Author/Authors :
Bernard Adroguer، نويسنده , , F.Bertrand، نويسنده , , P.Chatelard، نويسنده , , N.Cocuaud، نويسنده , , J.P.VanDorsselaere، نويسنده , , L.Bellenfant، نويسنده , , D.Knocke، نويسنده , , D.Bottomley، نويسنده , , V.Vrtilkova، نويسنده , , Gary Belovsky، نويسنده , , K.Mueller، نويسنده , , W.Hering، نويسنده , , C.Homann، نويسنده , , W.Krauss، نويسنده , , A.Miassoedov، نويسنده , , G.Schanz، نويسنده , , M.Steinbrück، نويسنده , , Stuckert، J. نويسنده , , Hozer، Zoltan نويسنده , , G.Bandini، نويسنده , , etal.، نويسنده ,
Abstract :
TheCOLOSSprojectwasa3-yearshared-costaction,whichstartedinFebruary2000.Thework-programmeperformedby19partnerswasshapedaroundcomplementaryactivitiesaimedatimprovingsevereaccidentcodes.Unresolvedrisk-relevantissuesregardingH2production,meltgenerationandthesourcetermwerestudiedthroughalargenumberofexperimentssuchas(a)dissolutionoffreshandhighburn-upUO2andMOXbymoltenZircaloy,(b)simultaneousdissolutionofUO2andZrO2,(c)oxidationofU–O–Zrmixtures,(d)degradation–oxidationofB4Ccontrolrods.
Correspondingmodelsweredevelopedandimplementedinsevereaccidentcomputercodes.UpgradedcodeswerethenusedtoapplyresultsinplantcalculationsandevaluatetheirconsequencesonkeysevereaccidentsequencesindifferentplantsinvolvingB4CcontrolrodsandintheTMI-2accident.
Significantresultshavebeenproducedfromseparate-effects,semi-globalandlarge-scaletestsonCOLOSStopicsenablingthedevelopmentandvalidationofmodelsandtheimprovementofsomesevereaccidentcodes.Break-throughswereachievedonsomeissuesforwhichmoredataareneededforconsolidationofthemodellinginparticularonburn-upeffectsonUO2andMOXdissolutionandoxidationofU–O–ZrandB4C–metalmixtures.TherewasexperimentalevidencethattheoxidationofthesemixturescancontributesignificantlytothelargeH2productionobservedduringtherefloodingofdegradedcoresundersevereaccidentconditions.
Theplantcalculationactivityenabled(a)theassessmentofcodestocalculatecoredegradationwiththeidentificationofmainuncertaintiesandneedsforshort-termdevelopmentsand(b)theidentificationofsafetyimplicationsofnewresults.
MainresultsandrecommendationsforfutureR&Dactivitiesaresummarizedinthispaper.
