Thermalhydrauliceffectoffuelplatesurfaceroughness

Thisstudypresentssurfaceroughnessmeasurementscharacteristicofthepre-filmlayerappliedtoatypicalAdvancedTestReactor(ATR)fuelplate.ThisdataisusedtoestimatethefrictionfactorforthermalhydraulicflowcalculationsofaGasTestLoop(GTL)systemproposedforincorporationintoATRtoprovideafastneutronfluxenvironmentforthetestingofnuclearfuelsandmaterials.Toattaintherequiredneutronflux,thedesignincludesboosterfuelplatescladwiththesamealuminumalloyastheATRdriverfuelandcooledwithwatersuppliedbytheATRprimarycoolantpumps.Theobjectivesofthisstudyareto(1)determinethesurfaceroughnessoftheprotectiveboehmitelayerappliedtotheATRdriverfuelpriortoreactoroperationsinordertospecifythemachiningtolerancesforthesurfacefinishonsimulatedboosterfuelplatesinaGTLhydraulicflowtestmodeland(2)assesstheconsequentthermalhydraulicimpactduetosurfaceroughnessonthecoolabilityoftheboosterfuelwithasimilarpre-filmlayerapplied.Whilethemaximumroughnessofthiscoatingisspecifiedtobe1.6μm(63μin.),noprecisedataontheactualroughnesswereavailable.ArepresentativesamplecouponautoclavedwiththeATRdriverfueltoproducethepre-filmcoatingwasanalyzedusingopticalprofilometry.Measurementsyieldedameansurfaceroughnessof0.53μm(21μin.).Resultsfromasensitivitystudyshowthata±15%deviationfromthemeanmeasuredsurfacefinishwouldhaveaminimaleffectoncoolanttemperature,coolantflowrate,andfueltemperature.However,frictionallossesfromroughnessesgreaterthan1.5μm(∼60μin.)produceamarkeddecreaseinflowrate,causingfuelandcoolanttemperaturestorisesharply.