ML19291D668
| ML19291D668 | |
| Person / Time | |
|---|---|
| Issue date: | 09/16/1981 |
| From: | Mark J Advisory Committee on Reactor Safeguards |
| To: | Palladino N NRC COMMISSION (OCM) |
| References | |
| FRN-46FR35280, RULE-PR-60 46FR35280-10, ACRS-R-0943, ACRS-R-943, NUDOCS 8109220357 | |
| Download: ML19291D668 (4) | |
Text
E[s,3 nc9]c, UNITE D STATES
.. rg; i NUCLEAR REGULATOPY COMMISSION ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 5
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'os' s.ge WASHtNGT ON. D. C. 20555 September 16, 1981 Honorable Nunzio J. Palladino Chai rman U.S. Nuclear Pagulatory Commission Washington, DC 20555
SUBJECT:
REPORT ON PROPOSED RULE ON " DISPOSAL OF HIGH-LEVEL RAD 10ACTb/E WASTES IN GEOLOGIC REPOSITORIES"
Dear Dr. Palladino:
During its 257th meeting, September 10-12, 1981, the Advisory Committee on Reactor Safeguards met with the NRC Staff, representatives of the U.S.
Department of Energy (DOE), and SCE and r1RC contractor personnel to discuss the proposed rule on " Disposal of High-Level Radioactive Wastes in Geologic Repositories" (10 CFR 60). This was also the subject of a meeting of the ACRS Subcommittee on Waste Management held in Washington, D.C. on Septem-ber 2 and 3, 1981.
1.
General Comments The NRC Staff is to be complimented on moving ahead even in the cbsence of confirmed, supporting standards which are t: be provided by the U.S. Envir-onmental Protection Agency.
Although we believe certain changes and im-provements should be made in the proposed rule, the published draft reflects a good grasp of the subject and incorporate: a wide range of input from other Federal agencies and outside groups.
2.
Comments on Key Issues In the proposed ruir comments were specifically requested on six key issues.
Our responses regar la
-re issues are as follows:
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a.
Prescrip tic ;
4 teria for a Repository We agree that the isle must include an overall safety goal or objec-tive for the repository.
However, only minimum performance standards for each of the major elements are needed.
Although we f avor the p.g-<S-QG/
approach ti at has been taken, we believe that the interpretation of the numerical standards needs further clarification.
Additional comments on this matter are given in Section 3.a of this report.
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Honorable Nunzio J. Palladino September 16, 1981 b.
Specif: cation of Design and Construction Criteria 43 We believe that detailed design and construction criteria should not be included in the rule.
It would be better to incorporate informa-tion of this type in supplementary regulatory guides, c.
Retrievability of the Wastes We t'elieve that more discussion of retrievability requirements should gj. g. C6-O C' be made a part of the text of the rule as opposed to including it primarily in the background information. The NRC should indicate the conditions under which retrieval would need to be performed, perhaps by postulating illustrative circumstances.
The type of waste to be inserted could influence the retrievability requirements as well as the performance of the repository.
Although we did not explore the question of tne impact of the retrievability option on design, it ap-pears that it cou'd be significar; in certain cases, such as a re-pository located in salt. The 50-year time span appears more than adequate for preserving the retriev3bility option, but other criteria might be considered such as the time needed to demonstrate stability of thermal conditions, structural movement, or containment effective-ness.
d.
Concern for Human Intrusion We believe the treatment of this subject is well done.
We recommend retention of the existing text.
e.
Population Related Siting Requirements We agree with the approach suggested in the proposed rule. We believe it is not necessary to include any siting criteria which relate to population density or the proximity of the waste repository to popula-tion centers.
f.
Application of the ALARA Critericn
.,g _g _ got Although it is appropriate that the ALARA criterion be applied to the overall safety goal for the repository, we believe it is not appro-priate to apply it to the individual performance criteria for every major subelement.
3.
Additional Comments In terms of other aspects of the proposed rule, the Committee offers the following comments:
a.
Alternative Approaches While we generally agree with the criteria specified in the proposed
Honorable Nunzio J. palladino September 16, 1981 rule, we believe that the licensee should be given a greater degree of flexibility for compliance with the overall safety goal. One approach would be to emphasize the fact that the NRC will be evalu-ating the anticipated performance of the total waste repository as a system, in contrast to the performance of its individual components.
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Since we foresee only one or two repositories being built within the next several decades, we believe that each should be evaluated in reiation to overall performance on a case-by-case basis.
b.
Validation of Compliance p g _pov One of the important issues concerning the rule will be the tech-nioues used for validating compliance with the specified criteria.
Specific mention should be made that acceptable models must be avail-able for evaluating repository performance, and that accelerated testing end certified data will be necessary for determinipg system performance over long periods of time.
Since absolute confonnance cannot De guaranteed, it may be useful to express compliance with numerical criteria in terms of the required confidence level that a certain fraction of a given system component (e.g., waste packages) must meet, keeping in mind what levels of confidence it may be prac-tical to achieve.
c.
Hantiling of Transuranic (TRU) Wastes We recommend that regulations for the management and disposal of
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TRU wastes be developed in a separate document.
If this were done, some of the complexity within the current proposed rule would be avoided. This approach would also allow attention to be directed to the unique aspects of the TRU waste disposal problem, especially for wastes in which radionuclide concentrations were low.
A supporting decision is needed to clarify the minimum radionuclide concentration which denotes TRU wastes, d.
Definition of Terms Many of the definitions used in the proposed rule, particularly those pertaining to geologic terms, are not technically correct.
Examples are the use of the terms, " fracture zone," and " fault rup-ture surface." In addition, in several instances the terms used do not convey the intentions. For example, reference is made to the
" geologic or tectonic" stability of the site when what was really being referred to was the stability of the " repository," itself.
We recommend that the text be carefully screened to correct these deficiencies, e.
Consideration of the Vadose Zone The rule would appear to be equally applicable to mined geologic re-positories in the Vadose Zone. As a result, a separate rule for
Honorable Nunzio J. Palladino September 16, 1981 disposal of high-level radioactive wastes in the unsaturated zone does not appear to be necessary.
f.
Evaluation of Computer Models At the present time, there are a number of organizations within the El-CV 09-6 0I U.S. that are involved in the development of computer models for estimating the environmental transport of radionuclides. To check for deficiencies in these models, and to assure that the best models are applied in estimating the performance of a high-level waste re-pository, we suggest that an evaluation program for such models be confucted.
In providing these connents, we again compliment the NRC Staff on a well-prepared document.
Sincerely, J. Carson Mark Chairman s