UncertaintyandsensitivityanalysisofMCPs’tripeventsatIgnalinaNPPOriginalResearchArticle

Eightmaincirculationpumps(MCPs)areemployedforthecoolingwaterforcedcirculationthroughtheRBMK-1500reactorattheIgnalinanuclearpowerplant(NPP).TherehavebeenafeweventswhenoneormoreMCPswereinadvertentlytripped. ThispaperpresentsinvestigationofaoneMCPtripeventandallMCPs’tripeventsatIgnalinaNPP.Thermal-hydraulicanalysiswasconductedusingthebestestimatesystemcodeRELAP5/MOD3.3.Uncertaintyandsensitivityanalysisofflowenergylossindifferentpartsofthemaincirculationcircuit(MCC),initialconditionsandcode-selectedmodelswasperformed.Suchanalysisallowstoestimatetheinfluenceofseparateparametersonthecalculationresultsandfindthosemodellingparametersthathavethelargestimpactontheinvestigatedevents.UncertaintyanalysisindicatesthatnaturalcirculationprovidesadequatecoolinginthecaseofallMCPstripped,andthatthereactorisreliablycooledbyforcedcirculationinthecaseofasingletrippedMCP.Onthebasisofthisanalysis,recommendationsforthefurtherimprovementofmodelaredeveloped.