ML21138A810
| ML21138A810 | |
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| Issue date: | 02/21/2021 |
| From: | Nathan Siu NRC/RES/DRA, Univ of California - Los Angeles |
| To: | |
| Siu, Nathan - 301 415 0744 | |
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Text
PRAandRiskInformedDecisionMakingattheNRC:
SomeTrendsandChallenges*
NathanSiu SeniorTechnicalAdvisorforPRA OfficeofNuclearRegulatoryResearch PresentedattheGarrickInstituteofRiskSciences UCLA,LosAngeles,CA February21,2020
- TheviewsexpressedinthispresentationarenotnecessarilythoseoftheU.S.NuclearRegulatoryCommission
2 Thatsso cool Arewe thereyet?
Outline
- UseofriskinformationatNRC
- Achangingworld:trendsand PRA/RIDMchallenges
- Challenge:treatmentof uncertainty
- Challenge:riskcommunication
- Closingthoughts
3 NRCUSEOFRISKINFORMATION Itisofthehighestimportanceintheartofdecisionmakingtobeable torecognize,outofanumberoffacts,whichareincidentalandwhich vital.Otherwiseyourenergyandattentionmustbedissipatedinstead ofconcentrated.
WithapologiestoSherlockHolmes (TheHoundoftheBaskervilles)
4 TripletDefinitionofRisk(KaplanandGarrick,1981)*
Risk{ i, i,
i }
Features
- Vector,notscalar
- Qualitativeand quantitative
- Differencesacross accidentspectrum
- Whatcangowrong?
- Whataretheconsequences?
- Howlikelyisit?
- AdoptedbyNRC.See:
WhitePaperonRiskInformedandPerformanceBasedRegulation(Revised),SRMtoSECY98144,March1,1999 GlossaryofRiskRelatedTermsinSupportofRiskInformedDecisionmaking,NUREG2122,May2013 ProbabilisticRiskAssessmentandRegulatoryDecisionmaking:SomeFrequentlyAskedQuestions,NUREG2201,September2016 NRCUseofRiskInformation
5 NRCUsesofRiskInformation PRAPolicyStatement(1995)
- IncreaseuseofPRAtechnologyinall regulatorymatters
- ConsistentwithPRAstateoftheart
- Complementdeterministicapproach, supportdefenseindepthphilosophy
- Benefits:
(1) Considersbroadersetofpotentialchallenges (2) Helpsprioritizechallenges (3) Considersbroadersetofdefenses U.S.NuclearRegulatoryCommission,UseofProbabilistic RiskAssessmentMethodsinNuclearActivities;Final PolicyStatement,FederalRegister,60,p.42622(60FR 42622),August16,1995.
Regulations and Guidance Licensing and Certification Oversight Operational Experience Decision Support NRCUseofRiskInformation
6 RiskInformedRegulatory DecisionMaking(RIDM) aphilosophy wherebyrisk insightsareconsidered togetherwithotherfactors toestablishrequirements thatbetterfocuslicensee andregulatoryattentionon designandoperationalissues commensuratewiththeir importancetopublichealth andsafety.[Emphases added]
WhitePaperonRiskInformedand PerformanceBasedRegulation,SECY98144, January22,1998.
Currentregulations Defenseindepth Safetymargins Risk Monitoring Integrated DecisionMaking AdaptedfromRG1.174 Adaptedfrom:U.S.NuclearRegulatoryCommission,AnApproachforUsingProbabilisticRiskAssessmentinRiskInformed DecisionsonPlantSpecificChangestotheLicensingBasis,RegulatoryGuide1.174,Revision 3,January2018.
NRCUseofRiskInformation
7 InAdditionto ImmediateDecision Support RiskInformation
- Results
- Insights
- Explanations
- Uncertainties
- Qualifications AdaptedfromNUREG2150 NRCUseofRiskInformation
8 ACHANGINGWORLD:TRENDSAND CHALLENGES Itstoughtomakepredictions,especiallyaboutthefuture.
YogiBerra
9 LookingAhead:PossibleFutures U.S.NuclearRegulatoryCommission,TheDynamicFuturesforNRCMissionAreas,2019.(ADAMSML19022A178)
TrendsandChallenges
10 DrivetoRIDM:Transformation
- Evolvingsituation(marketforces,newnucleartechnologies,new analyticalmethodsanddata,newprofessionals)
ApplyingthePrinciplesofGoodRegulationasaRiskInformedRegulator, October15,2019(ADAMSML19260E683)
- Vision:makesafeuseofnuclear technologypossible
- Continuingstandard:reasonable assuranceofadequateprotection
- Potentiallydifferentwaysof achievement-embracechange TrendsandChallenges
11 DrivetoRIDM:EffectofMarketForces "RiskInformedPerformanceBasedTechnologyInclusiveGuidanceforNonLightWater Reactors,"NEI1804,Rev.1,August29,2019.
