ML19310A473
| ML19310A473 | |
| Person / Time | |
|---|---|
| Issue date: | 05/15/1980 |
| From: | NRC COMMISSION (OCM) |
| To: | |
| References | |
| REF-10CFR9.7 NUDOCS 8006170800 | |
| Download: ML19310A473 (16) | |
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UNITED STATES OF AMERICA
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NUCLEAR REGULATORY COMMISSION,
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4 PUBLIC MEETING
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AFFIRMATION SESSION 80-22
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Nuclear Regulatory Commission i
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East West Towers Building 8
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Bethesda, MD.
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- Thursday, 15, 1980 og 10 i
3 The Commission met, pursuant to notice, at 3:20 p.m.
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BEFORE:
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JOHN F. AHEARNE, Chairman of the Commission d
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S JOSEPR M..HENDRIE,.Corhmissioner N..
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PETER A. BRADFORD, Commissioner 2
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NRC STAFF PRESENT:
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S. CHILK g
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ALDERSON REPORTING COMPANY, INC.
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3 (Whereupon, the recorded proceedings began at this gi.?
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MR. CHILK:
-- Considerations on the NEPA, the 3
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6 Commission by a three to two vote, with Commissioner Gilinsky e
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7 and Commissioner Bradford dissenting in part, approved the K
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Publication of a Federal Register notice containing a statement a
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9 of interim policy relative to accident considerations under NEPA.
10 The disagreements of Commissioners Gilinsky and Bradford will Ej 11 be noted in the Feder.al Register hotice.
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12 would you please affirm your votes?
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13 (There was a chorus of " Ayes.")
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mj 14 MR. CHILK:
SECY-80-53A or A-80-53, rather.
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15 Commission has unanimously approved an order which refers to g
16 an interlocutory motion from the Environmental Coalition on as y
17 Nuclear Power to the Safety and Licensing Appeal Board for E
18 appropriate action.
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.The Chairman asked for a report on LPDRs which will 8n 20_
be done by a separate action.
21 Will'you please affirm your votes?
22 (There was a chorus of " Ayes. ")
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MR. CHILK:
A-80-84.
The Commission has unanimously 24 approved a memorandum and order which denies a request of the Y::
25 Consumer Advocate of Pennsylvania to provide financial assistance ALDERSON REPORTING COMPANY, INC.
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g to interveners for retaining experts for the reasons contained
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in the o'rder.
Commission Bradford has filed a separate concurring 3
opihion with which Commissioner Gilinsky agrees with the points de 4
in that opinion.
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CHAIRMAN AHEARNE:
84 or 54?
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30-54.
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Would you please affirm your votes?
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(There was a chorus of " Ayes.)
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MR. CHILK:
A-80-58A.
The Commission has unanimously 2f h
10 approved a memorandum and order which makes it clear that the E
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11 Commission will not provide funds to the interveners to' plan
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taken in coordination with other ongoing safety related activities that are directly related to accident considerations in the areas of plant design, operational safety, siting policy, and emergency planning.
The Commission intends to continue the rulemaking on this matter when new siting requiremens and other safety related requirements incorporating accident considerations are in place.
DATES:
Comment period expires (date inserted to be 90 days after date of publication in the Fe'deral Register).
ADDRESSES:
The Commission intends the interim policy guidance contained
. herein to be immediately effective.
However, all interested persons who desire to submit written comments or ' suggestions for consideration in connection with this statement should send'them to the Secretary of the Commission, U.S. Nuclear Regulatory Commission, Washington, D.C. 20555, i
Attention:
Docketing and Service Branch.
FOR FURTHER INFORMATION CONTACT:
R. Wayne Houston, Chief, Accident Analysis Branch, Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington, D.C. 20555, Telephone:
(301) 492-7323.
4
- e SUPPLEMENTARY INFORMATION:
Accident Considerations in Past NEPA Reviews The proposed Annex to Appendix 0 of 10 CFR Part 50 (hereafter the " Annex")
was published for comment on December 1,1971 by the (former) Atomic Energy Commission.
It proposed to specify a set of standardized accident assumptions to be used in Environmental Reports submitted by applicants for construction pennits or operating licenses for nuclear power reactors.
It also included.a system of classifying accidents according to a graded scale of severity and probability of occurrence.
Nine classes of accidents were defined ranging fran. trivial to very serious.
It directed that "for each class, except classes 1 and 9, the environmental consequences shall be evaluated as indicated."
