ML20107D894
| ML20107D894 | |
| Person / Time | |
|---|---|
| Site: | Nuclear Energy Institute |
| Issue date: | 04/13/2020 |
| From: | Young D Nuclear Energy Institute |
| To: | Dennis Andrukat Office of Nuclear Material Safety and Safeguards |
| Andrukat, Dennis | |
| References | |
| 10 CFR Part 73, CAC/EPID: 001625 / U-2019-RU7-0000, NRC-2017-0227, RIN 3150-AK19 | |
| Download: ML20107D894 (13) | |
Text
1 Lappert, Glenna From:
YOUNG, David <dly@nei.org>
Sent:
Monday, April 13, 2020 3:21 PM To:
Andrukat, Dennis Cc:
NICHOL, Marcus; AUSTGEN, Kati
Subject:
[External_Sender] DRAFT B of NEI 20-05 Attachments:
NEI 20 Adv Rx Phys Sec Assessment Criteria - DRAFT B.docx
- Dennis, Since the draft rule wording has been made publicly available, Ive incorporated the proposed regulation references and text into our draft guidance document. The revised document, now at DRAFT B, is attached. Lets discuss this version at the public meeting on 4/22/20.
David From:YOUNG,David Sent:Friday,April10,202012:52PM To:Andrukat,Dennis<Dennis.Andrukat@nrc.gov>
Cc:NICHOL,Marcus<mrn@nei.org>;AUSTGEN,Kati<kra@nei.org>
Subject:
DRAFTAofNEI2005
- Dennis, Good afternoon.
As discussed today, attached is the current DRAFT of NEI 20-05, Methodological Approach and Considerations for a Security Assessment to Demonstrate Compliance with the Performance Criteria of 10 CFR 73.55(TBD).
Feel free to contact me with any questions.
David Young l Technical Advisor Nuclear Security & Incident Preparedness Nuclear Energy Institute 1201 F Street, NW, Suite 1100 Washington, DC 20004 (202) 739-8127
ThiselectronicmessagetransmissioncontainsinformationfromtheNuclearEnergyInstitute,Inc.Theinformationisintendedsolelyfortheuseoftheaddresseeanditsuseby anyotherpersonisnotauthorized.Ifyouarenottheintendedrecipient,youhavereceivedthiscommunicationinerror,andanyreview,use,disclosure,copyingordistributionof thecontentsofthiscommunicationisstrictlyprohibited.Ifyouhavereceivedthiselectronictransmissioninerror,pleasenotifythesenderimmediatelybytelephoneorby electronicmailandpermanentlydeletetheoriginalmessage.IRSCircular230disclosure:ToensurecompliancewithrequirementsimposedbytheIRSandothertaxing authorities,weinformyouthatanytaxadvicecontainedinthiscommunication(includinganyattachments)isnotintendedorwrittentobeused,andcannotbeused,forthe purposeof(i)avoidingpenaltiesthatmaybeimposedonanytaxpayeror(ii)promoting,marketingorrecommendingtoanotherpartyanytransactionormatteraddressed herein.
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- DRAFTB**nei.org NEI2005 MethodologicalApproachandConsiderationsfora TechnicalAnalysistoDemonstrateCompliancewith thePerformanceCriteriaof10CFR73.55(a)(7)
PreparedbytheNuclearEnergyInstitute
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Acknowledgements ThistechnicalreportwaspreparedbytheNuclearEnergyInstitute(NEI).Wegreatlyappreciate theeffortsbyourmembersandotherorganizationsthatcontributedtothepreparationand reviewthisdocument.