TrendsandChallenges
12 DrivetoRIDM:NewTechnologies
- Newdesigns
- Newoperationalconcepts
- SmartReactorSystems
- ImprovedAnalysis Imworried aboutthe mission,Dave.
- CmonHAL, openthepod baydoor TrendsandChallenges PhotocourtesyofNEAHalden ReactorProject
13 DrivetoRIDM:NewProfessionals Changing
- Experiences,knowledge
- Informationcontentand deliverypreferences
- Comfortwithanalytics, risk,probability
- Mobility TrendsandChallenges Source:https://www.nrc.gov/readingrm/doccollections/commission/slides/2019/20190618/staff20190618.pdf
14 Weneedtotalk Thatstoocomplicated[forPRA].
PRAwasnevermeanttomodelthat.
IgetnightmareseverytimeIthinkofthat[PRA]
course.
PRAisformyPhDs.
Wedontwantyou[PRA]guystobegatekeepers.
Youllneverriskthisrequirementaway.
DrivetoRIDM:IntegratedPRA PRA:
- Involvesmultipledisciplines
- Viewsaccidentsassequencesofevents
- Takestraditionalsystemsengineering(divideand conquer)approach Ideal
- Teamwideunderstandingofmodel(howthingsfail) andresults
- Fullownership:WenotThem Challenges
- Boxologyencouragedstovepiping,interactionsas handoffsacrosssimplifiedinterfaces
- Differenttechnicalcultures,differentperspectiveson treatmentofuncertainty(analysisandcommunication)
TrendsandChallenges
15 DrivetoRIDM:BacktotheFuture
- Earlyyears:progressiveevolutionof protectionconsideringmaximumcredible accident
- Remotesiting
- Containment
- Engineeredsafeguards,singlefailurecriterion
- Current:engineeringsolutionsconsidered
- Singlefailure
- Containment?
SECY190036,April11,2019(ML19060A081):
thestaffisseekingCommissionaffirmationthat themostdamagingsingleactivefailureofsafety relatedequipmentisrequiredtobeconsideredin performingdesign,andtransientandaccident analyses,unlesssuchafailurecanbeshownwith highconfidencetonotbecredible.
SRMSECY190036,July19,2019 (ML19183A408):Inanylicensingrevieworother regulatorydecision,thestaffshouldapplyrisk informedprincipleswhenstrict,prescriptive applicationofdeterministiccriteriasuchasthe singlefailurecriterionisunnecessarytoprovide forreasonableassuranceofadequateprotection ofpublichealthandsafety.
TrendsandChallenges
16 PRA/RIDMChallengesforNRC
- Heavierrelianceonriskinformation,e.g.,tocompareagainst establishedcriteria=>improvedmodels,improved characterizationandcommunicationofuncertainties
- Changingnucleartechnologies=>bepreparedtoreview
- Changinganalyticaltechnologies=>bepreparedtoreview, adaptforuse
- Changingstaff=>changingriskcommunication TrendsandChallenges
17 CHALLENGE:TREATMENTOFUNCERTAINTY Anytruthisbetterthanindefinitedoubt.
SherlockHolmes(TheYellowFace)
18 TreatmentofUncertainties:AnalystView TreatmentofUncertainties:General Manycalculationsbring success;fewcalculations bringfailure.Nocalculations atallspelldisaster!
SunTzu(TheArtofWar)
19 ABiggerPicture:UncertaintyAnalysisforRIDM OtherConsiderations Currentregulations Safetymargins Defenseindepth Monitoring Quantitative Qualitative AdaptedfromNUREG2150 TreatmentofUncertainties:General
20 UncertaintyTypesforRIDMSupport Apracticalclassification:
- Parameter
- Model
- Completeness mod*el,n. a representationofreality createdwithaspecific objectiveinmind.
