ML20030B822

Requests That Util Consider Class 9 Accidents in Environ Rept

ML20030B822
Person / Time
Site:	05000599, 05000600
Issue date:	08/10/1981
From:	Tedesco R Office of Nuclear Reactor Regulation
To:	Delgeorge L COMMONWEALTH EDISON CO.
References
NUDOCS 8108240290
Download: ML20030B822 (5)

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AUG 101981 DISTRIBUTION:

Docket Fi E J. Wilson Docket Nos. : 50-599 and 50-600 SSPB Reading NRC PDR

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1 NSIC Ar. Louis 0. DelGeorge

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Director of Nuclear Licensing TIC Commonwealth Edison Comrany ACRS (16)

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Dear Mr. DelGeorge:

L. Tremper I ~

Subject:

Class 9 Accident Analysis in the Carroll County Envir Report The Commission's Statement of Interim Policy dalc

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the reactor cDre. In this ret std. htien.on shall be Fnen both to the ::robab:!ity of occurrence of such re: cases and to the environmental consequences of such releases.This statement of interim

. policy is ta'aen ir+ coord: nation with other ongoing safety-related activities l

that av directly re?ated to accident I

ccesiderations in the areas of piant design.operationa' safety sitmg policy.

and eme gency planning The l

Commissienintends to contime the rulemakinF on this matter w'.en new t

siting requirements and other safety related requirements incorporatmg accident consideratiens are in place.

oArts: This statement of mienm policy f

is effectne June 13.1980 Comment

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penod expires September 11.1980.

I-10 CFR Parts 50 and 51 AcoatssEs:The Commissien intends the mienm policy guidance contained l

Nuclear Pcwer Plant Accident herein to be immediately etfectn e.

l Considerations Under the National However, allinterested persons who Environmental Policy Act of 1969 desire to submit written comments or suggestions for consideration in a cancy: U.S Nuclear Regulatory connection with this statement should Commission send them to the Secretary of the AcTiow: Statement of Interim Policy.

Commission. U.S. Nuclear Regulatory sUMM ARY:The Nuclear Regulatory Commission. Washington. O C. 20555.

Commission (NRC) is resising its policy Attention: DocketmF and Service for considering the more sesere kinds of Branch.

sery low probability accidents that are Pon FUnrMan woauario= CONTACT:

physica!1y pessib,ie in environmental R. Wayne Houston. Chief. Accident impact assess.nents required by the Evalua' tion Branch Office of Nuclear National Environmental Policy Act Reactor Regulation. U.S. Nuclear (NEPA). Such accidents are commonly Regulatory Commission. Washington.

referred to as C!m o wrihnu D.C. 20555. Telephene: (301) 492-73:3.

following an accicent classificaIion SUPPLEMENTARY thronM ATION:

scheme proposed by the Atomic Energy Commission (predecessor to NRC) in Accident Considerations in Past NEPA

• v.1 for purposes ofimplementing g, y;,,,

NEPA.'The March 28,1979 accident at Umt 2 of the Three Mile Island nuclear The proposed Annex to Appendis D plant has emphasized the need for of to CFR Part 50 (hereafter the changes in NRC policies regarding the

" Annex") was pubbshed for comment considerations to be given to serious on December 1.1971 by the (former) ace dents from an environmental as weh Aiemic Energy Commimon. It proposed as a safety pnint of view.

to specify a set of standardized accident This statement ofinterim policy assumptions to be used in announces the witharawal of the Environmental Reports submitted by proposed Arnex to Appendix D of to applicants for cons'ruction permits or CFR Part 50 and the suspension of the operating licenses for nuc! ear power rulemaking proceeding that began with reactors. it also included a sistem for the publication of that proposed Annex classifying accidents acccrding to a on December 1.1971. !t is the graded scale of seserity and probability l

Commission's position that its of occurrence.Nine classes of accidents, Envirrnmentallmpact Statements shall were defined. ranging from trivial to l

include considerations of the site-sery serious. It directed that "for each specific environmentalir pacts class. except classes 1 and 9. the attributable to accident sequences that environmental consequences shall be evaluated as indicated." Class 1 events

' Proposed as en Annes to to CTR Pari so.

were not to be considered beCause of Appad>> Das n ::ssi m comnnu.on. mA' their trivial conseSuences. whereas in imp'.ementing regu!. lions were subsequently tjuly regard to C!ais 9 esents, the Annex is. tro re...e3.nd rec. i.. so cra P.,i si boi an e.ii e the c-i..on no.ed thei"The Prorosed stated as follows:

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x. m.ce 9.n : o,e pesMawd im trie rt uturs iBWR' and pressurged water occur 9n;in the y' place was, s qn Ms f.e pmtectae sp:=rr.s and reactors (iWR). Beycnd these few q.ree ed safety featares.Their specifics. th.e d.scussians have essentiaQ ary Merent inag m, n6 consgem.es r.vid Le sesere. Hc aever, the retterated the guidance of the Annes h88'dP8"I38d'M** #""" * ""d I

pruab:.m of the. oc:grrence is so small and have relied upon the Annex's Order In the Matter of Of: snore rewer trat.ther eruron.?en ai rism is e ntrerne!)

conclusion that de probability of g

low' f* lense sn depth Imalt@le physical occurrence of a Class 9 esent is too Iow gg ba:9ers) cuahty aparance for ces.gn.

to warrant consideration. a con,clusion -

g manufacture. and operat.on. conunued F

suneaance and testing and conservatne based upon generally stated safety these cases has served to refocus desyn are all apphed to provide and considerations.

atuation on ine need to ree tphasize maintam the reqJred h:gh degree of With the publication of the Reactor that envtrenmental risk entails both asurance inat p-w:a; accidents in this Safety Study (WASH-1400). in draft prchabMn and consequences a point c! ass are. and will remam. sufucient;y remote form in AuFust 1974 and rmal form in that was made in the publication of the m pri::abdity that the environrnentai nsk is October 1975, the accident d:scussions Annex. but was not given adequate nEen Idiscus si 1 eEenh in EnvironmentalImpact Statements e

a s began to refer to this first detailed study 9-the NRC commissioned a apphcanis' Enviror:menta! Reports.

f the risks associated with nuclear Risk Assessment Review Group 'to A footnote to the Annex stated:

power plant accidents. particularly c!ari!}- the achievements and limitations Althow,. this annen refers to applicant,s events which can lead tc the melting of of the Reactor Safety Study. One og the Emironmental Reports, the current the fuelinside a reactor.8 The references c nelusions of this study. publisned,m assmptions and other provisions thereof are to this study were in keeping with the SePtar n as WEOM applicable. except as the content may intent and spirit of NEPA "to disclose-

" Risk Assessment Review Group Feport otr.erwise require to AEC draft and final relevant information. but it.is obvious.

to the U.S. Nuclear Regulatory Deiai ed Statements.

that WASH-1400 did not form the basis Comm.ission " was that *'The Review t

During the public comment period that for the conclusion expressed in the Croup was unable to determine whether followed publication of the Annex a Annex ir* 1971 that the probability of the absolute probabilities of accident number of criticisms of the Annex were oeurrence of Class 9 events was too 8 '9 "'"'" "

receis ed. Principal among these were low to warrant their (site-specific) the following:

consideration under NEPA.

n those estin ates are in general, (1)The philosophy of prescribing The Commission's staff has. however, greatly understated. This and other assumptions does not lead to objective identified in certain cases uni 9ue findings of the Review Group have also h

subsequently been referred to in 2)It iled to treat the probabilities of d

d EnvironmentalImpact Statements along or accidents in any but the most general consMeration of Class 9 events. One of with a reference to the Commission s these was the proposed Clinch River.d policy statement on the Reactor Safety j No supporting analysis was given eeder eact r an p PL a hqui Study in light of the Risk Assessment to show that C! ass 9 accidents are metal c led fast breeder reactor very Review Group Report.pubbshed on sufficiently low in probability that their different from the more conventional January 18.1979. The Commission's consequences in terms of environmental light water reactor plants for whien the statement accepted the findings of the risks need not be discussed.

safeb e?perience base is much broader.

Review Group both as to the Reactor (41 No guidance was given as to how In the Final Environmental Statement Safety Study's achievements and as to arrident and normal releases of for the CRBRP.8 the staffincluded a

'ts limitat discussion of the consideration it had A few aft Environmental pera should f ct ed t the gisen t Class 9 events.

Statements have been published cost. benefit analysis.

In the early site review for the subsequent to the Three Mile Island

($1The accident assumptions are not Perryman site. the Mff performed an accident. These w ere for cons entional Feneraily applicable to gas cooled or inf rmal assessment f the relative land. based licht wster reactor plants Immd erstal cooled reactors.

differences in Class 9 accident and continued to reflect the past 161 Safety and environmental risks are c nsequences among the alternative practice with respect to accidents at not essentially different considerations.

sites. (SECY-78-137) such plants. but noted that the Neither the Atomic Energy in the case of the application by esperience ga.ned from the Three Mde Commission not the NRC took any Offshore Power Systems to manufacture Island accident was not factored into further action on this rulemaking except U ating rnacker popu plants, the staff the discussion.

