RIS 2001-09, Control of Hazard Barriers
| ML003768935 | |
| Person / Time | |
|---|---|
| Issue date: | 04/02/2001 |
| From: | Matthews D B Division of Regulatory Improvement Programs |
| To: | |
| References | |
| RIS-01-009 | |
| Download: ML003768935 (8) | |
UNITEDSTATESNUCLEARREGULATORYCOMMISSIONOFFICEOFNUCLEARREACTORREGULATIONWASHINGTON,D.C.20555-0001April2,2001NRCREGULATORYISSUESUMMARY2001-09CONTROLOFHAZARDBARRIERS
ADDRESSEES
Allholdersofoperatinglicensesfornuclearpowerreactors,exceptthosewhohavepermanentlyceasedoperationsandhavecertifiedthatfuelhasbeenpermanentlyremoved fromthereactorvessel.
INTENT
TheU.S.NuclearRegulatoryCommission(NRC)isissuingthisregulatoryissuesummary(RIS)toinformaddresseesthatrecentchangestothemaintenancerule(Section50.65,
"Requirementsformonitoringtheeffectivenessofmaintenanceatnuclearpowerplants,"of Part50ofTitle10oftheCodeofFederalRegulations(10CFR50.65))haveabearingonplanthazardbarriers.Inaddition,therecentmajorrevisionof10CFR50.59,"Changes,tests,and experiments,"containsanewprovision,whichmodifiesitsapplicabilitytotheremovalofhazard barriers.ThisRISrequiresnoactionorwrittenresponseonthepartofanaddressee.
BACKGROUND
INFORMATIONHazardbarriersareplantfeaturesorstructuresthatarecreditedwithprotectingplantequipmentfromexternalandinternalhazardssuchasflooding,tornadomissiles,turbine missiles,andtheeffectsofdesignbasiseventssuchasaloss-of-coolantaccident(LOCA)ora highenergylinebreak(HELB).LicenseesandNRCinspectorshavepreviouslyraised questionsabouthowhazardbarriersshouldbecontrolledduringplantmaintenanceand modificationactivities.Forexample,mayabarrierberemovedforashorttimetofacilitate accesstoanareathatcontainssafety-relatedequipmentinordertoperformcorrective maintenance,ormayacontrolroomdoorthatiscreditedwithprovidingprotectionfromaHELB beremovedandrepairedwhiletheplantisoperatingatfullpower?Inthesecondcase,two unitssharethesamecontrolroom,makingitdifficulttoschedulemaintenanceonthedoor duringatimewhenthehazarddoesnotexist.TheNRCamendedthemaintenancerule(10CFR50.65)onJuly19,1999(64FR38551).Paragraph(a)(4)oftheamendedregulationrequiresnuclearpowerplantlicenseestoassess andmanagetheincreaseinriskassociatedwiththeperformanceofmaintenanceactivities.
Theguidanceonassessingandmanagingincreasesinriskassociatedwithmaintenance activitiesisprovidedinNRCRegulatoryGuide(RG)1.182,"AssessingandManagingRisk BeforeMaintenanceActivitiesatNuclearPowerPlants,"datedMay2000,whichendorsesthe February22,2000,revisionofSection11,"AssessmentofRiskResultingFromPerformanceofML003768935 RIS2001-09Page2of4MaintenanceActivities,"ofNuclearManagementandResourceCouncil(NUMARC)93-01,"IndustryGuidelineforMonitoringtheEffectivenessofMaintenanceatNuclearPowerPlants."
InaJune1,2000,FederalRegisternotice(65FR34913),theNRCannouncedtheavailabilityofRG1.182andthattheamendedmaintenancerulewouldbecomeeffectiveonNovember28, 2000.Newparagraph(c)(4)of10CFR50.59statesthattheprovisionsoftheregulationdonotapplytochangestothefacilitywhentheapplicableregulationsestablishmorespecificcriteriafor accomplishingsuchchanges.Fortheremovalofhazardbarriers,10CFR50.65(a)(4)isthe applicableregulationundercertaincircumstances.Theindustryguidanceforthe implementationoftherevised10CFR50.59iscontainedinNuclearEnergyInstitute (NEI)96-07,"Guidelinesfor10CFR50.59Implementation,"Revision1,datedNovember2000.