A.Mosleh,N.Siu,C.Smidts,andC.Lui,Model Uncertainty:ItsCharacterizationand Quantification,CenterforReliability Engineering,UniversityofMaryland,College Park,MD,1995.(AlsoNUREG/CP0138,1994)
PRAmodelsforNPPs Typicallyan assemblageofsub modelswith parameters Implicitlyinclude issuesconsideredbut notexplicitly quantified TreatmentofUncertainties:General
21 ParameterUncertainty MatureBayesianframeworkand mechanicsbutdiverseviewsonvalue SomeTechnicalChallenges Effectofdatapreprocessing
Selection
Interpretation Effectofanalysisshortcuts
Standardpriordistributions
Simplifiedexpertelicitation
Independenceassumption Ensuringcorrespondencewith stateofknowledge
Basicevents(micro)
Overallresults(macro)
TreatmentofUncertainties:Parameters
22 HurricaneAndrew:8/22/1992,1200UTC (about2daysbeforeFLlandfall)
PlotadaptedfromUniversityofWisconsinMilwaukee (https://web.uwm.edu/hurricanemodels/models/archive/)
Model Uncertainty:
Hurricane Example TreatmentofUncertainties:Models
23 Model Uncertainty:
Hurricane Example HurricaneIrma:9/8/2017,0000UTC (about2daysbeforeFLlandfall)
PlotadaptedfromUniversityofWisconsinMilwaukee (https://web.uwm.edu/hurricanemodels/models/archive/)
TreatmentofUncertainties:Models
24 ModelUncertainty:HRAExample Samemethod,differentteams Sameteam,differentmethods Allteams,allmethods NRI,CREAM NRI,DT+ASEP NRC,SPARH INL,SPARH ABye,etal.,InternationalHRAEmpiricalStudy,NUREG/IA0216,August2011.
TreatmentofUncertainties:Models
25 ModelUncertainty:HRAExample HFE2A HFE1C HFE1A HFE3A HFE1B HEPsbyHFE(AllMethods)
Decreasingdifficulty HumanErrorProbability(HEP) 1.0E+0 1.0E1 1.0E2 1.0E3 1.0E4 1.0E5 ASEPTeam1 ASEPTeam2 SPARHTeam1 SPARHTeam2 CBDT&HCR/ORETeam1 CBDT&HCR/ORETeam2 CBDT&HCR/ORETeam3 ATHEANATeam1 ATHEANATeam2 Empirical95th Percentile Empirical5th Percentile AdaptedfromNUREG2156 TreatmentofUncertainties:Models
26 ModelUncertainty:StatusandChallenges
- Consensus:importanttounderstand (consideringdecisionathand)
- Differenttechnicalpointsofviewon treatment:
- Competitionbetweenmodelsvs.multiple (correlated)sourcesofevidence
- Quantifyvs.characterize
- Includeorexcludeusereffects
- Methodstoquantifymodeloutput uncertaintyexist;*challengesinclude
- Uncertaintiesinunmeasuredparameters
- Submodellimitsofapplicability
- Representativenessofcomputedresults AdaptedfromV.M.Andersen,SeismicProbabilisticRiskAssessment ImplementationGuide,EPRI3002000709,ElectricPowerResearch Institute,PaloAlto,CA,December2013 M.H.Salley andA.Lindeman,VerificationandValidationof SelectedFireModelsforNuclearPowerPlantApplications, NUREG1824Supplement1/EPRI3002002182,November2016.
- See,forexample,E.Droguett andAliMosleh,Bayesianmethodologyformodeluncertaintyusing modelperformancedata,RiskAnalysis,28,No.5,14571476,2008.
TreatmentofUncertainties:Models
27 CompletenessUncertainty
- Potentialconcerns
- Knowngaps(missingscope)
- Excessiveamplification(Fearofthedark)
- Excessivediscounting(Outofsight,outofmind)
- Unknowngaps
- RIDMguidance(NUREG1855Rev.1,2017)
- Progressiveanalysis(screening,bounding, conservative,detailed)
- Nonprobabilisticapproaches
- Important(critical?)toacknowledgeand characterizeforriskcommunication Itwouldceasetobea dangerifwecould defineit.
