oversight

Nuclear Waste: Quarterly Report as of December 31, 1989

Published by the Government Accountability Office on 1990-04-30.

Below is a raw (and likely hideous) rendition of the original report. (PDF)

~lnitctd States   Genwal   Accounting   Offiw
Report -to Congressional Requesters




NUCLEAR WASTE
Quarterly Report as of
December 31, 1989
                   United States
GAO                General Accounting Office
                   Washington, D.C. 20648

                   Resources, Community, and
                   Economic Development Division

                   B-202377

                   April 30,lQQO

                   The Honorable J. Bennett Johnston
                   Chairman, Committee on Energy
                     and Natural Resources
                   United States Senate

                   The Honorable James A. McClure
                   Ranking Minority Member
                   Committee on Energy and Natural Resources
                   United States Senate

                   On March 26,1984, you requested that we provide quarterly status
                   reports on the implementation of the Nuclear Waste Policy Act of 1982
                   (NWPA). The act required the Office of Civilian Radioactive Waste Man-
                   agement within the Department of Energy (DOE) to implement a federal
                   program for the safe and permanent disposal of high-level nuclear waste
                   in one or more geologic repositories. It also assigned responsibility for
                   licensing and regulating repositories to the Nuclear Regulatory Commis-
                   sion (NRC) and development of environmental standards for disposal of
                   these wastes to the Environmental Protection Agency (EPA). An NRC deci-
                   sion to license a repository must be based on a determination that the
                   proposed repository complies with both EPA'S standards and NRC'S
                   regulations.

                   In November 1989 NRC staff questioned whether it is possible to satis-
                   factorily implement, in a repository licensing proceeding, an EPA stand-
                   ard on long-term containment of radioactive wastes. This report
                   addresses that issue and its implications for DOE'S program to determine
                   if a candidate site at Yucca Mountain, Nevada, is suitable for a nuclear
                   waste repository.


Results in Brief   ard may be written in such a way that it may be difficult, if not impossi-
                   ble, for DOE to satisfactorily demonstrate compliance with the standard
                   in an NRC licensing proceeding. The standard establishes limits on the
                   cumulative releases of radioactive materials to the environment over a
                   lO,OOO-yearperiod and requires that DOE demonstrate that the
                   probability of exceeding these limits is acceptably small. The specific
                   concern is that limitations and uncertainties in the methods and data for
                   making the necessary numerical calculations-such as predicting the
                   occurrence of uncertain events like earthquakes over the long period of


                   Page 1                       GAO/RCED-90-130Nuclear Waste Quarterly, Dec. 31, l@SB
             B202377




             time-could lead to lengthy licensing delays unless EPA and/or NRC pro-
             vide sufficient guidance on acceptable methods for addressing these lim-
             itations and uncertainties.

             NRC'S staff has taken initial steps in what it expects to be a collaborative
             process with EPA to develop additional guidance on how DOE is to demon-
             strate whether or not the Yucca Mountain site complies with the con-
             tainment standard. Of particular concern to the staff is that emphasis
             maintained on the quality of the scientific work that supports the
             numerical results of DOE’Scompliance analyses. Furthermore, both NRC
             and EPA expect that DOE'S experience over the next several years in dem-
             onstrating that its new repository for certain defense wastes--DOE’s
             Waste Isolation Pilot Plant (wrPP)-complies with EPA'S standards should
             provide valuable insights into the problems that can be expected in dem-
             onstrating compliance with the containment standard for an NRC-
             licensed repository.


             NWPA, as amended, requires DOE to characterize (investigate) the Yucca
Background   Mountain site and, if it is found suitable, to apply to NRC for a repository
             license. DOE must satisfactorily demonstrate to NRC that the combination
             of the site and the repository design complies with EPA'S standards and
             NRC'S regulations. WE would demonstrate compliance by collecting and
             analyzing data; developing, validating, and using predictive models; and
             assessing the potential repository’s expected performance. Until DOE
             applies for a license, NRC'S role in the program is limited to providing
             regulatory guidance and oversight of DOE'S program.

             EPA'S containment standard relies on the novel approach of using numer-
             ical probabilities to establish requirements for containing radioactivity
             within the repository. Specifically, cumulative releases of radioactivity
             from a repository to the environment for 10,000 years must have a like-
             lihood of less than 1 chance in 10 of exceeding limits established in the
             standard and a likelihood of less than 1 chance in 1,000 of exceeding 10
             times the limits. EPA does not require absolute proof that the standard
             can be met; rather, it established a test of “reasonable expectation” of
             compliance based on “practically obtainable” information and analysis.
             EPA added this qualifying language to its standard in 1986 after NRC had
             objected to the unqualified standard proposed by EPA in 1982.

             NWPA required NRC to establish licensing regulations that are not incon-
             sistent with EPA'S standards. NRC issued its regulations in 1981 and 1983.



             Page2                         GAO/RCED-SO-180
                                                        Nuclear Waste Quarterly, Dec. 31,1989
                        0-202277




                        Although NRC has had substantial experience in licensing nuclear reac-
                        tors and related facilities, licensing a geologic repository for nuclear
                        waste will be a new experience. Moreover, NRC has had only limited reg-
                        ulatory experience with standards that are based on numerical
                        probabilities. For example, NRC’S nuclear power regulations are gener-
                        ally qualitative in that determining compliance with the regulations ulti-
                        mately rests on engineering judgments.


                        Of special concern to NRC’S staff is whether EPA’S probabilistically-based
EPA’s Containment       containment standard can be implemented without paralyzing a reposi-
Standard Could Affect   tory licensing proceeding with litigation over numerous details of DOE’S
Waste Program           analysis supporting compliance with the standard. Specifically, the staff
                        believes that the standard can be implemented successfully in a licens-
Success                 ing proceeding only if the inherent uncertainties involved in making
                        long-term projections of repository performance can be satisfactorily
                        taken into account.

                        The contrasting approaches taken by EPA and NRC in developing the con-
                        tainment standard and nuclear power plant safety goals, respectively,
                        illustrate the NRC staff’s concern. In 1986, NRC established two safety
                        goals that broadly define acceptable levels of risk from operation of
                        nuclear power plants. The goals are stated in qualitative terms; specifi-
                        cally, there should be no “significant” additional risk to either individu-
                        als or to society from normal nuclear plant operations and accidents. To
                        help implement the goals, NRC established two safety objectives in which
                        risks are to be calculated numerically and expressed as a percentage of
                        other, non-nuclear, risks to individuals and society.’ Because of the size-
                        able uncertainties in the analytical methods and gaps in the data used to
                        calculate risks, however, NRC decided that (1) the safety objectives must
                        be subordinate to the qualitative safety goals and (2) analyses of compli-
                        ance with the safety goals may not be used as the sole basis for licensing
                        decisions.

                        EPA took the opposite approach in developing its containment standard
                        in that it established, as the centerpiece of the standard, specific
                        probabilities that cumulative releases of radioactive materials will not
                        exceed established limits. EPA then qualified this numerical standard to
                        recognize the inherent uncertainty and limitations in the required analy-
                        sis with its test of reasonable expectation.

                        ‘NRC definesrisk as a mathematicalexpressionof the probability that an event will occurmultiplied
                        by the estimatedconsequences(effects)of that event.



                        Page 3                                GAO/RCED-90-130
                                                                            Nuclear Waste Quarterly, Dec. 31,1989
                      R-202377                                                                                  r




                      NRC'S staff believes that additional clarification and guidance from the
                      NRC Commissioners and EPA are needed to decide how qualitative techni-
                      cal judgments are to be used by DOE in demonstrating compliance with
                      EPA'S containment standard. The staff plans to identify and resolve
                      potential implementation problems with the standard and encourage EPA
                      to clarify the standard. This would be accomplished through NRC and EPA
                      staff interaction and possible amendments to EPA'S regulations. Also, NRC
                      would amend its existing regulations, conforming them with EPA'S stan-
                      dards, and may issue new rules aimed at reducing technical licensing
                      impediments.

