSS.
(High Priority) e The Committoo will be briefod by a member of HRC's Nuclear Safety Research Review Committee relative to its findings on the NRC's radioactive waste research program.
(Medium Priority) e The Committee will be briefed on revisions to the Standard Format and content of a License Application for a Low-Lovel Radioactive Waste Disposal F4cility (NUREG-1199) and the Standard Review Plan for the Review of a License Application f or a Low-Lovel Radioactive Waste Disposal racility (NUREG-1200).
(Medium Priority)
LLECald2tr 12-1L 1990 e
The Committoo will meet with thn Commissioners to discuss i
items of mutual interest (tentativo).
(liigh Priority)
The Committee will be briefed by the Division of Low-Lovel Wasto Management and Decommissioning (DLLWMD) staff on other than Part 50 Decommissioning activities. (Modium Priority) e The Committee will hear a presentation by the Division of liigh-Lovel Waste Management (IILW) staff on the Technical Position on Repository Design Thermal Loads. (Iligh Priority)
The Committoo will be briefed by the DilLW staf f on the results e
of their reviews of the Study olans for characterization of volcanic features and mineralogy, petrology and chemistry of transport pathways (tentativo).
(High Priority)
Unscheduled:
(Will be considered as documents and timo becomo available)
The Committee will be briefed by the Division of Iligh-Lovel e
Wasto Management (DilLW) staff and the Center for Nuclear Wasto Regulatory Analyses (CNWRA)- staff on the feasibility of the substantially complete containment concept.
(iiigh Priority) e The Committee will be briefed and/or visit a proposed low-level radioactive wasto disposal site and meet with appropriate state and/or local officials.
(Low Priority) e The Committee will be briefed on the status of the decommissioning of the llanford Production Reactors.
(Low Priority) 17
The lionorabla };enneth M. Carr 4
September 7,1990 The Committoo will hear a report by PNL on in-place vitrifica-e tion.
(Low Priority) e The Committoo will schedulo a short update on tho status of the LLW compacts.
(Wanted periodically)
(Low Priority) 1 e
The Committee will be briefed on the r>otential problems that could ariso at a high-level radioactive wanto reponitory as a result of migration of carbon-14.
This will include a discussion of what fundamental assumptions are made in ovaluating the hazard f rom this radionuclido.
(liigh Priority)
The Committoo will hold discussions on the subject of human e
intrucion at a high-level radioactive wasto repository.
This review will be designed to exploro the range of curront thinking from various groups in the United Statou and other countries.
(liigh Priority) e The Committoo will bo brinfod on the NRC staff review of the DOE /USGS white paper on integration of the geophysical programs for repository sito characterization.
(High Priority) e Tho Committoo will bo briefod on the Exploratory Shaft Alternatives Study and the Surfaco Based Testing Prioritiza-tion study.
(Modium Priority)
The following items are areas where we hhvo an interest and can make a contribution.
We would welcomo an expression of your interest before proceeding.
e The Committee will review the use of export judgment or opinion and its rolo in performance assessment of high-level wasto disposal facilities.
(liigh Priority)
The Committoo will review potential long-range climate change e
and its impact on performance assessment.
(liigh Priority)
The Committee intends to prepare a summary and critique of the e
high-level waste repository standards formulated by other countries.
This would include standards proposed by Nordic countries, as well ns those by Canada, France, the IAEA and ICRP.
(liigh Priority)
The Committee intends to evaluato 10 CFR Part 61 as it relates e
to low-level wasto disposal facilities that utilize methods other than shallow land burial.
Questions to be addressed include whether Part 61 can be applied, in its existing l
format, to engineered facilities, such as below and above ground vaults.
(liich Priority) 18
l The lionorable Kenneth M.
Carr 5
ST tr e.t>er 7, 1990 Thin lint representis our beat entimate of the topico to be considered through December 1990.
If you or your follow Commin-nioners have additional itoma to suggent or propoced changen in prioritien, please let un know.
Sincerely, l
bl Of/
Q Dade W.
Moeller Chairman car Commincioner Rogers Comminnioner Curtica Commiccioner Remick Saniuel J.
Chilk, SECY Jamen M. Taylor, EDO Hobert M.
Bernero, !! MSS 19
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION c
E ADVISORY COMMIT 1FE ON NUCLE AR WAST [
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WASHINGTON. O C. 20656 o,
December 19, 1990 The Honorable Kenneth H. Carr Chairman U.S. Nuclear Regulatory Commission Washington, D.C.
20555
Dear Chairman Carr:
SUBJECTt PROGRAM PLAN FOR THE ADVISORY COMMITTEE ON NUCLEAR WASTE This is our fourth response to your memorandum of N9vember 6, 1989, in which you requested that the Advisory Committee on Nuc1 car Waste (ACNW) provide a program plan at four-month intervals.
This plan covers the period January-April 1991.
We hope you will find this a convenient source for anticipating our upcoming activities and for providing feedback on issues on which the Commission wishes un to focus our efforts.
In preparing this program plan, we have considered the list of specific technical issues of particular interest to the Commission, requests of individual Commissioners, the EDO's list of proposed agenda items for the ACRS and the I.CNW, the NRC's Five-Year Plan, and items of particular interest and/or concern to the Committee.
The priorities proposed are based on information provided by representatives of NMSS, NRR, RES, and the EDO office, as well as our own interpretation of the subject in relation to our activities as a Committee and our input into the regulatory process.
This program plan is based on the current best estimates of work output by the DOE, EPA, NRC staff, and their consultants and contractors, as well as our own estimates of how to deal with these issues offectively.
In addition to the full Committee meetings
- noted, Working Group meetings will be held as necessary to facilitate full Committee review and action.
There may be some revisions to this plan associated with the completion of NRC staf f, applicant, and/or contractor studies and reviews as well as other schedular problems beyond our control.
Full Committee meeting dates for this period are tentatively scheduled as follows:
27th Meeting - January 23-24, 1991 28th Meeting - February 20-22, 1991 29th Meeting - March 20-22, 1991 30th Meeting - April 23-24, 1991 21
-. - =.
The lionorable Kenneth M.
Carr 2
December 19: 1490 The Committee anticipates considering the topics listed below during this four-month period.
January 23-24, 1933 e
The Committee will continue discussions on 10 CFR Part 60, high level waste repository subsystem performance require-monts and their conformance with the EPA high-level waste standards.
(High Priority)
The Committee will continue deliberations concerning the NRC e
and EPA regulations governing the disposal of mixed waste.
Advice has been requested on the comparability of NRC and EPA requirements.
(liigh Priority)
The Committee will be briefed by Louisiana Energy Systems on e
their private uranium enrichment facility plans.
Topics of particular interest include the disposal of the depleted uranium and the licensing process for the facility.
This briefing is for information only.
(Medium Priority)
The Committee will discuss participation by a Committee member e
at the Waste Management 1991 Symposium in Tucson, Arizona on February 26, 1991.
(liigh Priority) e The Committee intends to evaluate 10 CFR Part 61 as it relates to low-level waste disposal facilities that utilize methods otner than shallow land burial.
Questions to be addressed include applicability of Part 61, in its existing form, to engineered facilities such as below and above ground vaults.
(High Priority) e The Committee will discuss its top three priorities for the review of nuclear waste issues and report these priorities to the Commission.
(High Priority)
The Committee will discuss issues relating to human intrusion e
of a
high-level radioactive waste disposal repository.
Methods for handling this potential event in the regulatory framework will be considered.
(High Priority) february 20-22, 1992 The Committee will be briefed on the NRC HLW staf f's position e
on penetration of the Calico Hills tuff.
(High Priority)
The Committee will discuss the information obtained during a e
recent ACNW Working Group Meeting on how expert judgment will be used in conducting performance assessments used in the licensing of high-level and low-level waste repositories.
(High Priority) 22
l I
The lionorable Kenneth M. Carr 3
December 19, 1990 o
The Committee will review and comment on an NRC Staff Technical Position regarding regulatory considerations in the design and construction of the exploratory L. haft facility.
(Medium Priority)
The Committee will be briefed on a technical feasibility study e
on the substantially complete containment concept by the Nhc staff and Center for Nuclear Waste Regulatory Analyses.
(Medium Priority)
The Committee will discuss the information obtained during a recent ACNW Working Group Meeting on computational techniques for estimating collective population doses from exposure to low levels of ionizing radiation.
(lligh Priority) e The Committee will be briefed on the revised 10 CFR Part 20
" Standards for Protection Against Radiation."
These discus-sions will focus on the effect these revisionn will have on nuclear waste issues.
(Medium Priority) liorch 20-22a 1991 e
The Committee will review and comment on the NRC stafI's interim criteria for decommissioning.
(Iligh Priority) e The Committee will review and comment on the NRC staff'a Technical Position on investigations to identify fault displacements and seismic hazards.
(Medium Priority) e The Committee will be briefed for information on the NRC staf f's approach to dealing with uncertainties in implementing the EPA's high-level waste radiation protection standard 40 CFR Part 191.
(Medium Priority) e The Committee will consider the results from a recent ACNW Working Group Meeting on methodologies used to date volcanic and tectonic features on the site of the proposed high-level waste repository.
(Tentative)
(Iligh Priority)
April 23-?du_1221 The Committee will review and comment on an NRC Staff Technical Position on the high-level waste repository design for thermal loads.
(Medium Priority) e The Committee will hear results from a Working Group on potential long-range climate change and tne impact on performance assessment.
(Iligh Priority) i 23
The Honorable Kenneth M.
Carr 4
December 19, 1990 The Committee will review and comment on a proposed NRC rule o
on a low-level waste uniform shipping manifest.
(liigh Priority)
{
e The committee will be briefed regarding decommissioning activities at specific sites such as United Nuclear Wood River Junction and AMAX West Virginia.
(Medium Priority)
Unscheduled:
(Will be considered as documents and time become available.)
The Comnittee intends to prepare a summary and critique of the e
high-level waste repository standards formulated by other countries.
This would include standards proposed by Nordic countries, as well as those by Canada, France, the IAEA and ICRP.
(High Priority) e The Committee will visit the Center for Nuclear Waste Regulatory Analyses in San Antonio, Texas and receive an updete on the Center's activities.
(High Priority)
The Committee plans to discuss the results of the NRC staff's e
review of the DOE /USGS " white paper" on the " Status of Data, Major Results, and Plans for Geophysical Activities, Yucca Mountain Project."
This report is impcrtant as it relates to an important theme on integration of tests,
- studies, and existing data in the NRC staff's comments on the DOE Site Characterization Plan.
(High Priority)
The Committee expects to be briefed and/or visit a proposed e
low-level radioactive waste disposal site and meet with appropriate state and/or local officials.
(Low Priority)
The Committee will be briefed on the status of the decommis-e sioning of the Hanford Production Reactors.
(T,ow priority)
The Committee will hear a report by PNL on in-place vitrifica-e tion (when possible).
(Low priority)
The Committee plans to invite a representative from AECL to e
discuss Canada's high-level waste standards.
(Medium Priority) e The Committee will be briefed on the exploratory shaft alternatives study and surface-based testing prioritization study.
These studies are being prepared by DOE.
The Committee will review these studies when available.
(High Priority) 24
The lionorable Kenneth M.
Carr S
December 19, 1990 This list represento our bent estimate of the topics to be considered through April 1991.
If you or your follow Commionioners have additional items to suggest or proposed changes in prioritien, please let un know.
Sincerely,
'N
(,/
Dade W.
Moeller Chairman cc:
Commissioner Itogers Commicsioner Curtins Commincioner llemich Samuel J.
Chilk, SECY Jamon M. Taylor, EDO ltobert M.
Bernero, 11 MSS L
25
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UNITED STATES
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p, NUCLEAR REGULATORY COMMISSION g,
.s ADVISOHY COMMIT'itt ON NUCit AR WASit a
8;,
WASHINGTON, O C. 20846 f
- ...+
January 29, 1991 The lionorable Kenneth M.
Carr Chairman U.S. Nuclear Regulatory Commission Washington, D.
C.
20555
Dear Chairman Carr:
SUBJECT:
PRIORITY ISSUES ON RADIOACTIVE WASTE MANAGEMENT In response to your memorandum of December 10, 1990, members of the Advisory committee on Nuclear Waste (ACNW) have identified several technical issues that we believe deserve priority attention.
These issues, which are summarized below, are based on discussions by the Committee during its 26th (December 12-13, 1990) and 27th (JanJary 23-25, 1991) meetings.
Serving as input to our l
response were discussions that individual ACNW members had with the NRC staff.
1.
Standards and Criteria for a liigh-level Radigilctive Waste EsI22sitory Items within this subject area that the Committee believes deserve special attention include:
(a) continued interaction with the NRC and the U.S.
Environmental ProtectiJn Agency (EPA) staffs on revisions in the EPA standards, with emphasis on the treatment of uncertainties; (b) ongoing interactions with the NRC staff on the development of related guidance documents, including technical positions, staf f positions, and regulatory guides; and (c) reviews and interactions related to the clarification of issues such as subsystem requirements, systematic regulatory
- analysis, and related rulemaking activities which include definition of a
specific dose criterien for design basis accidents involving a high-level radioactive waste (llLW) repository.
2.
S_i t e C h a r a c,l e r i z q t.i o D Characterization of the proposed llLW repository site at Yucca Mountain is in a critical period during which the NRC must provide overview of the U.S.
Department of Energy (DOE) program with guidance and reviews that relate to the site characterization process and the ultimate licensability of the 27
l The lionorable Kenneth M.
Carr 2
January 29, 1991 site.
The Committee believes that it can provide significant advice to the Commission on these items, particularly as they relate to the assessment of potentially adverse conditions such as volcanism, seismicity, changes in groundwater flow and climate, and the impacts of couplect processes.
Additionally, the Committee will advise the Commission on important topics currently under consideration such as exploratory shaft facility alternatives, surface-based testing priorities, and plans for terting the Calico liills formation.
3.
Performance Assenaments A key factor in evaluating a waste disposal facility is the ability to predict its performance. The capability to perforn such assessments in the case of an llLW repository requires supporting data, validated models, and the identification and quantification of potentially adverse conditions.
A specific goal of the Committee will be to confirm that the guidance being provided to DOE is adequate to ensure that sufficient information is obtained relative to various natural phenomena that can significantly influence the long-term performance of an llLW repository.
A key example is the potential impact of seismicity and volcanism on groundwater travel time and the integrity of waste canisters.
In this same regard, we plan also to address the performance assessment capabilities available for evaluating various types of low-levc.1 waste disposal facilities.
Although some guidance and a regulatory base exist for evaluating shallow land burial f acilition, few if any of the new f acilities being proposed will be of this type.
The Agreement States, in particular, need assistance in developing capabilities for assessing bunkered types of disposal facilities, and the urgency for such assistance is emphasized by the deadlines mandated by the Low-Level Radioactive Waste Policy Amendments Act.
Included in those considerations is the need for improved capabilities for assessing the magnitudes of the source terms for certain long-lived radionuclides, such as iodine-129 and carbon-14.
Records show that data on the quantitles of these radionuclides that have been disposed in existing facilities are inaccurate.
4.
Other Items The primary focus of the Committee is on licensing a high-level waste repository, however, the Commission and the NRC staff have asked for Committee advice on important issues dealing with low-level waste.