SherlockHolmes (TheAdventureoftheCopperBeeches)
TreatmentofUncertainties:Completeness Wheresthe goat???
28 KnownGaps(KnownUnknowns)
- Broadscenariocategories
- Contributorswithincategories TreatmentofUncertainties:Completeness
- Technology={methods,models,tools,data}
Rationale CommonExample(s)
Outofscope security/sabotage,operationoutsideapprovedlimits Lowsignificance(preanalysisjudgment) externalfloods(manyplantspreFukushima)
AppropriatePRAtechnology*unavailable managementandorganizationalfactors PRAnotappropriate software,security Category Example(s)
Externalhazards multiplehazards Humanreliability errorsofcommission,nonproceduralized recovery Passivesystems thermalhydraulicreliability
29 https://en.wikipedia.org/wiki/Hurricane_Irma#/media/File:Irma,_Jose_and_Katia_20170907.png MultipleHurricanes:
AKnownUnknown TreatmentofUncertainties:Completeness
30 UnknownUnknowns:YouSayTomto Model Known Unknowns Unknown Unknowns
- Explicitorimplicit?
- Extentofcoverage?
- Knownbywhom?
- Knownwhen?
- Timefromideatotheory toPRAimplementation?
Nowitsgarbage!
OscarMadison (TheOddCouple)
Classificationisonly importantifitaffects:
- Understanding
- Communication
- Decisionmaking TreatmentofUncertainties:Completeness
31 UnknownUnknowns:ADemonstratedProblem?
Model Known Unknowns Unknown Unknowns Then(asurprise?)
Now(treatedincurrentPRAs?)
BrownsFerryfire(1975)- alongrecognizedhazard;notindraft WASH1400butroutinelytreatednow Chernobyl(1986)- precursoratLeningrad(1975);nonroutinetest duringshutdowninanyLPSDanalyses?
TMI(1979)- precursorsincludeDavisBesse (1977);operatorEOCs notinmodels;currentrecognitionandsomeexplorations Blayais flood(1999)- externalfloodsoftenscreenedattime; currentrecognition,multihazardunderdevelopment Maanshan HEAF/SBO(2001)- HEAFphenomenonknown,inanyPRAs attime?Nowincludedasaninitiator;smokeeffect?
DavisBesse RPVcorrosion(2002)- RPVfailureanalysesfocusedon crackpropagation;M&OfailurenotinPRAs FukushimaDaiichi(2011)- precursors:Blayais (1999),IndianOcean (2004),hazardunderreviewattime;PRAmodelsunderdevelopment TreatmentofUncertainties:Completeness
32 WhatCanWe(PRAR&D)Do?
- Continuetodeveloptechnologytoaddress knowngaps
- Riskinformedprioritization
- Fullyengageappropriatedisciplines
- Takeadvantageofgeneralcomputationaland methodologicaldevelopments
- Facilitatereemphasisonsearching
- Demonstrationofefficiencyandeffectiveness (vs.checklist/screening)
- Developimprovedtools(includingOpE mining)
TreatmentofUncertainties:Completeness Event(NUREG/CR4839),1992 Aircraftimpact Avalanche Coastalerosion Drought Externalflooding Extremewindsandtornadoes Fire Fog Forestfire FrostHail Hightide,highlakelevel,orhigh riverstage
Wheresthe goat???
33 CHALLENGE:INTERNALRISKCOMMUNICATION Willsomebodyfindmeaonehandedscientist?!
SenatorEdmundMuskie (Concordehearings,1976)
I.Flatow,Truth,Deception,andtheMythoftheOneHandedScientist,October18,2012.Availablefrom:
34 InternalRiskCommunication OtherConsiderations Currentregulations Safetymargins Defenseindepth Monitoring Quantitative Qualitative AdaptedfromNUREG2150 InternalRiskCommunication With To
35 CurrentMechanisms Documentsand Presentations (Flatland)
Interactive Discussion (Storytelling)
InternalRiskCommunication
36 ItsComplicated Riskinformationcomplexity
- Hyperdimensional
- Heterogeneous
- Dynamic
- Uncertain Individualuserdifferences,e.g.,
- Knowledge
- Preferences/heuristics Socialfactors,e.g.,
- Trust
- Decisionandgroupdynamics Situationalcontext,e.g.,
- Availabletime
- Decisionsupportvs.informational Uhh,weseemtohave aTEPvulnerability, maybe,Ithink Thermal Exhaust Port InternalRiskCommunication
37 ThinkingAhead
- Tuftemodel:userichdisplaysandreports,encourageusertoexplore*
- Agraduatedtechnicalapproachtoassistandthengobeyond?
