AdvancedneutronicstoolsforBWRdesigncalculationsOriginalResearchArticle

ThispapersummarizesthedevelopmentsimplementedinthenewAPOLLO2.8neutronicstooltomeettherequiredtargetaccuracyinLWRapplications,particularlyvoideffectsandpin-by-pinpowermapinBWRs.TheMethodofCharacteristicswasdevelopedtoallowefficientLWRassemblycalculationsin2D-exactheterogeneousgeometry;resonantreactioncalculationwasimprovedbytheoptimizedSHEM-281groupmesh,whichavoidsresonanceself-shieldingapproximationbelow23eV,andthenewspace-dependentmethodforresonantmixturethataccountsforresonanceoverlapping.Furthermore,anewlibraryCEA2005,processedfromJEFF3.1evaluationsinvolvingfeedbackfromCriticalExperimentsandLWRP.I.E,isused.Thespecific“2005–2007BWRPlan”settledtodemonstratethevalidation/qualificationofthisneutronicstoolisdescribed.Someresultsfromthevalidationprocessarepresented:thecomparisonofAPOLLO2.8resultstoreferenceMonteCarloTRIPOLI4resultsonspecificBWRbenchmarksemphasizestheabilityofthedeterministictooltocalculateBWRassemblymultiplicationfactorwithin200pcmaccuracyforvoidfractionvaryingfrom0to100%.ThequalificationprocessagainsttheBASALAmock-upexperimentstressesAPOLLO2.8/CEA2005performances:pin-by-pinpowerisalwayspredictedwithin2%accuracy,reactivityworthofB4CorHfcruciformcontrolblade,aswellasGdpins,ispredictedwithin1.2%accuracy.