September1997U.S.NUCLEARREGULATORYCOMMISSIONREGULATORYGUOFFICEOFNUCLEARREGULATORYRESEARCHREGULATORYGUIDE1.172(DraftwasDG-1058)SOFTWAREREQUIREMENTSSPECIFICATIONSFORDIGITALCOMPUTERSOFTWAREUSEDINSAFETYSYSTEMSOFNUCLEARPOWERPLANTSA.INTRODUCTIONIn10CFRPart50,DomesticlicensingofProductionandUtilizationFacilities,paragraph55a(a)(1)requires,inpart,1thatsystemsandcomponentsbedesigned,tested,andinspectedtoqualitystandardscommensuratewiththesafetyfunctiontobeperformed.Criterion1,QualityStandardsandRecords,ofAppendixA,GeneralDesignCriteriaforNuclearPowerPlants,to10CFRPart50requires,inpart,1thatappropriaterecordsofthedesignandtestingofsystems//andcomponentsimportanttosafetybemaintainedbyorundercontrolofthenuclearpowerunitlicenseethroughoutthelifeoftheunit.AppendixB,QualityAssuranceCriteriaforNuclearPowerPlantsandFuelReprocessingPlants,to10CFRPart50describescriteriathataqualityassuranceprogramforsystemsandcomponentsthatpreventormitigatetheconsequencesofpostulatedaccidentsmustmeet.Inparticular,besidesthesystemsandcomponentsthatdirectlypreventormitigatetheconsequencesofpostulatedaccidents,thecriteriaofAppendixBalsoapplytoallactivitiesaffectingthesafety-relatedfunctionsofsuchsystemsandcomponentsasdesigning,purchasing,tinthisregulatoryguide,manyoftheregulationshavebeenparaphrased;see10CFRPart50forthefulltext.IDEinstalling,testing,operating,maintaining,ormodifying.Aspecificrequirementiscontainedin10CFR50.55a(h),whichrequiresthatreactorprotectionsystemssatisfythecriteriaofIEEEStd279-1971,CriteriaforProtectionSystemsforNuclearPowerGeneratingStations.2Paragraph4.3ofIEEEStd279-19713statesthatqualityofcomponentsistobeachievedthroughthespecificationofrequirementsknowntopromotehighquality,suchasrequirementsfordesign,inspection,andtest.SeveraloftheGeneralDesignCriteria(GDC)ofAppendixA,includingCriteria12,13,19,20,22,23,24,25,and28,describefunctionsthatarepartofthedesignbasesofnuclearpowerplantsandthatwouldbeincludedinthesoftwarerequirementsspecification(SRS)ofanydigitalcomputersoftwarethatispartofbasiccomponentsthatperformthesefunctions.InadditiontothecriteriaofAppendixA,AppendixBto10CFRPart50providesqualityassurancecriteriathat2RevisionIofRegulatoryGuide1.153,CriteriaforSafetySystems,endorsesIEEEStd603-1991,CriteriaforSafetySystemsforNuclearPowerGeneratingStations,asamethodacceptabletotheNRCstaffforsatisfyingtheNRC'sregulationswithrespecttothedesign,reliability,qualification,andtestabilityofthepower,instrumentation,andcontrolportionsofthesafetysystemsofnuclearpowerplants.31EEEpublicationsmaybeobtainedfromtheIEEEServiceCenter,445HoesLane,Piscataway,NJ08854.USNRCREGULATORYGUIDESTheguidesarelesuedInthefollowingtonbroaddivisions:RegulatoryGuidesaweitsuedtodescribeandmakeaailabletothepublicsuchi*rmalionasmethodsacceptabletotheNRCstfforimplementingspecificpartsofftCom-1.PooerReactors6.ProductsIn*on5sregulations,tscmquesusedbythestaffevaluatingspecificproblemsorps-2.ResearchaidTestReactors7.Transportationlulatedaccidents,enddataneededbytheNRCIitafflisreviewofapplitioforPer.FuetsandMaterialsFacilities8.OccupationalHealthmitsandlicenses.Regulatoryguidesnstusloregiitori,ncompilan.e4.FJMrontentald.anarFciniReviewwiththemIsnotraqtird.MeZthodsandobeonsdiffere5o.hosaOUtheg5MatedalsandPlantProtection10GeneralwibeacceptableIftheyprovideabasisforthefindingsrequisitetotheissuanceorconInuenceofapermitorlicensebytheCommission.SinglecopiesofregulatoryguidesmaybeobtainedkofchargebywingthePrinting,ThsguLidewasIssuedafterconsiderationofcommentsrecevedfromthepublc.Com-GraphicsardDisaibutonBrnch,O1ceofAdministrallon,U.S.NulareguatorymentsandsuggestionsforimprovemeIntiheseguldeswemecouragedatalltlhs,admission,Washington,DC20555-0001;orbyfaxat(301)415-5272.eswillberevised.esappropriate,toaccommodstecommentsandtoreflectnewin=onroerlece.issuedguidesmayalsobepurchasedfromtheNationalTechiwicalInformationServiceonWrittencommentsmaybeaubmittedtotheRuesReviewmidDirectivesBranch,DFIPS,astandingorderbasis.DetallsonthisservicemaybeIobtainedbywritingNS,5285PortADM,U.S.NuclearRegulatoryComnmissicn,Washington,DC20555-0001.RoyalRoad,Springfield.VA22161.designdocumentationfornuclearreactorsafetysystemsmustmeet.CriterionIII,DesignControl,requiresmeasuresfordesigndocumentationandidentificationandcontrolofdesigninterfaces,aswellasmeasuresforverifyingorcheckingtheadequacyofthedesign.ThisregulatoryguideendorsesIEEEStd830-1993,IEEERecommendedPracticeforSoftwareRequirementsSpecifications,'3withtheexceptionsstatedintheRegulatoryPosition.IEEEStd830-1993describesamethodacceptabletotheNRCstaffforcomplyingwiththeNRC'sregulationsforachievinghighfunctionalreliabilityanddesignqualityinsoftwareusedinsafetysystems.4Inparticular,themethodisconsistentwithGDC1andthecriteriaforqualityassuranceprogramsinAppendixBastheyapplytothedevelopmentofsoftwarerequirementsspecifications.ThecriteriaofAppendicesAandBapplytosystemsandrelatedqualityassuranceprocesses,andifthosesystemsincludesoftware,therequirementsextendtothesoftwareelements.Ingeneral,informationprovidedbyregulatoryguidesisreflectedintheStandard