InternalRiskCommunication Interface InteractionMode Hyperlinkeddashboardsandreports Manual Video AIassist Visualimmersion Multisensoryimmersion
- SeeTufteswebsite forcomplaintsaboutthecurrentPowerPointculture Time
38 InternalRiskCommunication Graphicadaptedfrom https://www.flickr.com/photos/83823904@N00/64156219/
(permissionCCBY2.0)
FromStatictoInteractiveDashboardtoSciFi?
M.Korsnick,RiskInformingtheCommercialNuclearEnterprise,PromiseofaDiscipline:Reliability andRiskinTheoryandinPractice,UniversityofMaryland,April2,2014.
39 CLOSINGTHOUGHTS Andwhatifthebirdwontsing?
Nobunaga:Makeitsing.
Hideyoshi:Makeitwanttosing.
Tokugawa:Wait.
Eiji Yoshikawa(Taik)
40 AnEvolvingEnvironment(1)
Ongoingchanges
- Marketforces
- Nucleartechnologies
- Analyticalmethods anddata
- Professional workforce ClosingThoughts Increasingdemands (qualitativeand quantitative)on PRA/RIDMtechnology (operatingfleetand newreactors)
41 AnEvolvingEnvironment(2) 0 5
10 15 20 25 30 35 40 45 50 0
100 200 300 400 500 600 700 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019
%NRCTotal ContractingBudget($M)
Year NRC Research Budget (FY 1976 - FY 2019)
Actual ($M)
Inflation Adjusted ($M)
% NRC Total ClosingThoughts BudgetdatafromNUREG1350(NRCInformationDigest)
42 ChallengetoNRC/RESandOpportunities Toincreaseeffectivenessandefficiency
- [Enterprise]riskinformedprioritization
- Considernewtechnicalapproaches
- Bettertargetavailableresources(e.g.,
universitygrantfunds)
- Leverageotherprograms
- Observe(learn,providefeedback)
- Cooperate
- Collaborate
- Goodideasarewelcome!
ClosingThoughts Dial1800CALLRES Dial1800CALLRES
43 ADDITIONALSLIDES
44 RIDMandNRCsPrinciplesofGoodRegulation
- Independence
- Openness
- Efficiency
- Clarity
- Reliability U.S.NuclearRegulatory Commission,PrinciplesofGood Regulation(ADAMS ML14135A076)
Highest Standards Best Information Public Coherent Logical Practical Competence Acceptable Readily Understood Candid Independence Openness Efficiency Clarity Reliability Risk Safety Margins Defense-In-Depth Current Regulations Performance Monitoring Integrated Decision Making
45 DaedalusProblem:ARIDMExample
46 Howtogetaway?
- Optionsconsidered
- Flightbysea
- Flightbyair
- Apparentmetric
- Successfulescapefor DaedalusandIcarus
- Adoptedsolution
- Practice
- SpecificcautionstoIcarus
- Flyingtooclosetothesun
- Flyingtooclosetotheocean
47 AgoodexampleofRIDM?
- Currentregulations:N/A(escaping authority)*
- DefenseinDepth:none
- Safetymargins:vaguecharacterization
- Riskassessment:incomplete(seenext)
- Performancemonitoring:inflight observationbutlittle/nochanceof intervention(seeDefenseinDepth)
- EvenifflighthadbeensanctionedbyKingMinos(Crete),nomentionofcurryingfavorwithOlympians
48 Onthatriskassessment
- DidDaedalusconsiderthefullsetofpotentially relevantmetrics?
- Didhefullyconsiderotherpotentialoptions?
- Didhehavetherightmodelsforhisscenarios?
- Didheknowaboutotherpossiblescenarios?
- Mightabetteranalysis(orevenachatwithhis buddydownthehall)havehelpedhimmakea better(inhindsight)decision?
Known Unknowns Unknown Unknowns Conceivability AltitudeEffects?
AltitudeEffects?