NEIProjectLead:DavidYoung
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TableofContents 1
Purpose.....................................................................................................1 2
TechnicalAnalysisGuidelines....................................................................1 2.1 ThreatCharacteristics.......................................................................1 2.2 ProbabilisticRiskAssessmentInformation........................................1 2.3 PlantConfiguration/ModeChanges..................................................2 2.4 DefinitionofTargetSetandRelationshiptoPerformanceCriteria....2 2.5 CreditforManualActions.................................................................3 2.6 CreditforLawEnforcementSupport.................................................3 2.7 Safety/SecurityInterface..................................................................3 2.8 HazardsfromAdjacentFacilitiesandTransportationRoutes.............4 2.9 NUREG/CR7145................................................................................4 2.10 UseofSecurityModellingTools.....................................................4 3
PerformanceCriteria.................................................................................5 3.1 PerformanceCriterion§73.55(a)(7)(i)(A)..........................................5 3.2 PerformanceCriterion§73.55(a)(7)(i)(B)..........................................5 3.3 PerformanceCriterion§73.55(a)(7)(i)(C)..........................................6 4
ConsequenceAnalysisGuidelines..............................................................7 4.1 GeneralInstructionsandAssumptions..............................................7 4.2 MeteorologicalParameters...............................................................8 4.3 AtmosphericTransportModeling......................................................9 4.4 ExposureParameters........................................................................9 5
Updates....................................................................................................9
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- DRAFTB**Page1 1 PURPOSE Thistechnicalreportprovidesguidanceforperformingatechnicalanalysistodemonstratethat anuclearpowerreactorapplicantqualifiesforthevoluntary,performancebasedalternatives tocertainphysicalsecurityrequirementscontainedinTitle10oftheCodeofFederal Regulations(10CFR)73.55,Requirementsforphysicalprotectionoflicensedactivitiesin nuclearpowerreactorsagainstradiologicalsabotage.Toqualifyforthealternative requirements,anapplicantmustdemonstratethatthenuclearpowerreactorfacilitymeetsone oftheperformancecriteriaspecifiedin§73.55(a)(7).Theguidanceinthisreportaddresses technicalanalysestargetedatanyofthethreeperformancecriterialistedin§73.55(a)(7).
2 TECHNICALANALYSISGUIDELINES 2.1 ThreatCharacteristics Thethreattobeconsideredinatechnicalanalysisisthedesignbasisthreatofradiological sabotageasstatedin§73.1,Purposeandscope,andreferredtoastheDBT.1Analysis elementsinvolvingconsiderationofspecificDBTcapabilitiesandtacticsshouldbeinformedby theguidanceinRegulatoryGuide(RG)5.69,GuidancefortheApplicationofRadiological SabotageDesignBasisThreatintheDesign,DevelopmentandImplementationofaPhysical SecurityProgramthatMeets10CFR73.55Requirements.2Anapplicantmayusean alternativeapproachtoagivencapabilityortacticintheiranalysis;however,thealternative approachshouldbeclearlyidentifiedandsupportedwithatechnicalbasis.
2.2 ProbabilisticRiskAssessmentInformation Atechnicalanalysismayconsiderinformationavailablefromaprobabilisticriskassessment (PRA)developedtomeetfacilitylicensingrequirements(e.g.,evaluationofsevereaccidents) establishedbytheU.S.NuclearRegulatoryCommission(NRC).Priortobeginningtheanalysis, anapplicantisencouragedtobecomefamiliarwiththeguidanceinRG5.81,TargetSet IdentificationandDevelopmentforNuclearPowerReactors.RG5.81includesadiscussionon theuseofPRAinformationandinsightstoassistwiththeidentificationoftargetsets.This materialcanhelpinformthecontentofatechnicalanalysisperformedtodemonstrate compliancewith§73.55(a)(7).
RG1.200,AnApproachforDeterminingtheTechnicalAdequacyofProbabilisticRisk AssessmentResultsforRiskInformedActivities,providesanapproachthattheNRChasfound acceptablefordevelopingaPRAsuitableforriskinformedregulatorydecisions.Theguidancein RG1.200shouldbefollowedtotheextentpracticalandapplicablewhenassessingthe acceptabilityofprobabilisticriskinformationusedinatechnicalanalysis.
1 An applicant planning to analyze a threat with characteristics different than the DBT (e.g., one with less capabilities) should also seek an exemption from this requirement as part of the facilitys licensing process.