in 1974 when 10 CFR Part 51 was ludged at the environmental nsks of Our experience with past NEPA promulgated. Over the intervening years s me Clas 9 events warranted special reviews of accidents and the TMI the accident considerations discussed in considers ion.The special accident clearly leads us to believe that EnCronmenta!!mpact Statements fer circumste.ces were the poteritially a change is needed.

proposed nuclear power plants reflected senous con, sequences associated with Accordingly, the proposed Annex to the guidance of the Annex with few

• 8'"Ih.au d) pathways leading to Appendix D of to CFR Part 50. published exceptions. Typically, the discussions of radiological exposures if a molten on December 1.1971. is hereby accident consequences through Class a reactor core were to fallinto the water withdrawn and shall not hereafter be

[ design basis accidents) for each case used by applicants not by the staff.The S'*d reasons for the withdrawal are as have reflected specific site

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ne.er term to nor.. ihe ierm -c..s.ccid'ent-characteristis associated with g,jj "'.

meteorology (the dispersion of releases

.iihoo,h in,. ienn i. comm.niy..,4.. loo.ely of radioactiie materialinto the ew.:eni to. core raeli ccideas.

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consequences shad be ch srscier:nd in ongai:q pra eed. ;

• 1 h ccf:n. tion of C: ass 9 ecc:dants terms cf po:ential rad:oiugical Ho eser. :t is a so the % n' of the r.c.

in 'he 2.nm is ac* suff%ntly pecise expcsures to indisiduals to pcpulat.on Cammission that the staff taw s p 'o to aarre es fo"her p in Cam,Ssion groups. and. where appl; cab!e. :o bacta.

ident:fy add;tional czsas tha' mant

• iealth and safety riske that may be warrant early censiderahon of echer pot.cy. ru,es. and rep. :.or s r.or as a assomated wnh npesures to people additional features or other actiar:s r

cec:sion cr :ewn m ne,c) practice.

1 The Anr.Ns precaphon of shall be dacussed in a manner that which would present er mitigate the assumpticas to be used in the ar lysis fairly reCects the current state of consepences o.Nerious acc. dents.

of the enuronmental ccusequences of knowiedge regaing such -isks.

Cases for such censideration are tho>e Socioecono nic rmpacts that might be for which a Fina; Environ:nental amden9 d*s not contribute to obiectn e consideration.

assoc:ated wnn emergency messures Statement has a: ready iseen issued at 4 Tne Annes does not gis e adequate during cr fol;owing an acc: dent should the Constructier. Permit stage but for censiderat:en to the detaded trdment aiso be d;scussed. The environmental whrch the n; erring License review of mmures tamen to prevent and to nsk of accioents should also be stase has not vet been reached. In mitisate the conse:;uences of accidents compared to and contrasted with carrying out this directive. the staff

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in the safety review of each appi cation.

radiological risks associated with should consider re:evant sne features.

The c!assification of accidents normal and anticipated operational including population density, associated with accident risk in companson to such proposed m that Annes shall no longer releases.

be used. In its place the following In promulgating this interim guidance, featurer at presently operating plants.

interim guidance is gn en for the the Commission is aware that there are Staff should also consider the likelihood that substantise changes in plant design treatment of accident nsk and will likelv remain for some time to considerations in NEPA reviews.

come man) u'ncertainties in the features which may compensate further application of risk assessment methods, for adserse site features may Se more and it experts that its Envircnmental easily incorporated in piants when Accident Considerations in Future Impact Statements willidentify mai r c nstmction has not yet progressed very NEPA Reviews it is the position of the Commission unceMaintin in as peaMshe fan f.

that its EnvironmentalImpact estimates. On the ther hand the Environmental Reports submitted by Statements. pursuant to Section 102(c)(i)

Commission beheses that the state of applicants for construction permits and 8

I' of the National Enuronmental Policy the art is sufficiently adsanced that a for operating licenses on or after July 1.

Act of 1969. shat! include a reasoned begmning should now be mace m the 1980 should include a discussion of the i

considerahon of the environmental risis f these metnodologies in the environmental nsis associated with use (impacts) attnbutable to accidents at the at ry process, and that such use accidents that fonows the guidance reg particular facihty or facilities within the wat represent a contructise and rational given herem.

scope of each such statement. In the f rward step in the d:scharge of its Related Policy Matters Under analysis and discussion of such risks.

reponsibihtaes.