Issues included here include the regulation of mixed wastes, "Below Regulatory Concern,"
and the decommissioning of nuclear power plants.
28
1 The Honorablo Kenneth M. Carr 3
January 29, 1991 Rocognizing that tho above listings are broad in scopo, wo have summarized below those issues that wo believo dosorvo priority attention over the short term 1.
critique of the revisions in the EPA standards; 2.
review of NRC guidance to DOE for charactorization of the proposed Yucca Mountain sito; and 3.
ovaluation of the performance assessment capabilition for newer types of low-level radioactive wasto disposal facilities.
We plan to address thoso subjects both through regular mootings of the Committoo and through working group sessions.
Experienco has shown that ACNW working group sessions provido an excellent forum for identifying and illuminating issues that are of critical importance relativo to upcoming decisions.
Most of the activition outlined above will be conducted on an iterativo basis.
As a result, it is anticipated that specific objectivos and goals will be modified as the work progresses.
We j
plan to koop you informed.
We trust this ic responsive to your request, and wo look forward l
to your comments on those plans and suggestions.
l sincerely, k
Dade W. Moeller chairman 29
=
l pos.e
,,1
,o UNITED STATES
+
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<g NUCLEAR HEGULATORY COMMISSION y
+4 4
ADVISOHY COMM111t t ON NUClt All WA611 o,
.f WAhHINGloN O C WMA
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January 29, 1991 The lionorablo Yonneth M. Carr Chairman U.S.
Iluclear Regulatory Commincion Washington, D.
C.
20555 Dear Chairman Carr SUl3 JECT:
STRIllGEllCY Ol' U.S.
1:llVIHollHEllTAL Pit 0TECTIoli AGl:11CY 41Gil-LEVEL RADIOACTIVE WASTE REPOSITORY STAR 1DARDS During our 25th muoting, October 24 and 25, 1990, Mr. I'loyd L.
- Galpin, Chief, Wanto Management Standards tira nch,
offico of Radiation Programn, U.S.
Environmental Protection Agency (EPA),
requeuted that the Advisory Committee on 11uclear wante
( ACllW) provide EPA the banon for the statementn, mado in uoveral of our reporta to you, that the utandardn developed by 1:PA for a
high-level radioactive wanto repository were overly ntringent.
There are neveral factorc and conuidorations that served an a banin for our statemento.
Thene are nummarized below.
1.
C9DDarl.IlOIL91_a_ Rep 0R110 ELt O_ALila t M ED LQ ell!Qd Y The introductory information provided in the EPA ntandardn (Reference 1) implies that one of EPA's goals was to onouro that the health impacts of a repository were no greater than thoso that would have been anacciated with a comparable amount of unmined uranium cro.
Although conservativo in its own right, thin appeared to be a roanonable approach.
Later we learned that thin approach did not, in tho !inal vernion, serve an a bania for the EPA standards.
Rather, EPA based its standards for the repository on what was conaldered to be achievablo using modern technology.
11onotholcan, the manner in which the existing standards are presented implion that they were based on relencon from a comparable ore body.
As a result, most groups, including the Aci1W, have evaluated the EPA standardo with this consideration in mind.
If one ancesses the EPA otandarda for a repository on the bania of a comparable ore body, there appear to be at 1 cast two steps taken by EPA that have led to unduo stringency:
a.
Reports publiched by EPA (Reference 2) of analyson of actual uranium ore bodien (aucuming 100,000 MTilM) indicate that annual releascu of Ra-226 over a 10,000-year period would range f rom 300,000 to 3,000,000 curies.
31
The Honorable Kenneth M.
Carr 2
January 29, 1991 The limit on releases for Ra-226 in the EPA standards is 10,000 curies.
In a similar manner, estimatos of the associated health offects (doaths) due to radionuclido releason from existing cro bodios over a 10,000-year period ranged from 1,000,000 to 10,000,000.
The limit in the EPA standards is 1,000, b.
An unmined uranium ore body represents a continuous source of release of radioactivo materials into the environment.
In other words, the chance ur probability that the oro body would cause radiation exposures to neighboring - populations is one..
In translating the estimated health offects from unmined ore bodies into a table of equivalent radionuclido releases from a high-level radioactive waste repository, EPA stated that there must be no more than one chance in ton of excooding the given radionuclido release limits (or more than one chance in one thousand of exceeding ten times the releaso limits) over the initial 10,000-year period of operation of the repository.
In other words, EPA added a factor of ton conservatism to releases from a high-level wasto repository that cro only slightly greater than rolcases 1
from an unmined ore body.
2.
Limits for Individual Radionuclide Rgleases In sotting permist.,1ble limits for releases of individual radionuclides from the repository, EPA assumed that the releases af fected the population of the entire world projected to number a constant level of 10 billion people over the 10,000-year assessment-period.
In taking this approach, epa did not specify a " critical" population group, nor did it specify a doso limit for the people who might - be exposed.
- Rather, it summed the resulting collectivo doses over the population of the world and set the individual radionuclide release limits so as not to excood a given collectivo dose limit (which, in turn,- was used to predict the associated health impacts).
Data indicate that a major contribution-to the collective dose apparently consisted of dose rates to individual members of the world's population of 0.01 mSv (1 mrem) por year or loss.
This calculational methodology is in sharp contrast to the proceduros recommended by the National Council on Radiation Protec t.lon and Monsurements (NCRP, Referenco 3).
To be specific, the NCRP recommends that "
assessments of c
increments of collectivo annual offectivo dose equivalents from any particular individual source or practice should i
exclude those individuals whose annual offective dose equivalents from such a source is 0.01 mSv (0.001 rem) or less."
(Section 20, Reference 3.)
32
l The lionorable Kenneth M. Carr 3
January 29, 1991 The overall impact of the calculational approach used by EPA is to " inflate," by a considerable margin, estimates of the health impacts of radionuclide releases from a repository.
This, in turn, results in the allowable quantition of upecitic radionuclide releases from a
repository to be overly conservative; that is, too low.
In making this comment, it is important to acknowledge that the NCRP recommendation was not published until June 1, 1987.
Now that it has been issued, however, EPA should be encouraged to reassens its calculations.
3.
Rele n p E mit for carbsn-1A over the past year or two, an increasing number of comments and papers in the literature indicates that gaseous emissions, specifically carbon-14 in the form of carbon-dioxide, may prohibit the propoued Yucca Mountain repository f rom complying with the EPA standards.
The permissible release limits for this radionuclide, au cpecified in the EPA standardo, are one moro example of its stringency.
This is illustrated by the following examplest a.
The total inventory of carbon-14 in a
repository containing 100,000 MTi!M is estimated to be about 100,000 curies.
This compares to a global production of carbon-14 by cosmic radiation of 28,000 curies per year, a global inventory of about 230 million curies, and an atmospheric inventory of 4 million curies (Reference 4).
In fact, release of all of the carbon-14 inventory in a repository would increase the atmospheric inventory by only about 2 percent; this compares to natural variations in the atmospheric inventory of 10 percent to 40 percent, b.
Based on an assumed inventory of 100,000 MTi!M,
the permissible rate of release of carbon-14 from a
repository would be about 1 curie per year.
Experience shows that any carbon-14 that is released would rapidly mix in the atmosphere, and estimates are that the accompanying dose rate to a person on top of Yucca Mountain would be far less than 0.01 mSv (1 mren) per year.
It is also interesting to note that the limit on the release rate of 1 curia per year for a repository compares to an average release rate of 10 curies per year from a typical 1,000 MWe light water reactor (Reference 4).
At the time the EPA standards were developed, considerations were limited to evaluations of a saturated site, In such a case, water transport and geochemical barriers would have been strongly influential in retaining the carbon-14.
Subsequent 33
. -. _ ~
... - _ -. - -.. - = -. -.. -. _
The lionorable Kenneth M.
Carr 4
January 29, 1991 consideration of Yucca Mountain (an unsaturated sito) makes the existing EPA standards inappropriato, overly stringent, and in need of revision.
4.
Indoor Radon The Offico of Radiation Programs af the U.S.
Environmental Protection Agency has the responsibility for setting limits for indoor radon as well as sotting standards for the high-level wasto repository.
A comparison of the risks for indoor radon and those for the repository indicates that the health offects resulting from radon exposures at permissible levels indoors will be significantly greater than those from the repository.
In summary, the statements by the ACNW that the EPA standards are l
overly stringent are based on:
(1) restrictions that limit the probability of exceeding the release limits by even a small amount to an order of magnitudo loss than that for a natural are body; (2) the application of inappropriate methodology in calculating collectivo dosos that, in turn, woro used to establj sn radionuclide release limits from a repository; (3) the establishment of release limits for certain radionuclidos, most notably carbon-14 to amounts that are only a small fraction of the quantities naturally present within the environment; and (4) the inconsistencies of the risk standards proposed for the repository and those for other radiation sources, such as indoor radon.
Sincoroly, Dado W. Moeller Chairman Referenceri:
1.
U.S.
Codo of Federal Regulations, " Environmental Radiation Protection Standards for Management and Disposal of Spent Nuclear Fuel, High-Lovel and Transuranic Radioactive Wastos,"
40 CFR Part 191.
2.
U.S.
Environmental Protection
- Agency, EPA 520/3-80-009,
" population Risks from Uranium Oro Bodies," October 1980.
3.
National Council on Radiation Protection and Measurements, Roport No.
91,
" Recommendations on Limits for Exposure to Ionizing Radiation," 1987.
4.
National Council on Radiation Protection and Measurements, l
Report No. 81, " Carbon-14 in the Environment," 1985.
34
..=-.
p@ Mo%k UNITED STATES
[,
7, NUCLEAR REGULATORY COMMISSION e
ADVISORY COMMirTE E ON NUCLE AR WALTE WAbHINGTON, D C. 20%6
- ..../
January 29, 1991 The lionorable Kenneth M.
Carr Chairman U.S. Nuclear Regulatory Commission Washington, D.
C.
20555 Dear Chairman Carrt
SUBJECT:
GUIDANCE ON LIMITS ON DOSES AND RISKS TO INDIVIDUAL MEMBERS OF Tile POPULATION During the 25th meeting of the Advisory Committee on Nuclear Waste (ACNW), held on October 24 and 25, 1990, Mr. Floyd L.
- Galpin, Chief, Waste Management Standards Branch, Office of Radiation
- Programs, U.S.
Environmental Protection Agency (EPA), requested that the ACNW provide the bases for the recommendation, made in several of our earlier reports to
- you, that EPA consider incorporating into its high-level radioactive waste repository standards some guidance on limits f or doses and risks to individual members of the general population.
The foundations for our position are outlined in the recommendations of the International Commission on Radiological Protection (ICRP), the International Atomic Energy Agency (IAEA) and the so-called " NORDIC" report.
As will be noted, all three of these groups endorse the use of individual dose and risk limits in the development of standards for a high-level radioactive waste repository.
This approach has alao been endorsed by the Board on Radioactive Waste Management, National Research Council.
The principal comments and/or recommendations of these organizations ore summarized below.
1.
Becommendations of the ICRP The basic principios on this subject, as recommended by the ICRP, are presented in their report on " Radiation Protection Principles for the Disposal of Solid Radioactive Waste,"
published in 1985.
In this report, the ICRP separates the releases from a repository into two categories:
(a) those that are gradual and lead to normal releases that are reasonably predictable in terms of estimates of their exposure pattern in space and time; and (b) those that are not gradual and have to be thought of as probabilistic.
Included in the latter category are releases that might occur as a result of coismic and tectonic phenomena.
(Paragraphs 28 and 29, Reference 1.)
35 l
The Honorable Kenneth M. Carr 2
a.
Evaluation ansL';ontrol of Normal Releases For release' in the first category (i.e.,
normal releases) tne ICRP recommends that its individual dose limits for members of the public should apply.
Expanding on this, the ICRp states that its recommendations with r'.,spect to the assessment and monitoring of radioactive materials in the environment would also apply, with the results being used in the optimization of protection and in judging compliance of a high-level radioactive waste disposal facility with the applicable doso limits and source upper bounds.
(Paragraph 30, R e f e r e n c,. '.. )
The ICRP goes on to say that "The application of the I
individual donc limits to the dose distribution from normal releases from a waste repository is the same as for releases from other types of facilities.
Two basic requirements are involved.
First, the critical group, i
1.e.
those who are expected to receive the greatest l
exposure, must be identified.
Second, the design and operation of the repository must provido assurance that the average dose in the critical group will not exceed the dose limits.
(Paragraph 45, Reference 1.)
b.
Evaluation and Control of Probabilistic Releases The ICRP recommends that risks from probabilistic events should be limited on a similar basic.
In this regard, the ICRP states that "Since significant doses might result from events that disrupt the normal behavior of a disposal f acility and which have an assumed probability of occurrence, in a given time, less than one, the objective ' of protecting individuals from all of the exposure events associated with radioactive waste disposal is best achieved by reverting to an individual risk limitation reauirement.
By dealing consistently in terms of risk, both the probability of an exposure and the magnitude of the exposure can be included.
To take account of this, the Commission recommends that a risk limit and risk upper bound be established in direct analogy to the dose limits and upper bounds fo.: normal releases."
(Emphasis Added.) (Paragraph 47, Roference 1.)
c.
Allowances for Future Activities and Individyglg "To allow for dose contributions from present practices and to provide a margin for unforeseen future activities, the Commission recommends that national authorities l
select a fraction of the dose limits as a source upper bound for each source of exposure, to ensuro that the l
36 L
The lionorable 1<enneth M.
Carr 3
exposure of individuals will remain below the relevant dose limit."
(Paragraph 54, Reference 1.)
1 g
"In a manner similar to the establishment of the cource upper bound, the Commission recommends that national authorities select some fraction of the risk limit as a risk upper bound for the source being evaluated."
(Paragraph 57, Reference 1.)
Expanding on this theme, the ICRP recommends ".
. that risks to future individuals should be limited on the same basis as are those to individuals living now."
(Paragraph 50, Reference 1.)
2.
Recommendations of__thg_ MEA Recommendations of the IAEA on this subject are presented in j
their preliminary draft report, " Safety Principles and Technical criteria for the Underground Disposal of liigh-Level Radioactive Wastes." In this document, the I AEA separates the releases from a repository into those that result from
" gradual processes" and those that result from " disruptive events."
Since the annual dose limit for prolonged exposure to individuals within the critical group due to releases arising through
" gradual processes" is 1
- mSv, the IAEA recommends that the dose rato due to " gradual processes" occurring within a single repository be limited to some fraction of this value.
For " disruptive events," the annual dose limit for individuals within the critical grcsup is that which has an associated ".
risk of health effects of one in a hundred thousand per year."
on the basis of estimates made at the time, this would cor/espond to a deso rate limit of 1 mSv per year.
(Sections 3.2.1 and 3.2.2, Reference 2.)
In essence, the IAEA report endorses the recommendations of the ICRP.
3.
Remlandations of ths._llerdiq_csuntries The recommendations of the Nordic countries pertaining to the disposal of high-level radioactive wastes are presented in a
- report,
" Disposal of liigh Level Radioactive Waste Consideration of Some Basic Criteria A
Consultative Document,"
issued in 1989.
Recommendations of this group on standards for a high-level radioactive waste repository are specified in terms of four general objectives and principles.
Statements of cignificance are as follows:
The Nordic group endorses the ICRP recommendation by stating that "The predicted risks to human health and the effects on the environment from waste disposal, at any 37
\\
The lionorable Kenneth M.
