ML19322E632
| ML19322E632 | |
| Person / Time | |
|---|---|
| Issue date: | 02/14/1980 |
| From: | Plesset M Advisory Committee on Reactor Safeguards |
| To: | Ahearne J NRC COMMISSION (OCM) |
| References | |
| FOIA-80-431, RTR-NUREG-0625, RTR-NUREG-625 NUDOCS 8004020032 | |
| Download: ML19322E632 (7) | |
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NUCLEAR REGULATORY COMMISSION c
ADVISORY COMMITTEE ON REACTOR SAFEGUARDS t
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o WASHINGTON, o. C. 20555 g*v February 14, 1980 Honorable John F. Ahearne Chairman U. S. Nuclear Regulatory Commission Washington, D.C. 20555
Subject:
NUREG-0625, " REPORT CF THE SITING POLICY TASK FCRCE"
Dear Dr. Ahearne:
The purpose of this letter is to provide you with ACRS ccnwnts on the
" Report of the Siting Policy Task Force" (NURIn-0625).
In preparing these comments, the Committee had the benefit of discussions with the NRC Staff
. at a Subecmmittee meeting on October 17, 1979 and at the full Committee meeting on January 10-12, 1980.
Sitino Goals In the abstract of the Report it is stated that a number of changes in siting policy have been rec:nmended in order to accomplish the following goals:
1.
Tb strengthen siting as a factor in defense in depth by establishing requirements for site approval that are in-dependent of plant design considerations 2.
Tb take into consideration in siting the risk associated with accidents bepnd the design basis (Class 9) by estab-lishing population density and distribution criteria.
3.
Tb require that sites. selected will minimize the risk from energy generation.
In connection with the third goal. the Siting Policy Task Force states that, "The, selected sites-should be amorg the best available in the region where new generating capacity is needed. Siting requirements should be stringent enough to limit the residual risk of reactor operation but not so stringent as to elimin' ate the nuclear option from large regions of the country. This is because energy generation from any source has its associated risk, with risks from some energy sources being greater than that of the nuclear option."
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Honorable John F. Ahearne February 14, 1980
'Ihe ACRS agrees with these goals but has some qualifications *ich are stated below. It is interesting to note that these goals are, in part, similar and are in part complementary to some siting policy recommendations made by the ACRS in a report
- to the Atomic Energy Commission prior to the adoption of 10 CFR Part 100.
In that report the ACRS stated the following:
1)
Everyone off-site must have a reasonably good chance of not being seriously hurt if an unlikely but credible reactor accident should occur.
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i 2)' The exposure of a large segment of society in terms of inte-grated man-rems should not be such as to cause a significant shortening of the average individual lifetime or a significant genetic damage or a significant increase in leukemia - should
, a credible reactor accident occur.
- 3) There should be an advantage to society resulting from locating a plant at the proposed site rather than in a more isolated area.
- 4) Even if the most serious accident.possible (not normally con-sidered credible) should occur, the numbers of people killed should not be catastrophic.
However, the AEE Part 100 Siting Criteria were written so as to provide greater flexibility in the choice of sites than was implicit in these ACRS recomendations and permitted the substitution of. engineered safety features for distance.
In the decade following adoption of Part 100 in 1962, sites were accepted having surrounding population densities less than or roughly equivalent to that typified by Indian Point Unit 1 which had been approved in 1956.
Although the engineered safety features provided in nuclear plants were judged to be sufficient to restrict estimated offsite doses to the specified limits, these estimates were bued on the stylized calculations of Part 100 which assumes a large fission produt.t release to an intact contain-ment. Historically, with regard to the engineering tiesign requirements for nuclear power. plants located on sites near the borderline of acceptability, the ACRS has recommended additional measures to prevent accidents and to mitigate their effects.
In recent years, sites approved for nuclear power plants have had surrounding population densities substantially less than 1
those of Indian Point Unit 1.
With regard to the goals discussed above, the ACRS agrees that siting, as a factor in the defense in depth itilosophy, should be strengthened.
- However, t
- the ACRS believes that any minimum requirements for parameters,such as the exclusion zone radius, surrounding population density, or distance from population centers should be established, if passible, wi. thin the framework of an overall Nuclear Regulatory Commission safety philosophy for future re-acto rs.
YRS letter to thTHonorab'lTJohn A. Etic 8de-~ Clairman, USAEC dated f
October 22, 1960,
Subject:
REAC'ICR SITE CRITERIA i
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Honorable John F. Ahearne February 14, 1980 Such a Etilosophy should be based on preestablished Commission objectives Bis will, of neces-for acceptable risk both to individuals and society.
sity, include consideration of matters such as the potential effects of a broad spectrtzn of reactor accidents, the identification of an ALARA cri-terion for the reduction of risk from accidents, and a general statement of policy concerning the objectives to be sought in teactor design with regard to the prevention and the mitigation of accidents.