DeityAction MidAirCollision DesignError ClearAirTurbulence MechanicalFailure PilotInexperience (Takeoff/Landing)
Scenarios Waxfailure(tooclosetosun)
Liftfailure(dampfeathers) 1000 1050 1100 1150 1200 1250 1300 1350 1400 0
2000 4000 6000 8000 10000 Irradiance(W/m2)
Altitude(m)
IrradiancevsAltitude MtIda Models Phasedescape Shipboard(stowaway,bribery,)
Outsiderescue HighTech(sub,fastsurface,)
Donothing Options CALL1800HELPRES CALL1800HELPRES Impacton:
Icarusmother FriendsonCrete Environment(postcrash)
Refugeehavens
RiskMetrics
49 RiskInfoUses-RegulationsExample (RiskInformedFireProtection)
- BrownsFerryNuclearPowerPlantfire (3/22/75)
- Candleignitedfoampenetrationseal, initiatedcabletrayfire;watersuppression delayed;complicatedshutdown
- SecondmostchallengingeventinU.S.
nuclearpowerplantoperatinghistory
- Spurredchangesinrequirementsand analysis TVAFilePhoto 8.5m 8.5m 11.5m 11.5m 3m 3m Adapted from NUREG-0050 Adapted from NUREG-0050 8.5m 11.5m 3m Adapted from NUREG-0050
50 RiskInfoUses-RegulationsExample (RiskInformedFireProtection)
PostBrownsFerrydeterministicfireprotection(10CFRPart 50,AppendixR)
- 3hourfirebarrier,OR
- 20feetseparationwithdetectorsandautosuppression,OR
- 1hourfirebarrierwithdetectorsandautosuppression Riskinformed,performancebasedfireprotection(10CFR 50.48(c),NFPA805)
- VoluntaryalternativetoAppendixR
- Deterministicandperformancebasedelements
- Changescanbemadewithoutpriorapproval;riskmustbe acceptable
- Morethan1/3U.S.fleethascompletedtransition Methodsadoptedbyinternationalorganizations FromCline,D.D.,etal.,InvestigationofTwentyFootSeparation DistanceasaFireProtectionMethodasSpecifiedin10CFR50, AppendixR,NUREG/CR3192,1983.
51 RiskInfoUses-LicensingExample (Changesinplantlicensingbasis-RG1.174)
- Voluntarychanges:licenseerequests, NRCreviews
- Smallriskincreasesmaybeacceptable
- Changerequestsmaybecombined
- Decisionsareriskinformed
52 RiskInfoUses-OversightExample (ReactorOversightProgram)
- Inspectionplanning
- Determiningsignificanceoffindings
- Characterizeperformancedeficiency
- Usereviewpanel(ifrequired)
- Obtainlicenseeperspective
- Finalize
- Performanceindicators CDF < 1E-6 LERF < 1E-7 1E-6 < CDF < 1E-5 1E-7 < LERF < 1E-6 1E-5 < CDF < 1E-4 1E-6 < LERF < 1E-5 CDF > 1E-4 LERF > 1E-5
53 RiskInfoUses-OpEExample (AccidentSequencePrecursorProgram)
- ProgramrecommendedbyWASH1400 reviewgroup(1978)
- Providesriskinformedviewofnuclear plantoperatingexperience
- Conditionalcoredamageprobability(events)
- Increaseincoredamageprobability (conditions)
- SupportedbyplantspecificStandardized PlantAnalysisRiskmodels LicenseeEventReports19692018 (Nosignificantprecursorssince2002) significant precursor precursor
54 RiskInfoUses-DecisionSupportExample (Research)
Typicalproducts(regulatoryresearch)
Waystolookatand/orapproachproblems(e.g.,
frameworks,methodologies)
Pointsofcomparison(e.g.,reference calculations,experimentalresults)
Jobaids(e.g.,computationaltools,databases, standards,guidance:bestpractices,procedures)
Problemspecificinformation(e.g.,results, insights,uncertainties)
Sidebenefits Education/trainingofworkforce Networkingwithtechnicalcommunity RegulatoryDecisionSupport Specific Analyses Methods,Models, Tools,Databases, Standards,
- Guidance, FoundationalKnowledge Decision R&D re*search,n. diligentandsystematicinquiryorinvestigationin ordertodiscoverorrevisefacts,theories,applications,etc.
