TransientanalysesforacceleratordrivensystemPDS-XADSusingtheextendedSIMMER-IIIcodeOriginalResearchArticle

TransientanalysesforPreliminaryDesignStudiesofanExperimentalAcceleratorDrivenSystem(PDS-XADS)wereperformedwiththereactorsafetyanalysiscodeSIMMER-III,whichwasoriginallydevelopedforthesafetyassessmentofsodium-cooledfastreactorsandrecentlyextendedbytheauthorssoastodescribetheXADSspecificssuchassubcriticalcore,strongexternalneutronsourceandlead–bismuth–eutectic(LBE)coolant.Astransientscenarios,thefollowingcaseswereanalyzedinaccordancewiththePDS-XADSprogram:spuriousbeamtrip(BT),unprotectedbeamoverpower(UBOP),unprotectedtransientoverpower(UTOP),unprotectedlossofflow(ULOF)andunprotectedblockage(UBL)inasinglefuelassembly.Inaddition,tocoversomecore-meltsituationsandinvestigatethepotentialforrecriticalities,so-calledsnap-shotanalyseswithadhocpostulatedsevereblockageconditionswerealsoinvestigated.