Class 1 events were not to be con-
'sidered because of their trivial consequences, whereas in regard to Class 9 events, the Annex stated as follows; "The occurrences in Class 9 involve sequences of postulated successive failures more severe than those postulated for the design basis for protective systems and engineered safety features.
Their consequences could be severe.. However, the probability of their occurrence is so small that their environmental risk is extremely low.
Defense in depth (multiple physical barriers), quality assurance for design, manufacture, and operation, continued surveillance and testing, and conservative design are all applied to provide and maintain the required high degree of assurance that potential accidents in this class are, and will remain, sufficiently remote in probability that the environmental risk is extrenely low.
For these reasons, it is not necessary to discuss such events in applicants' Environ-mental Reports."
A footnote to the Annex stated:
"Although this annex refers to applicant's Environmental Reports, the ' current assumptions and other provisions thereof are applicable, except as the content may otherwise require, to AEC draft and final Detailed Statements."
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During the public comment period that followed publication of the Annex a number of criticisms of the Annex were received.
Principal among these were the following:
(1)
The philosophy of prescribing assumptions does not lead to
. objective analysis, (2)
It failed to treat the probabilities.of accidents in any but the most general way, (3) 'No supporting analysis was given to show that Class 9 accidents are sufficiently low in probability that their consequences in terms of environmental risks need not be discussed, (4) No guidance was given as to how accident and normal releases of radioactive effluents during plant operation should be factored into the cost-benefit analysis, (5)
The accident assumptions are not generally applicable to gas cooled or liquid metal cooled reactors, and (6) Safety and environmental risks are not essentially different considerations.
The Commission took no further action on this rulemaking except in 1974 when 10 CFR'Part 51 was promulgated.
Over the intervening years the accident considerations discussed -in Environmental Impact Statements for proposed nuclear power plar.ts reflected the guidance of the Annex-with few exceptions.
Typically, the discussions of accident consequences through Class 8 (design basis accidents) for each case have reflected specific site characteristics associated with meteorology (the dispersion of releases of radioactive material into the atmosphere), the actual population within a fifty mile radius of the plant, and some differences between boiling water reactors (BWR) and pressurized water reactors (PWR).
Beyond these few. specifics,- the discussions have reiterated the guidance of the Annex and have relied upon the Annex's conclusion that the probability -
of occurrence of a Class 9 event is too low to warrant consideration, a conclusion based upon generally stated safety considerations.
With the publication of the Reactor Safety Study (WASH-1400), in draft
-fom in August'1974 and final fom in October 1975, the accident discussions in Environmental Impact Statements began to refer to this first detailed study of the risks associated with nuclear power plant accidents, par-ticularly events which can lead to the melting of the fuel inside a reactor.2 The references to this study were in keeping with the intent and spirit of NEPA "to disclose" relevant infomation but it is obvious that it did not fom the basis for the conclusion expressed in the Annex in 1971 that the probability of occurrence of Class 9 events was too low to warrant their (site specific) consideration under NEPA.
The Commission's staff has however, identified in certain cases unique circumstances which it felt warranted more extensive and detailed consid-eration of Class 9 events.
One of these was the proposed Clinch River Breeder Reactor Plant (CRBRP), a liquid metal cooled fast breeder reactor very different from the more conventional light water reactor plants for
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which our safety experience base is much broader.
In the Final Environmental Statement for the CRBRP,3 the staff included a oiscussion of the consideration it had given to' Class 9 events.
In the early site review for the Perryman site, the staff performed an in-formal assessment of the relative differences in Class 9 accident consequences among the alternative sites.
In the case of the application by Offshore Power Systems to manufacture floating. nuclear power plants, the staff judged that the environmental l
2It is of' interest that the Reactor Safety Study never refers to nor uses the tem " Class 9 accident" although it is commonly used loosely equivalent to a core melt accident.
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._, NOREG-0139,' February '1977.
risks of some Cass 9 events warranted special consideration.
The special circumstances were the potentially serious consequences associated with water (liquid) pathways leading to radiological exposures if a molten reactor core were to fall into the water body on which the plant floats.
Here the staff emphasized its focus on risk to the environ-ment but did not find that the probability of a core melt event occurring in the first place was essentially any different than for a land based plant.
In its Memorandum and Order In the Matter of Offshore Power Systems,4 the Commission has concurred in the staff's judgment.
- Thus, the Reactor Safety Study and our experience with these cases has served to refocus our attention on the need to reemphasize that environmental risk entails both probabilities and consequences, a point that while made in the publication of the Annex, was not given adequate emphasis.