55 RiskInfoUses-DecisionSupportExample (Research:Frameworks/Methodologies)
NRCsponsoredFirePRA R&D(universities)
StartedafterBrowns Ferryfire(1975)
DevelopedfirePRA approachfirstusedin industryZionand IndianPointPRAs (early80s),samebasic approachtoday Startedpathleadingto riskinformedfire protection(NFPA805)
TechnologyNeutral Framework Exploreduseofrisk metricstoidentify licensingbasisevents Inspirationandpart basisforcurrent Licensing Modernization Program
56 RiskInfoUses-DecisionSupportExample (Research:ReferencePoints)
NUREG1150 Continuingpointof comparisonfor Level1,2,3results Expectations (ballpark)
Basisforregulatory analysis (backfitting,generic issueresolution)
NUREG1150(Surry)
SOARCA Detailedanalysisof potentialsevere accidentsandoffsite consequences Updatedinsightson marginstoQHOs PeachBottom Surry Sequoyah
57 RiskInfoUses-DecisionSupportExample (Research:Methods/Models/Tools)
SPAR Independentplant specificmodels (genericdata)
Allhazards(many)
SupportSDP,MD8.3, ASP,GSI,SSCstudies Adaptableforspecific circumstances SAPHIRE Generalpurpose modelbuildingtool Multipleuser interfaces IDHEASG Improvedsupportfor qualitativeanalysis Explicittieswithcognitive science(models,data)
Generalframeworkfor developingfocused applications(e.g.,IDHEAS ECA)
BenefitsfromNPP simulatorstudies Consistentwithcurrent HRAgoodpractices guidance(NUREG1792)
Fromhttps://en.wikipedia.org/wiki/SAPHIRE IDHEASiscoming.
Resistanceisfutile!
58 Parameter Uncertainties:
Some Historical Results Industryresultsfrom:Garrick, B.J.,Lessonslearnedfrom21 nuclearplantprobabilisticrisk assessments,Nuclear Technology,84,No.3,319-339(1989).
59 ParameterUncertainties:LogarithmicvsLinear
60 GenericRuntimeFailureRates 2015Industrywideestimatesfrom:https://nrcoe.inl.gov/resultsdb/AvgPerf/
ServiceWaterPumps:2failuresin16,292,670hours NormallyRunningPumps:225failuresin59,582,350hours StandbyPumps(1sthouroperation):48failuresin437,647hours 1.00E09 1.00E08 1.00E07 1.00E06 1.00E05 1.00E04 1.00E03 ProbabilityDensityFunction (Normalized)
FailureRate(/hr)
RuntimeFailures ServiceWater NormallyRunning Standby Pointestimates wontalertuser topotential inconsistencies
61 ExampleQuantificationofModelOuput Uncertainty Time(s)
Experiment(K)
DRM(K) 180 400 450 360 465 510 720 530 560 840 550 565 Notes:
1)
Bayesianmethodologyaccountsforpossibilityofinhomogeneousdata.
2)
Verylargeuncertaintybandsmightbeunrealistic.
E.DroguettandAliMosleh,Bayesianmethodologyformodeluncertaintyusingmodelperformancedata,Risk Analysis,28,No.5,14571476,2008.
62 EarlyViewsonCompleteness W.F.Libby(ActingChairman,AEC)- March14,1956responsetoSenator Hickenlooper:itisincumbentuponthenewindustryandthe Governmenttomakeeveryefforttorecognizeeverypossibleeventor seriesofevents whichcouldresultinthereleaseofunsafeamountsof radioactivematerialtothesurroundingsandtotakeallstepsnecessaryto reducetoareasonableminimumtheprobabilitythatsucheventswill occurinamannercausingseriousoverexposuretothepublic.[Emphasis added]
- L.Silverman(Chairman,ACRS)- October22,1960lettertoAECChairman JohnA.McCone:Webelievethatasearchinganalysiswhichisnecessary atthisstage[reactorsitingapproval]shouldbedoneindependentlybythe ownerofthereactor[Emphasesadded]
63 ACRSConcernswithWASH1400Methodology*
Topic SignatureEvents[1]
PostWASH1400 Accidentinitiatorquantification (Presumablyexternalevents)
Fukushima Extensivetreatment:fires,earthquakes Inconsistenttreatment:floods Atypicalreactors Fermi1[2]
MultiplePRAsfornonLWRs Designerrors
[3]
Manydesignandoperationalimprovementsidentified byPRAs;databaseincludeseventsinvolvingdesign problems Operatorerrorquantification TMI2 Multiplemethodsemphasizingimportanceofcontext; stillanactiveareaofdevelopment Consequencemodeling Chernobyl,Fukushima Continuing,evolutionaryimprovements(MACCS)
Data Many Improvedhardwaredatabase;fitsandstartswith HRA;extremenaturalhazardsacontinuingchallenge
- ACRSlettertoCongressmanUdallre:adequacyforestimatinglikelihoodoflowprobability/highconsequenceevents(Dec.16, 1976)
TableNotes:
1.