Carr 4
time in the future, shall be low and not greater than would be currently acceptable.
The judgement of the acceptability of a dispor ~
option shall be based on radiological impacts to inc viduals irrespective of any national boundaries."
(Emphasis added.)
(Paragraph 66, Reference 3.)
In terms of radiation protection criteria, the Nordic countries recommend that "The predicted radiation dose to any individual, excluding doses from unlikely disruptive events, shall be less than 0.1 mSv per year.
In
- addition, the probabilities and conscquences of unlikely disruptive events shall be studied, discussed and presented in qualitative terms and whenever practicable, assessed in quantitative terms in relation to the risk corresponding to a dose of 0.1 mSv por year."
(Paragraph 85, Reference 3.)
As in the case of the IAEA, the Nordic group endorses the recommendations of the ICRP.
4.
Comments of the Board on Radioactive Waste ManacemenL National ResenrgjLQquncil The most recent recommendations of the Board on this subject are presented in their
- report,
" Rethinking High-Level Radioactive Waste Disposal," published in 1990.
In the recommendations included at the end of this report, the Board makes the following statements:
"The Environmental Protection Agency, during its revision of the romanded 40 CFR Part 191, should reconsider the detailed performance standards to be met by the repository, to determine how they affect the le,el of health risks that will be considered acceptable.
In addition, EPA should reexamine the use of quantitative probabilistic release criteria in the standard and examine what will constitute a reasonable level of assurance (i.e.,
by what combination of methods and stratenies can DOE demonstrate that those standards will be met?).
"All other countries use only a dose reauirement.
In settina regulatory standards and licensina recuirements, th_e _ EPA shquJd g,onsider usina only dose reauirements."
(Emphasis added.)
(Page 35, Reference 4.)
As may be seen, all four of the organizations and/or groups cited endorse standards for a high-level radioactive waste repository that have an associated limit on dose for normal or gradual releases and an associated limit on risk for 38
l The llonorable Kenneth M. Carr 5
disruptive or probabilistic releases.
In all cason, the limits apply to individuals within a critical population group.
The reasons that the ACNW endorses this approach, and is critical of the EPA approach, may be summarized as follows:
a.
The high-level radioactive waste repository standards, currently proposed by EPA, are based on limiting the
" global" collective dose, and estimates of the associated health effects, to a certain value (i.e.,
1,000 health offects in 10,000 years).
In taking this approach, neither the population to be protected nor the associated dose or risk limits are specified.
Any advantage to using collectivo dose as a method for avoiding the dilution and dispersion of radioactive wastes in the environment will be offset by the difficulties in determining compliance with standards based on this approach. There are other regulatory approaches that can be applied to prohibit unacceptable disposal practices such as these.
b.
The projection of collectivo dose estimates far into the future (as is necessary to comply with the high-level radioactive waste repository standards as proposed by EPA) is extremely difficult.
Factors that complicato such estimates include errors in predictions of regional and global population demographics (size and location) and of potential radionuclide pathways (groundwater flow and agricultural practices).
In contrast, long-range projections of the locations and living habits of individuals who may reside near a
repository are relatively straightforward, and estimates of their
~
potential doses can be made with greater certainty, c.
It appears that the EPA is alone in the approach that it recommends.
No other country or agency endorses this approach.
Sincerely, Dade W. Moeller Chairman 39
The lionorable Konnoth M.
Carr 6
[htigrencen t 1.
International Commicolon on Radiological Protection,
" Radiation Protection Principles for the Disposal of Solid Radioactive Wasto," Publication 46, Annala of the ICRP, Vol.
15, No. 4 (1985).
2.
International Atomic Energy Agency, " Safety Principlon and Technical critoria for the Underground Disposal of liigh-Lovel Radioactivo Wastos" (Proliminary Draft, 1989).
3.
" Disposal of liigh Lovel Radioactivo Wanto - Consideration of Some Basic Critoria - A Consultative Document," Report of The Radiation Protection and 11uclear Safety Authorition in Denmark, Finland, Iceland, Norway and Sweden (1989).
4.
Board on Radioact;.ve Waste Management, 11ational Roucarch Council, "Rothinkirg liigh-Lovel Radioactive Waste Disposal,"
11ational Academy P'Joca, Washington, DC (1990).
40
ac oset E[s-
,\\,
UNITED STATES
+
NUCLEAR REGULATORY COMMISSION n
I ADVISONY COMMmf f ON NUCll AH WASif pf WASHINGTON. D C. 20!46 a
February 28, 1991 Tho Honorable Kenneth M. Carr Chairman U.
S. Nuclear Regulatory Commission Washington, DC 2055S Dear Chairman Carr
SUBJECT:
REGULATION OF MIXED WASTES In responso to a request from Commincioner James R.
Curtisc, the Advisory Committee on Nuclear Waste (ACNW) has reviewed the problems and issues associated with the disposal of mixed wastes.
One focus of this review was the comparability of protection afforded by NRC and EPA regulations when applied to the disposal of mixed wastos.
This matter was the subject of an ACNW Working Group meeting held on December 11, 1990, and also a matter for discussion during the 24th, 25th, 26th, 27th and 28th meetings of the Committoo.
Interacting with the committoo during these meetings were representativos from the California Radioactive Materials Management Foru;n; Chem-Nuclear Systems, Inc. ; the Edison Electric Instituto; the Nuclear Management and Resources Council, Inc.;
the National Institutes of Health; New England Nuclear (du Pont); the State of Nebraska; the Lawrence Livermore National Laboratory; the Oak Ridge National Laboratory; the Savannah River Laboratory; the U.S.
Environmental Protection Agency; tho - U. S.
Department of Energy; and the U.S.
Nuclear Regulatory Commission.
The Committee also had the benefit of a wide range of documents, some of which are listed at the end of this report.
As you know, the subject of regulation of mixed wastes involves a wide range of incues and has the potential for having an impact on NRC and Agreement-Stato licensees.
Further, the regulatory process will have a significant economic impact on the disposal of theso wastes.
We provido heroin a summary of our findingu and our recommendations.
Wo have included some background information as well as highlights of recent and relevant studies and assessments conducted by the NRC staff and other groups.
1.
EltEn_Qf the PIqblsa Mixed wastes (i.e.,
those wastes that contain radioactive materials at concentrations equivalent to low-level wastes and 41
t The lionorable Kenneth H. Carr 2
February 28, 1991 also contain 1%zardous warto materials) are subject to regulation by both the NRC and the EPA as a result of congressional actions.
Complicating this dual regulation are fundamental differences betwoon the requirements of the two agoncles.
For examplot P
a.
The EPA regulations (pursuant to the Resourco Conservation and Recovery Act (RCRA)) require that a disposal facility for hazarde a wastos be equipped with a dual liner and loachute collection system; the IIRC regulations for low-lovel wasto disposal discourago the uso_ of trench liners because of the concern that infiltrating water w',1*
be retained and create a
i
" bathtub" offect.
y b.
The EPA regulations place primary reliance on activo 5
systems (o.g., the loachate collection system) to control releases of the waste; the NFC regulations place primary emphasis on the protection afforded by the wasto form and the location and design of the disposal facility.
c.
Treatment and packaging of radioactive wastes aro e
generally performed by the generator prior to shipment of the wantos to the disposal facility; in contrast, hazardous wastes are genera 1 W treated at offsito facilities or at the disposal site.
In addition, the EPA regulations prohibit the disposal of hazardous wastos that havo not been treated in accordance with EPA standards.
Ilowever, EPA has not published standards for the treatment of mixed wastes, d.
The EPA regulations require that radioactive wastes containing hazardous materials be subject to sampl'.ng and analysis and that mixed wastos in storago be pericdically inspected.
These requirements were developed without taking into account the risks assoniated with radioactive wastos and could add to occupational exposures and costs when applied to mixed wastos, e.
Whereas the NRC regulations for low-level wastos are incorporated into 10 CPR Part 61 and represent a fairly stable set of requirements, the EPA regulations are based on the RCRA, which has been subject to periodic amendment by the Congress and includes an'evor-increasing number of substances that the EPA has classified as hazardous, f.
The NRC regulations for. Class C low-level wastes require the construction and' operation of a facility designed to retain those wastes fcr up to 500 years; the EPA regu-lations for hazardous wastes provide for institutional protection and surveillance for only a maximum of -30 42 L
= -
The Honorable Kenneth M.
Carr 3
February 28, 1991 years beyond closure of the disposal facility and appear to require no inherent waste retention beyond that period.
These observations summarize the major dif ferences between the EPA regulations for the disposal of hazardous wastes and the NRC regulations for the disposa] of low-level radioactive wastes.
p e
2.
Protection Provided by EPA and NRC Reculations Commissioner Curtiss specifically requested that the ACNW compare the protection provided for public health und. safety by NRC and EPA regulations.
Unfortunately, only minimal direct information appears to be available on this important comparison, a.
A relevant study conducted by the Nuclear Management and Resources
- Council, Inc.
(NUMARC, 1990) contains a
comparison of the doses associated with the disposal of mixed wastes in a generic above-grade or below-grade facility and in a conventional shallow 1and burial facility.
The above-grade facility represented the NRC/ EPA conceptua) design for a mixed waste disposal facility.
To provide a full range of assessments, the facilities were assumed to have been located at two distinctly different sites -- a humid impermeable site (typical of the northeastern United States) and a humid permeable site (typical of the southenstern United States).
Althougn NUMARC stated that its data should be interpreted with
- caution, NUMARC found that the performance of a shallow land burial facility, designed and constructed in accordance with the NRC regulations, was superior by a small margin.
NUMARC concluded that, in general, inclusion of EPA regulation 40 CFR Part 264 design features neither demonstrates nor guarantees that the environmental performance of the mixed waste disposal facility will be superior to a disposal facility based on the requirements of 10 CFR Part 61.
b.
The NRC staff, in apparent contnst, has stated (MRC, 1989) that certain features of the disposal facility tased on EPA regulations, such as the double lirar and the leachate collection and retention provisions, " appear to offer enhanced protection of groundwater, at least temporarily."
In view of the proposed EPA " subsystem requirement" that groundwater contamination be limited so that no of fsite person will receive an ef fective dose rate greater than 0.04 mSv (4 mrem) per year, this potential attribute of the EPA regulations may be important.
43 l
1
The Honorable Kenneth M.
Carr 4
February 26, 1991 c.
A study conducted by the U.S. Department of Energy (DOE, 1987) was designed to provide a comparative ovaluation of the predicted performance of a full range of low-level radioactive waste disposal facilities constructed and operated in accordance with the NRC regulations.
Six types of disposal facilities were evaluated:
shallow land burial, intermediate-depth disposal, below-ground vaults, above-ground vaults, modular concrete canister disposal, and earth-mounded concrete bunkers. One of the conclusions of the DOE study, relevant to the comparative performance of facilities constructed and operated in accordance with EPA and NRC regulations, is that the dominant exposure pathway for an above-ground vault is "through release of radionuclides to surface water, and this results in a peak dose which is approximately one order of magnitude higher than the peak dose for the other (five) concepts."
In fact, under the conditions assumed in the study, the above-ground vault concept did not meet the licensing requirements of 10 CFR Part 61 that the maximum effective (whole-body) dose rate to a member of the public be less than 0.25 mSv (25 mrom) per year and that the dose rate to the thyroid be less than 0.75 mSV (75 mrem) per year, d.
Although one conclusion of the NUMARC study was that all three types of disposal facilities cculd meet the effective dose rate limit of 0.25 mSv (25 mrem) per year, this was not the case in terms of the protection of the groundwater pathway.
That is, for the conditions used to characterize the humid impermeable site and for the assumed design features, all three disposal facilities were projected to exceed EPA's draft proposed environ-mental protection standards for low-level waste disposal
[0.04 mSv (4 mrem) per year if groundwater is involved).
3.
Possible So}utions In evaluating possible solutions to these problems, we have focused our attention on the difficulties of managing dual regulations and on the adequacy of either set of regulations in meeting the requirements of the other agency.
Staff members of EPA and NRC have boon attempting for some time to develop an approach through which dual regulation of mixed wastes can be made more practical.
As a result of these
- efforts, three joint guidance reports have been issued pertaining to (a) the definition of mixed wastes, (b) siting requirements for a mixed waste disposal facility, and (c) a conceptual design for a mixed waste disposal facility that will meet both EPA and NRC regulations.
The efficacy of these joint guidance reports is not entirely clear and discussions with State representatives indicate that additional guidance 44
l l
The lionorable Kenneth M. Carr 5
February 28, 1991 is needed.
Examples of areas needing to be addressed include joint guidance on the sampling and analysis of wastes in l
- storage, on methods for integrating the administrative licensing procedures in the two sets of regulations, and on procedures for the consultative review and preapproval of State conceptual designs by Federal agencies (LLRWF, 1988).
The joint guidance reports do not alleviate the dual regulation burden.
Other developments also have bearing on the question posed by Commissioner Curtiss.
a.
In response to technical considerationn and concerns of the public, some State compacts have received proposalc to build concrete bunker facilities for the disposal of low-level wastes.
These facilities appear te be readily adaptable to meet EPA requironents for the disposal of hazardous wastes.
It is our belief that such a tacility, when slightly modified, would provido adequate protection of the public health and safety and meet the requirements of both agencies as they apply to mixed wastes.
The projected unit costs for t he disposal of mixed wastes in such a
modified facility would be relatively high compared to those for the d.isposal of low-level wastes.
This high cost is primarily a result of the unusually low volumes of mixed wastes anticipated to be sent to such facilities, and could be exacerbated by difficulties and delays in obtaining the necessary RCRA permits, b.
Dual jurisdiction of the regulatory process for mixed wastes appears to be wasteful of resources and lacks justification on the basis of benefit to the public.
Some groups have urcjed strongly that the responsibility for regulating mixed wastes be assigned to a single Federal agency.
One approach would be to request Congress to resolve this issue, but comments provided to the Committee indicate that this avenue is not likely to be viable at present.
A second approach would be for the NRC to exercise the option provided under Section 1006(a) of the RCRA, which allows the Atomic Energy Act to "take precedence in the event provisions or require-monts of the two acts are found to be inconsistent."
Inquiry by the Committee indicates that the definition of " inconsistent" is subject to considerable controversy and hence exercise of this option would be difficult.
c.
During its review, the Committee learned that most of the mixed wastes present or being produced in the United States result from DOE activities.
Although the capa-bility of DOE or its contractors to treat, store, and dispose of such wastes is still limited, the Department is developing plans to manage them.
It has been suggested that problems associated with disposal of mixed 45
The Honorable Kenneth M.
Carr 6
February 28, 1991 wastes generated commercially could be resolved if Congress were to assign DOE the responsibility for managing these wactes, similar to the responsibility assigned DOE for managing greater-than-Class-C wastes.
Even though this approach may be difficult, we believe it should be explored.
4.
Sunmary and Recommendations The Committee concludes that at present neither set of regulations alone satisfies the requirements of the other agency.
We make the following comments and recommendations that we believe represent possible steps for resolving the problems of regulating mixed waste disposal and also address the question posed by Commissioner Curtiss.
a.
One action that could lead to a useful result would be for NRC to establish, in accordance with its recently announced policy, a category of mixed waste that is below regulatory concern (BRC).
