Author/Authors :
B.L.Smith، نويسنده , , W.Leung، نويسنده , , A.Zucchini، نويسنده ,
Abstract :
ThepaperdescribessomeR&DactivitiesundertakeninsupportofthedesignandsafeoperationofMEGAPIE(MEGAwattPIlotExperiment)spallationsourcetarget,whichisscheduledtobeirradiatedbyaprotonbeamintheSINQfacilityatthePaulScherrerInstitutein2006.Thetargetmaterialisleadbismutheutectic(LBE),whichalsoactsastheprimarycoolant.Asaconsequenceofthespallationreactions,about600kWofheatwouldbedepositedinthetargetduringoperation,andconsiderableR&Deffortisbeingexpendedtodemonstratecontinuingcoolabilityandstructuralintegrityunderavarietyofoperationalandabnormalconditions.Thepapergivesthreeexamplesoftransientanalysescarriedoutaspartofthesafetyassessmentofthetarget:(1)abeamlinetripandrecovery;(2)failureoftheprimaryelectro-magneticpump(EMP);(3)failureofthesecondaryEMP(usedtocoolthebaseofthetarget).Thestudyinvolvesthesimultaneousapplicationofasystem-analysiscode,inourcaseaversionofRELAP5,acomputationalfluiddynamics(CFD)tool(CFX-4),andastructuralanalysiscode(ABAQUS).TheRELAP5codeisusedtoprovidetransientboundaryconditionsforalocalizedconjugateheattransferanalysisofthelowertargetregion,undertakenusingCFD,andincludesthefeed-backeffectsarisingfromthesecondarycoolingandcontrolsystems.AconjugateheattransferproblemisthensolvedusingCFD,whichprovidestime-dependentthermalandflowdatawithintheLBE,togetherwiththethermalandmechanicalloadstothetargetstructures.Finally,anin-houseinterfaceprogramisemployedtotransfermeshgeometry,modeltopologyand(time-dependent)thermal/mechanicaldatatoenablestressanalysisoftheprincipallower-targetstructuralcomponentstobeperformed.Itisdemonstratedthatnoneofthetransientsconsideredresultincriticalstressconditionsoccurringinthetargetcomponents,butthatfurtheroperationisnotrecommendedunlessbothpumpsarefullyoperational.