                      An advisory committee to NRC, the Advisory Committee on Nuclear
                      Waste, did not agree that the NRC staff’s proposed course of action is
                      sufficient to resolve implementation issues with EPA'S containment and
                      other standards.2 In a December 21, 1989, letter to the Chairman NRC,
                      the advisory committee said that it had continuing doubts about
                      whether compliance with the EPA standards could be effectively demon-
                      strated for a specific repository site, even with the present qualification
                      of “reasonable expectation” of compliance. According to officials of the
                      committee, the Commission subsequently asked the committee to pro-
                      vide it with additional information on the committee’s basis for this
                      objection and to recommend a possible solution to the standards-imple-
                      mentation issue.


                      DOE has a formidable task in demonstrating if a repository at Yucca
ChallengesDOE Faces   Mountain can safely isolate waste from the environment over 10,000
in Complying With     years. In fact, DOE recently extended by 7 years its repository develop-
EPA Containment       ment schedule because, in part, of the scientific challenge of adequately
                      investigating the site. According to DOE'S December 1988 site characteri-
Standard              zation plan, it will demonstrate compliance with the containment stand-
                      ard by conducting performance assessments of the natural features and
                      man-made components of the repository.3 These assessments are to be
                      based on various computerized, conceptual models describing the char-
                      acteristics of the Yucca Mountain site and knowledge of the processes
                      and events that could occur at the site.



                      “The Advisory Committeeon NuclearWaste,establishedin 1988,is the principal advisorto the NRC
                      Commissioners in nuclearwastematters.
                      %OE definesperformanceassessment     as any analysisthat predictsthe behaviorof a systemor com-
                      ponentof a systemunder a given set of constantor transientconditions.



                      Page 4                               GAO/RCED-90-130
                                                                         Nuclear Waste Quarterly, Dec. 31,1989
R-202377




NRC and others, including a group representing utilities who operate
nuclear power plants, have commented on DOE'S site characterization
plan. According to NRC'S staff, current information on the Yucca Moun-
tain site is inadequate to determine whether meaningful probability esti-
mates can be developed for that site; therefore, this major issue should
be resolved as early as practicable during site characterization. For
example, in its comments on DOE'S plan, NRC staff said that DOE should
assign high priority to investigating whether the site is subject to unac-
ceptably high chances of disruption due to occurrences of volcanic activ-
ity, faulting, or seismic movements.

The utility group believes that DOE's site characterization plan does not
reflect a full appreciation of, and concern for, difficulties that will be
encountered in reducing uncertainties about the site. According to the
group, difficulties with modeling are likely because heavy reliance must
be placed on the judgments of experts to interpret site data and to pre-
dict site conditions for 10,000 years, and there is likely to be disagree-
ment on these interpretations. Also, challenges to expert judgments can
be difficult to resolve.

NRC'S advisory committee raised related concerns about DOE'S site char-
acterization program. In a July 1989 letter to the Chairman, NRC, the
advisory committee stated that DOE was not giving sufficient emphasis
to limitations in its data collection techniques regarding preliminary site
characterization activities at Yucca Mountain, The committee said that
uncertainties and limitations in the data used to justify conclusions will
be the center of most repository contentions and that planning for man-
agement of the uncertainties and limitations by DOE is essential.

EPA and NRC believe that DOE'S future assessment of the performance of
its WIPPfacility, located near Carlsbad, New Mexico, may provide valu-
able insights into how readily EPA'S containment standard can be imple-
mented in a repository licensing proceeding. The WIPP project was
initiated in 1981 when DOE decided to develop a mined geologic reposi-
tory to store transuranic waste generated in its defense-nuclear activi-
ties.4 The WIPP facility must adhere to EPA'S disposal standards; however,
DOE,and not NRC, is responsible for deciding whether or not the facility
meets EPA'S standards.



4Transuranicwasteis trash that typically containssmall amountsof long-livedand hazardousradio-
active elements,such as plutonium.



Page 5                               GAO/RCED-90-130    Nuclear Waste Quarterly,   Dec. 31,1989
                        R-202377




                        Both EPA and NRC are concerned that if DOE’S experience with WIPP indi-
                        cates that EPA’S standards are unworkable, the standards should be clar-
                        ified or modified to allow NRC to make a reasoned licensing decision on
                        DOE application to construct a repository at Yucca Mountain or else-
                        where. EPA, in commenting on a DOE draft supplemental environmental
                        impact statement for WIPP, urged DOE to publish its performance assess-
                        ment for WIPP so that the public can review and comment on it. Also,
                        NRC’S staff has noted that a demonstration that a real repository can
                        achieve compliance with EPA’S containment standard could help develop
                        performance assessment capabilities at Yucca Mountain.


                        On March 22, 1990, the Nuclear Waste Technical Review Board, created
Recent Related Events   by the Nuclear Waste Policy Amendments Act of 1987, submitted its
                        first report to the Congress on DOE’S nuclear waste disposal program.
                        Among many topics addressed in its report, the Board noted that the
                        federal government is simultaneously embarking on two ventures: (1)
                        effort to characterize the Yucca Mountain site and determine its suitabil-
                        ity and (2) an evolving process of developing regulations that will
                        impact on site characterization activities and a repository’s design, con-
                        struction, and operation.

                        Concerning the first initiative, the Board recommended that DOE proceed
                        as rapidly as possible to develop the needed methodology for perform-
                        ance assessment and to begin making preliminary performance calcula-
                        tions with available scientific information and data. The Board believes
                        that an early application of performance assessment techniques may
                        help DOE identify critical problem areas in a timely manner and might
                        demonstrate the suitability-or     unsuitability-of  the site at an earlier
                        date.

                        Concerning the second initiative, the Board listed seven areas of concern
                        based on its review of the initial working draft of EPA’S revised disposal
                        standards. For example, the Board noted that it is not apparent how
                        geologic uncertainties and limitations are to be characterized in deter-
                        mining probabilistic computations and what burden of evidence is
                        needed to meet the standards’ requirements.


                        Although DOE has primary responsibility for achieving the nuclear waste
Observations
        v               disposal objectives of NWPA, the roles assigned to EPA and NRC, and the
                        potential effects that actions by these agencies could have on achieving
                        NWPA’S objectives, are critical to the program’s success. DOE must design



                        Page 6                       GAO/RCED-90-130   Nuclear Waste Quarterly,   Dec. 31,1989
E202377




and conduct its site characterization program at Yucca Mountain to
demonstrate to NRC that the site and repository design comply with EPA'S
standards and NRC'S regulatory requirements.

Unless EPA and NRC can resolve the latter’s concerns about EPA'S contain-
ment standard, demonstrating that a proposed repository complies with
the standard might not be possible and could result in a lengthy and
potentially unsuccessful NRC licensing proceeding. The potential impact
of NRC'S concern is highlighted by the contrast between its reactor safety
goals and EPA'S containment standard. NRC does not permit quantitative
objectives underlying its safety goals to be used as the sole basis for
regulatory decisions because of inherent uncertainty in the calculations
of risks. Compliance with EPA'S standard, on the other hand, requires
numerical calculations of the probabilities of exceeding specified release
limits,

EPA'S approach to the containment standard raises questions about
whether NRC could license a repository that meets, with a high degree of
assurance, all EPA and NRC criteria except for the containment standard.
In such a case, would the proposed repository be disqualified? Also, if
DOE'S analysis shows that the proposed repository only marginally com-
plies with EPA'S standard, could uncertainty in the analysis disqualify
the repository?

