RG1.096 沸水堆主蒸汽隔离阀泄漏控制系统的设计 1976

U.S.NUCLEARREGULATORYCOMMISSIONREGULATORYGUIDEOiFFICEOFSTANDARDSDEVELOPMENTREGULATORYGUIDE1.96DESIGNOFMAINSTEAMISOLATIONVALVELEAKAGECONTROLSYSTEMSFORBOILINGWATERREACTORNUCLEARPOWERPLANTSA.INTRODUCTIONGeneral.DesignCriterion54,PipingSystemsPenetratingContainment,ofAppendixA,GeneralDesignCriteria,to10CFRPart50,LicensingofProductionandUtilizationFacilities,requires,inpart,thatpipingsystemspenetratingprimarycontainmentbeprovidedwithleakdetection,isolation,andcontainmentcapabilitieshavingredundancy,reliability,andperformancecapabilitiesthatreflecttheimpoitancetosafetyofisolatingthesepipingsystems.ThisguidedescribesabasisacceptabletotheNRCstaffforimplementingGeneralDesignCriterion54withregardtothedesignofaleakagecontrolsystemforthemainsteamisolationvalvesofboilingwaterreactor(BWR)nuclearpowerplantstoensurethattotalsiteradiologicaleffectsdonotexceedguidelinesof10CFRPart100,ReactorSiteCriteria,intheeventofapostulateddesign-basisloss-of-coolantaccident(LOCA).IfanapplicantproposestouseamethoddifferentfromthatdescribedinthisguideforimplementingGeneralDesignCriterion54withregardtothecontrolorlimitationofleakagepastthemainsteamisolationvalvesofaboilingwaterreactor,theacceptabilityofthealternativemethodwill.bedeterminedbythestaffonacase-by-casebasis.TheAdvisoryCommitteeonReactorSafeguardshasbeenconsultedconcerningthisguideandhasconcurredintheregulatoryposition.B.DISCUSSIONDirectcycleboilingwaternuclearpowerplantssupplysteamdirectlyfromthereactorvesseltotheturbineviamainsteamlines.ThemainsteamlinesinstalledoncurrentBWRplantsareprovidedwithdualquick-closingisolationvalves.Thesevalvesfunctionto*LinesindicatesubstantivechangesfrompreviousIssue.isolatethereactorsystemintheeventofabreakinasteam-lineoutsidetheprimarycontainment,adesignbasisLOCA,orothereventsrequiringcontainmentisolation.Inthecaseofasteamlinebreak,theisolationvalveswouldterminatetheblowdownofreactorcoolantinsufficienttimetopreventanuncontrolledreleaseofradioactivityfromthereactorvesseltotheenvironment.InthecaseofaLOCA,thevalveswouldisolatethereactorfromtheenvironmentandpreventthedirectreleaseoffission.productsfromthecontainment.Thevalvesarepartofthereactorcoolantpressureboundary.Assuch,theyareQualityGroupAcomponentsandtheirintegritymustbemaintainedbystrictinserviceinspectionandtestingrequirements.However,operatingexperiencehasindicatedthatdegradationhasoccasionallyoccurredintheleak-tightnessofmainsteamisolationvalves,andthespecifiedlowleakagerequirementshavenotalwaysbeenmaintained.Thestaffhasconsideredtheneedtoprovideadditionalfeaturestoensurethelow-leakagecharacteristicsofthemainsteamisolationvalvesintheeventofapostulateddesign-basisloss-of-coolantaccident.1Theuseofaleakagecontrolsystemwouldreducedirectuntreatedleakagefromtheisolationvalveswhenisolationoftheprimarysystemandthecontainmentisrequired.TheresultsofstaffanalyseshaveindicatedthatcalculateddosesresultingfromthemaximumleakagellnitslettersontheconstructionpermitreviewsoftheDuaneArnoldandShorehamplants(December18,1969)andtheJamesA.FitzPatrickplant(January27,1970),theAdvisoryCommitteeonReactorSafeguardsnotedthatadditionalfeaturestocontrolmainsteamIsolationvalveleakageshouldbeconsidered.USNRCREGULATORYGUIDESCommentsshouldbesenttotheSecretaryoftheCommission.U.S.NuclearRegulatoryCommission.Washiogton.D.C20555.Attention:DocketingandRegulatoryGuidesweissuedtodescribeandmakeavailabletothepublicSergiceSection.methodsacceptabletotheNRCstaffofimplementingspecificpartsoftheCommission'sregulations.todelineatetechniquesusedbythestaffinevalu-TheguidesareIssuedinthefollowingtenbroaddivisions:stingspecificproblemsorpostulatedaccidents,ortoprovideguidancetoapplicants.RegulatoryGuidesarenotsubstitutesforrgulations.andcomplianceIPowerReactors1ProductswiththemisnotrequiredMethodsanJsolutionsdifferentfromthosesetOutin2.ResearchandTestReactors7.TransportationtheguideswillbeacceptableiftheyprovideabasisforthefindingsiequisatatoI.FuelsandMaterialsFacilities.OccupationalHealththeissuanceorcontinuanceofapermitorlicensebytheCommission4.EnvironmentalandSiting9.AntitrustReviewCommentsandsuggestionsfor.mprovementsintheseguidesareencouragedS.MaterialsandPlantProtection10.Generalatalllimes,andguideswritberevised.asappropriate.toaccommodatecommentsandtoreflectnewinformationorexperienceThisguidewasrevisedasaCopiesofpublishedguidesmaybeobtainedbywrittenrequestindicatingtheresultofsubstantivecommentsreceivedfromthepublicandadditionalstalffdivisionsdesiredtotheUSNuclearRegulatoryCommission.Washington.0Creview20655.Attention.Director.OfficeofStandardsDevelopmentRevision1June1976allowedunderthetechnicalspecificationforthemainsteamisolationvalvesinpostulateddesign-basisLOCAsituationswouldbeasmallfractionofthe10CFRPart100guidelines,2providedthemainsteamsystemfromtheisolationvalvesuptoandincludingtheturbinecondenserremainsintact.However,resultsofstaffanalysesonsometypicalplantsusingthestandardconservativeassumptionsforconsideringtheoffsiteconsequencesofapostulateddesign-basisLOCA(e.g.,lossofleak-tightnessbeyondtheturbinestopvalve,uncontrolledleak