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U.S.NUCLEARREGULATORYCOMMISSIONRevision1February1978,'REGULATORYGUIDEOFFICEOFSTANDARDSDEVELOPMENTREGULATORYGUIDE1.91EVALUATIONSOFEXPLOSIONSPOSTULATEDTOOCCURONTRANSPORTATIONROUTESNEARNUCLEARPOWERPLANTSA.INTRODUCTIONGeneralDesignCriterion4,EnvironmentalandMissileDesignBasis,ofAppendixA,GeneralDesignCriteriaforNuclearPowerPlants,to10CFRPart50,LicensingofProductionandUtilizationFacilities,requiresthatnuclearpowerplantstructures,systems,andcomponentsimportanttosafetybeappropriatelyprotectedagainstdynamiceffectsresultingfromequipmentfailuresthatmayoccurwithinthenuclearpowerplantaswellaseventsandconditionsthatmayoccuroutsidethenuclearpowerplant.Theselattereventsincludetheeffectsofexplosionofhazardousmaterialsthatmaybecarriedonnearbytransportationroutes.ThisguidedescribesmethodsacceptabletotheNRCstafffordeterminingwhethertheriskofdamageduetoanexplosiononanearbytransportationrouteissufficientlyhightowarrantadetailedinvestigation.Acceptablemethodsforevaluatingstructuraladequacywhenaninvestigationiswarrantedarealsodescribed.Thisguideis-limitedtosolidexplosivesandhydrocarbonsliquifiedunderpressureandisnotapplicabletocryogenicallyliquifiedhydrocarbons,e.g.,LNG.Itconsiderstheeffectsofairblastsonhighway,rail,andwaterroutesbutexcludespipelinesandfixedfacilities.B.DISCUSSIONInordertomeetGeneralDesignCriterion2,DesignBasisforProtectionAgainstNaturalPhenomena,ofAppendixAto10CFRPart50withrespecttotornadoes,thestructures,systems,andcomponentsimportanttosafetyofanuclearpowerplantmustbedesignedtowithstandtheeffectsofadesignbasistornado,includingwind,pressuredrop,andtheeffectsofmissiles,withoutcausinganaccidentandwithoutdamagethatwouldpreventasafeandorderlyshutdown.Inaddition,thosestructures,systems,andcomponentsmustbedesignedtoaccommodatethevibratorygroundmotionassociatedwiththeSafeShutdownEarthquake.Theeffectsofexplosivesthatareofconcerninanalyzingstructuralresponsetoblastareincidentorreflectedpressure(overpressure),dynamic(drag)pressure,blast-inducedgroundmotion,andblastgeneratedmissiles.ItisthejudgmentoftheNRCstaffthat,forexplosionsofthemagnitudeconsideredinthisguideandthestructures,systems,andcomponentsthatmustbeprotected,overpressureeffectsarecontrolling.Dragpressureeffectswillbemuchsmallerthanthoseduetothewindloadingassumedforthedesignbasistornado.Theeffectsofblastgeneratedmissileswillbelessthanthoseassociatedwiththeblastoverpressurelevelsconsideredinthisguide.Iftheoverpressurecriteriaofthisguideareexceeded,theeffectsofmissilesmustbeconsidered.Theeffectsofblast-inducedgroundmotionattheoverpressurelevelsconsideredinthisguidewillbelessthanthoseofthevibratorygroundmotionassociatedwiththeSafeShutdownEarthquake.Thisregulatoryguidedescribesamethodfordeterminingdistancesfromcriticalplantstructurestoarailway,highway,ornavigablewaterwaybeyondwhichanyexplosionthatmightoccuronthesetransportationroutesisnotlikelytohaveanadverseeffectonplantoperationortopreventasafeshutdown.Undertheseconditions,adetailedreviewofthetransportofexplosivesonthesetransportationrouteswouldnotberequired.Amethodforestablishingthedistancesreferredtoabovecanbebasedonalevelofpeakpositiveincidentoverpressure(designatedasPs,inRef.1)belowwhichnosignificantdamagewouldbeexpected.ItisUSNRCREGULATORYGUIDESCommentsshouldbesenttotheSecretaryoftheCommission,US.NuclearRegu.RegulatoryGuidesareissuedtodescribeandmakeavailabletothepublicmethodslatoryCommission,Washington,D.C.20555.AttentionDocketingandServiceacceptabletotheNRCstaffofimplementingspecificpartsoftheCommission'sBranch.regulations,todelineatetechniquesusedbythestaffinevaluatingspecificproblemsTheguidesareissuedinthefollowingtenbroaddivisionsorpostulatedaccidents,ortoprovideguidancetoapplicants.RegulatoryGuidesarenotsubstitutesforregulations,andcompliancewiththemisnotrequired.1.PowerReactors6.ProductsMethodsandsolutionsdifferentfromthosesetoutintheguideswillbeaccept-2.ResearchandTestReactors7.Transportationableiftheyprovideabasisforthefindingsrequisitetotheissuanceorcontinuance3.FuelsandMaterialsFacilities8.OccupationalHealthofapermitorlicensebytheCommission.4.EnvironmentalandSiting9.AntitrustReview5.MaterialsandPlantProtection10.GeneralCommentsandsuggestionsforimprovementsintheseguidesareencouragedatalltimes,andguideswillberevised,asappropriate,toaccommodatecommentsandRequestsforsinglecopiesofissuedguides(whchmaybereproduced)orforplacetoreflectnewinformationorexperience.However,commentsonthisguide,ifmentonanautomaticdistributionlistforsinglecopiesoffut-ireguide%inspecilicreceivedwithinabouttwomonthsafteritsissuance,willbeparticularlyusefulindivisionsshouldbemadeinwritingtotheU.S.NuclearRegulatoryCommission,evaluatingtheneedforanearlyrevision.Washington,D.C.20555.Attention.Director.DivisionofDocumentControlthejudgmentoftheNRCstaffthat,forthestructures,systems,andcomponentsofconcern,thislevelcanbeconservativelychosenat1psi(approximately7kPa).BasedonexperimentaldataonhemisphericalchargesofTNTcitedinReference1,asafedistancecanthenbeconservativelydefinedbytherelationshipRkW/3whereRisthedistanceinfeetfromanexplodingcharg