Because of DOE'S new extended repository development schedule, there
is time to address the containment standard issue before DOE character-
izes the Yucca Mountain site and applies to NRC for a construction
license. However, NRC'S and EPA'S progress in resolving concerns about
the standard bears watching by interested parties because the resolution
may also affect DOE'S site characterization program.

One potentially important contributor to resolution of the containment
standard issue is DOE'S future assessment of WIPP'S performance.
Although much about this facility differs from a potential repository at
Yucca Mountain, DOE must demonstrate in the same general way-data
collection and analysis; development, validation, and use of models; and
an overall assessment of the facility’s expected performance-that    WIPP
complies with EPA'S standards. Therefore, it is important that NRC and
EPA have complete and timely access to all DOE data and analyses that
are used in preparing the WIPP performance assessment. This would per-
mit the agencies to take advantage of whatever lessons can be learned
from DOE'S experience in applying EPA'S standards to an actual
repository.


Page 7                       GA0/RCED8&130   Nuclear Waete Quarterly,   Dec. 31,1989
              B-202377




Methodology   mented satisfactorily in a repository licensing proceeding conducted by
              NRC, we reviewed the NRC staff’s October 17, 1989, paper addressing the
              issue. We also attended the November 21,1989, briefing of NRC'S Com-
              missioners by their staff on this issue and obtained and reviewed a tran-
              script of the meeting. We also reviewed EPA'S final standards for disposal
              of nuclear waste in repositories issued in September 1986, a January 31,
              1990, working draft of EPA'S proposed revised standards, NRC'S regula-
              tions on high-level nuclear waste repositories, and its safety goals policy
              statement for nuclear power plant operations. Finally, we reviewed per-
              tinent parts of DOE'S site characterization plan for Yucca Mountain and
              comments on the plan by NRC, its Advisory Committee on Nuclear Waste,
              and a group representing utilities that operate nuclear power plants.

              We discussed the facts presented here with cognizant officials of DOE
              and NRC, and we incorporated their comments where appropriate. Our
              work was performed between November 1989 and February 1990.


              Appendix I discusses the development of EPA'S environmental standards
              for nuclear waste disposal and NRC'S actions concerning the containment
              standard. Appendix II discusses DOE'S plans to implement EPA'S stan-
              dards at Yucca Mountain and at WIPP.

              We are sending copies of this report to the Chairmen of the Senate Com-
              mittee on Governmental Affairs, the House Committee on Government
              Operations, and the House Committee on Energy and Commerce; the
              Secretary of Energy; the Chairman, Nuclear Regulatory Commission; the
              Administrator of EPA; and other interested parties. If you have any ques-
              tions, please contact me at (202) 275-1441.

              Major contributors to this report are listed in appendix III.




              Victor S. RezendesV
              Director, Energy Issues




              Page 8                        GAO/RCED-90-130   Nuclear Waste Quarterly,   Dec. 31,1989
Page 9   GAO/RCED-99-139
                       Nuclear Waste Quarterly, Dec. 31,1989
                                                                                             ~-,
contents


Letter
Appendix I                                                                                         12
Issues Concerning       Background
                        Can EPA’s Containment Standard Be Effectively
                                                                                                   12
                                                                                                   16
Development of              Implemented?
Environmental
Standards for Nuclear
Waste Disposal
Appendix II                                                                                        23
Challenges DOE Faces    DOE’s Plans to Comply With EPA’s Containment Standard
                        WIPP May Provide Valuable Insights to Implementing
                                                                                                   23
                                                                                                   27
in Complying With          Containment Standard
EPA’s Containment
Standard
Appendix III
Major Contributors to
This Report




                        Abbreviations

                        ACNW      Advisory Committee on Nuclear Waste
                        ACRS      Advisory Committee on Reactor Safeguards
                        C.F.R.    Code of Federal Regulations
                        DOE       Department of Energy
                        EPA       Environmental Protection Agency
                        GAO       General Accounting Office
                        NRC       Nuclear Regulatory Commission
                        NWPA      Nuclear Waste Policy Act
                        RCED      Resources, Community, and Economic Development Division
                        WIPP      Waste Isolation Pilot Plant


                        Page 10                    GAO/RCED-90-130Nuclear Waste Quarterly, Dec. 31,1989
Page 11   GAO/RCED-90-130
                        Nuclear Waste Quarterly, Dec. 31,1989
 Ppe

kiiks ConcerningDevelopmentof
Ehvironmental Standardsfor Nuclear
waste Disposal
              NRC and others have continuing concerns that one of the EPA'S standards
              for nuclear waste disposal might paralyze or even block NRC'S licensing
              process for nuclear waste repositories. The standard requires numerical
              projections of the probability that harmful radiation will escape from
              underground nuclear waste repository into the environment over a
              lO,OOO-yearperiod. At issue is whether EPA'S long-term containment
              standard that requires predictions be made of highly uncertain events,
              such as earthquakes, flooding, and fires, can be used effectively in a
              repository licensing proceeding. NRC anticipates that the DOE may have
              difficulty in demonstrating compliance with the standard before a
              licensing proceeding because the standard may emphasize the bottom-
              line numerical results of DOE'S analysis, rather than the quality of the
              scientific work supporting the analysis.

              EPA'S use of a probabilistic standard contrasts sharply with the regula-
              tory approach NRC took in developing safety goals for nuclear power
              plants. Because of the limitations and uncertainties in calculating the
              risks to individuals and to society from nuclear power plant operations,
              NRC subordinated such calculations to qualitative statements of its
              safety goals. In contrast, EPA'S containment standard sets out a quantita-
              tive standard and then qualifies the standard to recognize the inherent
              limitations and uncertainties in establishing compliance with the
              standard.


              NWPA established a federal program and policy for management of
Background    highly radioactive nuclear waste administered by DOE. The act mandated
              that the agency develop, site, construct, and operate one nuclear waste
              repository and select a site for a second repository. Subsequently, in
              December 1987 the Congress amended the act by, among other things,
              directing DOE to characterize (investigate) only one site-Yucca Moun-
              tain, Nevada-and deferring activities on a second repository until the
              twenty-first century.

              NWPA also assigned key responsibilities to EPA and NRC. EPA was directed
              to issue standards for protection of the general environment from
              releases of radioactive material in nuclear waste repositories. NRC was
              directed to issue technical requirements and criteria for use in approv-
              ing or disapproving any DOE applications for authorization to construct
              and operate nuclear waste repositories. NRC'S technical requirements and
              criteria must not be inconsistent with EPA'S standards.




              Page 12                      GAO/RCED-90-130   Nuclear Waste Quarterly,   Dec. 31,1989
                      Appendix I
                      Iseues Concerning Development of
                      Environmental   Standarde for Nuclear
                      Waste Disposal




                      Following site characterization, if DOE determines that Yucca Mountain
                      is suitable for a nuclear waste repository, it will recommend selection of
                      the site to the President. If the site is eventually selected, DOE will use
                      the information acquired during site characterization to prepare a
                      license application to NRC. To obtain a repository license from NRC, DOE
                      must demonstrate that the site and proposed repository comply with
                      EPA'S standards and NRC’S regulatory requirements.