Eventswhosekeycharacteristics(forthegiventopic)mightnothavebeencapturedbyaWASH1400vintageanalysis.
2.
Fermi1hadlimitedfuelmelting.However,withoutananalysis,itisntclearifaWASH1400vintageanalysiswouldhavecapturedthisscenario.
3.
Designweaknesseshaveplayedaroleinmultipleevents.Moredetailedreviewisneededtodetermineif:a)theseareerrors,andb)iftheywould havebeenmissedbyaWASH1400vintageanalysis.
64 EmpiricalExperience Accidents Year Plant(s)
Precursor?
1979 TMI DavisBesse (1977) 1986 Chernobyl Leningrad(1975) 2011 Fukushima Blayais (1999)
SomeSignificant*U.S.Precursors Year Plant(s)
Notes 1975 BrownsFerry Worstprecursor Fire=>lossofU1ECCS 1978 RanchoSeco Nextworstprecursor Humanerror(maintenance)=>loss ofNNI,LOFW 2002 DavisBesse Mostrecentsignificantprecursor Multiplehuman/organizationalfaults
=>RPVheadcorrosion
- PerAccidentSequencePrecursor(ASP)program
65 SomeOtherInterestingInternationalEvents Year Plant(s)
ScenarioType Notes 1957 Windscale1(UK)
Fire Graphitefireincore,releasetoenvironment.
1975 Greifswald1(EastGermany)
Fire Powercablefire,lossofmainfeedwater,pressurizersafety valvesfailtoreseat.
1977 Gundremmingen A(EastGermany)
LOOP/LOCA Partiallossofoffsitepower(LOOP)andsubsequentlossof coolingaccident(LOCA)withinternalflooding.
1978 Beloyarsk 2(SovietUnion)
Fire TurbineBuildingfirespreadsintoMainControlRoom,collapses TurbineBuildingroof.
1981 HinkleyPointA1,A2(UK)
ExternalFlood;LOOP(weather)
SevereweatherLOOPandlossofultimateheatsink(LOUHS).
1982 Armenia1(SovietUnion)
Fire Fireinducedstationblackout(SBO).
1989 Vandellos 1(Spain)
Fire Fireinducedinternalflood.
1991 Chernobyl2(SovietUnion)
Fire FireinducedTurbineBuildingroofcollapse.
1993 Narora 1(India)
Fire FireinducedSBO.
1993 Onagawa 1(Japan)
ReactivityExcursion Seismicallyinducedreactivityexcursion.
1999 Blayais 1,2(France)
ExternalFlood SevereweatherLOOPandpartialLOUHS.
2001 Maanshan 1(Taiwan)
SevereweatherLOOPandsubsequentSBO.
2003 Pickering 48;Darlington 1,2,and4;Bruce 3,4,and6(Canada);
Fermi2,Fitzpatrick,Ginna,IndianPoint 2and 3,NineMile Point 1and 2,OysterCreek,Perry(U.S.)
LOOP(weather)
NortheastBlackout.
2004 Madras2(India)
ExternalFlood TsunamiinducedLOUHS.
2009 Cruas 24(France)
ExternalFlood LOUHSduetoflooddebris.
2011 FukushimaDaiichi 56,FukushimaDaini 14,Onagawa 13, TokaiDaini,Higashidori 12(Japan)
ExternalFlood Earthquake andtsunamiinducedincidents(inadditionto accidentsatFukushimaDaiichi 13).
66 ExternalHazards ScenarioBased Classification:
AnAidfor Completeness?