EuropeanValidationoftheIntegralCodeASTEC(EVITA):FirstexperienceinvalidationandplantsequencecalculationsOriginalResearchArticle

ThemainobjectiveoftheEuropeanValidationoftheIntegralCodeASTEC(EVITA)projectistodistributethesevereaccidentintegralcodeASTECtoEuropeanpartnersinordertoapplythevalidationstrategyissuedfromtheVASAproject(4thECFWP).Partnersevaluatethecodecapabilitythroughvalidationonreferenceexperimentsandplantapplicationsaccountingforsevereaccidentmanagementmeasures,andcompareresultswithreferencecodes. ThebasisversionV0ofASTEC(AccidentSourceTermEvaluationCode)—commonlydevelopedandbasicallyvalidatedbyGRSandIRSN—wasmadeavailableinlate2000fortheEVITApartnersontheirindividualplatforms.Users’trainingwasperformedbyIRSNandGRS.Thecodeportabilityondifferentcomputerswascheckedtobecorrect.A“hotline”assistancewasinstalledcontinuouslyavailableforEVITAcodeusers.TheactualversionV1hasbeenreleasedtotheEVITApartnersendofJune2002.Itallowstosimulatethefront-endphasebytwonewmodules: • forreactorcoolantsystem2-phasesimplifiedthermalhydraulics(5-equationapproach)duringbothfront-endandcoredegradationphases, • forcoredegradation,basedonstructureandmainmodelsofICARE2(IRSN)referencemechanisticcodeforcoredegradationandonothersimplifiedmodels. Nextprioritiesareclearlyidentified:codeconsolidationinordertoincreasetherobustness,extensionofallplantapplicationsbeyondthevessellowerheadfailureandcouplingwithfissionproductmodules,andcontinuousimprovementsofusers’tools. AsEVITAhasverysuccessfullymadethefirststepintotheintentiontoprovideend-users(likeutilities,vendorsandlicensingauthorities)withawellvalidatedEuropeanintegralcodeforthesimulationofsevereaccidentsinNPPs,theEVITApartnersstronglyrecommendtocontinuevalidation,benchmarkingandapplicationofASTEC.ThisworkwillcontinueinSevereAccidentResearchNetwork(SARNET)inthe6thFrameworkProgrammewhereASTECplaysakeyroleasthereferenceEuropeanintegralcode.