2 RG 5.69 contains Safeguards Information (SGI) and is therefore not publicly available.
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- DRAFTB**Page2 2.3 PlantConfiguration/ModeChanges Asapplicabletothefacilitydesignandfeatures,atechnicalanalysisshouldconsidertheeffects fromplanned(routine)changestotheplantconfiguration,ormodeofoperation,ontheability tocontinuouslymeetatargetedperformancecriterion.Ifneeded,theanalysisshoulddescribe thecontrolsthatwillbeimplementedtoensurethattheperformancecriterionwillalwaysbe met.Alternatively,atechnicalanalysiscouldbedirectedattwo(orallthree)performance criteriawherebyoneperformancecriterionismetinoneplantconfigurationormode,and anothercriterionismetinadifferentconfigurationormode.
2.4 DefinitionofTargetSetandRelationshiptoPerformanceCriteria Asusedinthisdocument:
Atargetsetistheminimumcombinationofequipmentoroperatoractionswhich, ifallarepreventedfromperformingtheirintendedsafetyfunctionorprevented frombeingaccomplished,wouldlikelyresultinoffsitedosesgreaterthanthe referencevaluesin§§50.34(a)(1)(ii)(D)and52.79(a)(1)(vi).
AnachievabletargetsetmeansatargetsetthatiswithintheabilityoftheDBTto compromise,destroy,orrendernonfunctional,absentactionsbyanonsitearmed responseforce.
Therelationshipofatargetsettothethreeperformancecriteriapresentedin§73.55(a)(7)is shownbelow.
Performance Criterion FacilityTargetSet?
AchievableTarget Set?
MitigationMeasures forLossofTarget Set?
No N/A N/A
Yes No N/A
Yes Yes Yes
ThematerialinRG5.81canhelpinformtheidentificationanddevelopmentoftargetsets.
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- DRAFTB**Page3 2.5 CreditforManualActions Amanualactionperformedbythefacilitystaffmaybecredited3inatechnicalanalysisintended meet§§73.55(a)(7)(i)(B)or73.55(a)(7)(i)(C),includingactionstopreventormitigateoffsite radiologicalconsequences.Thebasisforassumingactionperformanceshouldprovide reasonableassurancethattheactioncouldbecompletedunderthepostulatedattack conditionsandbedocumentedintheanalysis.Forexample,anactiontoenableaphysical protectionelement,suchaschangingthepositionofabarrierorarmingadelayfeature,could becreditedprovidedthefacilityslayout,staffingandphysicalsecurityfeaturesgivereasonable assuranceofitscompletionduringanattack.Guidanceforassessingthecredibility(andthus acceptability)ofaproposedmanualactioncanbefoundinRG5.81.4 Manualactionsinitiatedfromaremotelocationmayalsobecredited.Inthesecases,thebasis shouldalsoaddresspotentialchallengestotimelyperformanceoftheactionandmitigative measures.Topicstoconsiderincludecyberattacks,reliabilityandredundancyof communicationssystems,andpotentialcollateraldutiesofpersonnelattheremotelocation.
2.6 CreditforLawEnforcementSupport Atechnicalanalysismaycreditanonsiteresponsefromalawenforcementagencytoneutralize thethreat;thiscreditmaybeappliedinananalysistargetedatanyofthethreeperformance criteria.Thescopeandtimingofthelawenforcementresponseshouldbeconsistentwiththe ReasonableAssuranceofProtectionTime(RAPT)describedinRG5.76,PhysicalProtection ProgramsatNuclearPowerReactors.ItispossiblethataresponsetimeshorterthantheRAPT couldbeused;however,thetechnicalanalysiswouldneedtoincludeasitespecificbasisfor theshortertime.[AugmentthisinformationwithdiscussioninpendingSECYonRAPT/SBT.]
2.7 Safety/SecurityInterface Theperformanceofphysicalprotectionelementsdescribedinatechnicalanalysismustbe consistentwiththerequirementsin§73.58,Safety/securityinterfacerequirementsfor nuclearpowerreactors.Morespecifically,thedesignandperformanceoftheseelements cannotadverselyaffectreactorsafetyand,conversely,plantandoperatorresponsestothe event(e.g.,changesinequipmentconfiguration)cannotadverselyaffectphysicalprotection elements.FurtherguidanceonthistopiccanbefoundinRG5.74,Managingthe Safety/SecurityInterface.
