PowerflatteninginthefuelbundleofaCANDUreactorOriginalResearchArticle

Thestrongnon-uniformityofthefissionpowerproductiondensityintheCANDUfuelbundlecouldhavebeenmitigatedtoagreatdegree.AsatisfactorypowerflatteninghasbeenachievedthroughanappropriatelyevaluatedmethodbyvaryingthecompositionoftheLWRspentfuel/ThO2mixtureinaCANDUfuelbundleinradialdirectionandkeepingfuelroddimensionsunchanged.Thiswillhelpalsotogreatlysimplifyfuelrodfabricationandallowahigherdegreeofqualityassurancestandardization. Threedifferentbundlefuelchargesareinvestigated:(1)thereferencecase,uniformlyfueledwithnaturalUO2,(2)abundleuniformlyfueledwithLWRspentfuel,and(3)abundlefueledwithvariablemixedfuelcompositioninradialdirectionleadingtoaflatpowerprofile(100%LWRspentfuelinthecentralrod,80%LWR+20%ThO2inthesecondrow,60%LWR+40%ThO2inthethirdrowandfinally40%LWR+60%ThO2intheperipheralfourthrow). Burn-upgradesforthesethreedifferentbundletypesarecalculatedas∼7700,∼27,300,and10,000MW.D/MTuntilreachingalowestbundlecriticalitylimitofk∞=1.06.Thecorrespondingplantoperationperiodsare170,660,and240days,respectively.