FragmentationofamoltencoriumjetfallingintowaterOriginalResearchArticle

Duringasevereaccidentofapressurizedwaternuclearreactor,alargemassofcoriumcouldpourintothevesselbottomasacompactjet.Whenthecoriummassreachesthewateratthebottomofthevessel,anintensefragmentationmayoccur.Thiscouldleadtoasignificantmixingofcoriumandwater,likelytocauseasteamexplosionwhichcoulddamagethestructures.Ananalyticalstudyhasbeenestablishedinordertoquantifythecoriumjetfragmentation.Thisstudyconsistsmainlyinmodelingthevaporflowsurroundingthejetaswellastheinstabilitywhichoccursatitsinterface.Incomparisonwithpreviousstudies,thismodelpaysparticularattentiontothejet-producedparticleswhichinteractwiththevaporflow.Acompletemodelhasbeensetupinordertocalculatethejetbreakuplengthandthegeneratedparticles’diameterundereachspecificsituationcharacterizedbyinitialconditions.Thismodelmainlyreliesuponresultsfromboundarylayertheoryandlinearinstabilitycalculations.Thefullmodel’sresultsarecomparedtoexistingexperiencesinthisfieldandafinalcorrelationoftheresultsisestablished.Agoodagreementisobtainedonthejetbreakuplength,howeverthepredictedparticlediametertendstobetoolarge.Thislastresultcouldbeexplainedbyasecondarybreakupoftheparticlesinwaterandbyalargeuncertaintyinthevaporflow.