AnexperimentalstudyonquenchingofaradiallystratifiedheatedporousbedOriginalResearchArticle

Thequenchingcharacteristicsofavolumetrically-heatedparticulatebedcomposedofradiallystratifiedsandlayerswereinvestigatedexperimentallyinthePOMECOfacility.Thesandbedsimulatesthecoriumparticulatedebrisbedwhichisformedwhenthemoltencoriumreleasedfromthevesselfragmentsinwateranddepositsonthecavityfloorduringapostulatedsevereaccidentinalightwaterreactor(LWR).Theelectrically-heatedbedwasquenchedbywaterfromawatercolumnestablishedovertopofit,andlateralsowithwatercomingfromitsbottom,whichwascirculatingfromthewateroverlayerthroughdowncomers.Aseriesofexperimentswereconductedtorevealtheeffectsofthesizeofdowncomers,andtheirlocationsinthebed,onthequenchingcharacteristicsoftheradiallystratifieddebrisbeds.Thedowncomerswerefoundtosignificantlyincreasethebedquenchingrate.Tosimulatethenon-condensablegasesgeneratedduringtheMCCI,airandargonwereinjectedfromthebottomofthebedatdifferentflowrates.Theeffectsofgasflowrateanditspropertiesonthequenchingbehaviourwereobserved.Theresultsindicatethatthenon-condensablegasflowsreducethequenchingratesignificantly.Thegaspropertiesalsoaffectthequenchingcharacteristics.