In July 1977 the NRC commissioned a Risk Asse'ssment Review Group "to clarify the. achievements and limitations of the Reactor Safety Study."
One of the conclusions of this study, published in September 1978, as NUREG/CR-0400 " Risk Assessment Review Group Report'to the U.S. Nuclear Regulatory Commission," was that "The Rqview Group was unable to determine whether the absolute probabilities of accident sequences in WASH-1400 are high or low, but believes that the error bounds on those estimates are in general, greatly understated." This and other findings of the Review Group have also subsequently been referred to in Environmental i
Impact Sta.tements, along with a reference to tne Comission's policy statement on the Reactor Safety Study in light of the Risk Assessment Review Group Report, published on January 18, 1979.
The Commission's i
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- 0ccket No. STN 50-437, September 14 1979
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statement accepted the findings of the Review Group, both as to the Reactor Safety Study's achievements and as to its limitations.
A few Draft Environmental Statements have been published subseqt.ent to the Three Mile Island accident. These were for conventional land based light water reactor plants and continued to reflect the past practice with respect to accidents at such plants, but noted that the experience gained from the Three Mile Island accident was not factored into the discussion.
Our experience with past NEPA reviews of accidents and the TMI accident clearly leads us to believe that a change is needed.
Accordingly, the proposed Annex to Appendix D of 10 CFR Part 50, published on December 1,_1971, is hereby withdrawn and shall not hereafter be used by applicants nor by the staff for the following. reasons:
1.
The Annex proscribes consideration of the kinds of accidents (Class 9) that the reactor Safety Study found dominate the accident risk.
2.
The definition of Class 9 accidents in the Annex is not sufficiently precise to warrant its further use in Commission policy, rules and regulations, nor as a decision criterion in agency practice.
3.
The Annex's prescription of assumptions to be use'd in the analysis of the environmental consequences of accidents does not contribute to objective consideration.
4.
The Annex doe not give adequate consideration to the detailed treatment of measures taken to prevent and to mitigate the consequences of accidents in_ the safety review of each application.
The classification ef accidents proposed 9
. in that Annex shall no longer be used.
In its place the following interim guidance is given for the treatment of accident risk considerations in NEPA reviews.
Accident Considerations in Future NEpA Reviews It is the position of the Comission that its Environmental Impact Statements, pursuant to Section 102(c)(i', of the National Environmental Policy Act of 1969, shall include a reasoned consideration of the environmental risks (impacts) attributable to accidents at the particular facility or facilities within the scope of each such statement.
In the analysis and discussion of such risks approximately equal attention shall be given to l
the probability of occurrence of releases and to the probability of occurrence of the environmental consequences of those releases.
Releases refer to radiation and/or radioactive meter 1als entering environmental exposure pathways including air, water, and ground water.
Events or accident sequences that lead to releases shall include but not be limited to those that can reasonably be expected to occur.
In-plant
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accident sequences that can lead to a spectrum of releases shall be discussed and shall include sequences that can result in inadequate cooling of reactor fuel and to melting of the reactor core.
The extent l
to which events arising from causes external to the plant which are l
considered possible contributors to the risk associated with the particular.
i plant shall also be discussed.
Detailed quantitative considerations j
- that form the basis of probabilistic estimates of releases need not be incorporated in the Environmental Impact Statements but shall be referenced therein.
Such references shall. include, as applicable, reports on safety evaluations..
The environmental consequences of releases whose probability of occurrence has been estimated shall also be discussed in probabilistic terms.
Such-consequences shall be characterized in terms of potentia'l radiological exposures to individuals, to population groups, and, where applicable, to biota. Health and safety risks that may be associated with exposures a
to people shall be discussed in a manner that fairly reflects the current state of knowledge regarding such risks.
Socio-economic impacts that might be associated with' emergency measures during or following an accident should also be discussed. The environmental. risk of accidents should also 'be compared to and contrasted with radiological risks associated with normal and anticipated operational releases.
In promulgating this interim guidance the Commission is aware that ther'e are and will likely remain for some time to come many uncertainties in the application of risk assessment methods and it expects' that its Environmental Impact Statements will identify major uncertainties in its probabilistic estima'tes.
On the other hand the Commission believes that.
'the state of the art 'is sufficiently advanced that a beginning should
- now be made in the use of these methodologies in the regulatory process and that such use will represent a constructive and rational forward step in the discharge of its responsibilities.
