Author/Authors :
JeffreyC.King، نويسنده , , MohamedS.El-Genk، نويسنده ,
Abstract :
TheSubmersion-SubcriticalSafeSpace(S4)reactor,developedforfuturespacepowerapplicationsandavoidanceofsinglepointfailures,ispresented.TheS4reactorhasaMo–14%Resolidcore,loadedwithuraniumnitridefuel,cooledbyHe–30%Xeandsizedtoprovide550kWthfor7yearsofequivalentfullpoweroperation.TheberylliumoxidereflectoroftheS4reactorisdesignedtocompletelydisassembleuponimpactonwaterorsoil.ThepotentialofusingSpectralShiftAbsorber(SSA)materialsindifferentformstoensurethatthereactorremainssubcriticalintheworst-casesubmersionaccidentisinvestigated.NinepotentialSSAsareconsideredintermsoftheireffectonthethicknessoftheradialreflectorandonthecombinedmassofthereactorandtheradiationshadowshield.TheSSAmaterialsareincorporatedasathin(0.1mm)coatingontheoutsidesurfaceofthereactorcoreandascoreadditionsinthreepossibleforms:2.0mmdiameterpinsintheintersticesofthecoreblock,0.25mmthicksleevesaroundthefuelstacksand/oradditionstotheuraniumnitridefuel.Resultsshowthatwithaboroncarbidecoatingand0.25mmiridiumsleevesaroundthefuelstackstheS4reactorhasareflectorouterdiameterof43.5cmwithacombinedreactorandshadowshieldmassof935.1kg.TheS4reactorwith12.5at.%gadolinium-155addedtothefuel,2.0mmdiametergadolinium-155sesquioxideinterstitialpins,anda0.1mmthickgadolinium-155sesquioxidecoatinghasaslightlysmallerreflectorouterdiameterof43.0cm,resultinginasmallertotalreactorandshieldmassof901.7kg.With8.0at.%europium-151addedtothefuel,alongwitheuropium-151sesquioxideforthepinsandcoating,thereflectorʹsouterdiameterandthetotalreactorandshieldmassarefurtherreducedto41.5cmand869.2kg,respectively.