Mixed wastes that are so designated could then be reclassified as hazardous *;actes and regulated only by EPA.
Information provided to the Committee indicates that more than 90 percent of biomedical wastos would meet the DRC criteria.
b.
In a concurrent action, EPA should be encouraged to develop and implement de minimis criteria for hazardous wastes and for mixed wastes.
- Further, EPA should reconsider and revise the analysis and sampling require-monts for mixed wastes to reduce the risk in such operations due to the presence of radioactivity.
- Also, EPA should be encouraged to modify its regulations to permit interim storage of mixed wastes awaiting disposal and to develop standards for the treatment of such
- wastes, c.
The C.mittee is convinced that a method for disposal of low-al waste that incorporates enhanced confinement (e.g.,
concrete bunker disposal for Class B or Class C waste) and adds provisions for groundwater protection (e.g., a leachate collection system in place for at least as long as would be required by EPA regulations) can meet the combination of disposa1 requirements for mixed wastes specified by NRC arid EPA.
bucia enhanced confinement methodology appear.s to be within the scope of the currently proposed designs for low-level radioactive waste disposal facilities.
46 l
i The Honorable Kenneth M.
Carr 7
February 28, 1991 The Committee concludes also that disposal of mixed wastes can be accomplished under the umbrella of NRC requirements for low-level wastes if these requirements are modified to provide for enhanced groundwater protection.
Further, if Items 4a and 4b, above, are implemoni3d, the volumes of wastes classified as " mixed" will be significantly reduced and the cost for the disposal of the exempted wastes could be similarly affected.
Another benefit of cost reduction and regulatory simp 1ification could be the reversal of debilitating trends by scientists to avoid the use of radioactive and hazardous materials in important research.
We trust these comments are helpful.
We plan to continue to review developments in this field as they arine and will keep the Commission informed about the relevance and consequences of these developments.
Sincerely, Ch Y
Dade W.
Moeller Chairman Be15:XSmees ;
[ DOE, 1987].
U.S. Department of Energy, " Conceptual Design Report
- Alternative Concepts for Low-Level Radicactive Waste Disposal,"
Report DOE /LLW-GOT, Washington, DC, June 1987.
[LLRWF, 1988].
Low-Level Radioactive Waste Forum, "An Assessment of Mixed Waste Management Issues and Pederal Guidance,"
Washington, DC, September 1988.
[NRC, 1989].
U.S.
Nuclear Regulatory Commicolon, Enclosure in letter from Robert M. Bernero, Director, Of fice of Nuclear Material Sately and Safegut.rds, to Alan Pasternak, Technical Director, California Radioactive Materials Management Forum, March 8, 1989.
[NUMARC, 1990].
Nuclear Management and Resources Council, Inc.,
Report on "The Management of Mixed Low-Level Radioactive Waste in the Nuclear Power Industry," 1776 Eye Street, N.W., Washington, DC, January 1990.
47 l
f[o.s ucy),
UNITED STATES NUCLEAR REGULATORY COMMISSION y
y' g
g.
t ADVISORY COMMITTEE ON NUCLE AR WASTE o,
[
WASHUJGTON. D C. 70555 p
....+
March 1, 1991 G
The Honorable Kenneth M.
Carr Chairman U.S. Nuclear Regulatory Commission Washington, DC 20555
Dear Chairman Carr:
SUBJECT:
COMMENTS ON 10 CFR PART 60.113, SUBSYSTEM REQUIREMENTS In response to a request from Commissioner James R.
Curtiss, the Advisory Committee on Nuclear Waste has for the past severa: months examined the subsystem perf ormance requirements of 10 CFR Part 60, with specific attention being directed to the following two questions:
1.
If a site meets the standards for a high-level radioactive waste repository as promulgated by the U.S.
Environmental Protection Agency (EPA, 1985), does that ensure that the site will meet the subsystem performance requirements of the U.S.
Nuclear Regulatory Commission (NRC, 1983a) in 10 CFR Part 60?
2.
If a site meets the NRC subsystem performance requirements, does that ensure that the EPA standards will be met?
The answer to both of these questions is "No."
In the course of our deliberations we examined a range of issues on this subject.
Through this letter, we share with you our observations and recommendations.
sal 2Hystem Perf_qrr,ance Rgpuirements According to the NRC regulations, a mined geologic repository will limit the rate of waste (radionuclide) release to the accessible environment by means of an engineered barrier system (EBS) and the geologic setting (natural system). The two systems differ in their contribution to isolation and in the associated degree of confidence.
The EBS is expected to be the main barrier during the times or conditions when the response of the system is most uncertain, and the geologic setting vill provide the major barrier to releases over the long term.
This approach cor forms with the long-established NRC policy of providing for defen':e in depth.
49 l
l
M'rch 1, 1991 The Honorable Kenneth M.
Carr 2
a of the three subsystem performance requirements specified in 10 CFR Part 60.113, the first two relate to the EBS, the third relates to the geologic setting, as follows' 1.
" Containment of HLW within the waste packages will be substantially complete for a period to be determined by the Commission provided that such period shall be not less than 300 years nor more than 1,000 years after permanent closure of the geologic repository...."
2.
"The release rate of any radionuclide from the engineered barrier system following the containment period shall not exceed one part in 100,000 per year of the inventory of that radionuclide calculated to be present at 1,000 years following permanent closure 3.
"... pre-waste-emplacement groundwater travel time along the fastest path of likely radionuclide travel from the disturbed zone to the accessible environment shall be at least 1,000 years In addition to these requirements there is a statement (10 CFR Part 60.112) that the overall system nerformance_,gblective is to have the repository
" conform to... environmental standards for radioactivity as may have been established by the Environmental Protection Agency with respect to both anticipated processes and events and unanticipated processes and events."
The NRC regulations also include language that permits the Commission to allow _ flexibility in the application of each of its subsystem requirements, provided that the overall system performance objective, as it relates to anticipated processes and events, is satisfied."
Relation Between Subsystem Reauirements and tile EPA Standards Interaction with - the NRC staff has revealed that no deliberate attempt was made to relate the NRC subsystem requirements to the EPA standards.
1.
Information developed by the NRC staff clearly tends to confirm the lack of a nexus.
For example, Table 1, Appendix A,
of the EPA standards provides maximum release limits for a range of radionuclides anticipated to be present in an HLW'
. repository.
Ca:culations show that, if radionuclides are annually released at a rate of one part in 100,000 of the inventory at 1,000 years (as specified in the NRC subsystem requirements), the quantities of certain isotopes of plutonium and americium released could be much larger than the limits specified in the EPA standards (NRC, 1983b).
50
The Honorable Kenneth M.
Carr 3
March 1, 1991
]
2.
It is also probable that compliance with the EPA standards might be accomplished without conforming to one or more of the NRC subsystem requirements.
For example, a repository that meets the EPA standards might very well have a groundwater travel time of less than 1,000 years.
3.
Commissioner Curtiss inquired also about the stringency of the NRC subsystem requirements.
The necessity of complying with two sets of regulations would appear to place an added burden on the licensee.
The stringency of the NRC requirements, however, cannot readily be evaluated against the EPA standards because (a) the NRC subsystem requirements were not based on the EPA standards and (b) a < comparison of the NRC and EPA requirements needs to be site specific.
Summary Comments In summary, our conclusions and observations are as follows:
1.
There is no nexus between the EPA standards and the NRC subsystem requirements.
This is not an oversight; apparently no nexus was intended.
As long as the NRC regulations include 10 CFR Part 60.112, this situation is primarily a regulatory issue, not a technical issue.
It is not a matter that will compromise the protection of public health and safety, 2.
Meeting the subsystem requirements specified in the NRC regulations does not ensure compliance with the EPA standards; the converse is also true. The NRC staff should be encouraged to continue to issue statements clarifying the subsystem requirements so that they are less subject to misinterpretation.
3.
Both the EPA standards and the NRC regulations include statements that are designed to permit flexibility in their application.
Implementing the flexibility, however, may be difficult particularly (as pointed out by Commissioner Curtiss, 1990) under the intense public scrutiny anticipated at the time the licensing process will be underway.
4.
It appears likely that. the applicant for an HLW repository license will need to address the NRC and the EPA requirements separately.
This appears to be true not only because there seems to be no technical relation between the two sets of regulations, but also because demor.-tration that the facility can meet both sets of requirements apears as an inherent part of the regulations.
In our opinion, the health and safety of the public is not likely to ht impaired by this situation.
We are not able to comment on the purely regulatory or legal I
aspects of the dual regulatory impacts of the subsystem requirements.
N 51 l
l
The l'onorable Kenneth M.
Carr 4
March 1, 1991 We trust these comments will be helpful.
Sincerely, Dade W.
Moeller Chairman
References:
[Curtiss, 1990).
Curtiss, James R., " Repository Performance -- The i
Regulatory Challenge," PapGr presented at Symposium on Radioactive Waste Repository Licensing, National Academy of Sciences, National l
Research Council, Washington, DC, September 17, 1990.
[ EPA, 1985).
U.S. Environmental Protection Agency, " Environmental
-l Radiation Protection Standards for Management and Disposal of Spent Nuclear Fuel, _High-Level and Transuranic Radioactive Wastes,"
Title 40, Part 191, Code of Federal Regalations, Washington, DC, 1985.
l l
[NRC, 1983a].
U.S.
Nuclear Regulatory Commission, " Disposal of l
High-Level Radioactive Wastes in Geologic Repositories," Title 10, Part 60, Code of Federal Regulations, Washington, DC, 1983.
[NRC, 1983b].
U.S. Nuclear Regulatory Commission, " Staff Analysis of Public Comments on Proposed Rule 10 CFR Part 60,
' Disposal of High-Level Radioactive Wastes in Geologic Repositories,'"
Report NUREG-0804, Washington, DC, December 1983.
l l
52
[
UNITED STATES NUCLEAR REGULATORY COMMISSION e
n
{
ADVISORY COMMITTEE ON NUCLEAR WASTE o
WASHINGTON. D.C. 20555 gs..../
March 26, 1991 Mr. Robert M.
Bernero, Director Office of Nuclear Material Safety and Safeguards U.S.
Nuclear Regulatory Commission Washington, D.C.
20555
Dear Mr. Barnero:
SUBJECT:
STAFF TECHNICAL POSITION ON REGULATORY CONSIDERATIONS IN THE DESIGN AND CONSTRUCTION OF THE EXPLORATORY SHAFT FACILITY During the 29th meeting of the Advisory Committee on Nuclear Waste (ACNW), March 20-22, 1991, the rtaff of the Office of Nuclear Material Safety and Safeguards (NMSS) presented its revised Staff Technical Position (STP) on Regulatory Considerations in the Design and Construction of the Exploratory Shaft Facility (ESF).
We find this revised STP greatly improved.
We recommend that it be issued af ter incorporation of additional minor revisions disc'1ssed by the ACNW with the NMSS staff.
We believe the STP needs a clear introductory statement that the singular purpose of the ESF is to facilitate the characterization of the proposed high-level waste repository.
However, the STP should then focus on the requirements as stated in 10 CFR 60,15(c) (1), " Investigations to obtain the required information [on site characterization) shall be conducted in such a manner as to limit adverse effects on the long-term performance of the geologic repository to the extent practical."
We also recommend that the staff issue a clarification, either in this STP or as a staff position, of the phrase "to the extent practical."
Furthermore, we urge that the staff include an additional statement that the principal focus of this STP is the need for the U.S. Department of Energy (DOE) to demonstrate that an approach has been used to design and construct the ESF that will avoid adverse impacts on the site should the ESF be collocated with the geologic repository operations area.
Several other revisions suggested during our discussions with the NMSS staff include removal of wording in the STP that could be considered as adversarial, modification of the flow chart presented in Figure 1, and expansion of item (7) (Establishment of Ranges of Site Parameters) of section 3.
A copy of the transcript of this portion of our meeting is enclosed.
I 53
Mr. Robert M.
Bernero 2
March 26, 1991 Finally, as with most of the technical positions that the staf f has presented to the ACNW, it is difficult to ascertain how this STP fits into the overall plan for providing guidance to DOE on site characterization.
We request that the staf f brief the ACNW on what other technical positions are planned and how they will be integrated.
Sincerely, Dade W. Moeller Chairman
Reference:
U.S.
Nuclear Regulatory Commission, " Staff Technical Position on Regulatory Considerations in the Design and Construction of the Exploratory Shaft Facility,"
February
- 1991, transmitted by memorandum from B.
J.
Youngblood, NMSS, dated February 25, 1991
Enclosure:
- Transcript of 29th ACNW Meeting, March 20, 1991, pp. 9-125
- See NUDOCS ANO-9103270366 54
C t e atoo
,\\,
UNITED STATES o
NUCLEAR REGULATORY COMMISSION g
E ADVISORY COMMITTEE ON NUCLEAR WASTE o,,
W ASHINGTON, D.C. 20555
%,..... /
April 29, 1991 Mr. Robert M. Bernero, Director Office of Nuclear Material Safety and Safeguards U.S. Nuclear Regulatory Commission Washington, DC 20555
Dear Mr. Bernero:
SUBJECT:
INDIVIDUAL AND COLLECTIVE DOSE LIMITS AND RADIONUCLIDE RELEASE LIMITS The Advisory Committee on Nuclear Waste has been developing comments, thoughts, and suggestions relative to individual and collective dose limits and radionuclide release limits.
Since we understand that your staff is reviewing these same topics, we wanted to share our thoughts with you.
In formulating these
- comments, we have had discussions with a number of people, including members of the NRC staff and Committee consultants. The Committee also had the benefit of the documents listed.
Basic DefinitioDE As a basic philosophy, individual dose limits are used to place restrictions on the risk to individual members of the public due to operations at a nuclear facility.
If the limits have been properly established and compliance is observed, a regulatory agency can be confident that the associated risk to individual members of the public is acceptable.
Because the determination of the dose to individual members of the public is difficult, the International Commission on Radiological Protection (ICRP) has developed the concept of the " critical group" and recommends that it be used in assessing doses resulting from environmental releases.
As defined by the ICRP, a critical group is a relatively homogeneous group of people whose location and living habits are such that they receive the highest doses as a result of radio-nuclide releases.
The group may be real (in which case their actual habits may be known or predicted) or hypothetical (in which case their habits may be assumed, based on observations of similar groups).
The dose to individuals within the critical group is assumed to be that received by a typical member of the group.
The purpose of this approach is to ensure that members of the public do not receive unaccepteble exposures while, at the same time, ensuring that decisions on the acceptability of a practice are not preju-diced by a very small number of individuals with unusual habits.
1 55 l
9 Mr. Robert M.
Bernero 2
April 29, 1991 If the number of people being exposed is large, the question often arises as to how to quantify the societal impact of the individual exposures.
The collective dose concept was developed for express-ing that impact in a quantitative manner and, as such, it is a numerical expression of the summed doses to a given population.
In many respects, placing limits on total radionuclide releases from a nuclear facility is comparable to placing a limit on its total societal impact.
In other words, placing a limit on the quantity of a given radionuclide that can be released is equivalent to placing a limit on the total societal impact that the facility can exert.
This was the basis used by the U.S.
Environmental Protection Agency (EPA) in setting release limits for a high-level radioactive waste repository, and it relates directly to EPA's basic criterion that the number of health ef fects should not exceed 1,000 during the first 10,000 years.
