U.S.NUCLEARREGULATORYCOMMISSIONFebruary1996RCsoA.INTRODUCTIONThethermalannealingrule,§50.66,RequirementsforThermalAnnealingoftheReactorPressureVessel,of10CFRPart50,DomesticLicensingofProductionandUtilizationFacility,providesthat:Forthoselightwaternuclearpowerreactorswhereneutronradiationhasreducedthefracturetoughnessofthereactorvesselmaterials,athermalannealingmaybeappliedtothereactorvesseltorecoverthefracturetoughnessofthematerial.Theuseofathermalannealingtreatmentissubjecttotherequirementsinthissection.Areportdescribingthelicensee'splanforconductingthethermalannealingmustbesubmittedinaccordancewith§50.4atleastthreeyearspriortothedateatwhichthelimitingfracturetoughnesscriteriain§50.61orAppendixGtoPart50wouldbeexceeded.ThisregulatoryguidedescribesaformatandcontentacceptabletotheNRCstafffortheThermalAnnealingReporttobesubmittedtotheNRCfordescribingthelicensee'splanforthermalannealingareactorvessel.ThisguidealsodescribestheThermalAnnealingResultsReportthatisrequiredby10CFR50.66tobesubmittedafterthethermalannealing.Useofthisformatbytheapplicantwouldhelpensurethecorn-USNRCREGULATORYGUIDESRegulatoryGuidesareissuedtodescribeandmakeavallabletothepublicsuchInformationasmethodsacceptabletotheNRCstaffforImplementingspecificpartsoftheCommission'sregulations,techniquesusedbythestaffInevaluatingspecificproblemsorpostulatedaccidents,anddataneededbytheNRCstaffInitsreviewofapplicationsforpermitsandlicenses.Regulatoryguidesarenotsubstitutesforregulations.andcomplianoewiththemIsnotrequired.MethodsandsolutionsdifferentfromthosesetoutIntheguideswillbeacceptableIftheyprovideabasisforthefindingsrequisitetotheIssuanceorcontinuanceofapermitorlicensebytheCommission.ThisguidewasIssuedafterconsiderationofcommentsreceivedfromthepublic.CommentsandsuggestionsforImprovementsIntheseguidesareencouragedatalltimes,andguideswillberevised,asappropriate,toacconmmodatecommentsandtoreflectnewInformationorexperience.pletenessoftheinformationprovided,wouldassisttheNRCstaffinlocatingspecificinformation,andwouldaidinshorteningthetimeneededforthereviewprocess.ThisregulatoryguidealsodescribesalternativemethodsthatareacceptabletotheNRCfordeterminingtherecoveryoffracturetoughnessafterthethermalannealingandforestimatingthedegreeofpostannealingreembrittlementexpectedduringsubsequentplantoperations;10CFR50.66requiresthesetobereported.Thisregulatoryguidecontainsguidanceonmandatoryinformationcollectionsthatarecontainedasrequirementsin10CFRPart50andthataresubjecttothePaperworkReductionActof1980(44U.S.C.3501etseq.).TheserequirementswereapprovedbytheOfficeofManagementandBudget,approvalnumber3150-0011.ThepublicreportingburdenforthiscollectionofinformationIsestimatedtobeanaverageof6000hoursperrespondent,includingthetimeforreviewinginstructions,searchingexistingdatasources,gatheringandmaintainingthedataneeded,andcompletingandreviewingthecollectionofinformation.Sendcommentsregardingthisburdenestimateoranyotheraspectofthiscollectionofinformation,includingsuggestionsforreducingtheburden,totheInformationandRecordsManagementBranch(T-6F33),U.S.WrittencommentsmaybesubmittedtotheRulesReviewandDirectivesBranch,DFIPS,ADM,U.S.NuclearRegulatoryCommission,Washington,DC20658-0001.Theguidesareissuedinthefollowingtenbroaddivisions:1.PowerReactors6.Products2.ResearchandTestReactors7.Transportation3.FuelsandMaterialsFacilities8.OccupationalHealth4.EnvironmentalandSiting9.AntitrustandFinancialReview5.MaterialsandPlantProtection10.GeneralSinglecopiesofregulatoryguidesmaybeobtainedfreeofchargebywrittheOfficeofAdministration,Attention:DistributionandServicestion,U.S.NuclearRegulatoryCommission.Washington,OC20655-0001.orbyfaxat(301)415-2260.IssuedguidesmayalsobepurchasedfromtheNationalTechnicalInformationServiceonastandingorderbasis.DetailsonthisservicemaybeobtainedbywritingNTIS,6285PortRoyalRoad,Springfield,VA22161.REGULATORYGUIDEOFFICEOFNUCLEARREGULATORYRESEARCHREGULATORYGUIDE1.162(DraftwasIssuedasDG-1027)FORMATANDCONTENTOFREPORTFORTHERMALANNEAUNGOFREACTORPRESSUREVESSELSNuclearRegulatoryCommission,Washington,DC20555-0001;andtotheDeskOfficer,OfficeofInformationandRegulatoryAffairs,NEOB-10202(3150-0011),OfficeofManagementandBudget,Washington,DC20503.B.DISCUSSIONBACKGROUNDCriterion31ofAppendixA,GeneralDesignCriteriaforNuclearPowerPlants,to10CFRPart50requiresthat:Thereactorshallbedesignedwithsufficientmargintoassurethatwhenstressedunderoperating,maintenance,testing,andpostulatedaccidentconditions,(1)theboundarybehaveinanonbrittlemannerand(2)theprobabilityofrapidlypropagatingfractureisminimized.Amajorconcerninthisregardisthatthematerialpropertiesofreactorvesselsdegradeprogressivelywhenexposedtoneutronradiationduringservice,resultinginalossinfracturetoughnessandductility.Tomaintainadequatetoughnessandprecludenonductilefailureinthevessel,anumberofmitigatingactionsaretakenduringtheoperatinglifeofareactor:periodicchangesaremadeinthepressure-temperature(P-T)limitsrequiredtoprecludenonductilefractureofthematerialsduringstartupandcooldown,limitationsareplacedonthereductionofCharpyupper-shelfenergy