IndirectaircoolingtechniquesforcontrolroddrivesinthehightemperatureengineeringtestreactorOriginalResearchArticle

Thehightemperatureengineeringtestreactor(HTTR)isthefirsthigh-temperaturegas-cooledreactorinJapanwithreactoroutletgastemperatureof950°Candthermalpowerof30MW.SixteenpairsofcontrolrodsareemployedforcontrollingthereactivitychangeoftheHTTR.Eachstandpipeforapairofthecontrolrods,whichisplacedonthetopheaddomeofthereactorpressurevessel,containsonecontrolroddrivemechanism.Thecontrolroddrivemechanismmaymalfunctionbecauseofreductionoftheelectricalinsulationoftheelectromagneticclutchwhenthetemperatureexceeds180°C.Because31standpipesstandclosetogetherinthestandpiperoom,16standpipesforthecontrolrods,whicharelocatedatthecenter,shouldbecooledeffectively.Therefore,thecontrolroddrivesarecooledindirectlybyforcedaircirculationthroughapairofring-ductswithproperairoutletnozzlesandinlets.Basedonanalyticalresults,apairofthering-ductswasinstalledasoneofstructuresinthestandpiperoom.Evaluationresultsthroughtherise-to-powertestoftheHTTRshowedthattemperaturesoftheelectromagneticclutchandtheambientheliumgasinsidethecontrolrodstandpipeshouldbebelowthelimitsof180and75°C,respectively,atfullpoweroperationandatthescramfromtheoperation.