ML20079E535
| ML20079E535 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 03/20/1980 |
| From: | Speth G COUNCIL ON ENVIRONMENTAL QUALITY |
| To: | Ahearne J NRC COMMISSION (OCM) |
| Shared Package | |
| ML20079E402 | List: |
| References | |
| FOIA-83-163 NUDOCS 8005210263 | |
| Download: ML20079E535 (24) | |
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EXECUTIVE OFFICE OF THE PRESIDENT COUNCIL ON ENVIRONMENTAI. QU AI.lTY 722 J ACKSoN PLACt. N. W.
wAsamaion, o. c. :ws March 20, 1980 The Honorable John Ahearne Chairman Nuclear Regulatory Cocnission Washington, D.C.
20555
Dear Chairman Ahearne:
Section 204(3) of the National Environmental Policy Act (NEPA) directs the Council on Environmental Quality "to review and appraise the various programs and activities of the Federal Covernment... for the purpose of determining the extent to which such programs and activities are contributing to the achievement of the policy (of NEPA]...." Last year, as part of the Council's overall effort to meet this responsibility, the Council initiated a study of the Nuclear Regulatory Commission's regulations and policy on the environmental analysis of possibic nuclear accidents under NEPA.
This letter contains the conclusions of our study.
We were assisted in this review by the Environmental Law Institute, which has prepared for us a report entitled "NRC's Environmental Analysis of Nuclear Accidents: Is It Adequate?", which I am providing to the Commission with this letter.
The Council believes the report constitutes an accurate and important assessment of the NRC's ' regulations and policy on the analysis of nuclear accidents in environmental impact statements.
The results of our review of impact statements prepared by the NRC for nuclear power reactors are very disturbing.
The discussion in these statements of potential accidents and their environmental impacts was found to be largely perfunctory, remarkably standardized, and uninformative to the public.
Despite the broad diversity of size, design, and location of the nuclear reactors licensed by the Commission over the years, virtually every EIS contains essentially identical, "boilerplate" language written in an unvarying format.
The typical EIS does not consider or analyze the possibility of a major accident even though it is these " Class 9" accidents which have the potential for greatest environmental harm and which have led to the greatest public concern.
Moreover, for those accidents which are typically discussed in an EIS, the potential impacts on human health and the environment are presented in a cursory and inadequate manner with little attention to public understanding.
Each EIS relies on the NRC accident analysis policy, which has remained essentially unchanged and in interim form since 1971, asserting that " correct manufacture, design, operation and quality assurance" will provide "a high degree of proteccion" against the occurrence of postulated accidents. A limited range of accidents with varying consequences are discussed.
Estimates of materials released from such accidents, or " release fractions," are provided.
However, based on the conclusion that it is highly improbable that serious accidents vill occur, the policy prohibits the discussion of certain-O severe accidents, the Class 9 events.
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n The accident analysis in the EIS for the Three Mile Island Nucicar Station, Units 1 and 2 (TMI), exemplifies the deficiencies of such a narrow approach to major accidents.
Not a single scenario for a Class 9 accident is pro-vided in the TMI EIS, yet as attested to by Commission staf f, a Class 9 accident occurred at TMI on March 28, 1979.
The reported releases of radio-activity from this accident have been low, but the TMI EIS failed to consider the range of possibilities suggested by the accident.
Typically, public comments, including those of other federal agencies, on the inadequacies of accident analyses in Draf t EISs receive NRC responses which simply reiterate the 1971 " interim" accident policy.
For example, the NRC response to a Department of Interior comment on the TML EIS vas as follows:
"The Interior Department suggests that a specific study of the consequences of a Class 9 accident at Three Mile Island, Unit No. 2 upon the Susquehanna River should be made.
The (NRC]
staf f disagrees with this view. A general discussion of Class 9 accidents has been given in the Reactor Safety Study.
The staff believes, in view of the remote possibility of occur-rence of a Class 9 cvent, that the environmental risk of such an event is acceptably low, and that generic discussion of these events are adequate."
The past failure to discuss the consequences of the full range of potential accidents and their effects undermines the basic purposes of the National Environmental Policy Act to inform the public and other agencies fully of the potential consequences of federal proposals and to provide a basis for informed decisions.