3 For the purpose of this document, credit means a determination that a proposed action or activity can be performed during an attack, thereby permitting the action or activity to be relied upon to support conclusions in the analysis. The determination should meet a reasonable assurance standard.
4 RG 5.81 uses the term operator action.
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- DRAFTB**Page4 2.8 HazardsfromAdjacentFacilitiesandTransportationRoutes Whenapplicable,thetechnicalanalysisshouldidentifyandevaluatehazardsfromanadjacent nonnuclearfacilitythatcouldpotentiallyaffectthesafetyorsecurityfeaturesrelieduponto meetaperformancecriterion.Theanalysisshouldalsoexaminesimilarhazardsemanating fromanonsiteornearbytransportationroute(e.g.,aroadwayorrailline).Consideration shouldbegiventohazardousconditionscreatedbytheDBTaswellasthosearisingfromother causes.Potentialhazardstoconsiderinclude:
Steamreleases Chemicalexplosions,releasesorspills Fires Misuseofindustrialradiationsources Thecharacteristicsofeachhazard,suchastiming,severity,andpersistence,shouldbe determined.Thetechnicalanalysisshouldthendescribethedesignprovisionsand/orresponse actionsthatwillmitigatetheimpactsofeachhazardandensurethatthecapabilitytomeetthe performancecriterionismaintained.HazardanalysesperformedtomeetotherNRClicensing requirements(e.g.,reactorsitingcriteria)maybereferencedasapplicable;thereisnoneedto performduplicativeanalyses.
2.9 NUREG/CR7145 Priortobeginningatechnicalanalysis,anapplicantisencouragedtobecomefamiliarwiththe guidanceinNUREG/CR7145,NuclearPowerPlantSecurityAssessmentGuide.NUREG/CR 7145providesguidancetodesigncertificationandcombinedlicenseapplicantsforoptimizing physicalsecurityduringthedesignphaseandminimizingrelianceonoperationalprograms (humanactions).ThematerialinNUREG/CR7145canhelpinformthecontentofatechnical analysisperformedtodemonstratecompliancewith§73.55(a)(7).
2.10 UseofSecurityModellingTools Anapplicantmayemployacomputerapplicationinatechnicalanalysistomodelthesecurity relatedaspectsofanattackonthefacility.Forexample,anapplicationcouldbeusedto evaluatethedetectionanddelaycapabilitiesdescribedintheanalysis.Foradditional informationonsecurityassessmentmodelingtools,seeSandiaNationalLaboratoriesReport SAND20075591,NuclearPowerPlantSecurityAssessmentTechnicalManual.
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- DRAFTB**Page5 3 PERFORMANCECRITERIA 3.1 PerformanceCriterion§73.55(a)(7)(i)(A)
Thisperformancecriterionstates:
Theradiologicalconsequencesfromahypothetical,unmitigatedeventinvolvingtheloss ofengineeredsystemsfordecayheatremovalandpossiblebreachesinphysical structuressurroundingthereactor,spentfuel,andotherinventoriesofradioactive materialsresultinoffsitedosesbelowthereferencevaluesdefinedin§§ 50.34(a)(1)(ii)(D)and52.79(a)(1)(vi)ofthischapter.
Tomeetthisperformancecriterion,afacilitymusthavenocombinationofequipmentor operatoractionsthat,ifpreventedfromperformingtheirintendedsafetyfunctionorprevented frombeingaccomplished,wouldlikelyresultinoffsitedosesexceedingthecitedreference values(i.e.,thefacilitydoesnothaveatargetset).Anapplicantcandemonstratecompliance withthiscriterionthroughatechnicalanalysisbasedonaconsequenceanalysisthat determinesoffsitedosesforthepostulatedsecurityevent.Theassessmentmayconsiderall engineeredsafetyandsecurityfeaturesinplaceatthebeginningoftheevent;manualactions tooperatethesefeaturesaftertheattackhasbegunshouldnotbeconsidered.
Guidelinesforperformingaconsequenceanalysisarepresentedinsection4ofthisdocument.