EPA’s Standards       EPA’S environmental standards for management and disposal of nuclear
                      waste in geologic repositories are in two sections.’ The management part
                      of the standards-subpart     A-addresses waste storage operations. The
                      disposal part-Subpart    B-establishes four standards for disposal of
                      nuclear waste as follows:

                  . Containment requirements: cumulative releases of radioactive materials
                    from a repository to the environment for 10,000 years after disposal
                    shall have a likelihood of less than 1 chance in 10 of exceeding limits
                    established in the standard, and a likelihood of less than 1 chance in
                    1,000 of exceeding 10 times the limits.2
                  . Individual protection requirements: exposures of radiation to individual
                    members of the public for 1,000 years must not exceed specified limits.
                  l Groundwater protection requirements: limits are placed on the concen-
                    tration of radioactivity for 1,000 years after disposal from the reposi-
                    tory to a nearby source of groundwater that (1) currently supplies
                    drinking water for thousands of persons and (2) is irreplaceable (i.e., no
                    reasonable alternative source of drinking water is available to that
                    population).
                  l Qualitative assurance requirements: these are prescribed technical or
                    institutional procedures or steps providing confidence that the contain-
                    ment requirements are likely to be met.3

                      In developing its disposal standards, EPA made a clear distinction
                      between the containment requirements and the individual and ground-
                      water protection requirements. The latter two standards primarily

                      ‘EnvironmentalStandardsfor the Managementand Disposalof SpentNuclearFuel, High-Leveland
                      TransuranicRadioactiveWastes.Final Rule(40 C.F.R.part 191).
                      “Although EPA recognizedthat radioactivity could be hazardousbeyond10,000years,it said that a
                      disposalsystemcapableof meetingrequirementsfor 10,000years after disposalwould continueto
                      protect the environmentwell beyondthis period.
                      :‘Theserequirementsapply only to DOErepositories,suchas WIPP,that are not licensedand regu-
                      lated by NRC.



                      Page 13                                 GAO/RCED-90-130   Nuclear Waste Quarterly,   Dec. 31,1989
Appendix I
Issues Chncerulng Development of
Envhumental     Stand-   for Nuclear
w&a! Disposal




require DOE to make informed technical judgments of compliance based
on traditional engineering and analytical techniques. DOE'S judgments
may also take into account such factors as systematic predictions of the
probability that certain events would occur and measurements of their
associated risks. These two standards also require that DOE make deter-
minations of compliance with the limits imposed by the standards based
upon the predicted “undisturbed performance” of the repository. Under
this criterion, DOE is not obliged to take into account relatively unlikely
processes and events that may disrupt the repository from performing
as intended, such as human intrusion (for example, inadvertent drilling
into the repository) or natural events (earthquakes, flooding, and fires).

In contrast, EPA linked compliance with its containment requirements to
quantitative (numerical) projections of how much radiation is likely to
be released to the accessible environment for 10,000 years after dis-
posal. In the scientific community, EPA'S containment standard is
referred to as a “probabilistic” standard because compliance with the
standard hinges on calculating the probabilities that potentially impor-
tant events will occur and multiplying the probabilities by predictions
the consequences (such as in terms of releases of radioactive materials
to the environment) of those events. Similar to the individual and
groundwater protection standards, EPA'S containment standard assigns
limits to the total amount of specific radioactive materials that can be
released into the accessible environment.4 Unlike the other two stan-
dards, however, the containment standard also states that compliance
with the standard requires a demonstration that the probability of
exceeding the limits is less than 1 chance in 10, and that the probability
of exceeding 10 times the limits is less than 1 chance in 1,000. Projec-
tions of the total releases must include releases resulting from processes
and events that are normally expected to occur and those that occur
from disruptions to the repository site by both natural phenomena and
human-induced events which have at least 1 chance in 10,000 of occur-
ring over 10,000 years.

In July 1987, the U.S. Court of Appeals (First Circuit) withdrew and
remanded the disposal standards to EPA to reconcile provisions related
groundwater contamination with its safe drinking water standards
promulgated under authority of the Safe Drinking Water Act. The Court
also found no basis for the l,OOO-year period of the individual protec-
tion standard and inadequate notice and comment opportunity of the

4Thereleaselimits of quantitiesof radioactivematerialsare found in appendixA to the EPA
standards.



Page 14                                GAO/RCED-90-130   Nuclear Waste Quarterly,   Dec. 31,1989
                                Appendix I
                                Issues Concemhg Development of
                                Environmental Standards for Nuclear
                                Waste Dbpoeal




                                groundwater protection standard. The Court did not find defective EPA’S
                                containment standard. EPA plans to propose new disposal standards in
                                late 1990 and anticipates a final rule in mid-1992. A January 31, 1990,
                                working draft of EPA’S proposed new standards indicates that the con-
                                tainment standard is not likely to change significantly.


NRC Technical                   NRC’S regulations set forth procedural and technical requirements appli-
Requirements and Criteria       cable to DOE, in submitting an application for a repository license, and to
                                NRC, in considering DOE’S application6 Through these regulations, NRC
                                will implement and enforce EPA’S disposal standards. In addition, NRC'S
                                regulations also require that DOE meet a number of performance objec-
                                tives and design criteria, including

                            . NRC standards for radiation protection,
                            l design criteria for the surface and underground facilities of a repository
                              and the waste packages,
                            l a minimum life (300 to 1,000 years) of the waste package to be emplaced
                              in the repository,
                            l a limit on the release rate of radiation from the engineered barriers of
                              the repository, and
                            l a minimum groundwater travel time of 1,000 years from the repository
                              to the accessible environment, determined without consideration of the
                              effects of the waste.

                                Until DOE applies for a repository license, NRC’S role in the repOSit0I-y
                                program is limited to providing regulatory guidance and oversight of
                                DOE’sprogram.


                                On November 21, 1989, the NRC staff briefed the NRC Commissioners on
Can EPA’s                       plans to continue their evaluation of EPA’S standards and on a proposed
Containment Standard            strategy for implementing the standards through NRC’S repository licens-
Ek Effectively                  ing regulations. The major issue of concern to the NRC staff is whether
                                NRC can implement EPA’S containment standard in a repository licensing
Implemented?                    proceeding without unduly delaying or paralyzing its licensing regula-
                                tory process. The staff noted that NRC had accepted EPA’S standards in
                                October 1985, but had some continuing reservations at that time about
                                how it would implement the standards. NRC'S staff intends to draw on its

                                “NWPApermittedNRCto issueita repositoryregulations(10 C.F.R.part 60) in advanceof EPA’s
                                standardsbut requiredNRCto amendits regulations,if necessary,to ensurethat the regulationsare
                                “not inconsistent”with EPA’sstandards.



                                Page 16                               GAO/RCED90-130   Nuclear Waste Quarterly,   Dec. 31,1989
                       Appendix I
                       Issues tinceruiug    Development of
                       Environmental     Standarda for Nuclear
                       waste Disposal




                       experience with probabilistic methods of assessing risk related to
                       nuclear power plants, such as application of NRC’Ssafety goals to
                       nuclear plants, to determine if the staff retains confidence that the
                       standard can be implemented.


NRC Is Reconsidering   The NRCstaff’s concern is that demonstrating compliance with EPA’S
EPA’s Containment      standard may rest too heavily on the numerical calculations and analy-
                       ses that DOEmust make in projecting the long-term performance of a
Standard               repository-a process that involves, among other things, predicting the
                       occurrence of highly uncertain events over a lO,OOO-yearperiod. Fur-
                       thermore, the staff believes that the standard does not sufficiently clar-
                       ify how expert technical judgments and other qualitative factors that
                       have traditionally played an important role in NRC’Sregulatory decisions
                       are to be weighed in licensing a nuclear waste repository.