UIL erlyina Assumptions d
Although it is generally accepted that the dose received by an individual is a reasonable expression of the associated risk, it is questionable whether the collective dose is a true measure of the societal impact of the aggregate of exposures to individual members of a population.
Implicit in the concept of collective dose is the assumption that the linear hypothesis is correct, that is, that there is a linear (non-threshold) relationship between the total dose to a population group and the associated health impacts.
In many ways, application of the collective dose concept leads to a paradox.
At high doses and high dose rates where the risk coefficients are best known, the concept of collective dose cannot be applied since the dose-response curve is nonlinear; at low doses and low dose rates where linearity between dose and the associated health effects is assumed to apply, the risk coefficients are far less cartain.
This leads to additional restrictions in the application of the collective dose concept, as follows:
The exposed population must be well known with respect to size and possibly age, sex, and temporal distributions.
The exposure pathways must be characterized for the population at risk.
Individual contributions to the collective dose must consist only of doses to the whole body, or to specific organs or tissues for which stochastic risk coefficients are known.
In short, application of the collective dose concept requires detailed knowledge of the exposed population and the radiation doses to its members.
The collective dose concept is valid for representing the collective risk only if both of these factors can 56 1
-. - - - _.. _ -. - _. _ - -... - - _ ~
I Mr. Robert M.
Bernero 3
April 29, 1991 be described and quantified, and it should be used for risk assessments only if the associated uncertainties are sufficiently small that the calculated collective dose itself is within an acceptable range of' uncertainty.
In addition, it is important to note that a high individual risk to a small number of people is not necessarily the same as a low individual risk to a large number of people, even though the collective dose may be the same.
For this_ reason, expressions of societal risk in terms of collective dose should always include detailed data not only on the number of people exposed, but also on the number of people receiving exposures within each dose range.
Although collective dose can be used as a surrogate for societal risk, its interpretation requires care.
Truncation of Collective Dose Calculations on a theoretical basis, there is no justification for t iing the application of the linear hypothesis to the evai.< tion and interpretation of the societal impact-of low doses and low dose rates on population _ groups.
This hypothesis, in fact, has been generally accepted by the scientific community, including organiza-tions such as the National Council on Radiation Protection and Measurements (NCRP) and the ICRP, as a valid basis for estimating the stochastic risks associated with low doses of ionizing radiation.
If one accepts this observation, calculations of collective. doses should include the doses to ell individuals within the population group, regardless of how small the-associated doses and/or dose - rates may be.
. At. the same time, however, it is important to recognize that there may be cogent reasons for not including within collective dose calculations extremely low doses to individual.r. embers of a population group.
Several approaches that have been proposed and/or applied to justify _such omissions are discussed below.
Following the concept that certain risks to individual members of the population are negligible, the NCRP has recommended (under what it defines as the concept of a " Negligible Individual Risk Limit")
that annual doses to individual members of the population that are less than 0.01 msv (1 mrem) be excluded from collective dose calculations.
In interpreting this recommendation, however, it is importcnt to understand the underlying principle on which-it was based.
Informal discussions with representatives of the -NCRP revealed that truncation in this case was considered to ha acceptable from the standpoint of societal impact, because the burden on-society represented by any additional cancers among people receiving exposures in this dose rate range would not necessitate any additional medical facilities.
Another approach for truncation that has been informally suggested by representa-tives of the NCRP is that it might be permissible to discard a co]lective dose (calculated on the basis of extremely low dose rates to members of _ an exposed population) provided that the 57
Mr. Robert M.
Bernero 4
April 29, 1991 associated collective dose would not be estimated to result in one additional cancer.
Variations in the dose rates from natural background radiation sources have been preposed as another basis on which to truncate collective dose calculations.
The contribution to collective dose from natural sources is large relative to that from many artificial sources.
Consequently, it is often difficult to measure in a meaningfully Juantitative manner very low dose rates to individual members of the population that arise from artificial sources.
Thus, although there may be no biological basis for excluding very low dose rates from collective dose calculations, there is justification for excluding them on a statistical basic because of the uncertainties in the associated calculations.
Determinatioss of Compliance With Standards From the previous discussion, it follows that the establishment of limits on the concentration of individual radionuclides in various environmental media (e.g.,
air and water) is comparable to the establishment of dose limits for individual members of the population.
Likewise, the placement of limits on total radio-nuclide releases from a nuclear facility is comparable to the establishment of limits on the associated permissible collective doses to the affected population.
In terms of the determination of compliance with-a set of standards, it is readily possible to measure the concentrations of individual radionuclides in various environmental media, and it is similarly possible to estimate the associated doses to individual members of the population.
In contrast, estimates of the total releases of radionuclides from a nuclear f acility would require not only knowledge of the concentra-tions of individual radionuclides in all environmental media, but also the determination of the rate of movement (transport) of each radionuclide (including the evaluation of site-specific pathways) within all such media from the facility to the accessible environ-ment.
Similar uncertainties would accompany estimates of the associated collective doses.
Summary In summary, the Committee offers the following statements on the benefits of the application of various limits for determining the i
public health risks associated with nuclear operations.
1.
Individual dose limits can be used to limit the risks to individual members of a population group.
2.
Collective dose limits can be used to limit the societal impacts of doses to a large number of individuals.
The accuracy of collective dose as a measure of societal risk, however, depends on the validity of the linear (non-threshold) 58 I
l
l Mr. Robert M.
Bernero 5
April 29, 1991 hypothesis in assessing the stochastic effects of ionizing radiation.
3.
Collective dose calculations are representative of societal risk only if certain conditions are satisfied; namely, the exposed population is defined and characterize' with respect to size, age, and sex; the distribution of doses to individual members of the population is within a limited range; the exposure pathways have been characterized for the population at risk; and individual contributions t' the collective dose consist only of doses to the whole body, or to specific organs or tissues for which stochastic risk coefficients have been adopted.
4.
Techniques for measuring the concentrations of individual radionuclides in various environmental
- media, and for estimating the associated dose rates to individual members of the population, are readily available, and compliance with such limits can be determined.
In contrast, the measurements that would be required to determine the total releases of individual radionuclides from a nuclear facility and estima-tions of thc associated collective dose to all offsite population groups would be difficult.
5.
Given the general acceptance of the linear hypothesis, there is no biological basis on which to truncate calculations of collective doses. Nonetheless, regulators must recognize thac estimates of dose rates frcm artificial radiation scurces, that represent only a few percent of those from natural radiation sources, carry with them large uncertainties and relatively little aggregate risk. Such uncertainties may well serve as a basis for truncating collective dose calculations at very low dose rates without adverso impacts on estimates of the associated risks.
We trust that these comments will be helpful.
We plan to review and comment on your report regarding this subject when it beccmes available, consistent with the SRM dated April 18, 1991.
Sincerely, Dade W.
Moeller Chairman 59
Mr. Robert M.
Bernero 6
April 29, 1991
References:
1.
International Commission on Radiological Protection, "1990 Recommendations of the International Commission on Radiologi-cal Protection," Publication 60, Annals of the ICRP (1991).
2.
Natione.1 Council on Radiation Protection' and Measurements, "Recor.anendations on Limits for Exposure to Ionizing Radia-tion," Report No. 91 (1987).
3.
National Radiological Protection
- Board,
" Radiological Protection Objectives for the Land-based Disposal of Solid Radioactive Wastes."
Consultative Document.
NRPB-M279, March 1991.
4.
" Possibilities and Limits of the Application of the collective Dose."
A~
Recommendation of the Radiological Protection Commission (SSK).
Bundesanzciger, No. 126a, July 1985.
i l
60
fa osoog y,
..,g UNITED STATES
{t-g NUCLEAR REGULATORY COMMISSION y
m t
ADVISORY COMMITTEE ON NUCLE AR WASTE g
8 o
WASHINGTON. D C. 20f45 f
April 29, 1991 The Honorable Kenneth M.
Carr Chairman U.S.
Nuclear Regulatory Commission Washington, D.C.
20555
Dear Chairman Carr:
SUBJECT:
CONSIDERATION OF HUMAN INTRUSION IN THE LICENSING OF A HIGH-LEVEL WASTE REPOSITORY In its report to you dated May 1, 1990, the Committee recommended that the U.S.
Environmental Protection Agency (EPA) standards for the disposal of high-level radioactive vaste be revised to permit the application of a separate approach for evaluating the potential impacts of human intrusion.
Mr. Floyd L.
Galpin, Chief, Waste Management Standards Branch, Of fice of Radiation Programs, EPA, has requested that the Committee provide additional comments and elaboration regarding this subject.
This letter is in response to that request.
One approach for evaluating human intrusion in the case of the geologic repository would be to apply techniques similar to those used by the NRC staff in assessing the threat of sabotage at nuclear power plants.
In evaluating this threat, the NRC uses a deterministic rather than a quantitative probabilistic approach.
The NRC approach recognizes the inherent uncertainties aseociated with the application of quantitative probabilistic techniques in assessing an issue of this nature.
The enclosed paper summarizes the NRC approach in the treatment and evaluation of the sabotage threat at nuclear power plants, and it addresses the issue of human intrusion as treated in the EPA standards.
The paper was prepared by Mr. Steven E. Mays (ACRS/ACNW Fe] low) at the request of the Committee.
It has been discussed with members of the NRC staff, and it is being provided to you for possible forwarding to Mr. Calpin.
Sincerely, Dade W.
Moeller Chairman
Enclosure:
As stated 61
COMPARISON OF TECHNIQUES FOR ASSESSING NUCLEAR POWER PLANT PROTECTION AGAINST SABOTAGE AND HIGH LEVEL WASTE (HLW) REPOSITORY PROTECTION AGAINST HUMAN INTRUSION Steven E.
Mays ACRS/ACNN Fellow a
April 1991 62
ABSTPACT Human actions have the potential to bypass the protective f eatures that minimize the likelihood of release of radioactive material to the environment f rom nuclear power plants or a geologic high level waste (HLW) repository.
Sabotage of nuclear power plants and human intrusion into a geologic repository are examples of acts of commission that the NRC and EPA respectively have concluded require specific regulations.
This paper compares the use of probabilistic techniques by the two agencies in dealing with these acts of commission.
The NRC chose a deterministic approach for assessing the impact of sabotage on power plants and limited the use of probabilistic techniques to qualitative assessments of the adequacy of licensee security plans.
EPA chose to require treatment of human intrusion quantitatively an an explicit part of the performance assessment required for licensing a geologic HLW repository.
63
.. _ - - - - ~
COMPARISON OF TECHN1 QUES FOR ASSESSING NUCLEAR POWER PLANT PROTECTION AGAINST SABOTAGE AND HIGH LEVEL WASTE (HLW) REPOSITORY PROTECTION AGAINST HUMAN INTRUSION INTRODUCTION Nuclear power plants have engineered features and proposed HLW repositories have engineered and geologic features that serve to limit the likelihood of release I
of radioactive material to the environment. In the case of nuclear power plants,.
i several engineered barriers exist including the fuel cladding, the reactor coolant system boundary, and the containment. For spent fuel at a nuclear plant, the barriers include the fuel cladding and the spent fuel pool (or dry uask storage at some locations). For a HLW repository the propoced barriers include the. f uel cladding, the containers for the spent fuel, and the geological formation (analogous to the reactor containment).
Human actions such as sabotage or human intrusion have the potential to bypass
- the features that limit the likelihood of release of radioactive material to the i
environment.
While the intent of the partisinants and the nature of thene two actJons are_different, such events are d t LQeuly to anal _yJe by probabilistic i_echnicues and at least sabotace is not so treated.
This naner examines the extent that the two acencies use orpigjb llp_t_1.q_techniones to reculate protection
'from these acts of commission.
It is not intended to ecuate the physicaj acts themoelves nor to state that the aporsach succested here is thq Jiqal word on
-the subiectu The NRC and EPA have regulations 1' requiring licensees to demonstrate their ability to maintain the ir.tegrity -of the features against certain acts of commission. In the case of nuclear power plants, physical security requirements for protection against sabotage.are contained in 10 CFR 73.55.
For a HLW repository, the EPA requirements for human. intrusion (HI) are contained in an appendix to_40 CFR 191.
While both agencies recognize tae potential for human actions to bypass these protective features, the use of probabilletic techniques in the licensing and regulatory process is vastly different.
Briefly stated,.the EPA regulations require a quantitat.1ve probabilistic analysis ( :alled -a performance assessment) of the performance of the-protective features of a repository over a 10,000 year period. This assessment must include human intrusion scenarios axplicitly. The NRC approach with respect to sabotage at nuclear power plants, on the other hand, eschews quantitative probabilistic criteria in favor of a deterministic evaluation supported by qualitative use of probabilistic analysos.
The purpose of this paper is to compare the methods used by the NRC and EPA to regulate protection from sabotage.at reactors and inadvertent human intrusion at a potential HLW repository. The paper specifically addresses the use of (or the lack of) probabilistic techniques in their regulations and applications.
While there may 'e concerns regarding the similarity of the events themselves o
(and therefore the applicability of comparing the types of regulation) and 1
64 l
I whether either agency has come upon the ultimate methodology f or regulating them, this paper compares the regulations and applications af they cu rrent1v ex ts_t.
It is for the reader to determine the applicability of these techniques to the regulation of protection against sab Tage at reactors and human intrusion at a llLW repository.
m P',ODABILISTIC TECHNIQUES In any discussion of probabilistic analysis, definitions are important. Since the terms used by the two agencies differ somewhat, it is necessary to define the terms in this paper with respect to the two agency's terms.
The EPA regulations require, as a licensing condition for a HLW repository, a
" performance assessment" of any potential site. The EPA has set release limits for various radionuclides and constructed a probabilistic criteria that the performance assosoment needs to satisfy.
Specifically, the assoasment muet analyze a variety of scenarios that could result in release of radioactive material to the environment and calculate a comple.centary cumulative distribution function (CCUF) that shows the likelihood of releases to be below the EPA's probabilistic limits.
In nuclear power plant probabilistic risk assessment language, this is known as a " risk curve".
This paper will une the termo CCDF and risk curve synonymously.
For nuclear power plants, risk curves are a quantitative part of the process known as probabilistic risk assessment (PRA) or probabilistic safety assessment (PSA).
Thun, the performance assessment of the EPA requirements is analogous to a PRA for a nuclear plant. The elements of a PRA needed to generate a risk curve are a set of initiating events, a model of the plant response to these eventu (event tress and fault treen), and a model of the consequences of the various sequences derived from the models.
Figure 1 shows the three rna jor elements of a PRA along with its equivalent olernent from a performance assessment required by the EPA.
The PRA risk curve is generated by propagating dath distributions for the initiating events, plant response models, and consequence models to arrive at a distribution for each of the undeuired sequences in the models. A distribution is derived f or the sum of the sequence distributions and
~
the risk curve (CCDF) for the result is produced.
The equivalent elements of an EPA perf ormance ansessment are scenario development, HLW containment behavior models, and transport models.
Distributions are propagated through these mathematical modeln in a manner similar to the PRA methods (although the mathematical models for containment and transport are much difforent from the event / f ault tree models of PRA). The combination of the resulting distributions is used to produce the CCDF for comparison to the EPA requirements.