Over the years the public and federal agencies have repeatedly requested the AEC and NRC to consider the severe consequences of nuclear accidents in the context of the Commission's environmental licensing reviews.
These requests for full disclosure have been consistently rejected during this period, this Commission's September 14, 1979, decision in offshore Power Systems being a conspicuous and encouraging exception.
Given the increasing public concern regarding nuclear safety and the need to improve public confidence in nuclear regulation, we believe the time is ripe for the Commission to depart sharply from the inherited policy in favor of a new approach stressing full and candid discussion of accident risks.
The Council's assessment of the Commission's statutory obligations to discuss fully the environmental effects of nuclear accidents, including Class 9 accidents, is set forth in the attachment to this letter.
Based on our review, we do not believe that the Commission's prior legal justification for severely limiting the discussion of nuclear accidents and their consequences in EISs is any longer sustainable, assuming it ever was.
For both legal and policy reasons, we believe that the Commission must move quickly to revise _its policy on accident analysis in EISs. A completely new policy, preferably involving a rejection of the existing accident classification system, should be adopted.
For these reasons, we commend the Commission for the important steps it has recently taken toward revising its policy in this
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- aren, especially your decision in of fshore Power Sy_ stems to hold a public rulemaking and to reexamine NRC policy on the inclusion of major accidents in EISs. We are also pleased to note that in the preamble to its proposed NEPA procedures the Comission has indicated that "this reconsideration of policy may result in adoption of dif ferent practices with regard to ' worst case' accidents at nuclear power reactors." 45 Fed. Reg. 13739, 13742 (Ma rch 3,1980).
We believe that the new policy should be based on the sensibic approach of discussfug the environmental and other consequences of the full range of accidents,that might occur at nuclear reactors, including accidents now classified,as Class 9.
'Ihis should include core melt events.
In addition, j
EISs should present the best estimates of the likelihood of such events.
In order to comply with the disclosure requirements of NEpA, the NRC should include in the analyses the likely range of environmental and oth'er conse-1 quences from severe and other accidents.
In describing reactor accidents and their possible effects in impact statements, the NRC should follow closely the relevant provisions of the Council's NEPA regulations, including the following provision on " worst case" analysis:
I "If... the information relevant to adverse impacts is important to the decision and the means to obtain it are not known (e.g., the means for obtaining it are beyond the state of the art), the agency shall weigh the need for the action against the risk and severity of possible adverse impacts were the action to proceed in the face l
of uncertainty.
If the agency proceeds, it shall include a worst case analysis and an indication of the probabili-ty or improbability of its occurrence." 40 C.F.R. S 1502.22(b)(1979).
The enclosed report suggests eight possible accident scenarios', with certain caveats, for consideration by the Commission for use in its EISs.
They have been selected because they " span the range of likely consequences" of severe nuclear events.
We believe that the use of such analyses could improve the Commission's siting, design, licensing and emergency planning decisions.
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We also urge the Commission to broaden its range of variables (e.g., radia-tion pathways) in determining accident impacts, and expand its discussions in EISs of the. impacts of nuclear accidents on human health, the natural environment and local economics.
Site specific treatment of data should be substituted for "boilerplate" assessment of accident initiating events and potential impacts, and EISs should be comprehensible to non-technical members of the, public.
Finally, the Commission should pursue the approach described here vigorously in order to fulfill to the fullest extent possible the requirements of NEPA and the Icgitimate public interest in full disclosure of nuclear plant hazards.
The Commission at a minimum should apply the approach described here to pro-ceedings where impact statements have not yet been issued.
We also encourage the Commission to consider preparing supplemental accident analyses for plants currently licensed for operation, particularly for those located near high population centers and those with unique features suggesting higher risk.
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-4 I would 'be pleased to discuss the Council's views with you at any time.
Please let me know how we can be of assistance to you in moving forward in thi.' important area.
Sincerely,
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Members of the Couunission W
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A_TTAChHENT This attachment analyzes the adequacy under the existing law of the present AEC/NRC policy on discussing nucicar accident impacts in environmental impact statements.