NEI96-07,Revision1,hasbeenendorsedbytheNRCinRG1.187,"Guidancefor Implementationof10CFR50.59,ChangesTestsandExperiments."ThisRISprovidesguidanceonthecontrolofhazardbarriersthatisconsistentwiththeprovisionsofthemaintenancerule,RG1.182,Section11ofNUMARC93-01,10CFR50.59, RG1.187,NEI96-07,Revision1,GenericLetter(GL)91-18,"InformationtoLicensees RegardingTwoNRCInspectionManualSectionsonResolutionofDegradedand NonconformingConditionsandonOperability,"andGL91-18,Revision1,"Informationto LicenseesRegardingNRCInspectionManualSectiononResolutionofDegradedand NonconformingConditions."SUMMARYOFISSUEAhazardbarriermayberemovedonatemporarybasistofacilitateplantmaintenance,theimplementationofadesignchange,ortheimplementationofcompensatorymeasuresto addressdegradedornonconformingconditions.TherevisedSection11ofNUMARC93-01 statesthatmaintenancemayinvolvetemporaryalterationsforthedurationofthemaintenance activity.Theexamplesgivenofsuchtemporaryalterationsincludebarrierremoval.Itfurther providesthattheriskassessment[requiredby10CFR50.65(a)(4)forthemaintenanceactivity]
shouldincludeconsiderationoftheimpactofthesealterationsonplantsafetyfunctions.Oneof thefactorsthatshouldbeconsideredintheriskassessmentistheactualdurationofthe maintenanceactivity.Inaddition,NUMARC93-01pointsoutthatduringpoweroperations,iftemporaryalterationsassociatedwithmaintenanceareexpectedtobeineffectformorethan 90days,thetemporaryalterationshouldbescreenedand,ifnecessary,evaluatedin accordancewith10CFR50.59priortoimplementation.(Section4.1.2ofNEI96-07, Revision1,providesthattemporaryalterationsinsupportofmaintenanceactivitiesaretreated asmaintenanceactivitiesthataregovernedby10CFR50.65(a)(4);therefore,consistentwith paragraph(c)(4)of10CFR50.59,evaluationofsuchmaintenance-relatedtemporary alterationsunder§50.59isnotrequiredunless(1)duringpoweroperations,thetemporary alterationwillremainineffectformorethan90days,or(2)thetemporaryalterationisnot removedandtheplantfullyrestoreduponcompletionofthemaintenance.)
1ReferenceismadetoGL91-18(hereandintheattachment)todemonstrateconsistencyoftheregulatoryapproach;itisnotmeanttoimplythatGL91-18shouldbeinvokedforconditionsotherthandegradedornon conformingconditionsthathavebeendiscovered.2TemporarymodificationsthatarecreditedwithrestoringormaintainingoperabilityofTSequipmentshouldbeassessedinaccordancewith10CFR50.59requirements;implementationofthetemporarymodificationsshould beassessedinaccordancewiththerequirementsofthemaintenancerule.RIS2001-09Page3of4Notethataslongastheplantisshutdown,the90-daytimelimitdoesnotapplywithregardto§50.59.However,shouldthemaintenanceactivityneedtobeprolongedbeyondthetime periodconsideredintheoriginalriskassessmentperformedinaccordancewith 10CFR50.65(a)(4),theriskassessmentmustbeupdatedtoreflecttheprolongedmaintenance activityandriskmanagementactionsupdatedaccordingly.Notealsothattreatmentofthe maintenanceactivityandanyassociatedtemporaryalterationsunder10CFR50.65maynot requireanyriskassessmentbecauseitmaynotinvolveorimpactplantstructures,systemsor components(includinghazardbarriers)thatarewithinthelimitedriskassessmentscope allowedbyparagraph10CFR50.65(a)(4).Therefore,itisconceivablethatremovalofacertain