NUREG-0625, 02-14-80 NUREG-0625, Report of the Siting Policy Task Force

02-14-80 NUREG-0625, Report of the Siting Policy Task Force

ML25169A313
Person / Time
Issue date:	02/14/1980
From:	Plesset M Advisory Committee on Reactor Safeguards
To:	Ahearne J NRC/Chairman
References
NUREG-0625
Download: ML25169A313 (1)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION ADVISORY COMMITTEE ON REACTOR SAFEGUARDS WASHINGTON, D. C. 20555 February 14, 1980 Honorable John F. Ahearne Chairman

u. s. Nuclear Regulatory Commission Washington, D.C. 20555

Subject:

NURFXH>625, "REPORT Cl 'DiE SITING POLICY TASK FCRCE"

Dear Dr. Ahearne:

'lhe purpose of this letter is to provide you with ACRS canments on the "Report of the Si ting Policy Task Force* (NlltEX;-0625).

In preparing these comments, the Committee had the benefit of discussions with the.NRC Staff at a Subcanmittee meeting on October 17, 1979 and at the full Committee meeting on January 10-12, 1980.

Siting Goals In the abstract of the Report it is stated that a mnber of changes in siting policy have been recanmended in order to accomplish the following goals:

1. 'lb strengthen siting as a factor in defense in depth by establishing requirements for site approval that are in-dependent of plant design considerations.

2.

'lb take into consideration in siting the risk associated with accidents beyond the design basis (Class 9) by estab-lishing population density and distribution criteria.

3.

'lb require that sites selected will minimize the risk from energy generation.

In connection with the third goal, the Siting Policy Task Force states that,

"'lhe selected sites should be anong the best available in the region "'1lere 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 eliminate the nuclear option from large regions of the COlD'ltry. 'lhis 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.*

3552

Honorable John February 14, 1980 The NJRS agrees with these goals but has some qualifications "1ich are stated below. It is interesting to note that these goals are, in part, similar and are in part complementary to some siting policy recanmendations 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.

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 m.111bers of people killed should not be catastrophic.

However, the AfX: Part 100 Siting Criteria were written so as to provide greater flexibility in the choice of sites than was implicit in these ACRS recommendations 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 l 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 based on the stylized calculations of Part 100 which assumes a large fission product release to an intact contain-ment. Historically, with regard to the engineering design 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 those of Indian Point Unit 1.

With regard to the goals discussed above, the ACRS agrees that siting, as a fa.ctor in the defense in depth i;tiilosophy, should be strengthened. However, the ACRS believes that any minimun requirements for paraneters such as the exclusion zone radius, surrolUlding population density, or distance from population centers should be established, if possible, within the franaiiork of an overall Nuclear Regulatory Commission safety piilosophy for future re-actors.

• ACRS letter to the Honorable John A. l't:Cone, Olairman, US~ dated October 22, 1960, SUbject:

RFAC'l'al SITE CRITERIA 3553

Honorable John F. Ahearne 3 -

February 14, 1980 Such a i;:hilosophy should be based on preestablished Commission objectives for acceptable risk both to individuals and society. 'Ibis will, of neces-sity, include consideration of matters such as the potential effects of a broad spectrlltl of reactor accidents, the identification of an At.ARA cri-terion for the reduction of risk from accidents, and a general statement of policy concerning the objectives to be sought in reactor design with regard to the prevention and the mitigation of accidents.

'lhe establishment of demographic-related site criteria will inevitably re-quire a considerable amount of judgment. li>wever, the choice will be less arbitrary if made within the franework of an overall NRC safety policy.

'!he ACRS believes that an overall NRC safety philosophy is also needed in connection with the third objective of the Task Force, nanely that of se-lecting sites to minimize the risk from the utilization of electricity generating sources.

'lhe ACRS believes that well-founded nuclear power plant siting policy and practice are a national as well as a regional need. 'lbe Committee suggests that as part of a broad approach to I.WR 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 other relevant factors, a better long-term basis for determining appropriate criteria for I.WR siting should be possible. 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 Reconmendations

'lhe Siting Policy Task Force has made nine recommendations, each of 111hich is followed by a discussion wich 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

'Ibis is the principal reconmendation of the Report. It proposes that Part 100 be revised to change the way in wich protection is provided for accidents.

'lhe recoomendation is very general in form and requires the addition of speci-fics to be meaningful.

3554

Honorable John February 14, 1980 Part 1 of the recommendation proposes the specification of a fixed minimlltl exclusion distance based on limiting the individual risk from design basis accidents. 'lhe ACRS believes that the specification 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 nlltlber of reactors at the site. Tm.y long-term criterion concerning a minimum exclusion distance would best be established within the framework of a general NRC pol icy on UiR safety. Interim guidance could be determined with the benefit of information developed from NRC Staff studies and information sul:Jnitted during a proposed rulemaking on interim changes in the site criteria.

Part 2 of the recanmendation proposes a fixed minimum emergency planning distance of ten miles. 'lhe ACRS generally supports this recanmendation with the tmderstanding that appropriate attention would be given to potential problems at greater distances.

Part 3 recommends the incorporation of specific population density and dis-tribution limits that are dependent on the average population of the region.

