Regulatory Guide 1.186

Guidance and Examples for Identifying 10 CFR 50.2 Design Bases

ML003754825
Person / Time
Issue date:	12/31/2000
From:	Office of Nuclear Regulatory Research
To:
Magruder S L, NRR, 415-3139
References
DG-1093 RG-1.186
Download: ML003754825 (5)

RegulatoryguidesareissuedtodescribeandmakeavailabletothepublicsuchinformationasmethodsacceptabletotheNRCstaffforimplementingspecificpartsoftheNRC'sregulations,techniquesusedbythestaffinevaluatingspecificproblemsorpostulatedaccidents,anddataneededbytheNRCstaffinitsreviewofapplicationsforpermitsandlicenses.Regulatoryguidesarenotsubstitutesforregulations,andcompliancewiththemisnotrequired.MethodsandsolutionsdifferentfromthosesetoutintheguideswillbeacceptableiftheyprovideabasisforthefindingsrequisitetotheissuanceorcontinuanceofapermitorlicensebytheCommission.Thisguidewasissuedafterconsiderationofcommentsreceivedfromthepublic.Commentsandsuggestionsforimprovementsintheseguidesareencour agedatalltimes,andguideswillberevised,asappropriate,toaccommodatecommentsandtoreflectnewinformationorexperience.Writtencommentsmayb esubmittedtotheRulesandDirectivesBranch,ADM,U.S.NuclearRegulatoryCommission,Washington,DC20555-0001.Regulatoryguidesareissuedintenbroaddivisions:1,PowerReactors;2,ResearchandTestReactors;3,FuelsandMaterialsFacilities;4,EnvironmentalandSiting;5,MaterialsandPlantProtection;6,Products;7,Transportation;8,OccupationalHealth;9,AntitrustandFinancialReview;and10,Gener al.Singlecopiesofregulatoryguides(whichmaybereproduced)maybeobtainedfreeofchargebywritingtheDistributionServicesSection,U.S.Nuclea rRegulatoryCommission,Washington,DC20555-0001,orbyfaxto(301)415-2289,orbyemailtoDISTRIBUTION@NRC.GOV.Electroniccopiesofthisguide areavailableatNRC'shomepageat<WWW.NRC.GOV>intheReferenceLibraryunderRegulatoryGuides.ThisguideisalsointheElectronicReadingRoomatNRC'shomepage,AccessionNumberML003754825,alongwithotherrecentlyissuedguides.U.S.NUCLEARREGULATORYCOMMISSIONDecember2000

REGULATORY

GUIDEOFFICEOFNUCLEARREGULATORYRESEARCHREGULATORYGUIDE1.186(DraftwasissuedasDG-1093)GUIDANCEANDEXAMPLESFORIDENTIFYING10CFR50.2DESIGNBASES

A. INTRODUCTION

In10CFRPart50,"DomesticLicensingofProductionandUtilizationFacilities,"Section50.2,"Definitions,"containsadefinitionof"DesignBases."AlthoughtheNRCstaffandthenuclearindustry havealwaysagreedthatitisimportanttounderstandwhatconstitutesthedesignbasesofaplant,therehas notbeenagreementabouttheimplementationofthedefinitionin10CFR50.2.Theguidancepresentedhereisnotmandatory,andlicenseesmaychoosenottochangetheirimplementationofthedefinitionofwhatconstitutesdesignbases.Licenseeswhochoosetoimplement thisguidanceareexpectedtoapplyitinauniformmanner.Theinformationcollectionscontainedinthisregulatoryguidearecoveredbytherequirementsof10CFRPart50,whichwereapprovedbytheOfficeofManagementandBudget,approvalnumber3150-

0011.IfameansusedtoimposeaninformationcollectiondoesnotdisplayacurrentlyvalidOMBcontrol number,theNRCmaynotconductorsponsor,andapersonisnotrequiredtorespondto,theinformation collection.

1CopiesareavailableforinspectionorcopyingforafeefromtheNRCPublicDocumentRoomat11555RockvillePike(firstfloor),Rockville,MD;thePDR'smailingaddressisUSNRCPDR,Washington,DC20555;telephone(301)415-4737or1-(800)397-4209;fax(301)415-3548;e-mail<PDR@NRC.GOV>.