hazardbarrierinsupportofmaintenancemayrequireneithera10CFR50.59evaluationnora 10CFR50.65(a)(4)riskassessment.Withregardtoremovalofhazardbarrierstofacilitateimplementationofadesignchange,Section4.1.2ofNEI96-07,Revision1,alsostatesthattheimplementationofadesignchange isconsideredtobeamaintenanceactivity.Therefore,aspartofthatmaintenanceactivity,the sameruleswouldapplytotemporaryalterations(includinghazardbarrierremoval)associated withthatdesignchangeimplementation.However,Section4.1.2furtherprovidesthattemporaryalterationsthatareimplementedascompensatorymeasuresfordegradedornonconformingconditions(i.e.,notassociatedwith maintenance,andregardlessofduration)shouldbescreenedand,ifnecessary,evaluated under10CFR50.59.Inadditiontotheseconsiderations,provisionsoftheoperatinglicense andotherregulationsmayalsoapply.Priortoremovingahazardbarrierformaintenancepurposes(eithertofacilitateplantmaintenanceortoperformmaintenanceonthebarrier),theriskassociatedwiththe maintenanceactivitymustbecontrolledandmanagedinaccordancewithparagraph 50.65(a)(4)ofthemaintenancerule.Theresultantriskmanagementactionsmayimposetime limitsforbarrierremoval.Inaddition,otherconsiderations,suchastheadministrative provisionsforcontrollingfirebarriersandtheplanttechnicalspecifications(TS),mayplace limitationsoncontinuedreactoroperationwithahazardbarrierremoved.Forexample,an auxiliaryfeedwater(AFW)pumpthatiscreditedwithmitigatingaHELBeventwouldbe renderedinoperableifabarrierthatiscreditedwithprotectingtheAFWpumpfromtheeffects ofthepostulatedHELBeventisremovedtoallowmaintenancetobeperformedintheAFW pumproom.TheAFWpumpwouldnotbeabletomitigatetheHELBeventwiththebarrier removedand,consistentwiththeguidanceprovidedinGL91-18,1theTSlimitingconditionforoperationfortheAFWpumpwouldapply.Itmaybepossibletotakecompensatorymeasures tomaintainpumpoperabilityandavoidenteringtheTSactionstatementforshuttingdownthe reactor(e.g.,installingatemporarybarrierthatprovidesequivalentprotection2).Also,ifthehazarddoesnotexistatthetime(e.g.,ifthehighenergylineisisolatedanddepressurized),the pumpwouldremainoperabl RIS2001-09Page4of4GL91-18providesguidanceforassessingandresolvingnonconforminganddegradedconditions,andthisguidanceisapplicabletohazardbarriersthatarediscoveredtobe degraded.TheoperabilityguidanceinGL91-18,allowscontinuedoperationofthereactorin thissituationprovidedthedegradedbarrierdoesnotcauseTSequipmenttobeinoperable.In additiontotheseconsiderations,theprovisionsoftheoperatinglicenseandotherapplicable regulations,suchastheadministrativerequirementsthathavebeenestablishedforcontrolling firebarriersmayalsoapplyandshouldbeconsidered.Attachment1providesseveralexamplesthatillustratetheapplicabilityofTSrequirementswithrespecttohazardbarriers.Althoughotherrequirementsmayalsoapply,theexamplesprimarily focusonTSconsiderations.BACKFITDISCUSSIONThisRISrequiresnoactionorwrittenresponse.Consequently,thestaffdidnotperformabackfitanalysis.FEDERALREGISTERNOTIFICATIONThestaffdidnotpublishanoticeofopportunityforpubliccommentintheFederalRegisterbecausetheRISisinformationalandpertainstoastaffpositionthatdoesnotrepresenta departurefromcurrentregulatoryrequirementsandpractice.PAPERWORKREDUCTIONACTSTATEMENTThisRISdoesnotrequestanyinformationcollection.