'1he 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. llnong the factors which require consideration are the following:

(a)

(b)

(c)

(d)

If some regions of the com try are permitted to employ higher maximl'ltl population densities, should there be any additional requirements for such plants in design, operation, or emergency planning? If not, wat basis will be provided for designating regionally dependent acceptable risks?

Should the NRC place a similar or a substantially greater emphasis on improbable, large accidents in its siting (and design) requirements than is utilized for other new societal activities posing hazards simi-lar in magnitude and probability?

How should the effectiveness of emergency measures, such as evacuation, sheltering and decontamination, be ascertained and factored into a judgment concerning minimtn exclusion and emergency planning distances?

Should meteorology not be given consideration in regard to the develop-ment of siting criteria?

3555

Honorable John February 14, 1980 Part 4 reconmends removal of the requirement to calculate radiation doses as a means of establishing miniml.lD exclusion distances and low population zones.

'!he ACRS agrees with the Task Force that the approach used for the past two decades has not provided enough emphasis on site isolation. 'lhe Committee believes that the emphasis on engineered safety features to meet Part 100 for the postulated accident without direct consideration of other, more serious possibilities has led to a less-than-optimlltl 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 canmendable objective, and that interim criteria should be developed, the Committee believes that the adequacy of such i;:eraneters will depend on the safety related design and operational requirements and on the effectiveness of emergency measures.

Also, the ACRS believes the establish-ment of such i;:eraneters involves the asslltlption of some accepted band of risk which should be specified. While the ACRS is not opposed to removal of the Part 100 requirement for calculation of radiation doses or to the specification of regionally dependent acceptable population densities, the Committee believes these matters need in-depth evaluation.

Reconmendation 2 This recommendation proposes minimllll standoff distances for potential haz-ards (X)sed by man-made activities and natural characteristics. '!he Com-mittee believes that such a recommendation is appropriate but the list is incomplete.

For example, ING terminals are inclt.~ed but not LR:;.

Similarly, hazardous cargo on rivers is not mentioned.

In addition, the proposed approach lacks an adequate rationale for specific nlltlbers suggested. A distance of at least 12.5 miles from all cai;:eble faults, with no distinction as to fault size, is proposed, as is a specification that no reactor sites located on a flood plain should be closer than five miles downstream of a major dam.

'!he reason why either of these two proposed nt.l'll-bers is suitable is not clear to the ACRS.

For example, dans 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 pose significant de-sign pr-oblems.

It is noted that the recommendation does not provide standoff distances be-tween nuclear plants. '!he potential adverse influence of one plant on its neighbors in the event of a serious accident requires consideration in de-sign.

3556

Honorable John F. Ahearne 6 -

February 14, 1980 Reconmendation 3 This recamnendation would change Part 100 to require reasonable assurance that interdictive measures are possible to limit groundwater contamination resulting from Class 9 accidents. 1he ACRS supports the recanmendation.

However, the Committee notes that the current wording is subject to a range of interpretations which could include, for example, the necessity for de-veloping interdictive measures for particulate fallout or rainout that could result in gromidwater contamination. 1he Committee recanmends that the wording of the reccmnendation be made more explicit.

Reconmendation 4 This recanmendation 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.

However, in the discussion section, the Task Force recanmends that specific guidance be removed from Appendix A and placed in Regulatory Guides.

The ACRS agrees that the NRC criteria for seismic siting should be revised and perhaps expanded. 1his clearly will require changes in Appendix A.

'lhe ACRS believes that Regulatory Guides can be used to provide increased guid-ance on the interpretation and application of the criteria.

The ACRS has in the past 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 canments on the specific changes as they are developed and proposed. 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.

Reconnendation 5 This recanmendation relates to post-licensing changes in offsite activities but does not specify viat 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? 1his should be clarified. 1he recanmendation also does not specify wat is considered to be a *significant increase in risk.* Another consider-ation that might be taken into accomit is the nature and use of the land sur-romiding a site. \\\\bether neighboring land is used for residential or industrial purposes, and whether it is fertile land or a desert, could also be important.

3557

Honorable John February 14, 1980 Reconmendation 6 This recOlllllendation pertains to methods for compensating for wifavorable site characteristics. 'lbe Committee suggests that the Ii'lrase, *wifavorable characteristics requiring unique or unusual design,* be clarified. Many characteristics that are *unfavorable" can be readily canpensated 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, *1.mfavorable,*

and substituting the word, *unproven," for *1.mique or 1.musual *.

Recomnendation 7 This recommendation relates to the timing of site reviews. 'lbe ACRS sug-gests that this recommendation could be improved by substituting the word

• decision" for "approach" (in the third line).

Recomnendation 8 This recanmendation relates to the role of a state agency in approving a site for a nuclear power plant. 'lbe ACRS has no comments on this item.

Recomnendation 9 This recommendation is to develop canmon bases for canparing the risks from all external events. 'lbe ACRS supports the general concept and would, if practical, extend it to internal events as well. 'lbe Committee believes that this concept represents a good long range goal; however, recognizing the complexity of the task, the Committee recanmends that priority be given to those areas thought either to introduce the greatest risk or to provide the best opportunities for improvements in safety.

1be Committee will be pleased to discuss the above items with you if you de-sire. In the meantime, we trust these canments will be helpful to you and the NRC Staff.

3558 Sincerely, Mil ton s. Plesset Olairman