ApplicationofanoptimizedAMprocedurefollowingaSBOinaVVER-1000OriginalResearchArticle

TheUniversityofPisawasinvolvedininvestigationsofanAccidentManagement(AM)procedurebasedonpassivefeedwaterinjection.Someexperimentswereperformedtovalidatethispossibility(e.g.inLOBIandBethsyfacilities)andfullyanalyzedbythermalhydraulicsystemcodes.RecentactivitiesinwhichtheUniversityofPisaisengaged(alsoasleader)arefocusedonVVER-1000safetyanalyses.TheideaisnowtousetheacquiredknowledgetoexploreifaprocedurebasedonpassivefeedwaterinjectionisapplicableandcanprovideanybenefitstotheRussiandesignpressurisedplant. Thepostulatedaccidentisastationblackout,insuchawayonlypassivesystemsareavailable.TheproposedAMisbasedonsecondaryandprimarysidedepressurisationinsequence.ThesecondarysidedepressurisationperformedbytheBRU-AvalveshasthescopetofeedpassivelytheSGswiththewaterleftinthefeedwaterlinesandinthedeaerators.Theprimarysidedepressurisation,viathePORV,isforeseentokeeptheplantatthelowestpressure(toreducetheenergyofthesystem)andtomaximizethe“gracetime”oftheplant.Threecasesarehereconsidered:nooperatoraction,applicationoftheoptimizedAMsequence,applicationoftheAMprocedureatthelasttimewhenitiseffective. TheintentionofthispaperistoshowthatincaseofanunlikelyeventsuchaSBOtheimplementationofastrategybasedonsystemsnotdesignedforspecificsafetyapplicationcanhavealargeimpactonthe“gracetime”oftheplant.