Ifthereareanyquestionsaboutthismatter,pleasecontactthepersonlistedbelow./RA/DavidB.Matthews,DirectorDivisionofRegulatoryImprovementPrograms OfficeofNuclearReactorRegulationTechnicalContact:JamesE.Tatum,NRR301-415-2805 E-mail:jet1@nrc.gov
Attachments:
1.ExamplesofHazardBarrierControl 2.ListofRecentlyIssuedNRCRegulatoryIssueSummaries RIS2001-09Page4of4GL91-18providesguidanceforassessingandresolvingnonconforminganddegradedconditions,andthisguidanceisapplicabletohazardbarriersthatarediscoveredtobe degraded.TheoperabilityguidanceinGL91-18,allowscontinuedoperationofthereactorin thissituationprovidedthedegradedbarrierdoesnotcauseTSequipmenttobeinoperable.In additiontotheseconsiderations,theprovisionsoftheoperatinglicenseandotherapplicable regulations,suchastheadministrativerequirementsthathavebeenestablishedforcontrolling firebarriersmayalsoapplyandshouldbeconsidered.Attachment1providesseveralexamplesthatillustratetheapplicabilityofTSrequirementswithrespecttohazardbarriers.Althoughotherrequirementsmayalsoapply,theexamplesprimarily focusonTSconsiderations.
BACKFITDISCUSSIONThisRISrequiresnoactionorwrittenresponse.Consequently,thestaffdidnotperforma backfitanalysis.FEDERALREGISTERNOTIFICATIONThestaffdidnotpublishanoticeofopportunityforpubliccommentintheFederalRegisterbecausetheRISisinformationalandpertainstoastaffpositionthatdoesnotrepresenta departurefromcurrentregulatoryrequirementsandpractice.
PAPERWORKREDUCTIONACTSTATEMENTThisRISdoesnotrequestanyinformationcollection.
Ifthereareanyquestionsaboutthismatter,pleasecontactthepersonlistedbelow./RA/DavidB.Matthews,Director DivisionofRegulatoryImprovementPrograms OfficeofNuclearReactorRegulationTechnicalContact:JamesE.Tatum,NRR301-415-2805 E-mail:jet1@nrc.gov
Attachments:
1.ExamplesofHazardBarrierControl 2.ListofRecentlyIssuedNRCRegulatoryIssueSummariesDistribution:RISFilePUBLICAccession#:ML003768935Template#:NRR-052Toreceiveacopyofthisdocument,indicateinthebox:"C"=Copywithoutattachment/enclosure"E"=Copywithattachment/enclosure"N"=Nocopy*SeepreviousconcurrenceOFFICESPLBESC:SPLBBC:SPLBETechEdD:DSSABC:RTSBNAMEJTatum*GHubbard*JHannon*PKleene*GMHolahan*WBeckner*DATE12/3/0012/26/0012/26/0011/17/001/3/0102/07/01OFFICEBC:IQMBBC:RGEBREXBBC:REXBD:DRIPOGCNAMETQuay*CCarpenter*JShapaker*LBMarsh*DBMatthewsAHodgdon*DATE1/23/011/26/0103/21/0103/26/0104/02/011/16/01OFFICED:ADPTNAMEBSheron*DATE02/28/01OFFICIALRECORDCOPY Attachment1RIS2001-09 Page1of3ExamplesofHazardBarrierControlExample1Anentrydoortothecontrolroommustberemovedforrepair.Thedoorformspartofthecontrolroomenvelope,andforthisexample,iscreditedwithprotectingcontrolroomequipmentand personnelfromtheeffectsofamainsteamlinebreakinthevicinityofthecontrolroom.Atechnical specification(TS)limitingconditionforoperation(LCO)specifiesallowedoutagetimes(AOTs)and actionrequirementsforthecontrolroomemergencyventilationsystem,whichmaintainsthecontrol roomatapositivepressureofgreaterthanorequalto1/4-inchwatergaugerelativetoatmospheric pressure.Inthissituation,notonlyisitnecessarytoassesstheincreaseinriskassociatedwithdoingmaintenanceonthecontrolroomdoorandimplementappropriatecompensatorymeasuresto managethisriskinaccordancewithparagraph50.65(a)(4)ofthemaintenancerule,butalsoto adheretoTSrequirementsforthecontrolroomemergencyventilationsystem.Withthecontrolroom doorremoved,bothtrainsofthecontrolroomemergencyventilationsystemareinoperablebecause