ML20205H759
| ML20205H759 | |
| Person / Time | |
|---|---|
| Issue date: | 03/18/1999 |
| From: | Shirley Ann Jackson, The Chairman NRC COMMISSION (OCM) |
| To: | J. J. Barton HOUSE OF REP. |
| Shared Package | |
| ML20205H762 | List: |
| References | |
| NUDOCS 9904090070 | |
| Download: ML20205H759 (8) | |
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! o NUCLEAR REGULATORY COMMISSION . . .
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\,...../ March 18, 1999
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CHAIRMAN f The Honorable Joe Barton, Chairman Subcommittee on Energy and Povier Committee on Commerce United States House of Representatives Washington, D.C. 20515-6115
Dear Mr. Chairman:
On February 26,1999, you forwarded to me a set of seven questions posed by Representative Edward Markey for the record of the February 10,1999, Subcommittee on Energy and Power hearing on H.R. 45, the Nuclear Waste Policy Act of 1999. Enclosed are the Nuclear Regulatory Commission's responses to those questions. j Sincerely, M c-- s Shirley Ann Jackson
Enclosures:
As stated gM cc: Representative Ra!ph M. Hall
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'o QUESTION 1. Does current law provide adequately for site suitability studies, licensing, transpc& tion, and permanent underground burial of radioactive waste?
ANSWER.
i The NRC believes that the existing statutory framework is adequate for site suitability studies, licensing, transportation and permanent underground burial of radioactive waste. However, the Commission supports the improvements made by H.R. 45, as reflected in our testimony at the February 10,1999, hearing.
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QUESTION 2. In your testimony, you suggest that to meet a standard of 100 millirem dose to the average person in the vicinity of Yucca Mountain the NRC l would set a limit of 25 millirem dose to the most affected group. Why do you think that the law would not mean what it says? ;
1 ANSWER.
To ensure tM there is no confusion regarding the approach tc the overall system performance objective related to H.R. 45, NRC is proposing altemative language that embraces the nationally and internationally accepted approach to establishing radiation protection standards.
The NRC believes that adopting nationally and intemationally recognized approaches for radiation protection standards for high-level waste disposal adds credibility to the process and will facilitate 'icensing of a geologic repository.
The intemational Commission on Radiological Protection (ICRP) and the National Council on Radiation Protection and Measurements (NCRP) are chartered, and internationally recognized, for the development of basic radiation protection standards. Their basic recommendations on '
radiat5n protection are contained in ICRP Publicatior S0 and in NCRP No.116, respectively.
Based on their review of health and societalissues, both organizations (while acknowledging the difficulty of setting standards for an " acceptable" public dose limit) arrive at an individual dose limit of 100 mrem per year (mrem /y) as an acceptable level. Generally, both organizations recommend apportioning this total dose limit to constrain exposure from specific man-made sources of radiation, excluding medical. In its recommendations on setting a health-based standard for the repository, the National Academy of Sciences reported that various countries allocate high-level waste disposal between 10 and 30 mremly as the individual dose limit. ICRP emphasizes that these partitions of the individual dose standard for individual activities, such as waste disposal, are not limits, but rather constra:nts, above which doses would not necessarily be considered unaccoptable. ICRP recommend 3 a constraint value in the range of 30 mrem /y.
Because dose estimates for many thousands of years into the future contain substantial uncertainty, NRC believes that to provide reasonabie assurance that individual doses will not exceed 100 mrem /y to members of the public from a repository at Yucca Mountain, doses to the average member of the critical group from all exposure pathways including grr-undwater should be constrained to 25 mrem /y.
As noted, NRC has testified that it believes it has the flexibility to implement the overall system performance objective in H.R. 45 by using, for design and licensing purpotes, an individual protection standard of 25 millirem total effective dose equivalent to the average member of the critical group based on an all pathway analysis and specified assumptions to be used for the reference biosphere, critical group, and evaluation of a human intrusion scenario. Such a standard, as proposed by the Commission in 10 CFR Part 63, includes consideration of the probability of human exposure. The NRC believes this approach is the best way to implement a hea!th-based, safety objective for long-term repository performance that is feHy protective of public health and safety, and the environment.
l QUESTION 3. H.R. 45 does allow NRC in consultation with EPA to override the bill's standard. How would you determine if the standard in the bill provides
" adequate protection of health and safety of the public"?
