Probabilisticpredictionoffretting-weardamageofnuclearfuelrodsOriginalResearchArticle

Thedevelopmentofaprobabilisticmethodtopredictthefretting-wearperformanceoffuelrodsispresented.Inthisapproach,thedynamicresponseofthenuclearfuelrodanditssupportsiscalculatedbyanon-linearvibrationmodel(calledVITRANforVIbrationTRansientAnalysis—Nonlinear).Thismodelpredictsthemotionofafuelrodexposedtoaturbulentflowandtakesintoaccountthepresenceoftherod-to-gridgapsintheassemblygrids.Numericalvaluesforthegridworkandwearratesarecalculatedfromthepredictedforcesduringtherodimpactsagainstthesupports.Duetothelargevariabilityofthefuelassemblyparametersaffectingthefretting-wearperformance,aMonteCarlomethodwaschosentoperformthetransientsimulations.Asaresult,averagevalues,standarddeviationsandotherstatisticalparametersoftheprobabilitydensityfunctionsofthewearratesandthewearscarspopulationcanbeestimated.AdescriptionofVITRANandanexampleofapplicationofthefretting-wearmethodologytoevaluatetheperformanceofafueldesignarepresented.