Optimal design of core flow distribution for 10 MW liquid fuel molten salt reactor

BackgroundThe flow distribution in core for the liquid fuel molten salt reactor (MSR) is an important part of the thermal hydraulic design, and the hydraulic structure of reactor core plays a decisive role on flow distribution.PurposeThis study aims to find out a suitable hydraulic structure design to make the core flow distribution match with the power distribution, and flatten the core temperature distribution for a 10 MW MSR.MethodsFirst of all, a one-twelfth core model of liquid fuel MSR was established. Then, ANSYS FLUENT16.0 software was employed to conduct three-dimensional numerical simulation of the flow field. The influence of hydraulic structure of reactor core was analysed by changing the structure of upper plenum, downcomer and lower plenum, and the corresponding flow distribution characteristics of the core are obtained. Finally, a suitable structure was proposed after step-by-step improvement.ResultsThe simulation results show that increasing of the height of upper plenum can balance the flow distribution between central and peripheral channels, increasing of the width of the downcomer can reduce the vortex flow at the downcomer outlet and flattens the flow distribution at the same time. The cylindrical lower structure with shroud in lower plenum can restrain the vortex to a certain extent and make the flow distribution more gentle. Based on the analysis above, a reasonable hydraulic structure is proposed for the molten salt reactor.ConclusionsThe results of this study provide important reference for the further optimization design of liquid fuel molten salt reactor.