NEPA's Mandate For Full Disclosure Under Section 102 of NEPA Congress has directed that
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1) 2)
all agencies of the Federal Government shall -
(C)
Include in every recommendation or report on pro-posals for legislation and other major Federal actions significantly affecting the quality of the human environment, a detailed statement by the responsibic official on -
(i)
The en ronmental impact of the proposed action As recognized by the United States Court of Appeals for the District of Columbia Circuit, "the sweep of NEPA is extraordinarily broad, compelling consideration of any and all types of environmental impact of federal action."
Calvert Cliffs' Coordinating Comm. Inc. v. Atomic Energy _
Commission 449 F.2d 1109,1122 (D.C. Cir. 19/1), cert. denied 404 U.S.
942 (1972).
Thus, NEPA requires Federal agencies to assess more than simply the probabic impacts of their proposed actions.
Environmental impact statements required by Section 102(2)(C) must, at a minimum, contain adequate information to alert the public and Congress to all known possible_ environmental consequences of proposed agency action." Environ-mental Defense Fund v. Corps of Engineers, 325 F. Supp. 749, 759 (E.D.
Ark. 1971) (emphasis in the original).*
Indeed, one of NEPA's prominent See also Sierra Club v. Frochlke,.486 F.2d 946, 951 (7th Cir.,
1973); Hanly v. Kleindienst, 471 F.2d 823, 836 (2d Cir,1972),
cert. denied 412 U.S. 9081(1973) (agency must consider the increased risk of crime that might result from operation of correctional center and the impacts from "the possible existence of a drug-maintentance program."); Appalachian Fountain Club v. Erinegar 394 F. Supp. 105, 114 (D. N.H. 1975); NRDC V. Grant. 355 F. Supp. 280, 286 (E.D. No. Car.1973); Brooks v. Volpe, 350 F. Supp. 269, 276 (W.D. Wash,1972) af f'd 487 F.2d 1344 (9th Cir.,1973)
Conservation l
Council of No. Carolina v. Frochlke. 340 F. Supp. 222, 225 (M.D.
No. Car.1972); Izaak Walton 1.cague of America v.
Schicsinger, 337 F. Supp. 287, 294 at n. 26 (D.D.C. 1971); accord, Monroe County Council, Inc. v. Volpe, 472 F.2d 693, 697 (2d Cir. 1972).
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'responsibic scientific opinion concerning possible adverse environmental affects'" even where such opinion "is contrary to the official agency position.
Committee for Nuclear Responsibility; Inc. v. Seaborg, 149 U.S. App. D.C. 380, 463 F.2d 783, 787 (1971)." Natural Resources Defense Council v. U.S. Nucicar Regulatory Comminsion, 547 F.2d 633, 645 (D.C. Cir.,1976), reversed on other grounds sub nom. Vermon_t Yankee _
Nuclear Corporation v. Natural Resources Defense Council, 435 U.S. 519 (1978).
As indicated by the Second Circuit, the study and "considera-tion of special hazards to the public health, safety and welfare are vital to g impact statement, and numerous statements have been over-turned for their failure to address these questions." Natural Resources
_ Defense Council v.
_U.S. Nuclear Regulatory Commission, 539 F.2d 824, 843 (2nd Cir., 1976), petition for rehearing denied, F.2d
, 9 ERC 1414, vacated and remanded for consideration of mootness sub nom.
Allied General Nuclear Services v. Natural Resources Defense Council, 434 U.S. 1030 (1977) (emphasis in original).
The Council's interpretation of this mandate under NEPA is codified in its regulations, which are binding on all federal agencies.
E.O. 11991 (May 24, 19 7 7) ; 40 C. F. R. 5 1500.3.
The regulations contain a special provision for situations in which information is incomplete or unavailable:
"When an' agency is evaluating significant adverse effects on the human environment in an environmental impact statement and there are gaps in relevant information or scientific uncertainty, the agency shall always make cicar that such information is lacking or that uncertainty exists.
(a)
If the information relevant to adverse impacts is essential to a reasoned choice among alternatives and is not known and the overall costs of obtaining it are not exorbitant, the agency shall include the information in the environmental impact statement.