thesystemcannotmaintaintherequiredpositivepressureinthecontrolroom.Consequently,the correspondingACTIONstatementwouldapplyand,ifthemaintenancecouldnotbeperformedwithin theCOMPLETIONTIME,themaintenanceactivityshouldbedeferredtoamoreappropriatetime.Analternativeapproachwouldbetoinstallatemporarybarriertopreservethecontrolroomenvelopeandallowtherequiredpressurizationofthecontrolroom.Ifthetemporarybarrierprovidesequivalent protection(i.e.,ensurescontrolroomintegrityforpostulateddesignbasisaccidents,includingthe mainsteamlinebreakaccident),thecontrolroomemergencyventilationsystemremainsoperable.WhileitisobviousthecontrolroomemergencyventilationsystemTSappliestothissituation,itislikelythatotherTSrequirementswouldneedtobeconsideredsinceessentiallyallsafety-related systemsinterfacewiththecontrolroom.ConsistentwiththeguidanceofGL91-18,thelicensee shouldalsoevaluatewhethercontrolroomequipmentthatisreliedupontomitigateamainsteamline breakcouldfunctionintheharshenvironmentwiththecontrolroomdoorremoved-andwhetherthe reactoroperatorscouldperformtheirdutiesinaccordancewiththefacilityEmergencyOperating Procedures.Example2Aninspectionportintheventilationductfortheelectricalareaheating,ventilationandairconditioning(HVAC)systemmustberemovedforabout10hourstoinspectadamperaspartofthe recommendedpreventivemaintenanceforthedamper.Theventilationductservesasapressure boundaryintheeventofaHELBinanauxiliarysteamline,buthasnoothersafetyfunctionandhas noTSoperabilityrequirements.TheonlypieceofequipmentthatwouldbeexposedtotheHELB environmentwiththeinspectionportremovedistheTrainAsafetyinjection(SI)pump.Thelicensee hasdeterminedthattheauxiliarybuildingfilteredventilation Attachment1RIS2001-09 Page2of3exhaustsystem(whichmustbeabletomaintainanegativepressureintheemergencycorecoolingpumprooms)willbeabletoperformitsfunctionwiththeinspectionportremoved,andthatthe relevantTSrequirementsforthissystemwillnotbeaffectedbythisactivity.TheSIpumpisnot requiredtomitigateanauxiliarysteamlinebreak,andtheauxiliarysteamlinebreakisnotmentioned intheTSbasesfortheSIpumps.RemovingtheinspectionportintheventilationductdoesnotrendertheTrainASIpumpinoperablebecausetheSIpumpisnotcreditedwithmitigatingabreakintheauxiliarysteamline.NoTS requirementsareaffectedbecause(1)theelectricalareaHVACsystemhasnoTSoperability requirements,(2)theelectricalareaHVACsystemisnotcreditedwithcoolingsafety-related equipmentduringpostulatedaccidentconditions,and(3)theauxiliarybuildingfilteredventilation exhaustsystemisabletoperformitsfunctionwiththeinspectionportremoved.Theonlyremaining applicablerequirementsisparagraph50.65(a)(4)ofthemaintenancerule.However,iftheinspection portwillremainopenformorethan90dayswhiletheplantisoperatingatpower,a10CFR50.59 reviewshouldalsobecompleted.Example3Toperformarequiredsurveillanceonthemainsteamisolationvalves,itisnecessarytorunatemporaryairlinethroughadoorintoanareathatiscreditedwithprotectingbothmotor-driven auxiliaryfeedwater(AFW)pumpsfromaHELB.Frompastexperience,thelicenseeexpectsthedoor tobeblockedopenforlessthan60minutes.TheTSprovideAOTsandactionrequirementsforthe AFWsystem,andtheTSbasesstatethatasafetyfunctionoftheAFWsystemistomitigateHELB events.Thelicenseehasconcludedthatthemotor-drivenAFWpumpswillnotbeabletofunction duringaHELBwiththedoorblockedopen,butthattheturbine-drivenAFWpumpanditsflowpaths