3.2 PerformanceCriterion§73.55(a)(7)(i)(B)
Thisperformancecriterionstates:
Theplantfeaturesnecessarytomitigateaneventandmaintainoffsitedosesbelowthe referencevaluesin§§50.34(a)(1)(ii)(D)and52.79(a)(1)(vi)ofthischaptercannot reasonablybecompromisedbyanadversaryasdefinedbythedesignbasisthreatfor radiologicalsabotage.
Tomeetthisperformancecriterion,afacilitymusthavenoachievabletargetsetthatwould likelyresultinoffsitedosesexceedingthecitedreferencevalues;inotherwords,thefacility doesnothaveatargetsetthatcanbecompromisedbyanadversarywithDBTcapabilitiestoan extentnecessarytoresultinoffsitedosesexceedingthecitedreferencevalues.Anapplicant candemonstratecompliancewiththiscriterionthroughatechnicalanalysisthatidentifiesplant targetsetsanddemonstratesthecapabilityofsafetyandsecurityfeaturestopreventtheDBT fromcompromisinganytargetset.Tomeetthiscriterion,theanalysisresultscannotrelyupon actionsbyanonsitearmedresponseforce.
Securityfeaturesthatmaybeconsideredintheanalysisinclude:
- Accesscontrolmeasures
- Detectionandassessmentcapabilities
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- Delayandbarrierfeatures
- Actionsbythefacilitystafforperformedremotely
- Insiderthreatmitigation 3.3 PerformanceCriterion§73.55(a)(7)(i)(C)
Thisperformancecriterionstates:
Plantfeaturesincludeinherentreactorcharacteristicscombinedwithengineeredsafety andsecurityfeaturesthatallowforfacilitymitigationstrategyimplementationifa targetsetiscompromised,destroyed,orrenderednonfunctional,suchthatoffsite radiologicalconsequencesaremaintainedbelowthereferencevaluesdefinedin§§ 50.34(a)(1)(ii)(D)and52.79(a)(1)(vi)ofthischapter.
Tomeetthisperformancecriterion,afacilityshouldhaveareactordesignwithalargeheat capacityandslowprogressionfromlossofsafetyequipmenttodegradationoffissionproduct barriersandreleaseofradionuclidesfromthefacility.Anapplicantcandemonstrate compliancewiththiscriterionthroughatechnicalanalysisbasedonaconsequenceanalysis thatdeterminestheshortestelapsedtimefromeventinitiationtotheonsetofconditionsthat wouldproduceareleasewithradiologicalconsequencesexceedingthecitedreferencevalues.
Theanalysiswillalsoneedtodescribetheplannedmitigationstrategiesthatwouldbe implemented,withinthetimeavailable,topreventtheconditionsleadingtotheradiological release.Guidelinesforperformingaconsequenceanalysisarepresentedinsection4ofthis document.
Astrategyshouldbeunderstoodasaplanofactionformaintainingorrestoringasafety functionthatischallengedduetothelossofatargetelementortargetset.Astrategycanbe implementedbyoneormoremethods.Amethodisaseriesofactionsdesignedto implementaspecificstrategy.Asanillustrativeexampleoftheseterms,considerthatplacinga portablepumpinservice(amethod)toinjectwaterintoareactorvessel(astrategy)would maintainorrestorethecorecoolingsafetyfunction.
Thedescriptionofamitigationstrategyshouldidentifythesafetyfunctionperformed,the eventsthatwouldpromptimplementation,theanticipatedtimeforperformance(with considerationofreasonablyexpectedconditionsprevailingduringanattack),andthefollowing elementsneededforexecution,asapplicable.
- Equipment(e.g.,portablepumps,generators,hoses,cables,etc.)
- Storagelocations(onsiteand/oroffsite)
- Transportanddeploymentarrangements(i.e.,provisionsformovingtheequipment fromastoragelocationtothelocationwhereitwillbeplacedintoservice)
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- Keyactionstoplaceequipmentinservice
- Staffing
- Communications Afacilitymeetingtheperformancecriterionin§73.55(a)(7)(i)(C)willneedtoperformperiodic administrativeandmaintenanceactivitiesthatsupporttheongoingcapabilitytoimplement mitigationstrategies.Tothisend,thetechnicalanalysisshoulddiscussthefollowingitems.
