Safetyevaluationonthedepressurizationaccidentinthegasturbinehightemperaturereactor(GTHTR300)OriginalResearchArticle

JapanAtomicEnergyAgencyhasbeendevelopingagasturbinehightemperaturereactor(GTHTR300)withelectricpowerofapproximately300MW.Oneoftheuniquesafetydesignconceptsofthissystemisthateventswithfrequencyofoccurrenceofhigherthan10−8/reactor-yearareevaluatedasdesignbasiseventsinordertoshowthatthefrequencyoflargeamountofFPreleaseislessthan10−8/reactor-year.Accordingtothisconcept,adepressurizationaccidentbyalargebreakofheliumpipingispostulatedasadesignbasisevent.Thisaccidentisoneofthemostseriousaccidentsinthehigh-temperaturegas-cooledreactorsfromtheviewpointoflossofcoolability.Thesafetyevaluationontheaccidentwasconductedbasedontheactualdesignofthesystem.Theshort-termandlong-termbehaviorsoffueltemperatureafteroccurrenceoftheaccident,internalpressureofthereactorbuilding,oxidationbehavioroffuelsandgraphitestructureswereevaluatedandexposuredoseofgeneralpublicwasalsoestimatedusingtheresultsofevaluationoffueltemperatureandfuelfailurebyoxidation.AlloftheevaluationresultsmeetthesafetycriteriaandfeasibilityoftheGTHTR300wasshownbythisstudy.