We establishment of demographic-related site criteria will inevitably re-However, the choice will be less quire a considerable amount of judgment.
arbitrary if made within the framework of an overall NRC safety policy.
We ACRS believes that an o'/erall NRC safety philosophy is also needed in connection with the third objective of the Task Force, namely that of.se-lecting sites to minimize the risk from the utilization of electricity generating sources.
me ACRS believes that well-founded nuclear power plant siting policy and S e committee suggests practice are a national as well as a regional need.
that as part of a broad approach to LWR siting, the NRC should explore the possible developnent of a nationwide program to identify a bank of near-opti-mal sites regionally distributed for various types of energy-generating plants.
By combining considerations of acceptable risk, the risks from various energy sources, and the national needs for energy, together with otner rele/ ant factors, a better long-term basis for determining appropriatb criteria for LWR siting should be passible.
In the absence of such a broad approach, the ACRS recommends that changes to' past siting policy be interim in nature and be designed primarily to provide an acceptable basis for near-term decision making.
Task Force Recomendations te Siting Policy Task Force has made nine recommendations, each of 'ahich is followed by a discussion which elaborates on the recommendation, frequently suggesting specific parameters and occasionally a significant additional recommendation. In this report the ACRS will deal primarily with the recom-mendations themselves, unless otherwise stated.
Recommendation 1 his I's the principal recoceendation of the Repart.
It proposes that'Part 100 be revised to change the way in which protection is provided for accidents.
We recm:nendation is very general in form and requires the addition of speci-fics to be meaningful.
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Honorable John F. Ahearne February 14, 1980 Part 1 of the reccrxnendation proposes the specification of a fixed minimun exclusion distance based on limiting the individual risk from design basis accidents. %e ACRS believes that the specificat' ion of a minimum exclusion distance should include consideration of the risk from all accidents, not just design basis accidents. It should include consideration of. the number of reactors at the site. Any long-term criterion concerning a minimum exclusion distance muld best be established within the framework of a general NRC policy on INR safety.
Interim guidance could be determined with the benefit of information developed from NRC Staff studies and information sutnitted during a proposed rulemaking on interim changes in the site criteria.
Part 2 of the recommendation proposes a fixed minimum emergency planning distance of. ten miles. We ACRS generally sup;nrts. this recommendation with the understanding that appropriate attention would be given to ptential problems at greater distances.
Part 3 recommends the incorpration of specific ppulation density and dis-tribution limits that are dependent on the average ppulation of the region.
We ACRS believes the wording of this recommendation is vague and it could be interpreted to be excessively restrictive or very permissive with regard to demographic requirements. Additional information is needed to establish interim criteria of this sort within the context of an NRC rule. Among the factors which require consideration are the following,:
(a)
If some regions of the country are permitted to employ higher maximum ppulation densities, should there be any additional requirements for such plants in design, operation, or emergency planning? If not, what basis will be provided for designatirg regionally dependent acceptable risks?
(b). Should the NRC place a similar or a substantially greater enphasis on
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improbable, large accidents in its siting (and design) requirements than is utilized for other new societal activities psing hazards simi-lar in magnitude and probability?.
(c) How should the effectiveness of emergency measures, such as evacuation, sheltering and decontamination,'be ascertained and factored into a judgment concerning minimum exclusion and emergency planning distances?
(d)
Should meteorology not be given consideration in regard to the develop-ment of siting criteria?
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1 Honorable John F. Ahearne February 14, 1980 Part 4 recommends removal of the requirement to calculate radiation doses as a means of establishing minimum exclusion distances and low population zones. De ACRS agrees with the Task Force that the approach used for the past two decades has not provided enough emphasis on site isolation. The Committee believes that the emphasis on engineered safety features to meet Part 100 for the pstulated accident without direct consideration of other, more serious possibilities has led to a less-than-optimum approach to safety.
However, if the recommendation of Part 4 is adopted, some alternative means of determining the need and adequacy of engineered safety features will be required.
In summary, although the ACRS agrees that the specification of minimum ex-clusion and emergency planning distances and population density and distri-bution limits is a commendable objective, and that interim crite.ria should ba developed, the Committee believes that the adequacy of such parameters will depend on the safety-related design and opeucional requirements and on the effectiveness of energency measures.