(b)
If (1) the information relevant to adverse impacts is essential to a reasoned choice among alternatives and is not known and the overall costs of obtaining it are exorbitant or (2) the information relevant to adverse impacts is important to the decision and the means to obtain it are not known (e.g., means for obtaining it are beyond the state of the art), the agency shall weigh the need for the action against the risk and severity of possible adverse impacts were the action to proceed in the face of uncertainty.
If the agency proceeds, it shall include a worst case analysis and an indication of the probability or improbability of its occurrence." 40 C.F.R. 5 1502.22 (1079).
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" The Council was created by NEPA and charted with the responsibility to review and appraise programs and activities of the Federal Covernment and to make appropriate recommendations in light of the policy set forth under the Act.
Andrus v. Sierra Club, _
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_, 47 ti.S.L.W. 4676, 4679 (June 11, 1979).
Accordingly, the Supreme Court has ruled that the Council's interpretations of NEPA are " entitled to substantial deference."
Id.
Thus, under NEPA, interpretative cases, and the Council's interpretative NEPA regulations, one of the NRC's most important obligations is to present "to the fullest extent possible" (5102) the spectrum of nucicar accidents that may result from NRC actions and the details of their potential consequences for the human environment.
The NRC's responsi-bilities under the Act are further discussed below.
The Cocnission's Policy on Class 9 Accidents and the Need For Revision The longstanding policy of the AEC and the NRC in the NEPA phase of its licensing proceeding has been not to consider " Class 9 accidents",
meaning those events with severe consequences that have low probability of occurrence.
The Commission's existing regulations regarding the content of EISs require staff to discuss only "the probable impact of the proposed action on the environment."
10 C.F.R. 5 5 51.23(a) and
- 51. 20(a)(1) (1979) (emphasis added).
Based on what staff perceives to be
" low risk", the Commission does not require Class 9 accidents to be discussed in either applicants' Environmental Reports or staff's EISs.
Such severe accidents are required to be discussed, however, in applicants' safety analysis reports.
10 C.F.R. 50.34 (1979).
This policy was first propounded in an Atomic Energy Commission directive to applicants, dated September 1,1971 (Appendix C to the enclosed report).
The directive explained how the types of accidents included in applicants' safety analysis reports were to be handled in applicants' environmental reports.
Subsequently, the Commission made the policy applicable to staff EISs as well.
36 Fed. Reg. 22851, n. 1, December 1, 1971.
The Commission believed that in the " consideration of the environ-mental risks due to postulated accidents, the probabilities of their occurrence and their consequences must both be taken into account.
It is not practicable to consider all possible accidents.
.. " The directive concluded that "The highly conservative assumptions and calculations legitimately used for safety evaluations are not suitable for environmental risk evaluation, because the probability of occurrence is so low for the unfavorable combinations of circumstances used.
For this reason, Class 8 events are to be evaluated realistically, and will have consequences predicted in this way that are far less severe than those given for the same events in Safety Analysis Reports, using conservative evaluations.
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The occurrences in Class 9 involve sequences of postuinted succ fa,ilures more severe than those postulated for the design basi essive protection systems and engineered safety features.
s for could be severe.
Their consequences so small that their environmental risk is extremely lowHov ve Based on anticipated efforts to assure quality of design and operation the directive concluded that
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" potential accidents in this class are, and will remain remote in probability that sufficiently For these reasons, the environmental risk is extremely low.
Environmental Reports."it is not necessary to discuss them in Applicants' The enclosed report demonstrates how the existing NRC policy o accidents originated from decisions hastily made in the early 1970s n Class 9 without. credible scientific support.
AEC staff for the Commission in immediate response to the de i iThe origina Calvert Cliffs' Coordinating Committee.
c s on in Inc. v. AEC, supra.
The staff's probabilities for each class of accidents discussed in the directive were not based on the then-existing accident risk assessment studies prepared by the AEC.*
staff, the conclusions in the directive regarding the consider tiEve Class 9 cvents could not have been based on those documents a on of failed to estimate probabilities of large nuclear accidents since they
- result, virtually non-existent.the record in support of the policy on accident analysi As a s was More recently, another attempt was made to quantify accident ties for reactors -- the Reactor Safety Study probabili-1975).
