RG1.004 评价LOCA的潜在放射性后果所使用的假设 1974

Revision2June1974U.S.ATOMICENERGYCOMMISSIONREGULATORYDIRECTORATEOFREGULATORYSTANDARDSGUIDEREGULATORYGUIDE1.4ASSUMPTIONSUSEDFOREVALUATINGTHEPOTENTIALRADIOLOGICALCONSEQUENCESOFALOSSOFCOOLANTACCIDENTFORPRESSURIZEDWATERREACTORSA.INTRODUCTIONSection50.34of10CFRPart50requiresthateachapplicantforaconstructionpermitoroperatinglicenseprovideananalysisandevaluationofthedesignandperformanceofstructures,systems,andcomponentsofthefacilitywiththeobjectiveofassessingtherisktopublichealthandsafetyresultingfromoperationofthefacility.Thedesignbasislossofcoolantaccident(LOCA)isoneofthepostulatedaccidentsusedtoevaluatetheadequacyofthesestructures,systems,andcomponentswithrespecttothepublichealthandsafety.Thisguidegivesacceptableassumptionsthatmaybeusedinevaluatingtheradiologicalconsequencesofthisaccidentforapressurizedwaterreactor.Insomecases,unusualsitecharacteristics,plantdesignfeatures,orotherfactorsmayrequiredifferentassumptionswhichwillbeconsideredonanindividualcasebasis.TheAdvisoryCommitteeonReactorSafeguardshasbeenconsultedconcerningthisguideandhasconcurredintheregulatoryposition.B.DISCUSSIONAfterreviewinganumberofapplicationsforconstructionpermitsandoperatinglicensesforpressurizedwaterpowerreactors,theAECRegulatorystaffhasdevelopedanumberofappropriatelyconservativeassumptions,basedonengineeringjudgmentandonapplicableexperimentalresultsfromsafetyresearchprogramsconductedbytheAECandthenuclearindustry,thatareusedtoevaluatecalculationsoftheradiologicalconsequencesofvariouspostulatedaccidents.ThisguidelistsacceptableassumptionsthatmaybeusedtoevaluatethedesignbasisLOCAofaPressurizedWaterReactor(PWR).Itshouldbeshownthattheoffsitedoseconsequenceswillbewithintheguidelinesof10CFRPart100.(Duringtheconstructionpermitreview,guidelineexposuresof20remwholebodyand150remthyroidshouldbeusedratherthanthevaluesgivenin§100.11inordertoallowfor(a)uncertaintiesinfinaldesigndetailsandmeteorologyor(b)newdataandcalculationaltechniquesthatmightinfluencethefinaldesignofengineeredsafetyfeaturesorthedosereductionfactorsallowedforthesefeatures.)C.REGULATORYPOSITION1.Theassumptionsrelatedtothereleaseofradioactivematerialfromthefuelandcontainmentareasfollows:a.Twenty-fivepercentoftheequilibriumradioactiveiodineinventorydevelopedfrommaximumfullpoweroperationofthecoreshouldbeassumedtobeimmediatelyavailableforleakagefromtheprimaryreactorcontainment.Ninety-onepercentofthis25percentistobeassumedtobeintheformofelementaliodine,5percentofthis25percentintheformofparticulateiodine,and4percentofthis25percentintheformoforganiciodides.b.Onehundredpercentoftheequilibriumradioactivenoblegasinventorydevelopedfrommaximumfullpoweroperationofthecoreshouldbeassumedtobeimmediatelyavailableforleakagefromthereactorcontainment.c.Theeffectsofradiologicaldecayduringholdupinthecontainmentorotherbuildingsshouldbetakenintoaccount.d.Thereductionintheamountofradioactivematerialavailableforleakagetotheenvironmentbycontainmentsprays,recirculatingfiltersystems,orotherengineeredsafetyfeaturesmaybetakenintoaccount,buttheamountofreductioninconcentrationofradioactivematerialsshouldbeevaluatedonanindividualcasebasis.e.Theprimaryreactorcontainmentshouldbeassumedtoleakattheleakrateincorporatedortobeincorporatedasatechnicalspecificationrequirementatpeakaccidentpressureforthefirst24hours,andat50percentofthisleakratefortheremainingdurationofUSAECREGULATORYGUIDESCopiesofpublishedguidemay.beobtainedbyrequestindicatingthedivisionsdesiredtotheUS.AtomicEnemgyCommilsso,Washlngton.D.C.20646,RegulatoryGuidesweissuadtodescribeandmakeavailabletothepublicAttention:DirectorofRegulatoryStandards.CommentsandsuggestionsformethodsacceptabletotheAECRegulatorystaffofimplementingspecificpartsofImpr°mentsIntheoseuldesweencouragedandshouldbesenttotheSecretarytheCommission'sregulations,todelineatetechniquesusedbythestaffinoftheCommislion,U.S.AtomicEnergyCommission,Washington,D.C.20645,eanluatingspecificproblemsorpostulatedaccidents,ortoprovideguidancetoAttention:Chief,PublicProcoedlnglStaff.applicants.RegulatoryGuidesarenotsubstitutesforregulationsandcompliancewiththemisnotrequired.MethodsandsolutionsdifferentfromthosesetoutinTheguidesareissuedinthefollowingtenbroaddivisions:theguideswillbeacceptableiftheyprovideabasisforthefindingsrequisitetotheIssuanceorcontinuanceofapermitor)iconsebytheCommission.1.PeOWrdReactors6.Products2.ResearchendTestReactors7.Transportation3.FuelsendMaterialsFacilitiesELOccupatlonalHealthPublishedguideswillberevisedperiodically,asappropriate,toaccommodate4.EnvironmentalandSiting9.AntitrustReviewcommentsandtoreflectnewinformationorexperienca.5.MaterialsandPlantProtection10.Generaltheaccident.,Peakaccidentpressureisthemaximumpressuredefinedinthetechnicalspecificationsforcontainmentleaktesting.2.Acceptableassumptionsforatmosphericdiffusionanddoseconversionare:a.The0-8hourgroundlevelreleaseconcentrationsmaybereducedbyafactorrangingfromonetoamaximumofthree(seeFigure1)foradditionaldispersionproducedbytheturbulentwakeofthereactorbuildingincalculatingpotentialexposures.Thevolumetricbuildingwakecorr