2CopiesareavailableatcurrentratesfromtheU.S.GovernmentPrintingOffice,P.O.Box37082,Washington,DC20402-9328(telephone(202)512-1800);orfromtheNationalTechnicalInformationServicebywritingNTISat5285PortRoyalRoad, Springfield,VA22161;(telephone(703)487-4650;<http://www.ntis.gov/ordernow>.CopiesareavailableforinspectionorcopyingforafeefromtheNRCPublicDocumentRoomat11555RockvillePike,Rockville,MD;thePDR'smailingaddressis USNRCPDR,Washington,DC20555;telephone(301)415-4737or(800)397-4209;fax(301)415-3548;emailis PDR@NRC.GOV.1.186-2

B. DISCUSSION

OBJECTIVEThestaff'sobjectiveistodevelopguidancethatprovidesabetterunderstandingofwhatconstitutesdesignbasesinformation.Thisguideisintendedtoclarifythetermdesignbasesin connectionwiththeNRC'sregulationsthatusethisterm.BACKGROUNDInthemid-1980s,theNRCstaffconductedmanysystem-specificengineeringinspectionsanddevelopedinspectionfindingsthatdemonstratedthatsomelicenseeshadnotadequately maintainedtheirdesignbasesinformationasrequiredbyNRCregulation.Inresponsetothe problemsidentifiedduringtheNRCinspectionsandthoseidentifiedbylicensees,mostreactor licenseesinitiateddesignbasesreconstitutionprograms.Theseprogramssoughttoidentifymissing designdocumentationandtoselectivelyregeneratemissingdocumentation.InOctober1990,theNuclearManagementandResourcesCouncil(NUMARC)publishedits"DesignBasesProgramGuidelines,"NUMARC90-12.

1Thestaffconcludedthattheseguidelinesprovidedausefulstandardframeworkforimplementingdesignreconstitutionprograms.The guidelinesbrieflydiscussedthedefinitionofdesignbasesinformationbutdidnotfocusonit.InFebruary1991,theNRCstaffpublishedNUREG-1397,"AnAssessmentofDesignControlPracticesandDesignReconstitutionProgramsintheNuclearPowerIndustry."

2Thisreportgavetheresultsofasurveyreflectingthescopeandperformanceofseveralutilitydesignchange controlprogramsanddesigndocumentreconstitutionprograms.Thisreportincludedadefinitions sectionthatstatedthatdesignbasesincludeonlythedesignconstraintsthatareincludedincurrent licensingbasesandformthebasesforthestaff'ssafetyjudgments.InAugust1992,theCommissionpublishedapolicystatementon"AvailabilityandAdequacyofDesignBasesInformationatNuclearPowerPlants."

1Inthepolicystatement,theCommissionconcludedthat:[M]aintainingcurrentandaccessibledesigndocumentationisimportanttoensurethat(1)theplantphysicalandfunctionalcharacteristicsaremaintainedandare consistentwiththedesignbasesasrequiredbyNRCregulation,(2)systems, structures,andcomponentscanperformtheirintendedfunctions,and(3)theplantis operatedinamannerconsistentwiththedesignbases.

3LetterfromJ.Taylor,EDO,NRC,toallnuclearutilityCEOs,October9,1996.CopiesareavailableforinspectionorcopyingforafeefromtheNRCPublicDocumentRoomat11555RockvillePike(firstfloor),Rockville,MD;thePDR'smailingaddressisUSNRCPDR,Washington,DC20555;telephone(301)415-4737or1-(800)397-4209;fax(301)415-3548;email

