ProbabilityassessmentofgraphitebrickintheHTR-10OriginalResearchArticle

AprobabilityfiniteelementassessmentprogramwasdevelopedtoevaluatethesecurityofgraphitecomponentsintheHTR-10(10MWhightemperaturegas-cooledreactor-testmodule),basedontheMARCnon-linearfiniteelementcodeandthestrengthuncertaintyofthegraphitematerial.Usinguser-definedsubroutines(UDS),theirradiationthermalanalysissubroutine,irradiationstaticanalysissubroutineandprobabilityassessmentsubroutineareembeddedintotheMARCprogram.TherecompiledMARCprogramtakeintoaccountirradiation-inducedchangesingraphitecomponentssuchasthethermalconductivitycoefficient,thethermalexpansioncoefficient,thecreepcoefficient,theelasticmodulus,andthestrength.ThefailureprobabilitiesofthegraphitecomponentsintheHTR-10,eitherundernormaloperatingconditionsorcoldshutdownconditions,wereevaluated.Additionalanalysesweredonewiththeirradiationdeformationincreasing20%andthecreepcoefficientdecreasing20%,toseetheinfluenceofirradiationdeformationandthecreepeffectonthefailureprobability.Thestudyshowedthattheprobabilityfiniteelementassessmentmethodisaneffectivetooltoassesstheprobabilityofstructurefailure.