Single-phaseCFDapplicabilityforestimatingfluidhot-spotlocationsina5×5fuelrodbundleOriginalResearchArticle

High-thermalperformancePWRspacergridsrequirebothoflowpressurelossandhighcriticalheatflux(CHF)properties.Therefore,anumericalstudyusingcomputationalfluiddynamics(CFD)wascarriedouttoestimatepressurelossinstrapandmixingvanestructures.Moreover,aCFDsimulationundersingle-phaseflowconditionwasconductedforonespecificconditioninawaterdeparturefromnucleateboiling(DNB)testtoexaminetheapplicabilityoftheCFDmodelforpredictingtheCHFrodposition.EnergyfluxaroundtherodsurfaceinawaterDNBtestisthesumoftheintrinsicenergyfluxfromarodandtheextrinsicenergyfluxfromotherrods,andincrementsoftheenthalpyanddecrementsofflowvelocityneartherodsurfaceareassumedtoaffectCHFperformance.CFDmakesitpossibletomodelthecomplicatedflowfieldconsistingofaspacergridandarodbundleandevaluatethelocalvelocityandenthalpydistributionaroundtherodsurface,whichareassumedtodeterminetheinitialconditionsforthetwo-phasestructure.Theresultsofthisstudyindicatethatsingle-phaseCFDcanplayasignificantroleindesigningPWRspacergridsforimprovedCHFperformance.