CHFenhancementbyvesselcoatingforexternalreactorvesselcoolingOriginalResearchArticle

In-vesselretention(IVR)isakeysevereaccidentmanagement(SAM)strategythathasbeenadoptedbysomeoperatingnuclearpowerplantsandproposedforsomeadvancedlightwaterreactors(ALWRs).OneviablemeansforIVRisthemethodofexternalreactorvesselcooling(ERVC)byfloodingthereactorcavityduringasevereaccident.AspartofajointKorean–UnitedStatesInternationalNuclearEnergyResearchInitiative(K-INERI),anexperimentalstudyhasbeenconductedtoinvestigatetheviabilityofusinganappropriatevesselcoatingtoenhancethecriticalheatflux(CHF)limitsduringERVC.Towardthisend,transientquenchingandsteady-stateboilingexperimentswereperformedinthesubscaleboundarylayerboiling(SBLB)facilityatthePennsylvaniaStateUniversityusingtestvesselswithmicro-porousaluminumcoatings.LocalboilingcurvesandCHFlimitswereobtainedintheseexperiments.Whencomparedtothecorrespondingdatawithoutcoatings,substantialenhancementinthelocalCHFlimitsforthecasewithsurfacecoatingswasobserved.Resultsofthesteady-stateboilingexperimentsshowedthatmicro-porousaluminumcoatingswereverydurable.Evenaftermanycyclesofsteady-stateboiling,thevesselcoatingsremainedratherintact,withnoapparentchangesincolororstructure.Moreover,theheattransferperformanceofthecoatingswasfoundtobehighlydesirablewithanappreciableCHFenhancementinalllocationsonthevesseloutersurfacebutwithverylittleeffectofaging.