ANSWER.
If the NRC cannot ensure that expected doses will not exceed 100 millirem per year (mrem /y),
then NRC may need to conclude that the standard in the billis not protective of public health and safety. l I
As stated in the Answer to Quesilon 2, the NRC is proposing alternative language to H.R. 45 I that embraces the nationally and internationally accepted approach to establishing radiation protection standards to ensure that there is no confusion regarding the overali system performance objective approach.
Specifically, the NRC adopted in 10 CFR Part 20 the national and internationally accepted individual dose limit of 100 mrem /y for exposure from all man-made sources of radiation excluding medical. The NRC also adopted the nationally and internationally accepted approach I of applying " constraint values" and the " average member of the critical group" concept to reduce the likelihood that any one individual would be exposed in excers of the 100 mrem /y !
public dose limit. The NRC also requires its licensees to apply the As Low As Reasonably Achievable (ALARA) principle to further reduce exposures.
l As a result of applying this approach, the NRC selected 25 mrem /y as a conservative constraint within the 100 mrem /y limit, which is consistent with existing limits for monitored retrievable storage facilities (10 CFR Part 72) and low-level waste fac.. :s (10 CFR Part 61). It is also within the international constraints that allocate doses from hign-level waste disposal to between 10 and 30 mrem /y and is comparable to the risk range recommended by the National Academy of Sciences for Yucca Mountain.
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QUESTION 4. You state in your testimony that 10,000 years is "a sufficient length of time to assess the isolation capability of the system." Models suggest that maximum exposure would occur after roughly 300,000 years. Won't you miss most of the health effects of the repository if you don't consider times at least that long?
ANSWER.
NRC believes that dose estirrates beyond 10,000 years become increasingly specuiative to the j extent that they are not especially valuable in regulatory decision making.
Although models can estimate higher doses at 300,000 years or greater. assumptions used in making these estimates are also highly speculative. For example, these higher dose estimates incorporate the effects of multiple glacial cycles on infiltration into the repository and flow and transport of radionuclides, while not considering, by necessity, technological changes in society and changes in living habits that would occur in response to these climate changes or mitigate the effects of such climate changes.
Nevertheless, NRC believes that analyses of repository system performance for time pencds greater than 10,000 years will be performed and that, although they should not be used as a compliance measure, they will provide insight into the performance of individual barriers of a repository system. Using these analyses to evaluate the ability of individual barriers to isclate waste will build confidence in the adequacy of the entire system.
With rc pect to the 10,000 year regulatory compliarce period used in NRC's proposed 10 CFR Part 63, both technical and policy considerations were taken into account. A 10,000 year compliance period is appropriate because it includes the period when the waste is inherently most hazardous. The inherent radiological hazard of spent fuel decreases rapidly and significantly during the initial 10,000 years primarily due to the decay of short-lived fission l products. At 10,000 years after waste emplacement, the relative radiological hazard is within a factor of ten of the hazard posed by a quantity of 0.2 percent urerdum ore, equivalent to typical ore grades that are mined and processed to produce the fuel used in reactors. Beyond 10,000 years, the relative hazard of the disposed waste diminishes very slowly over several hundreds of thousands of years, because decay at such late times is controlled by the activity of longer-lived radionuclides.
In addition, a 10,000 year compliance period is appropriate because it is sufficiently long, to .
include a wide range of conditions (e.g., seismic events, fault movement, climate variation) l which will challenge the engineered and natural barriers, providing a reasonable evaluation of the robustness of the geologic repository. Additionally, the Commission expects that in conducting its performance assessment, DOE will account for the susceptibility to early failure of some fraction of the more than 7,000 emplaced canisters (e.g., attributable to manufacturing defects), and evaluate the ability of the geologic barriers to limit exposures.