SABOTAGE VERSUS HUMAN INTRUSION As noted before, both the NRC and the EPA recognized the potential for human actions to adversely impact the protective features of a nuclear power plant or potentiC ULW repository. The method f or dealing with these two similar issues is vast different.
y Hunian act_ons that adversely impact the performance of protective features are 2
(> 5
generally characterized by the PRA community as either acts of omission or acts of commission 3.
Acts of omission are cases where a triqu[ red acM on does not g.q_c_ur.
Acts of commission are cases where actions occtr that adversely impact the protective f eatures in spite of the f act that the act ion 19 neithe u equired ngr desired.
This paper characterizes sabotago and human intrusion as examples of acts of commission. While the intent of the participants in both caece is drastically difforent as is the physical nature of the actions, probabilistic analysio of acts of commission is the same. Current PPA practice excludes acts of commission from the quantitative process due to the inability to calculate either the frequency of such acts or their effects on the protective features. This paper crimpare s the NRC use of probabilistic analysie techniques for regulating protection from sabotage to the EPA requirements for proMbilistic analysis of human intrusion f or a geological repository.' It is not intended to equate the actions themselves.
NRC Approach to Sabotage The NRC chose a deterministic, rather than a quantitative probabilistic approach, for dealing with sabotage.
In fact, even with the current maturity of PRA (as compared with the emerging performance accessment techniques), the NRC has not used a risk curve as a licensing criteria for any plant, much less for the subset of events that would include sabotage.
The NRC approach recognized the inherent uncertainties and lack of data for quantifying the r.a tu re of or the probability of a sabotage event.
It alno recognized the difficulty in assessing the damage a potential sabotage event wculd have on the operation of the engineered features for limiting the release of radioactivo material.
In other words, quantifying uabotage initiating events and their effects on plant nystems was impractical.
The NRC conducted studies to assess the threat level that plants would be l'
'6 required to address in their security plans. Their ruleo recognized that a graded approach to sabotage protection at nuclear power plants (in comparison with nuclear weapons facilities or weapons grade material facilities) was appropriate.
After determining the threat level that security plans must address, the NRC regulations specify the types of plant equipment that require protection and the level of protection required.
For nuclear power plants, 10CFR73.55 specifies general performance objectives and requirements for the plant's physical security organization, physical barriers, access, detection, and communications.
This approach is similar to other NRC actions, such as regulations dealing with the spectrum of loss of coolant accidents (LOCAs) that emergency core cooling cystems must be capable of mitigating. None of the sabotage regulations require quantitative analyses such as risk curves as a basis for acceptance.
- However, probabilistic techniques have played an important role in the NRC reviews of licensee security programs.
The NRC has used fault tree models as one tool for assessing the effectiveness of security programa.
Fault tree models for almost every plant in the United 3
)
66
States have been prepared by the NRC.
The models differ from typical PRA models by virtue of the fact that the vital equipment locations are included in the models.
In a PRA, the fault tree models are reduced by computer algorithms to produce minimal cut eets.
This qualitative analysis is necessary before data distributions can be propagated to produce a distribution for the system f ailure probability that eventually is part of the input to the rink curve (CCDF).
For evaluating security programs, the location information included in the models is used to produce minimal cut sets containing locatdon information instead of the actual vital equipment.
In addition, the fault tree modelo provide qualitative results that show the minimum number of areas that must be protected to ensure that the plant can be brought to a hot shutdown condition.
This kind of qualitative information provides the NRC with a list of areas that can provide for safe plar.t shutdown in the event of a specific sabotage scenario.
EPA Approach to Human Intrusion In contrast to the NRC, the EPA has chosen to include human intrusion (HI) in the quantitative analysis of performance assessment.
In fact, the EPn not only requires that H: be considered, but also specifies how HI affects are to be calculated.
The EPA specifies a drilling density assumed to occur over a 10,000 year period.
Further, the EPA allows no credit for active institutional controls beyond 100 years after repository closure. The EPA also states that passive institutional controle cannot be ausumed to be a successful deterrent to a potential intruder.
=
To date, several attempts at developing and applying performance assessment methodologies to potential repository systeme nave been made
,8,9 In cach case, 7
the HI scenario has dominated the CCDF In each case where the CCDP curves intersected the EPA requirements of part 191.13, removal of HI from the CCDP would eliminate the conflict. Figures 2 and 3 show CCDFs f rom studies along with the impact of HI on the numerical results.
COMMLNTARY Probabilistic techniques can be important tools in the regulatory arena.
The products of probabilistic tech..iques can either be qualitative or quantitative in nature.
The ability to use quantitative probabilistic techniquea 10 highly dependent on the availability of data, the uncertainties in the data, and the uncertainties in the processes.
The deerth of data relating to sabotage events along with the uncertainties associated with the range of potential sabotage events and their impacts on enoineered featureo led the NRC to chose a deterministic method for regulating licensee actions relating to physical plant protection in 10 CFR 73.55.
The NRC unen qualitative probabilistic techniquen as one measure of the ef fectiveness of licensee programa.
The EPA has decided to require development of a cuantitative probabilistic 4
67
analysis in the form of a risk curve covering repository performance over a 10,000 year 1>riod as the basis for licensing a geologic HLW repository.
Treatment of human intrusion is required as part of this analysis and the EPA standards specif y that it must be included quantitatively. Whether this analysis should be quantitative, however, appears to be in question.
Reasons for excluding human intrusion from the quantitative analysis follow.
Current PRA techniques have considerable difficulty quantifying human actions.
The actions that PRAs try to include are those where operators fail to follow required actions (typically known as acts of omission). Acts of commission (such as sabotage or actions that operatot s might take that bypass engineered f eatures when there is no compelling reason to take the action at all) are routinely excluded f rom quantitative risk assessments for nuclear power plants. The reason 13 simple.
No one has produced a reliable method for predicting either the frequency or the effects of such actions.
Qualitative methods using probabilistic techniques exist (such as conf usion matrices and other tools) that can help to identify potential interactions, but none of these claim to be comprehensive even in the qualitative sense. Analyzing acts of commission over a 10,000 year time frame as required in the case of a geologic HLW repos itory would be even more difficult.
Except human intrusion, the EPA guidelines in 40CFR191 do not specif y either the frequency of the scenarios that could adversely affect the protective features nor do they specify the ability of these features to withstand the potential scenario.
Rather, the EPA requires that the analyses provide
" reasonable expectation, based on performance assessments that the cumulative releases of radionuclides to the accessible environment for 10,000 years after disposal from all significant processes and events.." have less than a one in ten chance of exceeding the valuea in Table 1 of the rule and less than a one chance in 1,000 of exceeding ten times the Table 1 values.
For human intrusien, the EPA provides guidance on the frequency of the event, disallows any consideration of active institutional controls, and declarec that
~
passive controls can never be used to eliminate HI from consideration.
This appears to be different from the other parts of the analyses that make up the quantitative risk curve. Limited performance assessment activities to date have indicated that the prescribed method of analyzing HI leads to CCDFs that exceed the EPA requirements.
The EPA regulations do not address the po'.ential impact of human intrusion for alternate means of disposal compared to the deep geological HLW repository. HLW already exists and the only method currently approved for storing HLW is spent fuel pools or dry cask storage.
Potential human intrusion leacing to releases from these storage f acilities over a 10,000 year period (or f rom some other means of disposal not addressed by the regulations) might be greater than that allowed for a deep geological repository.
CONCLUSIONS Human actions have the potential to adversely af f ect the protective Dystems that l i.m i t the release of radioactive material to the ens i. ro nme n t.
The NRC and EPA have chosen v astly dif ferent ways to deal wi.th such actions in their regulations 5
tS
for nuclear power plants and HLW repositories.
The EPA has opted for a quantitative, probabilistic analysis that includes human intrusion as one of its parts. The EPA guidelinea specify the f requency of the HI events and the effectiveness of controls to prevent intrusion for the analysis.
No such specification of frequencies or effectiveness of engineered systems for other scanarios is stipulated.
The NRC has opted for a deterministic approach for plant security.
In a meth>d similar to their treatment of design basis event s, the NRC has specified a threat level that security plans must account for.
The NRC requires identification of vital equipment and the areas encompassing vital equipment.
Probabilistic techniques are used internally by the NRC staff to produce qualitative results that support the evaluation of the ef fectiveness of licensee security programs.
Quantitative risk curves are not a licensing requirement for this issue.
In fact, the NBC does not have any licensing criteria that require a risk curve comparison to a numerical standard.
This paper addresses the methods that the NRC and the EPA use to regalate protection from sabotage at reactors and inadvertent human intrusion at a potential HLW repository. While there may be concerns regarding the similarity of the events themselves (and theref ore the applicability of comparing the types of regulation) and whether either agency has come upon the ultimate methodology f or regulating them, this paper compares the regulations and applications ar they current 1v exist.
It is for the reader to determine the applicability of these techniques to the regulstion of protection against sabotage at reactore and human intrusion at a HLW repository.
REFERENCES 1.
Code of Jeral Regulations, Title 10, Part 73, Physical Protection of Plants and Materials.
2.
Code of Federal Regulations, Title 40, Part 191, Environmental Standards for the Management and Disposal of Spent Nuclear Fuel, High-Level and Transuranic Radioactive Wastes.
3.
NUREG/CR-2300, PRA Procedures Guide.
4.
NUREG/CR-1278, Handbook of Human Reliability Analysis with Emphasis on Nuclear Power Plant Applications.
5.
NUREG-0800, Standard Review Plan, Chapter 13.6 Physical Security.
6.
USNRC Review Guideline 17, Definition of Vit ' Areas and Equipment.
7 NUREG/CR-4510 (SANDB6-0121), Assessing Compliance With the EPA High-Level Waste Standard: An Overview.
3.
SANDIA presentation, 25th ACNW meeting transcript, October 24, 1990.
6 69
i 9.
NRC staff presentation, 25th ACNW meeting transcript, October 25, 1990.
10.
GAO Report to Congress, Security at Nuclear Power Planto-At Dest, Inadequate, April 7, 1977.
11.
GAO Report to NRC Chairman, Additional Improvements Needed in Physical Security at Nuclear Power Planto, July 13, 1983.
.?
7 70
i PROBABILISTIC RISK ASSESSMENT ELEMENTS PLANT CONSEQUENCE INITIATING MODEL ANALYSIS RISK EVENTS (EVENT TREES (SOURCE TERM CURVE ANALYSIS
& FAULT TREES)
AND RELEA3E)
I
?
N PERFORMANCE ASSESSMENT ELEMENTS i
TRANSPORT r
SCENARIO CONTAINMENT MODELS ANALYSIS ANALYSIS (NEAR FIELD CCDF
& FAR FIELD) l E
i Figure 1.
Comparison of PRA and PA Elements
1.0 i
EPA Cof4TAlt4MEf4T
- REQUIREMEt4T W
-1 m
10 4
W m.
J %
W >-
-2 POSSIDLC C
10
~f viot avion O
w p
O8 10
,l,,5~
J 55E
"- ]
<x
~4 J
CO A 10 Ox Q.
10' i
I i
+0 I
2 3
10'I 10 10 10 10 SlJMMED NORMAllZED RELEASES, R CCDF for the Exarcple plot,ted with EPA containment requirement.
Figure 3.
SANDI A Report SA11D86-0121-(11UREG/CR-4510)
Overview of Act,essing Compliance with 10 CFR 191 72 4
.__._._______________m
Oorchole fill Porosity and Hydtaulle Conductivity
- o. t.a tin i, t Pa coat..nmoni mequi<ement t...i r e. r et ne' veie..
/(t o-*,nie, c40) go.i.
h
,,n.c v.w..
L 9
(10 t m/s,0.141 :
u.ei r.,e,.u.-
v.w..on u.i.
L (10 " m/s. 0.0s) g
^ 10 8 l
2 l
l 6
o 3,.,
I at 1Cd 10 8 10 4 10 8 10 3 10 1 10' ici 108 108 summed weatta.d nei...... n 1Ri434) 3371 Conditional CCDF curves showing sensitivity to variations in borehole.plus porosity and hydraulic conductivity (Anderson e t al., 1990).
- Expectad' and *1 east favorable
- values for deteriorated borehole.plus porosity and hydraulic cot..hc.
tivity are shown. *Most favorable
- values, cc sponding to the properties of the repository seals, plot of f. scale, Curves asmu:se intrusion scenario El occurs.
Curves were calculated using the preliminary modeling systets described in Marietta et al. (1989) and cannot be used to judge com.
pliance or noncompliance because all significant scenarios are not included, crucial models and data are eissing, sur-face releases are omitted, and the Standard has been vacated.
They simply measure modeling sensitivity to varia-tions in the test parameters, 1igure 2.
SA!JDI A Analycio of WIl'l> I'ai ! ormimco for lluman Intrunion 73
+f* n o v
UNITED STA1ES
[, as 'S, NUCLEAR REGULATORY COMMISSION g
g, t
ADVISOHY COMM1114 t UN NUCit AR WAf>Ti g
.f WASHINGTON, D C N!M
\\
/
April 29, 1991 The lionorable Kenneth M. Carr Chairman U.S. Nuclear Regulatory Commianion Washington, D.C.
20555 Dear Chairman carrt SUBJECT PROGRAM PLAN FOR Tile ADVISORY COMMITTEE ON NUCLEAR WASTE This in our fifth response tn your memorandum of November 6,
- 1989, in which you requested that the Advidory Committee on Nuclear Waste (ACNW) provide a program plan at four-month intervala.
Thin plan covers the period May-August 1991.
We hope you will find this a convenient avenue for un to share information on our proposed upcoming activition and for you to provide feedback on inno w on which the Commisalon winhos un to focus our efforts.
In preparing this program plan, we have considered the lint of npocific technical lunues of particular interent to the Comminnion, requestn of individual Commisalonera, the EDo's list of proposed agenda itema for the ACRS and the ACHW, the NHC's Five-Year Plan, and items of particular interest and/or concern to the Committee.
The priorities proposed are based on information provided by representatives of HMSS, NRR, RES, and the EDO office, an uell an our own interpretation of the subject in relation to our activities as a Committee and our input into the regulatory procean.
This program plan is based on the current best estimaten of work output by the DOE, EPA, NRC staff, and thel't consultants and contractors, as well an our own estimatou of how to deal with these innues effectively.
In addition to the full Committee meetings
- noted, Working Group meetings will be held ao neconsary to facilitate full Committee review and action.
There may be nome revisions to this pian associated with the completion of NRC staf f, applicant, and/or contractor studies and reviews as well as other schedule problems beyond our control.
Full Committee meeting dates for thiu period are tentatively scheduled as follows:
31st Mocting May 22-23, 1991 32nd Meeting June 20, 1991 33rd Meeting July 24-26, 1991 34th Meeting August 28-29, 1991 The Committee anticipates considering the topics listed below during this four-month period.
76
The lionorable 1:enneth M.
Carr 2
April 29, 1991 liay_2 2 -2 3, 1991 e
The Committee will be briefed on Working Draft #3 of the Environmental Protection Agency's 40 CPR Part 191, liigh-Lovel Waste Repository Standards, if available.
(Iligh Priority)
The Committee may continue discussions which address dealing 6
with uncertainties in implementing the EPA liigh-Level Waste Standard 3.
(High Priority) e The Committee will hear a report from ito Working Group Chairman on a
recent menting concerning Integration of Geophysics into Site Characterization of a hlgh-Level Waste Repository.
