RG1.007 安全壳可燃气体浓集的控制 2007

TheU.S.NuclearRegulatoryCommission(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(DraftwasissuedasDG-1117,datedAugust2002)CONTROLOFCOMBUSTIBLEGASCONCENTRATIONSINCONTAINMENTA.INTRODUCTIONInSeptember2003,theU.S.NuclearRegulatoryCommission(NRC)issuedarevisionofSection50.44,“CombustibleGasControlforNuclearPowerReactors”(Ref.1),whichamendedTitle10,Part50,oftheCodeofFederalRegulations(10CFRPart50),“DomesticLicensingofProductionandUtilizationFacilities”(Ref.2).Thisregulationisapplicabletoallreactorconstructionpermitsoroperatinglicensesunder10CFRPart50,exceptforthosefacilitiesforwhichthecertificationsrequiredunderSection50.82(a)(1)havebeensubmitted,andtoallreactordesignapprovals,designcertifications,combinedlicensesormanufacturinglicensesunder10CFRPart52,“EarlySitePermits;StandardDesignCertifications;andCombinedLicensesforNuclearPowerPlants”(Ref.3).ThisregulatoryguidedescribesmethodsthatareacceptabletotheNRCstaffforimplementingtherevisedSection50.44forreactors,subjecttotheprovisionsofSections50.44(b)or50.44(c).Thisregulatoryguiderelatestoinformationcollectionsthatarecoveredbytherequirementsof10CFRParts50and52,whichtheOfficeofManagementandBudget(OMB)approvedunderOMBcontrolnumbers3150-0011and3150-0151,respectively.TheNRCmayneitherconductnorsponsor,andapersonisnotrequiredtorespondto,aninformationcollectionrequestorrequirementunlesstherequestingdocumentdisplaysacurrentlyvalidOMBcontrolnumber.Rev.3ofRG1.7,Page2B.DISCUSSIONSection50.44providesrequirementsforthemitigationofcombustiblegasgeneratedbyabeyond-design-basisaccident.Inexistinglight-waterreactors,theprincipalcombustiblegasishydrogen.Inanaccidentmoreseverethanthedesign-basisloss-of-coolantaccident(LOCA),combustiblegasispredominatelygeneratedwithinthecontainmentasaresultofthefollowingfactors:(1)fuelclad-coolantreactionbetweenthefuelcladdingandthereactorcoolant(2)moltencore-concreteinteractioninaseverecoremeltsequencewithafailedreactorvesselIfasufficientamountofcombustiblegasisgenerated,itmayreactwithoxygenpresentinthecontainmentataraterapidenoughtoleadtoacontainmentbreachoraleakagerateinexcessoftechnicalspecificationlimits.Additionally,damagetosystemsandcomponentsessentialtocontinuedcontrolofthepost-accidentconditionscouldoccur.InSECY-00-0198,“StatusReportonStudyofRisk-InformedChangestotheTechnicalRequirementsof10CFRPart50(Option3)andRecommendationsonRisk-InformedChangesto10CFR50.44(CombustibleGasControl)”(Ref.4),theNRCstaffrecommendedchangesto10CFR50.44thatreflectthepositionthatonlycombustiblegasgeneratedbyabeyond-design-basisaccidentisarisk-significantthreattocontainmentintegrity.Basedonthoserecommendations,theSeptember2003revisionof10CFR50.44eliminatesrequirementsthatpertainonlytodesign-basisLOCAs.Attachment2toSECY-00-0198(Ref.4)usedtheframeworkdescribedinAttachment1tothepaperwithriskinsightsfromNUREG-1150(Ref.5)andtheintegratedplantevaluationprogramstoevaluatetherequirementsin10CFR50.44.Insodoing,Attachment2notedthatcontainmenttypesthatrelyonpressuresuppressionconcepts(i.e.,icebask