Author/Authors :
PZanocco، نويسنده , , MGiménez، نويسنده , , DDelmastro، نويسنده ,
Abstract :
Thestabilityofaself-pressurizednaturalcirculationintegralreactorisstudiedbymeansofalinearapproach,takingtheCAREM-25reactorasreference.
Athermohydrauliccodehasbeenimprovedforanalysisoflinearstability,greatemphasishavingbeenplacedontheminimizationofnumericaldiffusionandintegrationerrors.Alinearizationmethodisimplementedbymeansofnumericalperturbations.Theresultsareobtainedwithinthefrequencydomain.Thecodeiscomparedtoasimpleranalyticalmodel,bycontrastingstabilitymapsobtainedfrombothmodelsforatestconfiguration,showinggoodagreement.
Inthistypeofreactor,oscillationsarepromotedbythetwo-phaseregimeinitslongriser,andtakeplaceduetothecounteractionbetweenmassflowandbuoyancyforce.
Thestabilityofthesystemisstronglyinfluencedbythesteam-domedynamics.Condensationinthesteamzone,togetherwithreactorpower,determinesthedynamicalstateofthesystem.
Thephase-lagintroducedbythecoredynamicregardingtherisertiming,togetherwiththesensitivityofthebuoyancyforceduetoflowchanges,determinesthesustainabilityoftheoscillation.Aparametricstudyiscarriedout,graduallyincreasingthecomplexityofthemodel,toanalyzetheinfluenceofdifferentfactorsontheoscillationsustainability,concerningphysicalprocessandmodelingapproaches.Theanalysisincludestherelativevelocitiesbetweenphases,theaxialpowerprofilealongthecore,thebuoyancyforceduetosubcooleddensitychanges,theflashingeffect,thecoredynamicandthepressurefeedbackduetoself-pressurization.Thesteam-dome-pressurefeedbackisidentifiedasastabilizingeffect,aslongasitdecreasesthesensitivityofthebuoyancyforce.
