Meltquenchingandcoolabilitybywaterinjectionfrombelow:Co-injectionofwaterandnon-condensablegasOriginalResearchArticle

Theinteractionandmixingofhigh-temperaturemeltandwateristheimportanttechnicalissueinthesafetyassessmentofwater-cooledreactorstoachieveultimatecorecoolability.Forspecificadvancedlightwaterreactor(ALWR)designs,deliberatemixingofthecoremeltandwaterisbeingconsideredasamitigativemeasure,toassureex-vesselcorecoolability.Thegoalofourworkistoprovidethefundamentalunderstandingneededformelt–waterinterfacialtransportphenomena,thusenablingthedevelopmentofinnovativesafetytechnologiesforadvancedLWRsthatwillassureex-vesselcorecoolability.Theworkconsiderstheex-vesselcoolabilityphenomenaintwostages.ThefirststageisthemeltquenchingprocessandisbeingaddressedbyArgonneNationalLabandUniversityofWisconsininmodifiedtestfacilities.Givenaquenchedmeltintheformofsolidifieddebris,thesecondstageistocharacterizethelong-termdebriscoolingprocessandisbeingaddressedbyKoreanMaritimeUniversityviatestandanalyses.Inthispaper,experimentsonmeltquenchingbytheinjectionofwaterfrombelowareaddressed.Thetestsectionrepresentedone-dimensionalflow-channelsimulationofthebottominjectionofwaterintoacoremeltinthereactorcavity.Themeltsimulantwasmoltenleadoraleadalloy(Pb–Bi).Fortheexperimentalconditionsemployed(i.e.,meltdepthandwaterflowrates),itwasfoundthat:(1)thevolumetricheatremovalrateincreasedwithincreasingwatermassflowrateand(2)thenon-condensablegasmixedwiththeinjectedwaterhadnoimpairingeffectontheoverallheatremovalrate.ImplicationsofthesecurrentexperimentalfindingsforALWRex-vesselcoolabilityarediscussed.