, WASH-1400 (October, Lewis' Risk Assessment Review Group initiated by the NRCH Group concluded that WASH-1400 did not adequately indicate th The Lewis extent of the consequences of reactor accidents; e full probability; and that the WASH-1400 bounds of error that it failed to of accident sequence probabilities were greatly underestimated of to these uncertainties critical gaps are present in th In addition pertaining to nucicar accident analysis.
e NRC's information Recently, H.W. Lewis, the Icast identified for the Commission the relative importan a at accident types.
follow-up research effort.Unfortunately, this had not resulted in the appropriate various Quoting from his Croup's report, Lewis stated
"'For example, WASH-1400 concluded that transi
[ loss-of-coolant accidents] and human errors are important con ents, small LOCA tributors to overall risk, yet their study is not adequat reflected in the priorities of either the research or regulatory ely groups.'
These three items - transients, small less-of-coolant Mile Island accident." accidents and human errors - were the ce Scientific American (March 1980), p. 64.H.V. Lewis, "The Safety of Fission Re l
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C RASH-740 (March,1957) was the first study carried out by th to assess nuclear power plant risk.
e AEC issued in 1965.
An update of VASH-740 was
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-S-Technical and len.'1 weaknesses in the policy's foundation, discussed more fully in the ELI report, would of themselves require a change in
'the NRC's stand on accident analysis.
However, new develouments make the need for a policy revision even voro compelling.
Significantly, the NRC staff found that:
"the accident at Three Mile Island Unit 2 involved a sequence of successive failures (i.e., small-break loss-of-coolant accident and failure of the emergency core cooling system) note severe than those postulated for the design basis of the plant.
Therefore, we conclude that the acciden: at Three Mile Island was a Class 9 event."
tiatter of Public Service Electric and Gas Co. (Salem Nucledr Generating Station, Unit 1), Decket 50-272, NRC staff response to question no. 4 of the Atomic Safety and Licensing Board" at,3 (emphasis added).
The President's Commission on the accident at Three Mile Island made the further finding that
"... ti c probability of occurrence of an accident like that at Three Mile Island was high encugh, based on WASH 1400, that since there had been more than 400 reactor years of nuclear power plant operation in the United States, such an accident should have been cxpected during that period."
Report of the President's Commission on the Accident at Three Mile Island 32 (1979) (emphasis added).
Clearly the realities of Three Mile Island warrant a prompt reexamination of the Commission's narrow policy on accident analysis.
In the Commission's Memorandum and Order dated September 14, 1979 (In the Matter of Of fshore Power Systems, Docket No. STN 50-437), it determined that the potential consequences of a Class 9 accident at a floating nuclear power plan (FNP) should be considered in the context of the Commission's NEPA review of the application to deploy FNPs.
Phile the Commission did not express any definitive views on the need for the i
environmental consideration of Class 9 accidents at land-based reactors, it did declare its concern about that question and its intention to reexamine Commission policy and to complete the r,ulemaking begun in 1971.
Id. at 9.
In so doing, the Commission held that-it was not bound
+ by the policy on accident analysis formulated under 'the AEC.
Ijl. at 4, 7.
The Commission. ruled that "we are free to decide on the basis of the-facts known to us today whether the Licensing Board should be allowed to consider the environmental consequences of a Class 9 accident at the FNPs which Offshore proposes to manufacture.". Id. at 7.
The Commission recognized that NRC staff had aircady prepared a report on -the environ-uental consequences of a Class 9 accident at an FNP.
t-The Commission's formulation of the issue is most significant.
It determined that the question before it was whether it wished "to order the Licensing Board to blind itself" to the information in the staff report.
Id. at 7.
The Commission concluded that under NEPA's full
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Id. at 8.
- Earlier, the Appeal Board had acknowledged "that the NEPA mandate to study the environmental consequences of major federal actions to the fullest extent possible supported a policy of deciding open questions in favor of considering matters of potential environmental significance."
Id. at 6, citing 8 NRC 194, 220-21 (1978).
Just as the Commission recognized that it could not blind its Licensing Board to the available information on Class 9 accidents at FNPs, neither should the Commission blind itself to similar in' formation on the consc-quences of Class 9 accidents at land-based nucicar reactors.
The potential consequences of a Class 9 accident at either type of facility would be of such a magnitude that they must be given consideration under NEPA.