Consideration approsimately equal attention shall be

!!is the intent of the Commission in given to the probabihty of occurrence of issuing this St atement of Intenm Pohcy In additi n to its reiponsihdities releases and to the probabdity of that the stafi will initiate treatments of under NEPA. the NRC also bears occurrence of the environmen'tal accident considerations,in accordance responsibility under the Atomic Energy consecuences of those releases.

with the foregoing guidance. in its Act for the protection of.he public Releases refer to radiation and/or ongoing NEPA reviews, i.e.. for any health and safety from the hazards associated with the use t ' nuciear radioactive mate.ials entenng proceeding at a licensing stage where a environmental exposure pathways, Final Environmental Impact Statement energy. Pursuant to this esponsibihty includme air. water. and ground water.

the Commission notes th u there are Events or accident sequences that has not yet been issued. These new lead t.i wIeees shallinclude but not be treatments, which will take into account currently a nurnber of orgomy activities limited to those that can reascnably be significant site-and plant-specific being considered by thr Camm ssion features will result in more detailed and its staff which intimately relate to espected to occur. In. plant accident discussions of accident risks than in the "Cla s s 9 accident" question and sequences that can lead to a spectrum of which are either the subject of current releases shat! be discussed and shall previous environmental statements, rulemaking or are candidate subjects for include sequences that can result in particularly for those related to conventionallight water plants at land-rulemaking.

inadequate cooimg of reactor fuel and to based sit.:s. It is espected that these On December 19.1979 the melting of the reactor core. The extent to revised treatments willlead to Commission issued for pubhc comment

• which events ansing from causes conclusions regarding the environmeraal a proposed rule which would extemal to the plant which are risks of accidents similar to those that significantly revise its requirements in considered possible contnbutors to the would be reached by a continuation of 10 CFR Part 50 for emergency p:anning nsk associated with the particular plan

• sha!! also be discus:ed Detailed current practices. particularly for cases for nuclear power plams. One of the invo ving special circumstances where considerations in this rutemaking was quantitatne considerations that form Class 9 nsks have been considered by the basis of probabilistic estimates of releases need not be incorporated in the the staff. as described above.Thus, this

'comrm...onm can.h y no sr.diord d...aree

• "h 'he inclusior' of the preced" s t-o senter.ces Environmental Impact Statements but change ir. policy is not to be construed shall be referenced therem. Such as any tack of confidence in conc!usions

{'fj'M*Q,*'y'$'jgg,';"' ""h references shall include. as appbcable, regarding the environmental nsks of

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accidents espressed in any previously

.s4 m r3:st reports on safety esaluations.

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% m.de recummendat:ons w;th rn;ct in aun.bie changes in NRC r:.co = on; po;i:3 and cntena.'

cc-en4 set forth in 10 CFR Part 1m As s o ed therein. Its reccmmendations w e made to accccphsh (among cnus! t..* f;" cains Hal:

To take ante Corsace aiton in sit.rg the rish

... wared i ace dams beyerd the desp h.. 3 (Cass of y -o'a%shtrg p pu'afion d as$ ed disin5unon c-tena Th:r m;tter is currently before the

<%.a mis s:o n.

Tkis aad other recornmendations that hoe neen made as a esult of the invesi.gations into the Three Mile Island ccideri am currently being brought egef..er by the Comrn:ssion~s staffin ihe form of proposed Action P!ans.'

Ar ong other matters. these incorporate recc,mmendations for ru emaking related to degraded core cochng and core rnel!

accidents. The Cc,mmission expects to issue dec:sions on these Action Plans in the near future. It is the Commission's pohcy and intent to devote NRC's maior resou.ces to matters which the Com mis ue. t>e!ieses will make eustmg and future r ; clear power plants safer, and to present a recurrence of the kind of.ccident that occurred at Three Mile Is and In the in! nm. however, and t

pending complet.un of ru!emaking

.ectmises in the areas of emergency plan ung. siting cntena. and design and operational safety. all of which insolve considerations of senous accident potential the Commission finds it essential to improv-i'e procedures for i

describing ard d;sclusing to the public ibe basis for arnving at conclusions resarding the environmental nsis due to acadents at nuclea ;~er plants. On cor,p:etion of the ru!emaking activities in these areas. and band also upon the experience gained with this statement of inten.n pohcy and guidance. the Commiss,n intends to pursue possible

< %ngs or odditions to 10 CFR Part 51 to cod,fy its position on the role of

.sccident risk s under NEPA.

'Cf Nt liEFA3% "P!annmg Penis fee the D

s. pmeni of biete and Local Co.ernment Rad.okvas! Emergency Response P;ere m Support si Lses % caer Neeer Po=er Pieriis " No= ember Grs

• NUM Wees Report of the Lims Poig Teek Forea " A wssi tre

'D th NUW EG ews Acison Piene for leer'ementing Enovendehens of the P co, dent e Conroe,on end Other Stud,es of ihe TV12 Atodent. December 10. iir9 e

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