Analysisofgas–liquidmetaltwo-phaseflowsusingareactorsafetyanalysiscodeSIMMER-IIIOriginalResearchArticle

SIMMER-III,asafetyanalysiscodeforliquid-metalfastreactors(LMFRs),includesamomentumexchangemodelbasedonconventionalcorrelationsforordinarygas–liquidflows,suchasanair–watersystem.Fromtheviewpointofsafetyevaluationofcoredisruptiveaccidents(CDAs)inLMFRs,weneedtoconfirmthatthecodecanpredictthetwo-phaseflowbehaviorswithhighliquid-to-gasdensityratiosformedduringaCDA.Inthepresentstudy,themomentumexchangemodelofSIMMER-IIIwasassessedandimprovedusingexperimentaldataoftwo-phaseflowscontainingliquidmetal,onwhichfundamentalinformation,suchasbubbleshapes,voidfractionsandvelocityfields,hasbeenlacking. ItwasfoundthattheoriginalSIMMER-IIIcansuitablyrepresenthighliquid-to-gasdensityratioflowsincludingellipsoidalbubblesasseeninlowergasfluxes.Inaddition,theemploymentofKataoka–Ishii’scorrelationhasimprovedtheaccuracyofSIMMER-IIIforgas–liquidmetalflowswithcap-shapebubblesasidentifiedinhighergasfluxes.Moreover,anewprocedure,inwhichanappropriatedragcoefficientcanbeautomaticallyselectedaccordingtobubbleshape,wasdeveloped. Throughthiswork,thereliabilityandtheprecisionofSIMMER-IIIhavebeenmuchraisedwithregardtobubblyflowsforvariousliquid-to-gasdensityratios.