In view of the questionable basis for the NRC's Class 9 policy and the strong policy of the Atomic Energy Act that the NRC act to protect fully public health and safety, revision of the Commission's policy and regulations ought to be undertaken consistent with the provisions of the Atomic Energy Act of 1954, as amended.
Under the Act, Congress specifi-cally determined that the utilization of special nuclear material "must be regulated in the national interest and in order to provide for the common defense and to protect the health and safety of the public." 42 U. S. C. 5 2012(d).
Likewise, utilization facilities, such as nucicar reactors, have been found by Congress to require regulation to protect the health and safety of the public." 42 U.S.C. 5 2012(e).
With respect to license applications, the Act provides in part that the Commission require the development of such information as is necessary "to enable it to find that the utilization or production of special nuclear material will be in accord with the common defense and security and will provide adequate protection to the health and safety of the public.
42 U.S.C. 5 2232(a).
The Commission is further authorized to require new information at any time during the life of an operating license "to determine whether a license should be modified or revoked."
Id.
These provisions are, of course, supplemented by NEPA's requirements.
Calvert Clif fs' Coordinating Committee v. AEC, supra at 449 F.2d 1112; 42 U. S.C. 5 4335.
Among other requirements NEPA provides that "it is the continuing responsibility of the Federal government to use all practical means, consistent with other essential considera-tions of national policy, to approve and coordinate federal plans, functions, programs, and resources to the end that the Nation may.
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, undesirable and unintended consequences." 42 U.S.C.
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(b) (3) (emphasis added).
The NRC is unde'r a legal obligation to exercise its statutory powers in furtherance of these and the other provisions of the Act.
Public Service Co. of New Hampshire v. _ Nuclear Regulatory Commission, 582 F.2d 77 (lat Cir. 1978), cert, denied 439 U.S.
1046.
UEFA's requirement that federal agencies strive to attain the videst range of beneficial uses of the environmeat without risk to health or safety or other undesirable or unintended consequences (5101(b)(3)) is equally as rigorous a standard as that created under the Atomic Energy Act.
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. Considerations Under NEPA" FEDERAL REGISTER NOTICE Nuclear Pcwcr Plant Accident Considerations Under the National Environmental Policy Act of 1969 AGENCY:
U.S. Nuclear Regulatory Cemission ACTION:
Statement of Interim Policy SL9 MARY:
The Nuclear Regulatory Comission is revising its policy for considering the more severe kinds of very low probability accidents that are physically possible in environmental impact assessments required by the National Environmental Policy Act (NEPA).
Such accidents.are cemenly referred to as Class 9 accidents, following an accident classification scheme proposed in 1971 for purposes of implementing NEfA.I The March 28, 1979 accident at Unit 2 of the Three Mile Island nuclear plant has.
cmphasized the need for changes in our policies regarding the considerations to be given to serious accidents from an environmental as well as a
. safety point of view.'
This stateme'nt of intarim policy announces the withdrawal of the preposed Annex to Appendix D of 10 CFR Part 50 and th'e suspension of the rule-making proceeding that began with the publication of that proposed Annex on December 1,1971.
It is the Ccmission's position that its Environmental Impact Statements shall include considerations of the site specific environmental impacts attributable to accident sequences that lead to releases of radiation and/or radioactive materials, including sequences that can result in inadequate cooling of reactor fuel and to melting of the reactor core.
In this regard, attention shall be given both to the probability of occurrence of such releases and to the environmental consequences of such releases.
This statement of interim policy is I
Proposed ? an Annex to 10 CFR Part 50, Apoendix 0, 36 F.R. 22851.
The Ccmission's NEPA-imolementing regulatiens were subsequently (July 18, 1974) revised and recast as 10 CFR Part 51 but at that time the Ccmission noted that "The Pr: posed Ancex is still under c:ns i de ra tion... " 39 F.R. 25279.
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taken in coordination with other ongoing safety related activities that are directly related to accident ccnsiderations in the areas of plant The design, operationa, safety, siting policy, and emergency planning.
1 Commission intends to continue the rulemaking on this matter when new siting require.aens and other safety related requirements incorporating accident considerations are in place.
