ExperimentalstudyandmodellingofliquidejectionthroughorificesbysparginggasOriginalResearchArticle

CoriumcoolabilityafteraseverePWRaccidentinvolvingcoremeltdownandRPVfailureisoneofthemainissuesinnuclearsafety.Thecaseconsideredhereisasituationinwhichthecoriumisassumedtospreadoveraconcretefloorandisfloodedbywater.Inthisframework,manyresearcheffortsareperformedtostudythephysicalphenomena,whichmayenhancetheheattransferbetweenthecoriumandthewaterpool.Amongthesephenomena,meltentrainmentabovethecoriumcrustbythesparginggas,releasedbytheconcreteablationappearstobeapotentiallyefficientcoolingmechanism.ThemaintargetofthePERCOLAexperimentalprogramistoprovidequalitativeandquantitativeinformationonthisentrainmentphenomenon.ItconsistsinanalyticaltestsperformedwithsimulantmaterialsofincreasingviscositytosimulatetheenrichmentofthecoriuminSiO2duringtheMCCI.Afterashortreminderabouttheassessmentoftheefficiencyoftheejectionmechanism,thesecondpartofthispaperisdevotedtoageneraldescriptionofthetestprogramandtothepresentationofthemainresults.Inthelastpart,attentionfocusesonmodellingtheliquidentrainmentphenomenonandoncomparisonbetweentheexperimentaldataandthecalculationresultsoftwodifferententrainmentmodels.