                       NRCbelieves that a strict interpretation of EPA’Scontainment standard
                       could paralyze its repository licensing process. The NRCstaff recognizes
                       that EPAdoes not intend that repository licensing decisions be based
                       solely on numerical estimates of the probability of occurrence of infre-
                       quent events. For example, EPArecognizes that DOEand NRCmay have to
                       make qualitative judgments when necessary to evaluate a proposed
                       repository. In an October 17, 1989, paper prepared for the Commission,
                       the NRCstaff noted, however, that (1) the probabilistic standard is still
                       the governing standard, (2) an acceptable approach to implementing the
                       containment standard has not been clearly established, and (3) a ques-
                       tion still remains as to whether probability estimates for very unlikely
                       events can be derived in any meaningful way. The NRCstaff summarized
                       its concerns in the paper as follows:

                       “Differing views on implementation of the [EPA] standards ultimately derive from
                       different perceptions of the statistical rigor required for estimates of the probabili-
                       ties of potentially disruptive events such as fault movement,volcanic activity, and
                       climate change.A rigorous application of EPA’snumerical standards would require
                       estimates of the probabilities of potentially disruptive events that are derived from
                       a statistical data baseof previous occurrencesof those events at the repository site.
                       Someof the events of interest may be relatively rare comparedto the length of the
                       geologicrecord for the repository site. . . Moreover, somepotential events may not
                       even be evidencedin the geologicalrecord (e.g., human-initiated events). Therefore,
                       a rigorous application of the EPA standards would lead to the conclusion that the
                       standards cannot be implementedin a licensing review.” (Underscoring added.)

                       An NRCofficial who spoke at the November 1989 Commission meeting
                       stated that the best alternative standard to the present containment


                       Page 16                                   GAO/RCED-99-130   Nuclear Wade Quarterly,   Dee. 31,1989
                            Appendix1
                            Ii3euef1 Cawerning Development of
                            Ebdronmentd       Stendarda for Nuclear
                            we&! Dlepotd




                            standard that NRC staff could identify was a purely qualitative standard.
                            According to the official, an advantage of a qualitative standard is flexi-
                            bility of implementation, but there is also a loss of precision in such a
                            standard.


NRC Approaches to           NRC'S staff is exploring options on how it can best implement EPA'S
Resolving the Containment   nuclear waste standards. Specifically, the staff believes that additional
                            clarification and guidance from the Commission and EPA are needed to
Standard Issue              decide how qualitative technical judgments are to be used by DOE in
                            demonstrating a “reasonable expectation” of compliance with EPA'S con-
                            tainment standard.

                            In its October 1989 paper, the NRC staff said that NRC could (1) reaffirm
                            its original acceptance of the containment standard if EPA clarified areas
                            of concern to NRC or (2) petition EPA to reissue the standard in an altered
                            or non-probabilistic form if NRC decides that the standard cannot be
                            implemented. NRC'S staff believes that either of these two actions may
                            also have to be combined with appropriate amendments to NRC'S regula-
                            tions. Therefore, the NRC staff identified four alternative courses of
                            action:

                            Alternative 1: Maintain the probabilistic format of the EPA standard in
                            conjunction with NRC'S current licensing regulations, with minimal
                            changes to resolve implementation problems and ensure consistency
                            between the regulations.

                            Alternative 2: Make the EPA standard more qualitative, and implement it
                            through NRC'S current licensing regulations.

                            Alternative 3: Maintain a probabilistic format for the EPA standard, but
                            have EPA expand its interpretation of the standard and NRC appropri-
                            ately amend its regulations.

                            Alternative 4: Assume that revised EPA standards will not be in place
                            before a repository licensing proceeding. NRC would use a qualitative cri-
                            terion of “no unreasonable risk to public health and safety” from its
                            existing regulations.

                            In evaluating the four alternatives, the NRC staff recommended that
                            alternative 3 be adopted, and in fact, had already begun pursuing this
                            approach. Under this alternative, the staff would attempt to identify
                            and resolve potential implementation problems with EPA'S containment


                            Page 17                                   GAO/RCED-BO-130 Nuclear Waste Quarterly,   Dec. 31,lBBB
1                                                                                      ,




    Appendix I
    Iseues Concerning Development of
    Environmental Standards for Nuclear
    Waste Disposal




    standard and encourage EPA to clarify the standard. This would occur
    through NRC interaction with EPA'S staff, preferably before EPA issues
    revised standards to comply with the 1987 court decision.

    NRC staff also would amend its licensing regulations to resolve, where
    practicable, any outstanding disagreements between EPA and NRC. The
    NRC staff believes that it may have to develop and issue two or three
    rules to accomplish this. One proposed rule would conform NRC'S reposi-
    tory licensing regulations with EPA'S revised disposal standards. In a sec-
    ond proposed rule, NRC staff would identify a basis for DOE to make site-
    specific determinations of “potentially disruptive” processesand events
    in calculating projected radiation releases. NRC is also considering the
    possibility of developing a third rule that will provide DOE guidance on
    acceptable means to implement the standards, such as specification of
    methods to validate DOE models and computer codes used to support
    compliance with the standard. According to NRC staff, these actions
    should help resolve certain controversial issues before a repository
    licensing proceeding and reduce impediments that may otherwise delay
    or prevent a licensing decision.

    NRC staff does not favor alternative 1 because it m ight complicate the
    licensing process by leaving many issues unresolved until that process
    begins. For example, the NRC staff said, unless NRC identifies and clari-
    fies acceptable methods for DOE to estimate the likelihood of potentially
    disruptive events, it could be virtually impossible to resolve related
    issues within the 3-year repository licensing period permitted by NWPA.
    The staff believes that alternative 2 m ight allow more flexibility for
    implementation of EPA'S containment standard by substituting qualita-
    tive terms (such as likely, unlikely, etc.) for the numerical expressions
    of probabilities now contained in the standard. However, the staff did
    not recommend this approach becausethe lack of a clearly acceptable
    standard m ight introduce significant uncertainties in interpreting the
    standard during the licensing process.

    The NRC staff is not in favor of alternative 4 becauseit presumes that
    EPA'S revised standards will be available when they are needed. NRC
    plans to keep abreast of EPA'S plans to reissue the standards as directed
    by the court, and if necessary, to reevaluate the desirability of exploring
    this alternative.

    An advisory committee reporting to NRC on high-level nuclear waste pol-
    icy and nuclear reactor safety matters, the Advisory Committee on
    Nuclear Waste (ACNW), did not agree that the NRC staff’s proposed


    Page 18                               GAO/RCED-90-130 Nuclear Waste Quarterly,   Dec. 31,lBBB
                        Appendix I
                        Iesues Concerning Development of
                        Environmental   Standards for Nuclear
                        Waste Disposal




                        approach was adequate to resolve implementation issues with EPA’S con-
                        tainment and other disposal standards. In a December 21, 1989, letter to
                        the Chairman, NRC, ACNW noted that it had continuing concerns.about
                        whether compliance with the EPA standards could be effectively demon-
                        strated for a specific repository site, even though EPA had added the
                        qualification of a “reasonable expectation” of compliance to the stan-
                        dards. It also stated that one alternative that NRC should consider was to
                        object to the EPA'S proposed revisions to the standards because the stan-
                        dards (1) may be unrealistic, (2) are overly stringent and inconsistent
                        compared to those for other health and safety risks, and (3) according to
                        strong evidence, will be wasteful of resources and provide little com-
                        mensurate benefit. It recommended that the NRC staff be more aggres-
                        sive in dealing with EPA to ensure that the EPA standards are
                        scientifically sound, consistent, and readily subject to implementation
                        and interpretation. According to ACNW officials, the NRC Commissioners
                        asked ACNW to provide them with additional information on ACNW’S basis
                        for objection and to recommend a possible solution to the standards-
                        implementation issue.


NRC Objected to EPA’s   EPA  published draft standards for nuclear waste repositories in Decem-
                        ber 1982, and NRC commented on the standards in May 1983. NRC
Original Proposed       objected to the probabilistic nature of the proposed containment stand-
Containment Standard    ard. NRC contended that demonstrating compliance with this standard
                        would require a degree of precision in evaluating a real waste disposal
                        system that is not likely to be achievable. It would, NRC said, presumably
                        require the use of numerical risk analysis techniques to identify poten-
                        tial sequences of events or processes leading to releases of radioactive
                        materials, followed by preparation of a numerical probability estimate
                        for each of these sequences. NRC considered the latter step both unwork-
                        able and unnecessary for determining the acceptability of a proposed
                        repository.