Com.ent period expires (date inserted to be 90 days after date DATES:
of publication in the Fe'deral Register).
ADDRESSES _: The Commission intends the interim policy guidance contained
. herein to be immediately effective.
Hewever, 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 Ccmmission, Washington, D.C. 20555, Attention:
Docketing and Service Branch.
FOR FURTHER INFORMATION CONTACT:
R. Wayne b'ouston, Chief, Accident Analysis Branch, Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory Commissicn, Washington, D.C. 20555 Telephone:
(301)492-7323.
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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 ccament on December 1,1971 by the (former) Atcmic Energy Ccmmission.
It proposed to spe' ify a set of standardized accident c
assumptions to be used in Environmental Reports submitted by applicants for construction permits 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 from. trivial to very serious.
It directed that "for each class, except classes 1 and 9, the environ.nental 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 extrenely 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 extremely 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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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) fio supporting analysis was given to show that Class 9 accidents are sufficiently low in probability that their consequences in tenus of environmental risks need not be discussed, (4)' 'to guidance was given as to how accident and normal releas !s 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 plants reflected the guidance of the Annex I
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. specifies, the discussions have reiterated the guidance of the Annex 'and have relied upon the. Annex's conclusion that the probability
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of occurrence of a Class 9 cvent 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 fona in August 1974 and final fonn in October 1975, the accident discus ti t
in Environmental Impact Statccents 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 in i
and spirit of NEPA "to disclose" relevant information but it is obvious that it did not fonn the basis for the conclusion expressed in the Annex in-1971 that the probability of occurrence of, Class 9 cvents was too.lc to warrant their (sita specific) consideration under NEPA.
i The Comission's staff has however, identified in certain cases unique circumstances which it felt warranted more extensive an i
One of these was the proposed Clinch River eration of Class 9 events.
Breeder Reactor plant (CRERP), a liquid meD1 cooled. fast bree very different from the more conventional light, water reactor plants In the Final Environmental which our safety experience base is much broader'.
Statement for the CRBRP,3 the staff included a discussion of the c f
it ha'd given to Class 9 events.
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IntheearlysitereviewforthePerrymansite,thesNaffperformedanin-
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fonnal assessment of the relative differences in Class 9 accident conse among the alternative sites.
(SECY-78-137) 1 In the case of the application by Offshore Power Systems to manufac floating nuclear power plants, the staffJudged that the environme It is of interest that the Reactor Safety Study ne i
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Z to a core melt accident.
x 3NUREG-0139, February 1977.
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(1 of occurrence of a Class 9 cvent is tea idw to warrant consideration, a conclusion based upon generally stated safety considerations.
With the publication of the Reactor Safety Study (WASil-1400), in draft '
fona in August 1974 and final fann 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-s 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 information but it. is obvious that it did not fonn the basis for the conclusion expressed in the Annex in 1971 that the probability of occurrence of' Class 9 events was too.lcw to warrant their (site specific) considera. tion 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 cvents.
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 r
which our safety experience base is much broader.
In the Final Environmental Statement for the CRBRP,3 the staff included a discussion of the consideration it had given to Class 9 events.
In the early site review for the Perryman site, the~ staff performed an in-fannal 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 nit isjof sinterest that the Reactor Safety Study never refers to nor uses
<,, the te'rm " Class 9 accident" although it is cormonly used locsely equivalent
' to a ' core. melt accident.
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N0 REG-0139. Febpary 1977.
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The risks of some Class 9 cvents warran'ted 'special consideration.
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were the potentially serious consequences 7
special circumstances associated with w'ater (liquid) pathways leading to radiological exposures if a molten reactor core were to fall into the water body on which the plani. floats. Here the staff emphasized its focus en risk to the enviren-r.:ent 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 i*.s Memorandum and Order In the Matter of Offshore Power Systems.4 the Comission-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 Assessment Review Group "to clarify the Echievements 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. Mbclear Regulatory Comission," was that "The Review Group was unable to determine whether the absolute probabilities of accident sequences in WASH-1400 l
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 Impact Statements, along with a reference to the comission's policy l
statement on the Reactor Safety Study in light of the Risk Assessment Review Group Report, published on January 18, 1979. The C: mission's j
Docket No. STN 50-437, September 14, 1979 t
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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 limitaticns.
