ExperimentalstudyonnaturalcirculationanditsstabilityinaheavyliquidmetalloopOriginalResearchArticle

Motivatedbytheincreasinginterestinheavyliquidmetal(HLM)cooledfastreactorsandacceleratordrivensystem(ADS),theTALLtestfacilitywasdesignedandconstructedatKTHtoinvestigatethethermal-hydrauliccharacteristicsofHLM.Inthispaper,theHLMnaturalcirculationcharacteristicsinaHLMloopwereinvestigatedwithexperimentsintheTALLtestfacility.Thestudyincludesmeasurementson(1)start-upofnaturalcirculationfromdifferentinitialconditions;(2)stabilityofnaturalcirculation;(3)effectsofinfluencingparametersand(4)capabilityofnaturalcirculation.Theexperimentaldataarecomparedtopredictionswitharelevantcode(RELAP5).Significantnaturalconvectionflowwasobservedintheexperiments.Itwasfoundthatthenaturalcirculationwaseasilyestablishedandstabilized.Ittookonlyafewminutestohaveastablenaturalcirculationprevailingfromcoldconditions.Thenaturalcirculationflowratedependsontheloopresistance,andthetemperaturedifferencebetweenthehotlegandthecoldleg,asdeterminedbythepowerlevelandtheheatsinkcapacity.Theexperimentsshowthatthemaximumflowrateforthenaturalcirculationis∼0.5kg/s(correspondingto∼0.5m/sintheheatexchanger),resultinginheatremovalof∼15kWfromthecoretank,whichiscomparabletothecapacityof∼100W/cmoftheelectricheaterelements.ThepreliminaryanalysisperformedwiththeRELAP5codeisinreasonableagreementwiththeexperimentaldata.