                        At that time, NRC did not completely rule out EPA’S probabilistic
                        approach to the containment standard. Rather, NRC recognized that the
                        approach may be useful to the extent that meaningful data are availa-
                        ble, as one of the bases for establishing disposal system performance.
                        NRC suggested that EPA substitute qualitative terms to the proposed con-
                        tainment requirements, emphasizing that expert technical judgment is
                        needed in determining compliance with them. Moreover, NRC stated that
                        there should be a test of “reasonable assurance” rather than of absolute
                        certainty that the containment standard could be met.



                        Page 19                                 GAO/RCED-90-130   Nuclear Waste Quarterly,   Dec. 31,1989
                                                                                            .
Appendix I
Issues Concerning Development of
Environmental   Standards for Nuclear
Waste Disposal




EPA incorporated some of the modifications that NRC had suggested into
its final containment standard. For example, EPA emphasized that it did
not expect unequivocal proof of compliance with the standard because
of the substantial uncertainties inherent in making long-term projections
of repository performance. Instead, EPA established a test of “reasonable
expectation” of compliance based upon practically obtainable informa-
tion and analysis.

Based on EPA'S changes to its proposed containment standard, NRC with-
drew its objections. In an October 1985 paper, the staff informed the
Commission that, although implementing EPA'S probabilistic standard
would pose a significant challenge to NRC, the final standard neverthe-
less could be implemented. The NRC staff also stated that it planned to
conduct technical analyses to determine whether any changes were nec-
essary to the repository performance objectives in NRC'S regulations to
ensure consistency of its regulations with EPA'S standards. The NRC Com-
missioners accepted the staff’s recommendations.

The Advisory Committee on Reactor Safeguards (ACRS), the predecessor
NRC advisory group to the ACNW, did not agree with NRC'S staff. The ACRS
was highly critical of EPA'S final standards and, in particular, the con-
tainment standard. For example, in an October 1985 letter to the NRC
Chairman, ACRS described the probabilistic containment standard as
“unreasonably restrictive” and containing “serious deficiencies.” ACRS
also stated that the overly restrictive nature of the probabilistic stand-
ard would introduce unnecessary licensing obstacles with only minimal
benefit to the public health and safety. Finally, ACRS stated that because
of the combination of the low level of allowable risk and the probabilis-
tic nature of the containment standard, it had no confidence that NRC
would succeed in making a formal determination that a proposed DOE
repository complies with the standard.

The NRC Commissioners reaffirmed their support of EPA'S standards, but
concluded that NRC should accelerate its efforts to develop analytical
methods to determine whether a proposed repository would comply
with EPA'S standards. Moreover, it said that ACRS' concerns should be
addressed by (1) clarifying ambiguities in the application of the proba-
bilistic standard and (2) conforming NRC'S repository performance objec-
tives to EPA'S standards. In June 1986, NRC subsequently published a
proposed rule to conform its regulations to the EPA standards. However,
before NRC could complete the rulemaking, the 1987 court decision to
withdraw and remand the standards to EPA for further work was issued,
and NRC curtailed its initiatives to conform its rules to EPA'S standards.


Page 20                                 GAO/RCED-90-130   Nuclear Waste Quarterly,   Dec. 31,1989
                           Appendix I
                           Iseues Concerning Development of
                           Environmental   Standards for Nuclear
                           Waste Disposal




Contrast Between EPA’s     As discussed above, one concern of the NRC staff is that, although EPA'S
Containment Standard and   containment standard only requires “reasonable expectation” of compli-
                           ante, the numerical standard is the governing standard. This approach
NRC’s Safety Goals         is in sharp contrast to NRC'S safety goals for nuclear power plants. Those
                           goals are stated in qualitative terms and supported by probabilistic
                           objectives. Furthermore, in adopting the safety goals, NRC made it clear
                           that, because of the limitations of risk assessment technology and
                           related data, the probabilistic objectives were not to be substituted for
                           existing safety regulations.

                           In response to recommendations of the President’s Commission on the
                           Accident at Three Mile Island, between 1981 and 1986 NRC developed a
                           policy statement on safety goals for the operations of nuclear power
                           plants. The objective of the policy statement was to establish goals that
                           broadly define an acceptable level of radiological risk to the public as a
                           result of the operation of nuclear power plants during both normal oper-
                           ations and accidents. In the policy statement, NRC adopted two qualita-
                           tive safety goals as follows:

                       . Individual members of the public should be provided a level of protec-
                         tion from the consequences of nuclear power plant operation such that
                         individuals bear no significant additional risk to life and health.
                       . Societal risks to life and health from nuclear power plant operation
                         should be comparable to or less than the risks of generating electricity
                         by viable competing technologies and should not be a significant addi-
                         tion to other societal risks.

                           In addition, NRC established two quantitative (probabilistic) objectives
                           that were to be used in determining achievement of the safety goals. The
                           objectives are as follows:

                       l The risk to an average individual in the vicinity of a nuclear power
                         plant of prompt fatalities that might result from reactor accidents
                         should not exceed one-tenth of 1 percent of the sum of prompt fatality
                         risks resulting from other accidents to which members of the U.S. popu-
                         lation are generally exposed.
                       . The risk to the population, in the area near a nuclear power plant, of
                         cancer fatalities that might result from nuclear power plant operation
                         should not exceed one-tenth of 1 percent of the sum of cancer fatality
                         risks resulting from all other causes.

                           According to NRC'S policy statement, progress in developing the tech-
                           niques for quantitatively estimating risks made it feasible to begin to


                           Page 21                                 GAO/RCED-90-130   Nuclear Waste Quarterly,   Dec. 31,1989
Appendi% I
lssuea Concernlug Development of
Enviroumental   Stamlads for Nuclear
waste Disposal




use quantitative safety objectives for limited purposes. However,
because of the sizable uncertainties present in the methods and the gaps
in the data base-essential elements needed to gauge whether the objec-
tives have been met-the quantitative objectives should be viewed as
aiming points or numerical benchmarks of performance, In particular,
because of the present limitations in the state of the art of quantita-
tively estimating risks, the quantitative objectives are not a substitute
for existing regulations.

Finally, NRC specified in the policy statement that the safety goals were
not meant to be used as a sole basis for licensing decisions but could be
considered as one factor in a licensing decision. This position was consis-
tent with our conclusion in a June 1985 report on NRC’S use of probabil-
istic risk assessment technology in regulating commercial nuclear
activities.” In that report, we cautioned that NRC should not use probabil-
istic risk assessments as the sole or primary basis for regulatory deci-
sions; rather, NRC should use this technology to supplement its more
traditional analytical and engineering methods.

Thus, in developing safety goals for nuclear power plant operations, NRC
made quantitative estimates of risks to both individuals and society
subordinate to qualitative statements of its safety goals. In contrast,
EPA’S containment standard sets out a quantitative standard and then
qualifies the standard to recognize the inherent limitations and uncer-
tainties in establishing compliance with the standard.




%-obabilistic Risk Assessment:An EmergingAid To NuclearPowerPlant Safety Regulation(GAO/
     86-l 1, June 19,1986).



Page 22                                GAO/RCED-90-130   Nucleas Waste Quarterly,   Dec. 31,1989
Appendix II

ChallengesDOE Facesin ComplyingWith EPA’s
ContainmentStandard

                         DOE has a formidable task in successfully determining if a repository at
                         Yucca Mountain can safely isolate waste from the environment for at
                         least 10,000 years. Its site characterization plan lays out an approach
                         that recognizes the considerable uncertainties in achieving this objec-
                         tive. Also, DOE recently extended its repository schedule 7 years
                         because, in part, of the scientific challenge of adequately investigating
                         the site. DOE now expects to begin investigating the site in about 1 year.
                         If the results are favorable and the site is selected, DOE plans to apply
                         for an NRC license to construct a repository in about 2001. With a 3-year
                         licensing period followed by repository construction, DOE projects that it
                         could begin waste disposal operations by 2010.