A few Oraft Environmental Statements have been published subsequent 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 acdidents at such plants, but noted that the experience gained from the Three Mile Island accident was not factored into the discussion.-
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Our experience with past NEPA reviews of accidents and the TMI accident i
' clearly leads us to believe that a change is needed.
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Accordingly, the proposed Annex to Appendix 0 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 acr.idents in the Annex is not sufficiently precise to warrant its further use in Commission policy, rules and reculations, nor as a decision criterion in agency practice.
3.
The Annex's prescription of assumptions to be used 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
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consequences of accidents in the safety review of each application.
The c'lassification of accidents proposed '
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('i in that Annex shall no longer be used.
In its place the'folicwing 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)'a'ttributable to accidents at the particular facility or.
facilities within the scope of each such statement.
In the ana1ysis and discussion of such risks approximately equal attention shall be given to 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 materials 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-p1' ant 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 tne reactor core.
The extent to which events arising from causes external to the plant which are censidered possible contributors to the risk associated with the particular plant sha11. also be discussed.
Detailed quantitative considerations-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.
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The environmental consequences of releases whose probability of occurrence
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has been estimated.shall also be discussed in probabilistic tems.
Such consequences shall be characterized in terms of potential radiological exposures to individuals, to population groups, and, where applicable, to biota. Health and safety risks that may be associated with exposures to people shall be discussed in a canner 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 nennal and anticipated operational releases.
In premulgating this interim guidance the Comnission is aware that there are and will likely renain 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 Comaission 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 respons'ibilities.
It is the intent of the commission in issuing this Statement of Interim policy.that the staff will initiate treatnents of accident considerations in accordance with the foregoing guidance, in its on-going NE?A 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 ac ount significant site and plant specific features, will result
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o in more detailed discussicns 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 tr'eatments 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 censidered by the staff, as described above.
Thus, thi:
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 proceedins 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 Co'nstruction Pennit stage but for which the Operating License
,, review stage has not yet been reached.
In carrying out this directive, the staff should consider relevant site features, including population de'nsity, associated with accident risk in comparison to such features at presently operating plants and,the likelihood that substantive changes
' n plant design features which may compensate further for adverse site i
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 forraer, erroneous position on class 9 accidents.
10
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O Environmental Reports submitted by applicants for construction permits and for operating licenses on or after July 1,19S0 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 'undcr.NEPA, the NRC also bears responsibility under the Atomic Energy Act for the protection of the public heaith and safety from the hazards associated with the use of nuclear energy. Pursuant to this responsibility we note that there are currently a number of on-going activities within the Cocraission and its staff which intimately relate to the " Class 9 accident" question and either are the subject of current rulemaking or a're candidate subjects for rulemaking.
On December 19, 1979 the Ccmission issued for public comment 5 a p.roposed rule which would significantly revise its requirements in 10 CFR Part 50 for emergency planning for nuclear power plants.
One of the considerations in this rulemak'ing 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 recomendations 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 recomendations were made to accomplish (among others) the following goal:
'44 F.R. 75167 6cf. NUREG-0396, " Planning Basis for the Development of State and local Government Radiological Emergency Response Plans in Supporc of Light Water Nuclear Power Plants," November 1978.
7NUREG-0525, " Report of the Siting Policy Task Force," August 1979.
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"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.
Th.is and other recommenda tions that have been cade as a ' result of the investigations into the Three Mile Island accident are currently being brought together by the Commissien's staff in the fom of proposed Action Plans.8 Among other matters these incorporate reccmendations for rulemaking related to degraded core cooling and core melt accidents'. We expect to issue' decisions on these Action Plans in fhe near future.
I t, is our policy and intent to devote our major resources to matters which we believe will make existing and future nuclear pcwer plants safer, and to prevent a reoccurrence of the kind of accident that occurred at Three Mile Island.
In the interim, however, and pendi,ng completion of
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rulemaking activities in the areas of emergency planning, 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 environmental 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.
SDraft NUREG-0660, " Action Plans for Ieplementing Recocmendations cf the President's Cocaission anc Other Studies of the TMI-2 Accident," December 10, 1979.
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