Scalingmethodologyforareduced-heightreduced-pressureintegraltestfacilitytoinvestigatedirectvesselinjectionlinebreakSBLOCAOriginalResearchArticle

Ascalingmethodologyforasmall-scaleintegraltestfacilitywasinvestigatedinordertoanalyzethermal–hydraulicphenomenaduringaDVI(directvesselinjection)lineSBLOCA(smallbreakloss-of-coolantaccident)inanAPR1400(advancedpowerreactor1400MWe)pressurizedwaterreactor.ThetestfacilitySNUF(SeoulNationalUniversityFacility)wasutilizedasareduced-heightandreduced-pressureintegraltestloop.TodeterminesuitabletestconditionsforsimulatingtheprototypeintheSNUFexperiment,theenergyscalingmethodologywasproposetoscalethecoolantmassinventoryandthethermalpowerforareduced-pressurecondition.Theenergyscalingmethodologywasvalidatedwithasystemcode(MARS)analysisforanideallyscaled-downSNUFmodelandthatpredictedareasonabletransientofpressureandcoolantinventorywhencomparedtotheprototypemodel.FortheactuallyconstructedSNUF,theeffectofscalingdistortionsinthetestfacilityʹsthermalpowerandtheloopgeometrywasanalyticallyinvestigated.Toovercomethelimitationofthethermalpowersupplyinthefacility,theconvectiveheattransferbetweenprimaryandsecondarysystemsatthesteamgeneratorU-tubeswasexcludedandamodifiedpowercurvewasappliedforsimulatingthecoredecayheat.FromthecodeanalysisresultsfortheactualSNUFmodel,theapplicationofthemodifiedpowercurvedidnotaffectthemajoreventsoccurringduringthetransientcondition.TheresultsrevealedthatthescalingdistortionintheactualSNUFgeometryalsodidnotstronglydisturbsignificantthermal–hydraulicphenomenasuchasthedowncomersealclearing.Thus,withanadoptionoftheenergyscalingmethodology,thethermal–hydraulicphenomenaobservedintheSNUFexperimentcanbeproperlyutilizedinasafetyanalysisforaDVIlinebreakSBLOCAintheAPR1400.