                         NRC, its advisory group on nuclear waste, and utility representatives are
                         concerned that uncertainties associated with data to be collected and the
                         analysis of the data using computer models simulating site conditions
                         may be great enough to prevent DOE from convincingly demonstrating
                         compliance with the containment standard. Accordingly, they are con-
                         cerned that compliance with the standard could be an issue subject to
                         protracted litigation in a future licensing proceeding. In this regard, EPA
                         and NRC believe that DOE'S pending assessment of the WIPP facility’s com-
                         pliance with EPA'S disposal standards may provide valuable information
                         for implementing the standards at Yucca Mountain.


                         In 1985, after EPA had modified its draft containment standard to recog-
DOE’s Plans to Comply    nize qualitative considerations, DOE concluded that EPA'S standards were
With EPA’s               flexible enough to be implemented in its repository program. The
Containment   Standard   agency’s December 1988 site characterization plan describes its
                         approach for implementing the standards in investigating the Yucca
                         Mountain site and in developing a repository design.1 DOE will address
                         the EPA standards, particularly the probabilistic containment standard,
                         by conducting performance assessments of the natural features and
                         man-made components of the repositoryS2

                         According to DOE's plan, performance assessments are to be based on
                         various conceptual models used to describe the characteristics of the site
                         and on knowledge of the processes and events that could occur at the

                         ‘DOE recognizedin its site characterizationplan that the EPA standardswere vacatedby the 1987
                         court decision.However,until suchtime as changesto the EPA standardsare implemented,DOE
                         plans to collect data on the YuccaMountainsite and repositorybasedon EPA’s1986standards.
                         2WE defies performanceassessmentaa any analysisthat predictsthe behaviorof a systemor com-
                         ponentof a systemunder a given set of constantor transient conditions.



                         Page 23                              GAO/RCED-90-130    Nuclear Waste Quarterly,   Dec. 31,1989
                                                                                                                         .
                               Appendix II
                               Challenges DOE Faces ln Complying   With
                               EPA’s Containment Standard




                               site acquired through site investigations. The latter includes infre-
                               quently occurring events such as volcanic activity, earthquakes, flood-
                               ing, and climate changes. Using these inputs, DOE will develop
                               computational models of site and repository performance.

                               DOE plans to conduct its performance assessment of Yucca Mountain in
                               the following sequence:

                           . Identify all significant anticipated and unanticipated processes and
                             events that may affect the geologic repository.
                           . Group related processes and events into various classes or scenarios for
                             the release of radiation.
                           . Screen the scenario classes in terms of their probability of occurrence
                             and the potential releases of radioactivity associated with them.
                           . Develop appropriate computational models for evaluation of the scena-
                             rio classes.
                           l Evaluate the effect of the related processes and events on the release of
                             radiation into the accessible environment.
                           . Calculate an overall probability distribution for the cumulative release
                             of radiation to the accessible environment, taking into account the
                             uncertainties in the parameters of the computational models and the
                             probability of occurrence for each scenario class.

                               DOE  acknowledges that to demonstrate overall waste system (site, repos-
                               itory, and waste package) performance, it will place heavy reliance on
                               the conceptual models of the repository site, physical systems, and the
                               hypotheses on which they are based. If the models can be confirmed by
                               tests conducted during site characterization, then its testing strategy
                               should be sufficient, according to DOE, to resolve repository performance
                               and design issues, However, DOE recognizes that some of the conceptual
                               models and its associated testing strategies may need to be modified as
                               site characterization progresses.


Uncertainties Related to       DOE  recognizes that each conceptual model of one or more repository
                               systems has some degree of uncertainty associated with it, and this
Yucca Mountain                 uncertainty is reflected in the fact that DOE must also consider alterna-
                               tive conceptual models. In other words, more than one set of hypotheses
                               may be consistent with the data that DOE collects. According to DOE offi-
                               cials, it is evaluating many alternative conceptual models as part of its
             *
                               site characterization program. DOE’S challenge is to identify those alter-
                               native models that are potentially descriptive of the site and to ensure



                               Page 24                             GAO/RCED-99-130   Nuclear Waste Quarterly,   Dec. 31,1989
                           Appetdx   II
                           Challengen DOE Faces in Complying    With
                           EPA’s Containment Standard




                           that these models are given appropriate consideration in its perform-
                           ance assessments. Moreover, DOE has noted that expert judgment will
                           also play an important part in,developing performance assessments and
                           in selecting scenarios and scenario classes necessary to calculate the
                           overall probabilities of projected cumulative radiation releases.

                           During site characterization, DOE intends to evaluate and reduce the
                           uncertainty in its estimates of repository performance that are sup-
                           ported through predictive models. DOE’s goal is to ensure that its model-
                           ing efforts result in a level of uncertainty that is acceptable to NRC and
                           that regulatory requirements will be satisfied with a reasonable degree
                           of assurance.

                           In addition, DOE plans to validate its performance assessment models
                           and the underlying conceptual models on which they are based. The val-
                           idation process will demonstrate that mathematical representations of
                           repository performance adequately replicate the repository’s actual per-
                           formance. DOE also plans to validate the quality and appropriateness of
                           its data, including the assumptions it uses to build predictive models.
                           Overall, DOE believes that outside peer reviews may be necessary to
                           assess the competence of its scientific investigations and to judge the
                           uses made of results.


Utility Group’s Comments   The Edison Electric Institute and the Utility Nuclear Waste and Trans-
on Uncertainties           portation Program jointly commented on DOE’S site characterization
                           plan.3 The group is concerned that DOE’S final plans do not reflect a full
                           appreciation of the difficulty in reducing site-related uncertainties. In
                           addition, the group believes that DOE’S processes of gathering, analyzing,
                           interpreting, and summarizing its data on Yucca Mountain involve con-
                           siderable judgments which may be challenged during a licensing
                           proceeding.

                           According to the utility group, difficulties with modeling are likely
                           because heavy reliance must be placed on the judgments of experts to
                           interpret site data and predict site conditions over the next 10,000
                           years, and there is likely to be disagreement on these interpretations.
                           Also, challenges to expert judgments can be difficult to resolve during
                           licensing. The group said DOE should anticipate and acknowledge the

                           3TheEdisonElectric Institute is the associationof the nation’sinvestor-ownedelectricalcompanies.
                           The Utility NuclearWasteand TransportationProgramis an associationof electric utilities that moni-
                           tors the implementationof federal statutesand regulationsconcerningnuclearwastemanagement.



                           Page 26                               GAO/RCED-90-120    Nuclear Waste Quarterly,   Dec. 31,1889
                        Appendix II
                        Challenges DOE Facea in Complying   With
                        Ji?PA’r Containment Stadard




                        problems associated with making and defending modeling-related judg
                        ments that are critical to site evaluation and repository licensing.

                        The group also noted that although the site characterization program is
                        extensive, DOE will, quite appropriately, sample only a small fraction of
                        the site’s volume. The resulting database will be used primarily by
                        experts in making judgments, such as predictions about future volcanic
                        activity, Moreover, because of the site’s complexity, expert predictions
                        will have wide ranges of uncertainty. According to the group, when
                        uncertainties are combined in models assessing the performance of the
                        site and repository, the assessment results will also be uncertain.
                        Because the group believes that resolving issues related to the site’s suit-
                        ability and performance will be more difficult than implied in DOE'S plan,
                        it urged DOE to develop and describe strategic plans for coping with
                        these issues.