<PDR@NRC.GOV>.1.186-3Inthepolicystatement,theCommissionalsosaidthatallpowerreactorlicenseesshouldassesstheaccessibilityandadequacyoftheirdesignbasesdocumentationanddecidewhethera designreconstitutionprogramisnecessary.WithregardtotheNUMARCguidance,the Commissionstatedthat:Theguidanceoutlinesaframeworktoorganizeandcollatenuclearpowerplantdesignbasesinformation.Thisinformationprovidestherationaleforthedesign basesconsistentwiththedefinitionofdesignbasescontainedin10CFR50.2.Inresponsetothefindingsrelatingtotheregulatoryburdenofteaminspectionsidentifiedinthe1991RegulatoryImpactSurveyandvoluntaryimplementationoftheNUMARCguidanceby licensees,thestaffreduceditseffortonspecific,resource-intensive,design-relatedteaminspections andfollowedtheissueofaccurateandaccessibledesigndocumentationatplantsprincipallyasan elementofinspectionandfollowupofoperations-relatedactivities.In1996,thestaff'sfindingsduringinspectionsandreviewsbegantoidentifybroadprogrammaticweaknessesthatresultedindesignandconfigurationdeficienciesatsomeplants;

thesedeficienciescouldhaveaffectedtheoperabilityofrequiredequipment,raisedunreviewed safetyquestions,orindicateddiscrepanciesbetweentheplant'sUpdatedFinalSafetyAnalysis Reportandtheas-builtoras-modifiedplantorplantoperatingprocedures.Asaresultofthese findings,thestaffissuedaletter

3inaccordancewith10CFR50.54(f)toalllicenseesrequestinginformationtoprovidetheNRCaddedconfidenceandassurancethattheplantswereoperatedand maintainedwithinthedesignbasesandanydeviationswerereconciledinatimelymanner.

SECY-97-160, 1datedJuly24,1997,informedtheCommissionofthefollowupactivitiesresultingfromthestaff'sreviewoflicenseeresponsestothe10CFR50.54(f)request.Inthispaper, thestaffstatedthat--Basedonthereviewoflicenseeresponsestothe50.54(f)letter,thestaffconcludedthatwhilelicenseeshadestablishedprogramsandprocessestomaintaintheir facility'sdesignbases,therewasaneedtoimplementplant-specificfollowup activities.Thisdeterminationwasbaseduponthestaffhavingidentified:(1)

instancesinwhichlicenseesfailedtoreconcileregulatoryperformancewiththeir assertionsthattheirprogramsandprocesseswereeffectiveinmaintainingtheir designbases,or(2)thattherewasaneedtogainabetterunderstandingortovalidate aparticularaspectofalicensee'sprogramsandprocesses.SECY-97-160referredtotheabove-mentionedfollow-upactivitiesasPhase4andstatedthattheyweretobeacombinationofarchitect-engineerdesignteaminspectionsledbytheOfficeof NuclearReactorRegulationandregion-ledinspections,suchassafetysystemfunctionalinspections andsafetysystemengineeringinspections.Inadditiontothe10CFR50.54(f)lettersandtheinspectionactivities,thestaffconductedlessons-learnedreviewsregardingMillstoneandMaineYankee.Oneoftheconclusionsofthese

1.186-4reviewswasthatthedefinitionofdesignbasesshouldbeclarified.InSECY-97-205, 1 datedSeptember10,1997,thestaffprovidedtheCommissionwithseveraloptionsforanintegrated approachtosolvingtheproblemsidentifiedduringthelessons-learnedreviews.Inthestaff requirementsmemorandum

1onSECY-97-205,datedMarch24,1998,theCommissiondirectedthestafftocontinuetodevelopguidanceregardingdesignbasesissues,suchasspecifyingthetypeof informationtobeconsideredasdesignbasesinformation.Thiseffortwassubsequentlyincludedin thestaff'sresponsetotheChairman'staskingmemorandum

