Title of article
SimplifiedmodelingofaPWRreactorpressurevessellowerheadfailureinthecaseofasevereaccidentOriginalResearchArticle
Author/Authors
V.Koundy، نويسنده , , M.Durin، نويسنده , , L.Nicolas، نويسنده , , A.Combescure، نويسنده ,
Issue Information
روزنامه با شماره پیاپی سال 2005
Pages
9
From page
835
To page
843
Abstract
Inordertocharacterizethetiming,modeandsizeofapossiblelowerheadfailure(LHF)ofthereactorpressurevessel(RPV)intheeventofacoremeltdownaccident,severallarge-scaleLHFexperimentswereperformedundertheUSNRC/SNLLHFprogram.Theexperimentsexaminedlowerheadfailureathighpressures(10MPainmostcases)andwithsmallthroughwalltemperaturedifferentials.AnotherUSNRC/SNLLHFprogram,calledtheOLHFprogram,hasbeenundertakenintheframeworkofanOECDproject.Thiswasanextensionofthefirstprogramanddealtwithlowandmoderatepressures(2–5MPa)butwithlargethroughwalltemperaturedifferentials.Theseexperimentsshouldleadtoabetterunderstandingofthemechanicalbehaviorofthereactorvessellowerhead,whichisofimportancebothinsevereaccidentassessmentandthedefinitionofaccidentmitigationstrategies.Awell-characterizedfailureofthelowerheadisofprimeimportancefortheevaluationofthequantityofcorematerialthatcanescapeintothecontainment,sincethisdefinestheinitialconditionsforallexternal-vesselevents.Thelargequantityofescapingcoriummayleadtodirectheatingofthecontainment.Thisisanimportantsevereaccidentissuebecauseofitspotentialtocauseearlycontainmentfailure.Theexperimentsalsoprovidedataformodeldevelopmentandvalidation.Forourpart,asoneoftheprogrampartners,numericalmodelingwasperformedtosimulatetheseexperiments.Thispaperpresentsadetaileddescriptionofthreeofournumericalmodelsusedforthesimulation.Thefirstmodelisasimplifiedsemi-analyticalapproachbasedonthetheoryofasphericalshellsubjectedtointernalpressure.Thetwoothermethodsdealwith2Dfiniteelement(2D-FE)modeling:onecombinestheNorton–BaileycreeplawwithadamagemodelproposedbyLemaitre–Chabochewhiletheotherusesonlyacreepfailurecriterionbuttakesintoaccountthermo-metallurgicalphasetransformations.Oneoftheobjectivesofthesimulationisthedevelopmentofasimplifiedandvalidanalyticalcodethatcanbeimplementedinintegralsevereaccidentcomputercodes.Thenumericalresultsareconsistentwiththeexperimentalmeasurements.Theeffectonthenumericalresultsofthemultiphasetransformationoftheshellmaterialandofthetwofailurecriteriaused,oneinvolvingnecking(Considèreʹscriterion)andtheotherinvolvingcreepdamage(Lemaitre–Chaboche)isdiscussed.
Journal title
Nuclear Engineering and Design Eslah
Serial Year
2005
Journal title
Nuclear Engineering and Design Eslah
Record number
894891
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