- Anticipatedoractualdocumentationofsupportfromoffsiteresourceproviders (e.g.,letterofagreement,memorandumofunderstanding,contract,etc.)andhow thisdocumentationwillbeperiodicallyverifiedandupdated.
- Plantdesignchangeandconfigurationcontrolmeasurestoensurethatcredited strategiescanbereadilyimplementedormodifiedasneeded.
- Maintenanceandtestingofequipment.
- Traininganddrillstovalidatestrategiesandmaintainproficiencyofpersonnel.
Anapplicantcomplyingwiththerequirementsof§50.155,Mitigationofbeyonddesignbasis events,isencouragedtobecomefamiliarwiththeguidanceinRG1.226,FlexibleMitigation StrategiesforBeyondDesignBasisEvents.RG1.226identifiesmethodsandproceduresthe NRCstaffconsidersacceptablefornuclearpowerreactorapplicantsandlicenseesto demonstratecompliancewithNRCregulationscoveringplanningandpreparednessforbeyond designbasisevents.ThematerialinRG1.226canhelpinformthecontentofatechnical analysisperformedtodemonstratecompliancewith§73.55(a)(7)(i)(C).
4 CONSEQUENCEANALYSISGUIDELINES 4.1 GeneralInstructionsandAssumptions Forthepurposeofthisdocument,aconsequenceanalysisisanactivityperformedbythe applicanttodetermineradiationdosesattheboundaryoftheexclusionareaandtheboundary ofthelowpopulationzone.Asnotedabove,aconsequenceanalysiswillbeneededtosupport demonstrationofcompliancewithPerformanceCriteria§§73.55(a)(7)(i)(A)and 73.55(a)(7)(i)(C).Theanalysisshoulddescribetheinitiatingevent(i.e.,theactionstakenbythe DBT),thecompromisedtargetset(foranalysesdirectedat§73.55(a)(7)(i)(C)),andthe subsequentresponsesbytheplant,facilitystaffandsupportingorganizationsandagencies, includinglawenforcement.Withthisinformation,theanalysisshouldthendeterminethetype andamountofradioactivityreleasedtotheenvironment.
Thefollowingassumptionsshouldbeemployedinaconsequenceanalysis.
- a. Bothactiveandpassivesafetyfeaturesmaybeconsideredintheanalysis.
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- b. Theatmosphericreleasepathwayistheriskdominantcontributortooffsitedoses(i.e.,
noconsiderationofdirectexposuresfromthefacilityorreleasestoliquidpathwaysis necessary).
- c. Theatmosphericreleaseconsistsofaerosolsorgasses(withradioactivedecayandin growthcorrectionsasappropriate).Ifareleasepathwayrequiresmorecomplex atmospherictransportmodeling,additionalanalysesmaybeneeded.
- d. AstraightlineGaussianplumesegmenttypeatmosphericdispersionmodel,with modificationsasneededtoaccountfornearfielddispersionphenomena,isusedto estimateatmosphericconcentrations.Suchmodelsaregenerallymostsuitablefor relativelysimpletransportsituations,suchasopenandlevelterrain,relativelysteady meteorology,andrelativelyclosedistances(<10km).Useofamoreadvanced dispersionmodelmayrequireadifferentsetofassumptionsormethodologicalsteps thanthosedescribedinthisdocument.
Forfacilitieswithrelativelysmallexclusionareas,astraightlineGaussianplumemodel mayoverestimatenearfieldradiologicalconsequences.Inthesecases,other consequenceanalysismodelsmaybeused.
- e. Thereisnocreditforpreplannedoffsiteprotectiveactionssuchasevacuationor sheltering.
- f. Theexposuredurationsshouldbeconsistentthedurationsspecifiedin§§ 50.34(a)(1)(ii)(D)and52.79(a)(1)(vi).
- g. Theanalysisneednotpostulatecoincidentevents(e.g.,aseismicorfloodingevent),or failuresofstructures,systemsorcomponentsunrelatedtotheevent.