1ofAugust7,1998.ThisregulatoryguideprovidestheguidancerequestedbytheCommission.DEVELOPMENTOFINDUSTRYGUIDELINE,NEI97-04InOctober1997,NEIsubmittedNEI97-04,"DesignBasesProgramGuidelines,"whichisanupdatetoNUMARC90-12.NEI97-04gaveadditionalexamplesofdesignbasesinformation anddirectlyaddressedthereportabilityofconditionsoutsidethedesignbasesoftheplant.This submissionstartedaseriesoflettersandpublicmeetingsthatledtotheNRCstaffproposingto endorseAppendixBtoNEI97-04,withexceptions,inDraftRegulatoryGuideDG-1093.DG-1093 wasissuedforpubliccommentinApril2000.Afterthepubliccommentperiod,thestaffheldapublicmeetingwithNEItodiscussthepubliccommentsreceivedandadditionaleditorialchangestotheNEIdocumentproposedbythe NRCstaff.NEIagreedtomakerevisionstoAppendixBtoNEI97-04toaddressthesecomments andtoincorporatesomeoftheeditorialchanges.OnJuly27,2000,NEIsubmittedaprepublication draftofarevisedAppendixBtoNEI97-04forNRCendorsement.NEI97-04wasdevelopedtohelputilitiesorganizeandcollatedesignbasesinformationandsupportingdesigninformation.Thestaffhasconcludedthattheseguidelinesprovideauseful standardframeworkforimplementingdesignreconstitutionprograms;however,theindustryhasnot requestedstaffreviewandendorsementoftheentiredocument.Thisregulatoryguideonlyapplies toAppendixBofNEI97-04.DEFENSEINDEPTHThestaffconsidersaspectsofthedesigneddefense-in-depthstrategiessuchasredundancy,diversity,andindependencetobeimportantaspectsoftheplant'sprincipaldesigncriteria.These strategiesandcriteriaarespecificallyrequiredbyseveralregulations,especiallytheGeneralDesign Criteria.Thesecriteriarequirethatsuchcapabilitiesbeimplementedforindividualstructures, systems,andcomponentsthroughplantdesignfeatures,suchasmultiplecomponents,independent powersupplies,andphysicalseparation.Thesecriteriaprovidepartofthestandardforjudgingthe adequacyoftheplant'sdesignbases.

4CopiesofAppendixBtoNEI97-04areavailableon<WWW.NRC.GOV>throughNRC'sPublicElectronicReadingRoomunderAccessionNumberML003771698.CopiesareavailableforinspectionorcopyingforafeefromtheNRCPublicDocumentRoomat11555RockvillePike(firstfloor),Rockville,MD;thePDR'smailingaddressisUSNRCPDR,Washington, DC20555;telephone(301)415-4737or1-(800)397-4209;fax(301)415-3548;e-mail<PDR@NRC.GOV>.1.186-5C.REGULATORYPOSITIONAppendixB,"GuidelinesandExamplesforIdentifying10CFR50.2DesignBases"(datedNovember27,2000), 4toNEI97-04providesguidanceandexamplesthatareacceptabletothestaffforprovidingaclearerunderstandingofwhatconstitutesdesignbasesinformation.

D. IMPLEMENTATION

ThepurposeofthissectionistoprovideinformationtolicenseesandapplicantsregardingtheNRCstaff'splansforusingthisregulatoryguide.ExceptinthosecasesinwhichanapplicantorlicenseeproposesanacceptablealternativemethodforcomplyingwiththespecifiedportionsoftheNRC'sregulations,themethodsdescribed inthisguidewillbeusedintheevaluationofsubmissionsinregardtodesignbasesinformation.

1.186-6VALUE/IMPACTSTATEMENTAseparateValue/ImpactStatementwasnotpreparedforthisregulatoryguide.TheValue/ImpactStatementthatwaspreparedforandprintedwiththedraftofthisguide,DG-1093,in April2000,isstillapplicable.ThatValue/ImpactStatementconcludedthatthevaluetoindividual licensees,theindustry,theNRC,andthepublicthatresultsfromaclearerunderstandingofthe interpretationof10CFR50.2designbasesoutweighsthecoststolicenseesandtheNRCthatare currentlyassociatedwithconfusionregardingthedefinition.CopiesoftheValue/ImpactStatementareavailableforinspectionorcopyingforafeefromtheNRCPublicDocumentRoomat11555RockvillePike(firstfloor),Rockville,MD;thePDR's mailingaddressisUSNRCPDR,Washington,DC20555;telephone(301)415-4737or(800)397-

4209;fax(301)415-3548;e-mail<PDR@NRC.GOV>.ADAMSAccessionNumberofRegulatoryGuide1.186:

ML003754825ADAMSAccessionNumberofAppendixBtoNEI97-04:

ML003771698