NRC Comments on         NRC has been actively monitoring the progress of DOE's site characteriza-
Uncertainty and EPA’s   tion program, including its efforts to address EPA'S nuclear waste stan-
                        dards. Comments by NRC'S staff in its October 1989 staff paper indicate
Containment Standard    that DOE'S plans for site characterization appear to correspond well with
                        the staff’s interpretation of what the standards require. However, the
                        staff is particularly concerned that DOE emphasize the scientific work
                        needed to support the required probabilistic analyses rather than the
                        comparison of the analyses’ results with the release limits specified in
                        EPA'S containment standard.

                        NRC'S staff believes that meaningful, though not statistically  rigorous,
                        probability estimates can be developed and reasonably defended for
                        repository sites that are not complex or unusually geologically active. In
                        fact, the staff believes that the required probability estimates will help
                        determine how well a site is understood and, therefore, how much confi-
                        dence can be placed in its future performance as part of a repository.
                        However, the staff added that it is too early to tell whether meaningful
                        probability estimates can be developed for Yucca Mountain. According
                        to the NRC staff’s October 1989 paper, this issue is to be resolved as
                        early as practicable during site characterization. For example, in review-
                        ing and commenting on DOE'S site characterization plan, NRC staff noted
                        that DOE should assign high priority to conducting investigations to
                        determine whether the site is subject to unacceptably high chances of
                        disruption due to occurrences of volcanic activity, faulting, or seismic
                        movements.



                        Page 26                             GAO/RCED-B&130   Nuclear Waste f&uuterly,   Dec. 31,1989
 .                     Appendix II
                       Challenger DOE Facelr in Complying   Wlth
                       EPA’s Containment Standard




                       For several years, advisory groups to NRC have raised concerns about
                       DOE'S site characterization program and compliance with the EPA stan-
                       dards. For example, in July 1989 ACNW advised the NRC Chairman that
                       DOE was not giving sufficient emphasis to the limitations and uncertain-
                       ties in its databases concerning preliminary site characterization activi-
                       ties at Yucca Mountain. The Committee said that uncertainties and
                       limitations in DOE'S data will be the center of most repository conten-
                       tions and that planning for the management of these uncertainties and
                       limitations by DOE is essential. Finally, the committee stated that DOE
                       may have considerable difficulty in calculating an overall probability
                       distribution necessary for demonstrating compliance with EPA'S contain-
                       ment standard. According to ACNW, this problem could represent a dis-
                       qualifying feature for the proposed repository.


                       NRC and EPA are seeking ways in which they can resolve present and
WIPP May Provide       future implementation issues associated with the latter agency’s nuclear
Valuable Insights to   waste standards. The specific issue is whether there is adequate confi-
Implementing           dence that the standards-particularly    the probabilistic containment
                       requirements-can be implemented in an NRC licensing proceeding for a
Containment Standard   repository at Yucca Mountain or elsewhere. One approach that both
                       agencies have suggested to address this issue is to look at the experience
                       being gained through other programs for radioactive waste storage in a
                       geologic environment. In particular, the agencies identified DOE'S WIPP
                       repository near Carlsbad, New Mexico, as a possible precedent for deter-
                       mining how much confidence can be placed in the present or revised EPA
                       standards.

                       The WIPP facility is the culmination of many years of effort to find a site
                       for permanent disposal of transuranic wastes generated as a by-product
                       of the federal government’s defense-nuclear activities. The WIPP project
                       was initiated in 1981 when DOE decided to proceed with the development
                       of a mined geologic repository to store such wastes. To date, DOE has
                       spent about $800 million to complete WIPP site characterization, con-
                       struction, and preoperational activities.

                       Unlike the principal source of nuclear waste to be emplaced in Yucca
                       Mountain-spent (used) nuclear reactor fuel-transuranic      waste forms
                       typically contain smaller amounts of radioactivity. Yet, because this
                       waste contains long-lived and hazardous radioactive elements, such as
                       plutonium, it warrants isolation from the environment. Accordingly,
                       WIPP, like a potential repository at Yucca Mountain, must comply with
                       EPA'S disposal standards, An important distinction for the WIPP facility,



                       Page 27                              GAO/RCED-90-130   Nuclear Waste Quarterly,   Dec. 31,1989
Appendix II                                                                              .
Challenges DOE Faces in Complying   With
EPA’s Containment Standard




however, is that it is exempt from NRC regulation. DOE itself makes the
determination of whether or not the facility meets EPA'S standards.

DOE will conduct a computer-simulated performance assessment of WIPP,
similar to that of Yucca Mountain, to determine if the facility complies
with EPA'S standards. Specifically, using assumptions on the total inven-
tory of various elements to be disposed of in WIPP and computerized
models, DOE will identify, categorize, and analyze significant processes
and events that could affect the repository’s performance; will estimate
the cumulative releases of radiation to the accessible environment and
potential doses to individuals; and will compare the predicted release
rates and doses to release rates and doses contained in the standards.4

DOE designated the first 5 years of WIPP operation as a research and
development phase for the purpose of demonstrating the safe disposal
of transuranic waste. According to the agency’s latest estimate, this
phase is expected to begin as early as July 1990, and the performance
assessment is expected to be completed within 4 years. Our recent
report on WIPP provides additional details on the status of the facility,
DOE’S plans for the testing phase, and potential problems that DOE must
deal with in demonstrating compliance with EPA'S standards.”

EPA and NRC believe that DOE'S preparation of the WIPP performance
assessment may provide valuable insights on how readily EPA'S stan-
dards can be implemented in a licensing proceeding. Both agencies share
a concern that if DOE’S experience indicates that EPA'S standards appear
unworkable, the standards should be clarified or modified to allow NRC
to make a reasoned licensing decision on a DOE application to construct a
repository.

EPA has stated its intention to reexamine its disposal standards and issue
alternative standards if necessary. Moreover, EPA has recognized that
WIPP may prove to be useful in assessing the feasibility of implementing
the current environmental standards. In its comments on a draft supple-
mental environmental impact statement for WIPP, EPA urged that DOE
publish WIPP performance assessments as an additional supplement to
the environmental impact statement, or a similar document, for public

4Accordingto DOE,it will establishWIPP’scompliancewith EPA’sgroundwaterprotectionstandard
by demonstratingthat there is no specialsourceof groundwater,as definedin EPA’sdisposalstan-
dards,in the vicinity of the facility.
“Nuclear Waste:StorageIssuesat DOE’sWasteIsolationPilot Plant in New Mexico(GAO/
RCED-So-1,



Page 28                             GAO/RCED-90-130   Nuclear Waste Quarterly,   Dec. 31,1989
.   Appendix II
    Challenges DOE Faces in Complying   With
    EPA’s Contaiument Standard




    review and comment. According to EPA, this should be done after the 5-
    year test phase at WIPP but before DOE begins waste disposal operations
    at the facility.

    In its October 1989 staff paper, NRC'S staff also recognized that DOE'S
    application of EPA'S standards to WIPP could help answer questions about
    implementing the standards, NRC noted that a demonstration that a real
    repository can achieve the risk levels of EPA'S containment standard has
    not been made. NRC'S staff believes that it should review the perform-
    ance assessments for WIPP as they are released for public comment
    because the assessments could provide significant insights into the
    development of performance assessment capabilities at Yucca Mountain.




    Page 29                              GAO/RCED90-130   Nuclear Waste Quarterly,   Dec. 31,1989
Appendix III
                                                                                                        .
Major Contributors to This Report


                        Judy A. England-Joseph, Associate Director
Resources,              Dwayne E. Weigel, Assistant Director
Community, and          Victor J. Sgobba, Evaluator-in-Charge
                        Richard A. Renzi, Advisor
Economic                Shirley Christensen, Writer-Editor
Development Division,
Washington, D.C.




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