Abstract :
AconceptofradialneutronreflectorofAPWRbringsaboutsafetyproblemsrelevanttotheflowinducedvibrationandthermaldeformation.TheCFDcodehasbeenexpectedtosolvethembycalculatingpressurefluctuationsofturbulentflowinthedowncomerandtheflowdistributionintotheneutronreflector.AseriesofhydraulicflowtestswasconductedbyNUPECfrom1998to2002todemonstratethenewdesignoftheneutronreflectorandtoobtaintestdataforvalidatingtheCFDcode.ThemeasuredpressurefluctuationsinthedowncomerandtheirstatisticswereutilizedforvalidatingthespecificturbulentmodeltobeabletocalculateaspectrumofpressurefluctuationsuchastheLESmodel.Themeasuredflowratesatinletholesofthelowercoreplatewereutilizedforvalidatingforthegeneralturbulentmodel,forexample,thek–ɛturbulentmodel.ThecalculatedresultswiththeLESmodelagreedwellwiththemeasuredpressurefluctuationsandtheirspectrum,butdidnotagreewiththecorrelationbetweenadjacentpressurefluctuations.Ontheotherhand,thecalculationresultswiththek–ɛturbulentmodelagreedwellwiththemeasuredflowratesatinletholesofthelowercoreplate.
