ComparisonofpressurevesselintegrityanalysesandapproachesforVVER1000andPWRvesselsforPTSconditionsOriginalResearchArticle

Currently,licenserenewalsandplant-lifeextensionareimportantissuesfornuclearindustry.Pressurevesselintegrityisoneofthemainconcernsrelatedtotheseissues.Pressurevesselintegrityisofprimeconcernforpressurizedreactors,sincetheyoperateathigherpressuresandneutronfluxeswhencomparedtoboilingwaterreactors.Pressurevesselintegrityanalysesfortwocommercialpressurizedwaterreactorsareperformedinthisstudy;aWestinghouse4loop1000MWPWRandaVVER1000/320.Twomostlimitinglossofcoolantaccidents(LOCA)forpressurizedthermalshock(PTS)areconsideredanddeterministicandprobabilisticfailureanalysesareperformed.Differencesineasternandwesternregulatoryapproachesarealsotakenintoaccount.Amongthevesselssimulated,themaximumnilductilitytransitiontemperaturesarefoundtobebelowtherelevantregulatorylimit.However,theresultsofprobabilisticanalysesareobservedtobeabovetheprescribednationallimits.Thisisattributedtotheuseofratherconservativeassumptionsusedinthisstudy.Findingsofthisstudymayhelpthere-evaluationeffortsofPTSscreeningcriteria.