(Medium) e The Committee will be briefed by representatives from the State of South Carolina on the implementation of its agreement state program.
(Medium Pciority)
The Committee will discuss information obtained by members from attendance at the Second Annual International liigh-Level Radioactive Waste Management Conference and a field trip to Lunar Craters.
(Medium Priority)
The Committee will be briefed on a digital data set prepared e
for the Yucca Mountain site.
(Medium Priority) e The Committee will be briefed on rescarth sponsored by the Department of - Encrgy related to site characterization.
An overview of this research is sought.
(lligh Priority) iTune 20, 1991, The Committee will respond to a staf f Requirements Meuorandum concerning the need Ior revision to 10 CFR Part 61 as it relates to low-level waste form leachability and groundwater protection requirements.
(lligh Priority)
The Committee will hear a report by a member on a recent visit e
to the West Valley Demonstration Project.
(Medium Priority)
The meeting with the Commission which was scheduled for the e
June ACNW meeting has been tentatively deferred to July by SECY.
This meeting may still be scheduled for the Juno ACNW meeting if appropriate Commissioners can be available.
76
l The lionorable Kenneth M.
Carr 3
April 29, 1991 dull 23-2h_L911 The Committee will meet with the Commissionern to discuno itema of mutual interent.
(lligh Priority)
The Committee will review and comment on an liitC staf f report e
that dincunces exemptionn to 10 CI'It Part 20 that allow newer dinpocal for certain wante ntroamn.
(Illgh Priority)
Linting of Facilitien and Structuren in One Document.
The e
Committee will review and comment on a proposed rulo dealing with record keeping for modif3 cations and procedurou taade during decommlunioning.
This rulemaking in in response to a Congrounional requent.
(Iligh Priority)
The Committoo will review 2nd comment on the first of the two e
g rout
- of draf t llegulatory Guides implementing the revised 10 Crit part 20, Standarda for Protection Against Radiativi.
(liigh Priority)
The Committee will d.incunn ite recent trip to and mooting at the Center for 11uc1cer Waste llegulatory Analyses.
(Medium Pri,rity)
Tne Cemmittee will discuno and report on how expert judgment e
will
.;c used in conducting performance annenuments unod in the licensing of high-level and low-level waste repositories.
(lligh Priority) bl1GRE.t_211-21h_l221 e
The Committee will invite the State of Nevada to present a nummary and diccuccion of the State's review and comments on DOE's Sito Characterization Plan and related Study Plans.
(iiigh Priority) e The Committee will invito DOC to present a summary and discussicn of the DOC responsen to comments by EPA, 11RC and State of 11ovada on the Yucca Mountain Site Characterization Plan.
(Illgh Priority) e The Committen will review and comment on the 11RC staff's Technical Position on Investigations to Identify Fault Displacements and seinmic Ilazards.
(Medium Priority) e The Committee will hear a precentation on the proactive program for llLW.
This involven planned rulemakings, guidelinen, and technical ponition in support of the IILW program.
(liigh Priority)
/7
The lionorable Kenneth M.
Carr 4
April 2.9, 1991 e
The Committee will hear a report from its Working Group on Quaternary Dating Methods.
(Medium Priority)
The Committee will review and comment on the staff's analysis of the benefits and limitations of using collective dose and ind!vidual dose approaches as the basis for establishing stande rds for a high-level waste repository.
(Iligh Priority)
Uni hedulc.d_Dh cussionst_ (Will be considered as documents and time become available.)
The Committee will be briefed on the NRC llLW staf f's position e
ori penetration of the Calico lillls tuif.
(iiigh Priority)
The Committee plans to invite a representative from AECL to e
discuss Canada's high-level waste standards.
(Low Priority)
The Committee will be briefed on the staff's review of the e
Exploratory Shaft Alternatives Study and the Surface Based Testing Prioritization study.
The studies are being prepared by DOE.
The Committee will review these studies when available.
(iiigh Priority)
The Committee will be briefed by EPA on their adeption of a e
revised liezard Ranking System used in assessing the threat associated with the release or potential release into the environment of hazardous chemicals and/or radioactive materials.
(Low Priority)
The Committee will be briefed by the NRC staff on a recent technical meeting on the Alligator River Analogue Project.
This project is designed to investigate the Koongarra uranium ore body, a natural analogue to a high -level waste repository.
(High Priority)
The Committee will discuse an alternative probabilistic format e
for the containment requirements in EPA's high-level waste standards.
Processes and events potentially affecting a repository would be divided into three categories (likely conditions, unlikely conditions, and very unlikely conditions).
(High Priority) e The Committee will discuss issues related to post closure monitoring of a high-level waste repository.
(liigh Priority) e The Committee will discuss a
recent report concerning Mortality Among Workers at Oak Ridge National Laboratory, e
The Committee will discuss and make recommendations on criteria for the cleanup of sites contaminated with residual 78
The Honorable Kenneth M.
Carr 5
April 29, 1991 level of radioactivity (e.g.,
natural
- uranium, depleted uranium, thorium, etc.).
This list represents our best estimate of the topics to be considered through August 1991.
If you or your fellow Commissioners have additional items to suggest or proposed changes in priorities, please let us know.
Sincerely, h
4 4
Dade W.
Moeller Chairman cc:
Commissioner Rogers Commissioner Curtiss Commissioner Remick Samuel J.
Chilk, SECY James M. Taylor, EDO Robert M.
Ber 1ro, NMSS 79
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v UNITED STATES
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NUCLEAR REGULATORY COMMISSION y
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ADVISORY COMMITTf f ON NUCLLAR WASTE 0,
"[
WASHINGTON. D C 20%$
~%,,,,,E May 30, 1991 The lionorable Kenneth M. Carr Chairman U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Dear Chairman Carr
SUBJECT:
ALTERNATIVE APPROACll TO Tile rnoBABILISTIC SECTION OF Tile CONTAINMENT REQUIREMENTS IN 40 CFR PART 191 (" Tile TilREE-BUCKET APPROACil")
With the issuance of Working Draft 3 of 40 CFR Part 191, the proposed revised standards for the management and disposal of high-level radioactive vastes, the U.S. Environmental Protection Agency (EPA) has requested comments on the proposed "three-bucket approach" for classifying events that may affect repository performance.
The Committee discussed this matter with the NRC staff during our 30th meetinJ, April 23-24, 1991, and with the EPA staff during our 31st meeting, May 22-23, 1991.
On the basis of those discussiont., we offer the following comments.
In ganeral, we endorse the three-fold classification system outlined in the enclosure, and we believe it will be helpful in addressing the problems of assessing inadvertent human intrusion.
We also endorse the deterministic treatment of scenarios that are assigned to " bucket number two."
We accept the fact that the presence of natural resources represents a potentially adverse condition (10 CFR 60.122(c)).
If there are potential resources present at a site in largo enough amounts to create a high probability for human intru3 ion, the site should be rejected.
We expect that no scenario involving inadvertent human intrusion will be assigned to " bucket number one."
As part of our continuing study of the "three-bucket approach," we are evaluating the bounding probability limit for distinguishing between scenarios that are unlikely (" bucket number two") and very unlikely (" bucket number three").
l 81
The lionorable Kenneth M.
Carr 2
May 30, 1991 We hopo these comments will be helpful.
Sincerely, N
Dado W. Mooller Chairaan Reference EPA, 40 CFR 191 - Draft Environmental Standards for the Management and Disposal of Spent Nuclear Fuel, liigh-Level and Transuranic Radioactive Wastos, dated April 26, 1991, with attachments.
Enclosure:
Viewgraph from presentation by EPA representatives to the Advisory Committoo on Nuclear Wasto, May 22, 1991 4
82
T7ree-Bucket Proposal Dist:ributed Separa:ely for Comment 1985 Standards Suggested Wording Quantitative, probabilistic Bucket One:
performance assessment Scenarios >1/10: quantitative for scenarios down to probabilistic performance 1/1,000 assessment Bucket Two:
a l
Scenarios <1/10 but
>1/10,000: individual scenario, deterministic analysis, comparison to 10X the release limits
, Bucket Three:
Scenarios <1/10,000: analysis g
not required y
i 5
ACN W 2 - 5 m
/[g %,*k UNITID STATES
'q NUCLEAR HEGULATORY COMMISSION
{
7f ADvit.ony coMMitili ON NUCLE AH WAS11 WASHINGTON, D C Mh Hay 30, 1991 The Honorable Kenneth C.
Rogers U.S.
Nuclear Itogulatory Commission Washingtois, D.C.
20555 Dear Commissioner Rogerst fiUBJ ECT:
REVIEW OF REGULATORY GUIDES ON RTVISED 10 CFit PART 20 In response to laat quantion of your memorandum of April 29,
- 1991, wo are pb ased to provido the following information concerning the regulatory guidos that are being developed in support of reviaod 10 CFR Part 20.
The plan for reviewing thoso guidos was based oli discuscions betwoon James Carroll, then Chairman of the cognizant Advisory Committoo on Reactor Safeguards (ACRS) subcommittoo and Dado Hooller, Chairman of the Advisory Committoo on Nuclear Wasto (ACHW) with input from Raymond Fraloy, Executive Director, ACRS/ACNW.
J.
Ernest Wilkins, Jr. (ACHS) has subsequently boon assigned as the Chairman of this subcommittoo and has no objection to this plan of action.
Becauso of their significance and direct applicability to nuclear power plants, Mr. Carroll noted the ACRS intent to review four of the proposed guidos.
Those are 1.
Radiation Protection Programt, for Nuclear Power Plants 2.
Control of Access to liigh and Very liigh Radiation Areas in Nuclonr Power Platits 3.
Instructions for Recording and Reporting occupational Radiation Exposuro Data 4.
Planned Special Exposures The ACHW assumed load responsibility for the remaining regulatory g.t id o s.
A review of their titles, however, indicates that only savon relate to the control of or impact frcm radionuclidos that might be reloaced as a result of wasto management activities or to the assessment of their associated risks.
Thoso guides, which the ACNW plans to review, are 1.
Interpretation of Dionssay Measuromonts 2.
Critoria and Procedures f or Summation of Internal and External Occupational Exposures 3.
Air Sampling 85
k I
A The lionorable Kenneth C.
Rogers 2
May 30, 1991 4.
Assessing External Radiation Doses from Airborno Radioactive Materials 5.
Instructions on llealth Hisks from Occupational Radiation Exposures (Regulatory Guido 8.29) 6.
Dono to Embryo /rotus 7.
Instructions to Prognant Moneri (Regulatory Guido 8.13)
The regulatory guidos that romain are 8.
Preparation of Applications for Use of Scaled Sources and Devices for Performing Industrial Radiography (Appendix to Regulatory Guido 10.6) 9.
Preparation of Applications for Medical Uses (AppOndix to Regulatory Guido 10.8)
The ACNW plans to give these last two guides a preliminary review in order to determine if a more detailed review appears warranted.
It abould be noted that both the ACRS and the ACNW will koop the other committee informed regarding each other's activities with respect to thoso guides so that areas of mutual interest / concern can be coordinated, consistent with Chairmitn Carr's memorandum of November 6, 1989 We trust this responds to the last question in your memorandum.
Although we believe your first two questions address issues of far higher priority, we nonetheless have mado plans to assist in reviewing these regulatory guidos in accordance with our inter-protation of SECY-91-023 (Development of Regulatory Guides for 10 CFR Part 20) and the priorities established for co:iduct of ACNW activities.
Should you have questions concerning this responso, or believe that we should handle these reviews in a different manner, we would welcomo your comments.
Sincerely, W
Dado W.
Moeller Chairman 86 l
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UNITED STATES NUCLEAR REGULATORY COMMISSION 3'
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ADVISORY COMMITTEE ON NUCLEAL, WA$1E WA$HINGTON, D C. 20%6 o,,
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Hay 30, 1991 Mr. Robert H. Bornero, Director Office of Nuclear Material Safety and Safeguards U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Dear Mr. Bernero
SUBJECT:
REVIEW OF DRAFT SECY PAPER Off DEALING WITH UNCERTAINTIES The Advisory Committee on Nuclear Waste has reviewed a copy of the draft SECY paper, " Staff's Approach for Dealing with Uncertainties in Implementing the EPA High-Level Waste Standards."
As you know, j
the NRC staff is writing this paper in response to a request from the commission for an explanation of the management of uncertain-ties during the process of evaluating compliance of a proposed repository with the probabilistic standards of the U.S. Environ-mental Protection Agency (EPA).
During our 30th meeting, we had extensiva discussionc on this topic with members of your staff.
The transcript of our April 24, 1991 meeting contains details of our comments and concerns.
(
The draft SECY paper and its accompanying document provide a broad view of the uncertainties that will need to be addressed during site characterization and the subsequent licensing process.
.T1though the draft SECX paper includes discussion or methods to reduce uncertainties, we believe the staff has insufficiently clarified its role in the management of uncertainties that will remain after a license application is submitted.
The draft SECY paper is also substantially silent on (1) the general program plan envisioned by the NRC staf f for managing uncertainties, (2) the way in which rulemaking and similar protocols will be used to manage uncertainties that are likely to Locome important at the time of license hearings, and (3) the distinction between the role of the NRC and that of the U.S.
Department of Energy in reducing and managing technical uncertainties. At the same time, the draf t SECY paper includes extensive coverage of topics that could be interpreted as not being portinent to the questions that need to be addressed.
One example is the discussion of the benefits to be derived from the existing version of the EPA Standards.
The discussion of collective versus individual dose limits should also be removed from the SECY paper.
Although the draft paper is partially responsive to the request of the Commission for a discussion of the management of uncertainties, there is a need to develop a program plan that (1) establishes guidelines for developing responses to a broad range of uncertainty 87
Mr. Robert M.
Bernero 2
May 30, 1991 issues; (2) describes the bases for actions by the utaff, for example, the method of balancing reliability and rick; and (3) serves as a guide to the preparation of additional reports that systematically explore the application of the overall plan to various parts of the licensing process, such as the approach to reconciling expert judgments that conflict.
Such a plan would provido assurance of long-term regulatory consistency and completeness; in casence, it would serve as a " road map."
The existing draft paper and our discussions with the NRC staff can readily serve as a beginning for the preparation of a program plan.
We believe that the staff is approaching the difficult and complex topic of uncertainty issues with growing insight.
Although the present draf t SECY paper represents an improvement over the earlier version, it demonstrates the need to organize the variety of issues to be addressed so that uncertainties are minimizod and managed satisfactorily, Icading to the formulation of defensible policies.
Some parts of the draft paper, particularly portions of section 2 and much of section 3,
could, after revision, be issued as a partial response to the Commission's request.
We look forward to working with the staff on these matters and to reviewing additional documents on this important topic as they are developed.
We would be pleased to meet with you to elaborate on our comments and suggestions.
Sincerely, Dade W.
Moeller
~
Chairman Eclerence:
Draft SECY Paper, " Staff's Approach for Dealing with Uncertainties in Implementing the EPA High-Level Waste Standards," undated, received April 26, 1991.
88
/e e,'\\
UNITED STATES l'
NUCLEAR REGULATORY COMM!SSION
,'.i 4 ((i ADVISORY COMMITit[ ON NUCL L AR WASit.
WASHINGlON. D C. 205%
O, f
June 27, 1991 The lionorable };enneth M.
Carr Chairman U.S. 11uclear Regulatory Commission Washington, D.C.
