Abstract :
Theinternationalfusionmaterialsirradiationfacility(IFMIF)isaimedtoprovideanintenseneutronsourcebyahighcurrentdeuteronlinearacceleratorandahigh-speedlithiumflowtarget,fortestingcandidatematerialsforfuturefusionreactors.
AnactivityaimedatthesafetyassessmentoftheIFMIFplantasawholehasbeencarriedoutapplyingtheprobabilisticriskassessment(PRA)approachtoidentifyandquantifyintermsofexpectedfrequencies,thedominantaccidentsequencesrelatedtotheplantoperation,anddefinethereferenceaccidentscenariostobefurtheranalyzedthroughdeterministictransientanalysis,inordertoverifythefulfilmentofthesafetycriteria.
Theaccidentsequenceshavebeenmodeledthroughtheeventtreetechnique,whichallowsidentifyingallpossiblecombinationsofsuccessorfailureofthesafetysystemsinrespondingtoaselectionofinitiatingevents.Theidentificationofaccidentinitiators,providedbythefailuremodeandeffectanalysis(FMEA)procedure,isfollowedbythesystemsanalysisbasedonfaulttreetechnique,fortheunavailabilityassessmentofthesafetysystems:finallytheaccidentsequencescenariosareassessedbyRISKSPECTRUMsoftware.
ThestudyhasallowedforthedevelopmentofallaccidentsequencesresultingfromselectedinitiatorsrelativetoIFMIFplantandtheirgroupingwithinsequencefamilies,denotedasplantdamagestates,onaccountoftheplantresponseandexpectedconsequences.Thefrequencyassignedtoeachfamilysequenceisthesumofthecontributorsrelativetoallsequencesendingintothatparticularplantstate.
TheoutcomeoftheanalysisshowsthatIFMIFplantisquitesafeandpresentsnosignificanthazardtotheenvironment:infactallthesequencesimplyingpotentialundesiredeffectsasradioactivereleasetotheoutside,showverylowfrequencies,wellbelowthelimitforcredibleaccident(1.0E−6/year).Inaddition,duetothenoveltyofthedesignandthelargespreadingassignedtothefailureparameterprobabilisticdistributions(datautilizedintheprobabilisticanalysisofthisoneofakindplantarelargelyofagenericnature),anuncertaintyanalysishasbeenperformedtoaddcredittothemodelquantificationandtoassessifthesequenceshavebeencorrectlyevaluatedontheprobabilitystandpoint.