wouldbeunaffected.AccordingtoGL91-18,bothmotor-drivenAFWpumpsareinoperablebecauseneitherpumpcanmitigateaHELBwhenthedoorisblockedopen.Inthiscase,withonlytheturbine-drivenAFWpump operable,theTSrequiretheplanttobeinatleastHOTSTANDBYwithin6hoursandinHOT SHUTDOWNwithinthenext6hours,unlessthelicenseecanmaintainorrestoreoperabilityofthe AFWsystembyimplementingcompensatorymeasurestoprovideequivalentprotectionorby removingthehazard(i.e.,isolatinganddepressurizinghigh-energypipingsectionsthatposethe threat).Therefore,inthiscase,evenafterperformingariskassessmentinaccordancewith paragraph50.65(a)(4)ofthemaintenanceruleandconsideringcompensatorymeasures,TS requirementsthatwouldrequireanorderlyplantshutdownandplacespecifictimelimitationsonthe maintenanceactivityapply.Example4Thelicenseemustremovethedoortotheemergencyservicewater(ESW)pumphousetofacilitatetheinstallationofadesignchange.Thedoorprotectsthesafety-relatedequipmentintheESWpump housefrompossiblefloodingduringahurricane.AlthoughthereareTSrequirementsthatpertainto theESWsystem,therearenoTSrequirementsthatspecificallyapplytothedoor.Toeliminatethe threatofflooding,thedesignchangeisbeingimplementedduringatimeofyearwhenahurricaneis notlikelytooccu Attachment1RIS2001-09 Page3of3ConsistentwiththeguidanceofGL91-18,thelicenseeshouldusejudgmentindecidingwhethertheremovalofabarrierislimitedbyaTSrequirement.Inthiscase,sincethedoorwill beremovedwhenahurricaneisnotavalidthreat,theoperabilityoftheESWsystemwillnotbe affectedandtheTSrequirementfortheESWsystemdonotapply.Therefore,theremaining applicablerequirementisparagraph50.65(a)(4)ofthemaintenancerule.However,ifthedoor willberemovedformorethan90dayswhilethereactorisoperatingatpower,a10CFR50.59 reviewshouldbecompleted(inadditiontothe10CFR50.59evaluationofthedesignchange itself).
______________________________________________________________________________________OL=OperatingLicense CP=ConstructionPermitAttachment2RIS2001-09 Page1of1LISTOFRECENTLYISSUEDNRCREGULATORYISSUESUMMARIES_________________________________________________________________________________RegulatoryIssueDateofSummaryNo.SubjectIssuanceIssuedto_________________________________________________________________________________
2001-08OperatingReactorLicensingActionEstimates04/02/01Allpowerreactorlicensees2000-11,Supp.1NRCEmergencyTelecommunicationsSystem03/22/01Allholdersofoperatinglicensesfornuclearpowerreactors2001-0710CFR50.75(f)(1)ReportsontheStatusofDecommissioningFunds (DueMarch31,2001)02/23/01Allholdersofoperatinglicensesfornuclearpowerreactors2001-06CriteriaforTriggeringaReviewUnder10CFR50.80forNon- OwnerOperatorService Companies02/15/01Allholdersofoperatinglicensesfornuclearpowerreactors2001-05GuidanceonSubmittingDocumentstotheNRCby ElectronicInformationExchange oronCD-ROM01/25/01Allholdersofoperatinglicensesfornuclearreactorsandall vendorswhoarerequiredtomake submittalstotheU.S.Nuclear RegulatoryCommission(NRC)
pursuanttoPart50ofTitle10of theCodeofFederalRegulations (10CFRPart50),"Domestic LicensingofProductionand UtilizationFacilities."2001-04IssuanceofUpdatedGuidanceontheTransferofOwnershipor ControlofLicensedActivities (NUREG-1556,Volume15)01/24/01Allmaterialandfuelcyclelicensees.2001-03Changes,Tests,andExperiments01/23/01AllU.S.NRCPart50andPart72licenseesandPart72Certificate ofComplianceholders.