20555
Dear Chairman Carr:
SUBJECT:
COMMEliTS REGARDING 10 CPR PART 61 PROPOSED REVISIONS RELATED TO GROUllDWATER PROTECTION In a report-dated September 6,
1990, the Advisory Committee on Nuclear Waste (ACNW) urged that the revised technical position on the waste form be published, and stated that the Committee had reveral additional concerns, including the need to revice Part 61 to show more direct emphasis on the resistance of low-level waste (LLW) forms to leaching by groundwater.
The report also called attention to the effects of aging on the waste and the consequent changes 3n chemical and physical properties.
These concerns were focused on the question of groundwater protection.
In a Staff Requirements Memorandum (SRM) of December 31, 1990, the Commission requested that we specify our current position on the need to revise 10 CFR Part 61 and justify our position by an evaluation of the officacy of the existing Part 61 in meeting our concerns.
In a subsequent SRM dated April 18, 1991, the Commission indicated the response date was postponed until June 28, 1991, so that we could study this subject furthec.
We have discussed with representat3ves of the office of Nuclear Material Safety and Safeguards (NMSS) and the Office of Nuclear Regulatory Research (RES) the general topic of groundwater protection as reflected in NRC regulations and the related regulatory background. The staff noted the history and experiences of the six licensed LLW disposal facilities, particularly as related to the migration of radioactive elements into and with the groundwater.
The staff considered this experience in developing Part 61, and the environme'stal impact statement for that regulation clearly demonstrates that groundwater migration is the most significant radionuclido pathway to the environment.
We alprove of the recently initiated effort by NMSC to develop a specific regulatory guide for the performance assessment of LLW d>Tposal facilities.
During the development of this regulatory gw de, we expect that additional insight into issues such as groundwatti protection will be garnered by the staff and, through such a
mechanism, transferred to the LLW dispcsal facility developern.
We tentatively plan to schedule a Working Group 89
)
l The lionorable Kenneth M.
Carr 2
June 27, 1991 meeting to discuno, among other related topica, the modeling and performance annessment of LLW disposal f acilities.
Staff prcgress on the development of this regulatory guide will be included in the agenda for this meeting, and we plco at that time to explore further the role of groundwater protection ;. visions.
During our 32nd meeting we heard a procentation on the May 23, 1993
" brainstorming" sesnion involving
- HMSS, RES and several contractors.
In this seculon, the participanto explored options that might be uced to improve radionuclide retention in, or to retard radionuclide migration from, low-level radioactive wante.
We are interested in the technical evaluations associated with these activitics and intend to follow their evolution.
We are mindful (of the staff's response to our discussionn of last September, we appreciate the cooperation of the staff in its endeavors to better understand the relevant issues, and wo look forward to continuing tne dialogue on relevant major technical isnuou and developments.
On the basin of these interactions, we have concluded that we can act acide our suggention that Part 61 be revised to explicitly include a
requirement for vaste performance that enhances groundwater protection.
We plan to provide periodic reports to you concerning progrenn made on this matter.
c sincerely, Dade W.
Moeller Chairman 90
((pe nsag'h, UN11ED STATES h
NUCLEAR REGULATORY COMMISSION E
ADVISORY COMMIT 1Ef ON NUCLE AH WAST [
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- I O,
WASHINGTON, D C,2%%
~4,
f June 27, 1991 The lionorable Kenneth M. Carr Chairman U.S.
Nuclear Regulatory Commission Washington, D.C.
20555
Dear Chairman Carr:
SUBJECT:
RESPONSE TO QUESTIONS ACCOMPANYING WORKING DRAFT #3 OF Tile EPA STANDARDS Draft #3 of the proposed Environmental Protection Agency (EPA)
Standards for,the management and disposal of spent nuclear fuel, high-level and transuranic radioactive wastes includes six questions.
With the thought that our comments would be helpful, we have prepared the following summary responses to each of these questions.
Question 1:
Two options are presented in Sections 191.03 and 191.14 portaining to maximum exposures to individuels in the vicinity of waste management, storage and disposal facilities:
a 25 millirems / year ede limit and a 10 millirems / year ede limit.
Which is the more appropriate choice and why?
Relip_cDra:
o The
- question, as
- phrased, refers to
" maximum" exposures to
" individuals."
Because radionuclide releases from a high-level waste (llLW) repository, if they occur, could continuo for a number of years, we have responded to the question in the sense of what would be the maximum acceptable annual exposure (dose) to members of the public over an extended period of time, in contrast to what might be considered an acceptable maximum exposure over a single year.
This is in accord with the approach taken by both the National Council on Radiation Protection and Measurements (NCRP) and the International Commission on Radiological Protection (ICRP).
In a similar manner, we assume that by maximum exposures to
" individuals," the EPA means maximum exposures to a " critical population group," following the approach recommended by the ICRP.
With those caveats, our res,ponse follows.
Wn believe an effective dose rate limit of 0.10 mSv (10 mrom) per year is more appropriate for several reasons:
91
l The 11onorable Kenneth M. Carr 2
June 27, 1991 1.
Recent evaluations indicate that the biological effects of ionizing radiation may be higher than previously estimated.
2.
The population in question may be exposed to more than one radiation source.
3.
A fraction of the current dose limit should be reserved for potential future radiation sources.
4.
Radionuclide releases f rom a repository, if they occur, could continue over a long period.
Such a done rate limit would also be consistent wjth the recommon-dations of 2nternational organizations such as the ICRP, the International Atomic Energy Agency, and as noted in the 1989 report prepared by the' radiation protection and nuclear safety authorities of Denmark, Finland, Iceland, Norway and Sweden (commonly referred to as the " Nordic" Study).
Quantion 2:
A new assurance requirement is presented in Section 191.13 that would require a qualitative evaluation of expected releases from potentini disposal systems over a 100,000-year timeframe. Are such evaluations likely to provide useful information in any future selecting of preferred disposal sites?
Resnonne:
We recognize that the specification of the 10,000-year time limit is somewhat arbitrary.
It is important that significant geologic or climatic changes do not occur in the near-term period following the 10,000-year limit.
We also agree that many geologic and climatic events that may affect the evaluation of nite performance can be meaningfully extended beyond 10,000 years.
In these cases, such an extension could provide information that would be useful for comparing the relative merits of several potential repository sites.
In general, howcVer, and particularly in the evaluation of the merits of a single site, the uncertainties involved in such an extension would make the value of the associated assessments questionable.
It is important to note that, although evaluations of site performance may be quantitative, the results are subject to interpretation.
Question 3:
Two options are presented in Section 191.14 and 191.23 portaining to the length of time over which the individual and ground water protection requirements would apply:
a 1,000-year duration and a 10,000-year duration.
Which is the more appropriate timeframe and why?
92 l
The lionorable Kenneth M. Carr 3
June 27, 1991 E'FdlQ11E !
Title LO Psrt 60 of the 11RC regulations specifies that containmant of the radionuclides within the waste be substantially complete for a period not less than 300 years nor more than 1,000 years.
This constraint, coupled with other requirements, including the stipulation that the groundwater travel time to the ancessible environment be at least 1,000 years, is designed to ensure that protection of the !ndividual and the groundwater will extend well beyond 1,000 yea c.
When one also considers the fact that, after only a few thousand years of decay, the health hazards of the high-level wastes will be no greater than that of the original unmined uranium oro, it becomes readily apparent that it should be possible to ensure individual and ' groundwater protection for a duration of 10,000 years.
We therefore endorse the extension of this time period.
Such an extension would also nake this requirement compatible with the limitation on health of fects resulting from an llLW repository.
CBICAti_Qll_ii In Subpart C
'he Agency proposes to prevent degradation of
" underground sources of drinking water" beyond the concentrations found in 40 CFR Part 141 -- the 11ational Primary Drinking Water Regulations.
The Agency is aware, however, that there may be some types of ground waters that warrant additional protection because they are of unusually high value or are more susceptible to con-tamination.
Should the Agency develop no-degradation requirements for especially valuable grcund waters? If so, what types of ground waters warrant this extra level of protection?
Raupan n:
We agree that pollution of " underground sources of drinking water" should not be permitted beyond the limits specified in the flational Primary Drinking Water Regulations.
Wo believe that a no-degradation requirement for certain large volume aquifers, that represent major long-term existing or potential drinking water sources, may represent undue stringency.
A preferred approach would be to reject as potential sites for the storage or disposal of high-level radioactive wastes those land areas which, if contaminated, could have the potential for polluting such aquifers.
llowever, the volume and present value of an aquifer should not be the sole criteria for identifying those that should be protected.
Other criteria may become significant with the passage of time.
At the same time, we believe it is important to recognize that the dose rate from underground sources of drinking water, even if contaminated to the limits specified in the flational Primary Drinking Water Regulations, would still contribute only a small 93 l
\\
The lionorable 1(onneth M.
Carr 4
June 27, 1991 fraction (4 percent) of the current long-term dose rate limit for members of the public.
1;ven considering the more restrictive limit for an llLW repository (as nuggested in our response to Que;*. ion 1 above), groundwater complying with the Drinking Water Regulations would contribute no more than 40 percent of the dose rate limit.
In this sense, application of the Drinking Water Regulations to a repository represents a degree of stringency, especially because the primary pathway for public exposures f rom auch f acilities is through drinking water.
OEat.19B 5:
Two options are presented in liotes 1(d) and (e) of Appendix B pertaining to the transuranic waste units a 1,000,000 curies option and a 3,000,000 curies option.
Which is the more ap-propriate TRU waste init and why?
EctmsIlant The number of curies of transuranic waste that would be comparable to 1,000 MTitM of spent fuel ranges from 1 to 6 million curica, depending on when the assessment in made.
Accordingly, we believe that it would be reasonable to adopt the 3 million curie option.
Q.RC.?il9n_f:
The Agency in investigating the impacts of gaseous radionuclide releases from "adioactive waste disposal systems and whether, in light of these releases, changes to the Standards are appropriate.
To assist us in this effort, we would appreciate any information pertaining to gaseous release source terms, chemical forms, rates, retardation factors, mitiration techniques and any other relevant technical information.
RRfD91129 :
Two reports that ma" be helpiul are 1.
W.
D.
- Light, et al.,
"C-14 Release and Transport from a Nuclear Waste Repository in an Unsaturated Medium," Lawrence Dorkeley Laboratory, Report LDL-28923 (June 1990).
2.
W.
B.
- Light, et al.,
" Transport of Gaseous C-14 from a Repository in Unsaturated Pock," Lawrence Berkeley Laboratory, Report LDL-29744 (September 1990).
In commenting on this subject previously, we have noted the following:
a.
The total inventory of carbon-14 in a
repository containing 100,000 MTHM is estimated to be about 100,000 94 1
Tho lionorable Kenneth M. Carr 5
JIune 27, 1991 curies.
This comparco to a global production of carbon-14 by cosmic radiation of 28,000 curlos por year, a global inventory of about 230 million curiou, and an atuouphoric inventory of 4 million curion.
In fact, rolonno of all of the carbon-14 inventory in a repository would incroaco the atmospheric inventory by only abot 2 percent; thin comparon to natural variations in th(
atmospheric inventory of 10 porcent to 40 porcent.
b.
Daned on an annumed inventory of 100,000 MTl!M, the rate of roloano of carbon-14 from a repository that would bo permissible under the existing EPA Standards would be about I curio por year.
Experienco shows that any carbon-14 that in reloaned would rapidly mix in the atmonphere, and estimaton are that the accompanying doso rato to a person on top of Yucca Mountain would be far 1000 than 0.01 mSv (1 mrem) por year.
We also note that the limit on the reloaco rato of I curio por year for a repository ec paron to an average relcano rato of 10 curiou por year from a typical 1,000 MWo light-water reactor.
At the timo the EPA Standards woro developed, conuidorationn woro limited to ovaluationn of a saturated site.
In such a caso, water transport and geochemical barriers would have been strongly influential in retaining the carbon-14.
Subuoquent conaideration of Yucca Mountain (an unsaturated uito) makes the existing EPA Standards inappropriato.
We believe the limit for carbon-14 as specifiod in the propocod Standarda should be relaxed.
For additional discussion on thin topic, we refer you to the transcript and minutos of the Advisory Committee on liuclear Wasto Working Group rooting hold on March 19, 1991.
We trust theso comments will be helpful.
If appropriato, we request that you forward them to Mr. Floyd L.
Galpin of the U.S.
Environmental Protection Agency.
Sincoroly, Dado W. Mooller Chairman
}loferenca EPA, 40 CPR 191 - Draft Environmental Standards for the Management and Disposal of Spent liuclear Fuel, liigh-Lovel and Transuranic Radioactive Wantes, dated April 26, 1991, with attachments.
95
SUIL1ECT INDEX 12, 85 10 CFR PART 20 10 CFR PART 60 49 11, 89 10 CFR PART 61 40 CFR Part 191 1,
31, 35, 49, 50, 68, 81, 87, 91 Advinory Committee on Reactor Safeguards 85 llolow Regulatory Concern (BRC) 46 Board on Radioactive Wanto Management, National Roscarch Council.
35, 38 Carbon-14 33, 95 11, 42 Class II or Class C low-level wasto Collectivo dono limito 55 Complomontary cumulative distribution function (CCDP) 65 Decommissioning.
5, 9
De minimin critoria 46 Drinking water 93 Engincorad barrjor system.
49 1,
27, 31, 35, 50, 56, 91 Environmental Protection Agency (EPA)
Exploratory Shaf t Facility (ESP) 53 Groundwater protection 11, 89, 93 llazardous wastos 41 1,
27, 31, 33, 35, 50, Iligh-level waste disposal standards 81, 87, 91 liigh-level wanto repoultory uito 27, 53, 61 Iluman intrusion.
61, 81 Individual dono limits 32, 36. 55 35, 37 International Atomic Energy Agency (IAEA)
International Commionion on Radiological Protection (ICRP) 35, 55, 91 11, 89 Leaching Low-level wasto disposal facilities 44 Low-level wasto forms 11 Mixed wastos 41 l
97 I
i
1 i
SUBJECT INDEX Hational Council on Radiation Protection and Measurements (NCRP) 32, 57, 91 Natural ore bodies 31 Nordic countries 37, 92 Pathfinder Atomic Power Plant 5
Performance assessment 28, 89 Probabilistic risk assessment 65 Program plan 15, 21, 75 Radiation protection program 85 Radon.
34 Regulatory Guides.
85 Sabotage 64 Sito characterization plan 27 Subsystem performance requirements 49 "Three-bucket approach" 81 Transuranic waste 94 Uncertaintles.
1, 87 Uranium ore 31 98
une um m u s wucts An nicut aions coMwmow i ci roni wouni n U.%.
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DIBLIOGRAPHIC DATA SHEET l
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- 2. m te Awo wo m ti NUREG-1423 Volume 2 A Compilation of Reports of the Advisory Committee 3
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{ 1991
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- 11. ASSI M ACI (Au# peaan er *es This compilation contains 20 reports issued by the Advisory Committee on Nuclear Waste (ACNW) during the third year of its operation.
The reports were submitted to the Cnairman, U.
S.
Nuclear Regulatory Commission, or to the Director, Office of Nuclear Material Safety and Safeguards.
All reports prepared by the Committee have been made available to the public through the NRC Public Document Room and the U.
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Library of Congress.
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