Advancedtreatmentofzircaloycladdinghigh-temperatureoxidationinsevereaccidentcodecalculations:PartIII.VerificationagainstrepresentativetransienttestsOriginalResearchArticle

Thetreatmentofzirconiumoxidationkineticsinsevereaccident(SA)codeshasbeenthesubjectofmanydiscussionsandcontroversiesinrecentyears.Themainproblemwastheexistenceofseveralcorrelationswhichcouldleadtolargedifferencesinthecalculatedresults.Itappearedclearlythattherewasaneedtoconvergetowardsacommonunderstandingofthephysicalprocessesthatmustbemodeled(oxygendiffusion,blanketingeffect,etc.)andanagreeddatabaseamongcodedevelopersandusers.ItwouldhelpreducinganimportantsourceofuncertaintiesinSAcalculations. Thekineticcorrelationdatabase,obtainedasaresultofexaminationofcomplementaryexperimentaldatainPartsIandII,isappliedheretoanalyzeafewhigh-temperatureseparate-effectstestsandbundleexperimentswhereZryoxidationreactionplayedadominantrole.TheICARE/CATHAREcomputercodedevelopedbyIRSNisusedtocheckthevalidityofthehigh-temperaturecorrelationsderivedinPartsIandII.Thephysicalmodelingprovidedbythecodeincludesdetailedaccountofspecificfeaturesofchemicalinteractionsbetweenfuelrodcladdingandsteam.Inparticular,highreactionratesatT>2000Karemoderatedbytwoeffects,examinedinPartI:steamblanketingduringthinoxidelayersgrowthandtransitiontooxidationofα-Zr(O)phaseaftertotalconsumptionofprimaryβ-Zrincladdingmetallicpart. Whenappliedtoseparate-effectstests,theevaluatedparaboliccorrelationshaveshowntheirapplicabilitytodifferenttypesoftemperaturetransientstakingintoaccountZryoxidationspecificsinrodgeometry.ThebundleintegralexperimentsQUENCH-06andPHEBUSB9+didnotleadtoextremelylargetemperatureexcursions.Calculatedtemperatures,hydrogenproductionandoxidethickness,aswellasparametersofmeltrelocationwerefoundtoagreewellwithexperimentallymeasuredvalues.Asaresultofthisstudy,webelievethatthenewbest-fittedcorrelations,obtainedinagreementwithavailableexperimentaldata,canbeusedinfurtherstudiesandcanimprovepredictivepowerofthecodes.ThecontinuationofthecurrentworkwillbetheapplicationofICARE/CATHAREcodewithbest-fittedZryoxidationcorrelationstoNPPaccidentscenarios.