It is the intent of the Commission in issuing this Statement of Interim Policy.that the staff-will ~ initiate treatments of accident considerations in accorda_nce with the foregoing guidance, in its on-going NEPA reviews, i.e., for any ~ proceeding at a licensing stage where a Final Environmental Impact Statement-has not yet been issued. These new treatments, which will take into account significant site and plant specific features, will result in more detailed discussions of accident risks than in previous environmental statements, particularly those related to conventional light water plants at land based sites.
It is expected that these revised treatments will lead to similar conclusions regarding the environmental risks of accidents as would be reached by a continuation,of current practices including cases involving special circumstances where Class 9 risks have been considered by the staff, as described above.
Thus, this change in policy is not to be construed as any lack of confidence in conclusions regarding the environmental risks of accidents expressed in any previously issued Statements, nor absent a showing of similar special circumstances, as a basis for opening, reopening or expanding any 1/
previous or ongoing proceedin'g7 However, it is also the intent of the Commission that the staff take steps to identify additional cases that might warrant early consideration of additional features or other actions to prevent or to mitigate the-consequences of serious accidents.
Cases for such consideration are those for which a Final Environmental Statement ~ has,already been issued at the. Construction Permit stage but for which the Operating License
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review ttage has not yet been reached.
In carrying out this directive, the staff.should consider relevant site features, including population density, associated with accident risk in comparison to such features at presently operating plants and,the likelihood that substantive changes in plant ~ design features which may compensate further for adverse site features may be more easily incorporated in those plants when construction has not yet progressed very far.
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Commissioners Gilinsky and Bradford disagree with the
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inclusion of the preceding _two sentences.
They feel that they are absolutely inconsistent with'an even-handed reappraisal of-the former, erroneous position on. Class.9 accidents.
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Environmental Rehrts submitted by applicants for construction permits and for operating licenses on or after July 1,1980 should include a discussion of the environmental risks associated with accidents that follows the guidance given herein.
Related Policy Matters Under Consideration In addition to its responsibilities under NEPA, the NRC also bears responsibility under the Atomic Energy Act for the protection of the public health and safety from the hazards associated with the use of nuclear er.crgy.
Pursuant to this responsibility we note that there are currently a number'of on-going activities within the Commission and its staff which intimately relate to the " Class 9 accident" question and either are the subject of current rulemaking or are candidate subjects for rulemaking.
On December 19, 1979 the Cominission issued for public comment 5 a proposed rule which would significantly revise its requirements in 10 CFR Part 50 for emergen'cy planning for nuclear power plants.
One of the considerations in this rulemaking was the potential consequences of Class 9 accidents in a generic sense.6 In August 1979, pursuant to our request, a Siting Policy Task Force made 1
recommendations to us with respect to possible changes in our reactor siting policy and criteria,7 currently set forth in 10 CFR Part 100.
As stated therein, its recommendations were made to accomplish (among others) the following goal:
544 F.R. 75167 6cf. NUREG-0396, " Planning Basis for the Development of State and Local Government Radiological Emergency Response Plans in Support of Light Water Nuclear Power Plants," November 1978.
'7NUREG-0625, " Report of the Siting Policy Task Force," August 1979. !
"To take into consideration in siting the risk associated with accidents beyond the design basis (Class 9) by establishing population _ density and distribution criteria."
This matter is currently before us.
-This and other recommendations that have been made as a result of the
. investigations into the Three Mile Island accident are currently being brought together by the Commis!
's staff in the form of proposed Action Plans.8 Among other matters these incorporate recommendations for rulemaking relatt:d to degraded core cooling and core melt accidents'.
We expect to issue' decisions on these Action Plans in the near future.
It is our policy and intent to devote our major resources to matters which we believe will make existing and future nuclear power plants safer, and to prevent a reoccurrence of the kind of accident that occurred at Three Mile Island.
In the interim, however, and pending completion of f
rulemaking activities in the areas of emergency _p.lanniig, siting criteria, and design and operational safety, all of which involve considerations of serious accident potential, we find it essential to improve our procedures for describing and disclosing to the public the basis for arriving at conclusions regarding the envir'onmental risks due to accidents at nuclear power plants.
On completion of the rulemaking activities in these areas, and based also upon the experience gained with this statement of interim policy and guidance, we intend to pursue possible changes or additions to 10 CFR Part 51 to codify our position on the role of accident risks under NEPA.
80raf t NUREG-0660, " Action Plans for Implementing Recommendations of the-President's Commission and Other Studies of the TMI-2 Accident," December 10, 1979.
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