RG1.201 核电厂内系统结构与设备按照其安全重要性进行分级的导则 2006-05

1CommissionpaperscitedinthistrialregulatoryguideareavailablethroughtheNRC’spublicWebsiteat(GPO)at(NRC)issuesregulatoryguidestodescribeandmakeavailabletothepublicmethodsthattheNRCstaffconsidersacceptableforuseinimplementingspecificpartsoftheagency’sregulations,techniquesthatthestaffusesinevaluatingspecificproblemsorpostulatedaccidents,anddatathatthestaffneedinreviewingapplicationsforpermitsandlicenses.Regulatoryguidesarenotsubstitutesforregulations,andcompliancewiththemisnotrequired.MethodsandsolutionsthatdifferfromthosesetforthinregulatoryguideswillbedeemedacceptableiftheyprovideabasisforthefindingsrequiredfortheissuanceorcontinuanceofapermitorlicensebytheCommission.Thisguidewasissuedafterconsiderationofcommentsreceivedfromthepublic.TheNRCstaffencouragesandwelcomescommentsandsuggestionsinconnectionwithimprovementstopublishedregulatoryguides,aswellasitemsforinclusioninregulatoryguidesthatarecurrentlybeingdeveloped.TheNRCstaffwillreviseexistingguides,asappropriate,toaccommodatecommentsandtoreflectnewinformationorexperience.WrittencommentsmaybesubmittedtotheRulesandDirectivesBranch,OfficeofAdministration,U.S.NuclearRegulatoryCommission,Washington,DC20555-0001.Regulatoryguidesareissuedin10broaddivisions:1,PowerReactors;2,ResearchandTestReactors;3,FuelsandMaterialsFacilities;4,EnvironmentalandSiting;5,MaterialsandPlantProtection;6,Products;7,Transportation;8,OccupationalHealth;9,AntitrustandFinancialReview;and10,General.Requestsforsinglecopiesofdraftoractiveregulatoryguides(whichmaybereproduced)shouldbemadetotheU.S.NuclearRegulatoryCommission,Washington,DC20555,Attention:ReproductionandDistributionServicesSection,orbyfaxto(301)415-2289;[e-mail]ideandotherrecentlyissuedguidesareavailablethroughtheNRC’spublicWebsiteundertheRegulatoryGuidesdocumentcollectionoftheNRC’sElectronicReadingRoomat’sAgencywideDocumentsAccessandManagementSystem(ADAMS)at(ForTrialUse)(Previouslyissuedfortrialuse,January2006)GUIDELINESFORCATEGORIZINGSTRUCTURES,SYSTEMS,ANDCOMPONENTSINNUCLEARPOWERPLANTSACCORDINGTOTHEIRSAFETYSIGNIFICANCEA.INTRODUCTIONTheU.S.NuclearRegulatoryCommission(NRC)haspromulgatedregulationstopermitpowerreactorlicenseesandlicenseapplicantstoimplementanalternativeregulatoryframeworkwithrespectto“specialtreatment,”wherespecialtreatmentreferstothoserequirementsthatprovideincreasedassurancebeyondnormalindustrialpracticesthatstructures,systems,andcomponents(SSCs)performtheirdesign-basisfunctions.Underthisframework,licenseesusingarisk-informedprocessforcategorizingSSCsaccordingtotheirsafetysignificancecanremoveSSCsoflowsafetysignificancefromthescopeofcertainidentifiedspecialtreatmentrequirements.ThegenesisofthisframeworkstemsfromOption2ofSECY-98-300,“OptionsforRisk-InformedRevisionsto10CFRPart50,‘DomesticLicensingofProductionandUtilizationFacilities’,”datedDecember23,1998.1InthatCommissionpaper,theNRCstaffrecommendeddevelopingrisk-informedapproachestotheapplicationofspecialtreatmentrequirementstoreduceunnecessaryregulatoryburdenrelatedtoSSCsoflowsafetysignificancebyremovingsuchSSCsfromthescopeofspecialtreatmentrequirements.TheCommissionsubsequentlyapprovedtheNRCstaff’srulemakingplanandissuanceofanAdvancedNoticeofProposedRulemaking(ANPR)asoutlinedinSECY-99-256,“RulemakingPlanforRisk-InformingSpecialTreatmentRequirements,”datedOctober29,1999.2NEI00-04,“10CFR50.69SSCCategorizationGuideline,”isavailablethroughtheNRC’sAgencywideDocumentsAccessandManagementSystem(ADAMS),(65FR11488)onMarch3,2000,andsubsequentlypublishedaproposedruleforpubliccomment(68FR26511)onMay16,2003.Then,onNovember22,2004,theCommissionadoptedanewsection,referredtoas§50.69,withinTitle10,Part50,oftheCodeofFederalRegulations,onrisk-informedcategorizationandtreatmentofSSCsfornuclearpowerplants(69FR68008).ThistrialregulatoryguidedescribesamethodthattheNRCstaffconsidersacceptableforuseincomplyingwiththeCommission’srequirementsin§50.69withrespecttothecategorizationofSSCsthatareconsideredinrisk-informingspecialtreatmentrequirements.ThiscategorizationmethodusestheprocessthattheNuclearEnergyInstitute(NEI)describedinRevision0ofitsguidancedocumentNEI00-04,“10CFR50.69SSCCategorizationGuideline,”datedJuly2005.2Specifically,thisprocessdeterminesthesafetysignificanceofSSCsandcategorizesthemintooneoffourrisk-informedsafetyclass(RISC)categories.TheNRCissuedadraftofthisguide,DraftRegulatoryGuideDG-1121