Also, the ACRS believes the establish-ment of such parameters involves the assumption of some accepted band of risk which should be specified. While the ACRS is not oppsed to removal of the Part 100 requirement for calculation of radiation doses or to the specification of regionally dependent acceptable ppulation densities, the Committee believes these matters need in-depth evaluation.
Recommendation 2 This recommendation proposes minimum standoff distances for ptential haz-ards psed by man-made activities and natural characteristics. We Com-mittee believes that such a recommendation is appropriate but the list is incomplete. For example, ENG terminals are incitried but not LP3.
Similarly, hazardous cargo on rivers is not mentioned.
In addition, the proposed approach lacks an adequate rationale for specific numbers suggested. A distance of at least 12.5 miles from all capable faults, with no distinction as to fault size, is' proposed, as is a specification that no reactor sites located on a flood plain sould be closer than five miles downstream of a major dam. We reason why either of these two proposed num-ber's is suitable is not clear to the ACRS.
For example, dams many miles away could be equally or more dangerous to a nuclear plant; on the other hand, small capable faults nearer than 12.5 miles might not pse significant de-sign problems.
It is noted that the recommendation does not provide standoff distanc'es be-tween nuclear plants.
The potential adverse influence of one plant on its neighbors in the event of a serious accident requires consideration in de-sign.
Honorable John F. Ahearne February 14, 1980 Recomendation 3 bis recommendation would change Part 100 to require reasonable assurance that interdictive measures are pssible to limit groundwater contamination resulting from Class 9 accidents. Se ACRS supprts the recommendation.
However, the Committee notes that the current wording is subject to a range of interpretations which could include, for exanple, the necessity for de-veloping interdictive measures for particulate fallout or rainout that J
could result in groundwater contamination. te Committee reccranends that the wording of the reccomendation be made more explicit.
Recomendation 4 This reccmendation is very general, merely stating that Appendix A to 10 CFR 100 should be revised to better reflect the evolving technology in assessing. seismic hazards.
Bowever, in the discussion section, the Task Force reccmends that specific guidance be removed from Appendix A and placed in Regulatory Guides.
te ACRS agrees that the NRC criteria for seismic siting should be revised and perhaps expanded.
Bis clearly will require changes in Appendix A.
We ACRS believes that Regulatory Guides can be used to provide increased guid-j I
ance on the interpretation and application of the criteria.
Se ACRS has in the pst worked closely with the NRC Staff on the developnent of seismic siting criteria, and expects to continue to do so in the future and to provide comments on the specific changes as they are developed and l
propsed. At this time, however, the ACRS cannot agree that all specific guidance can be removed from the criteria, in the absence of a quantitative safety goal.
Recomendation 5 i
This recccmendation relates to post-licensing changes in offsite activities but does not specify Wat population / time period would be used. For example, would it be the present population, that at the projected end of life of the plant, or an average over the time period during Wich the plant will be oper-ated? tis should be clarified, te reccamendation also does not specify what is considered to be a "significant increase in risk." Another consider-ation that might be taken into account is the nature and use of the land.sur-round'ing a site. Whether neighboring land is used for residential or industrial purposes, and whether it is fertile land or a desert, could also be imprtant.
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Honorable John F. Ahearne Fe W ary 14, 1980 Reecernendation 6 mis recernmendation pertains to methods for compensating for unfavorable site characteristics. We Committee suggest.s that the phrase, " unfavorable characteristics requiring unique or unusual design," be clarified. Many characteristics that are " unfavorable" can be re.adily compensated for by de-sign, including some of an " unusual" nature. Design features to provide permanent site improvements should be permissible when suitably reliable.
Perhaps these problems could be solved by deleting the word, " unfavorable,"
and substituting the word, " unproven," for " unique or unusual.".
Recomendation 7 This recommendation relates to the timing of site reviews. We ACRS sug-gests that this reccrnmendacion could be improved by substitutirg the ward
" decision" for " approach" (in the third line).
l Recomendation 8 Wis recommendation relates to the role of a state agency in approving a site for a nuclear power plant. Se ACRS has no comments on this item.
Recomendation 9 This recommendation is to develop common bases for comparing the risks from all external events. We ACRS supports the general concept and would, if practical, extend it to internal events as well. Be Committee believes that this concept represents a good lorg range goal; however, reccgni::ing the ccmplexity of the task, the Committee recommends that priority be given to those areas thought either to introduce the greatest risk or to provide the best opportunities for improvements in safety.
We Ccanittee will be pleased to discuss the above items with you if pu de-sire.
In the Tneantime, we trust these comments will be helpful to you and the'NRC Staff.
. Sincerely, l
l Milton S. Plesset Qairman l
.