A 10,000 year compliance period also is cunsistent with other regulations involving geologic disposal of long-lived hazardous materials, including radionuclides. EPA has already codified a 10,000 year compliance period at 40 CFR 191 applicable to the Waste isolation Pilot Plant, a similar type of disposal system as that proposed at Yucca Mountain. A 10,000 year compliance period is also referenced in EPA guidance on no-migration petitions for facilities seeking exemption from certain land-disposal restrictions for long-lived hazardous, nonradioactive materials.
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QUESTION 5. o c. 205(d)(2) of H.R. 45 states that "The Commission shall assume that, I following repository closure, the inclusion of engineered barriers and the l Secretary's cost-closure actions at the Yucca Mountain site, in )
accordance with subsection (b)(3), shali be sufficient to ...(B) prevent any l
! increase in the exposure of individual members of the public to radiation l beyond allowable limits as specified in paragraph (1)." Do you think this
- provision would, as suggested in EPA's testimony, require NRC to find that the radiation release standard would be met, regardless of evidence from modeling or other scientific studies?
ANSWER.
i The NRC has a different understanding than the view expressed in the EPA testimony.
The Commission agrees with the referenced portion of H.R. 45 because it provides flexibility to NRC in its determination of protection of public health and safety regarding human intrusion into the repositcy.
l The EPA testimony suggested that the Sec. 205(d)(2) of H.R. 45 applies to rneeting the release
! standard for all post-closure analyses. NRC believes this is an incorrect interpretation of H.R. '
- 45. NRC understands Sec. 205(d)(2) of H.R. 45 to refer only to the evaluation of human intrusion.
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l QUESTION 6. Are the site characterization studies of Yucca Mountain that have bc onducted to date sufficient for a license application for a pe: aunt repository at Yucca Mountain?
l ANSWER.
No. The NRC, having reviewed DOE's Viability Assessment (VA), believes that additional data and analyses ere necessary to ensure that a License Application, if provided, would be complete and of high-quality.
In its VA, the DOE recognizes the need for additional site characterization and design l l confirmation data and analyses so that it will be able to provide a complete and high quality i postclosure safety case in a license apolication. The DOE, also in the VA, has specifically identified those aspects of the repository system that need additional data based on the results of a total system performance assessment.
Although the NRC and the DOE are in agreement on many aspects of what is needed, we plan to provide comments to them in the near future on how much additional information is needed in particular topical areas in the NRC review of the VA and future updates of the NRC issue Resolution Status Reports.
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OUESTION 7. Please describe the quality assurance deficiencies in the DOE site l assessment program and explain how these deficiencies, if not j corrected, might result in an incomplete or unacceptable license l application.
I ANSWER.
Although NRC staff has reviewed and accepted the DOE Quality Assurance (QA) program, the DOE has consistently had problems implementing the program. Deficiencies identified during DOE audits and surveillance of its suppliers raised the issue of whether the data and products <
produced by these suppliers will be acceptable and appropriately qualified for licensing. Some data in the Management and Operating Contractor's (M&O) technical data base have been determined to be unqualified, not traceable, inaccurate, or indeterminate based on various deficiencies which have also surfaced as a result of DOE audits. The Technical Basis Document, which supports the Viability Assessment (VA) Total System Performance Assessment, indicates that a major portion of the data supporting the VA is not qualified. l DOE's License Application (LA) Plan does not recognize the current situation with regard to implementation of its OA program and the activities needed to address it. 4 To obtain authorization to construct a HLW repository, the DOE must be able to demonstrate in its LA that data, analysis, and designs of barriers and systems important to safety or waste l isolation mee: OA requirements of Appendix B to 10 CFR Part 50.
The OA program applies to all systems, structures, and components important to safety and waste isolation. Confidence in the DOE demonstration that public health and safety will be protected is based, in part, on the confidence in the adequacy of data, data analyses, construction activitica, and other items and activities associated with the LA which are obtained through a OA program.
We understand that the DOE management agrees with the need for improving the OA program and is moving aggressively to make the necessary upgrades prior to submitting its license application. Our staffs continue to work together to address these important issues.
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