Forthereleasescenarioanddoseprojections,aquantitativeradiologicalsourcetermshouldbe developedbyspecifyingatmosphericreleasecharacteristicssuchasthetimedependent isotopicreleaseratestotheatmosphere,releasedurations,releaselocations, physical/chemicalform,plumebuoyancy,etc.Theradiologicalsourcetermshouldbeestimated usinganalysismethodsandcodesevaluatedbyanNRCacceptedprocess.Incaseswheremore thanonereleasescenarioisidentified,theconsequenceanalysisshouldusethescenario(i.e.,
theeventsequence)thatproducesthegreatestoffsitedoseattheboundariesoftheexclusion areaandlowpopulationzones.
4.2 MeteorologicalParameters Ananalysistodevelopmeteorologicaldatamaybeneededtoevaluatearangeof meteorologicalconditionsinaprobabilisticfashion.Alternately,conservativetransportand dispersionconditionsmaybeassumed,althoughtheconservatismoftheselectedconditions shouldbeevaluatedtoensurethatthecombinationofparametersselectedfortransportand dispersionmodelingwasinfactconservative.Forexample,withappropriatejustification,site
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- DRAFTB**Page9 specificmeteorologicalinformationcouldbeusedtodevelopaverageexpectedatmospheric dispersioncharacteristics(i.e.,50thpercentilemeteorologyforthesite),whichwouldthenbe employedintheanalysis.
Selectionofasourceofmeteorologicaldatawouldincludeanevaluationofdataneedssuchas windspeeds,atmosphericstability,precipitation,mixingheight,etc.,fortemporaland geographicalrepresentativeness.Thequalityandcompletenessofthemeteorologicaldata shouldbeassessed,andsignificantuncertaintiesidentifiedandcharacterized.Itisexpected thatsitespecificmeteorologicaldatawillbeused;however,theremaybeinstanceswheresite specificdataisnotavailableorofsufficientqualityandcompleteness.Inthesecases,there shouldbeanexplanationoftheappropriatenessofthemeteorologicaldatausedforthe analysis.
4.3 AtmosphericTransportModeling Anatmospherictransportmodelappropriatefortherangeofdistancesunderconsideration shouldbeidentified.ForGaussiantypemodels,dispersionparametersappropriatetothe characteristicsoftheareaanddistancerangesunderconsiderationshouldbeidentified,and conceptualapproachesforthetreatmentofnearfieldeffectssuchaselevatedreleases, buildingwakeeffects,plumemeander,plumerise,etc.shouldalsobeidentified.Theselection ofanatmospherictransportmodelshouldalsoinvolveselectionofaconceptualapproachfor treatmentofwetanddrydeposition.Anyassumptionsmadeintheatmospherictransport modelshouldbeidentified.
4.4 ExposureParameters Therelevantexposurepathwaysshouldbeidentified;forexample,exposuretobothairborne anddepositedradioactivityfromatmosphericreleaseswouldinvolvebothexternal (groundshineandcloudshine)andinternal(inhalationofairbornematerialduringcloud passageorasaresultofresuspension)exposure.Inordertoassessthedose,theexposure parameters(e.g.,shieldingfactors,breathingrates,exposuredurations,etc.)wouldneedtobe characterized.Doseestimationsshouldbecarriedoutbycombiningtheresultsoftherelease, transport,andexposureassessmentwitharecognizedsourceofdoseconversionfactors(such asFederalGuidanceReportsissuedbytheU.S.EnvironmentalProtectionAgency)toestimate thedosesattheboundariesoftheexclusionareaandlowpopulationzone.
5 UPDATES Asneeded,atechnicalanalysisshouldbeupdatedtoreflectchangestofacilityfeaturesor offsitesupportresourcesdescribedintheanalysis.TheNRCshouldbenotifiedofachangethat affectscompliancewithanapplicableperformancecriterion(e.g.,ananticipatedchangewill resultintheperformancecriterionnolongerbeingmet).
Documentationofsupportfromoffsiteresourceprovidersshouldbeverifiedonanannual basis.