AnevaluationofreactorcoolingandcoupledhydrogenproductionprocessesusingthemodularheliumreactorOriginalResearchArticle

Thehigh-temperaturecharacteristicsofthemodularheliumreactor(MHR)makeitastrongcandidateforproducinghydrogenusingeitherthermochemicalorhigh-temperatureelectrolysis(HTE)processes.UsingheatfromtheMHRtodriveasulfur-iodine(SI)thermochemicalhydrogenproductionprocesshasbeenthesubjectofaU.S.DepartmentofEnergysponsoredNuclearEngineeringResearchInitiative(NERI)projectledbyGeneralAtomics,withparticipationfromtheIdahoNationalLaboratory(INL)andTexasA&MUniversity.WhilethefocusofmuchoftheinitialworkwasontheSIthermochemicalproductionofhydrogen,recentactivitiesincludeddevelopmentofapreconceptualdesignforanintegralHTEhydrogenproductionplantdrivenbytheprocessheatandelectricityproducedbya600MWMHR. ThispaperdescribesATHENAanalysesperformedtoevaluatealternativeprimarysystemcoolingconfigurationsfortheMHRtominimizepeakreactorvesselandcoretemperatureswhileachievingcoreheliumoutlettemperaturesintherangeof900–1000°CthatareneededfortheefficientproductionofhydrogenusingeithertheSIorHTEprocess.Thecoolingschemesinvestigatedareintendedtoensurepeakfueltemperaturesdonotexceedspecifiedlimitsundernormalortransientupsetconditions,andthatreactorvesseltemperaturesdonotexceedAmericanSocietyofMechanicalEngineers(ASME)codelimitsforsteady-stateortransientconditionsusingstandardlightwaterreactorvesselmaterials.PreconceptualdesignsforSIandHTEhydrogenproductionplantsdrivenbyoneormore600MWMHRsatheliumoutlettemperaturesintherangeof900–1000°Caredescribedandcompared.AninitialSAPHIREmodeltoevaluatethereliability,maintainability,andavailabilityoftheSIhydrogenproductionplantisalsodescribed.Finally,apreliminaryflowsheetforaconceptualdesignofanHTEhydrogenproductionplantcoupledtoa600MWmodularheliumreactorispresentedanddiscussed.