Optimization design of core flow distribution for 45MW solid fuel molten salt reactor

The Molten Salt Reactor-Solid Fuel is a Generation IV advanced nuclear reactor concept where optimal core flow distribution is crucial for efficient nuclear heat removal. The core's hydraulic configuration significantly influences flow distribution characteristics. This study aims to optimize the hydraulic configuration of a 45MW solid fuel molten salt reactor to match flow distribution with power distribution in the core. A one-twelfth scale core model of the 45MW solid fuel molten salt reactor is developed in this investigation. To systematically evaluate the effects of varying downcomer annulus widths, lower plenum heights, and geometries on flow distribution, three-dimensional computational fluid dynamics (CFD) simulations are conducted. The results demonstrate that increasing the width of the descending annulus and the height of the lower chamber can reduce the molten salt velocity in the lower chamber, thereby enhancing flow distribution consistency. Nevertheless, excessive height of the lower chamber can induce vortex formation within it, leading to flow distribution non-uniformity. The standard deviation of matching factor initially decreases from14.2%% to 6.2%, and then increases to 23.5% with increasing lower plenum height. Compared to an elliptical lower plenum, the cylindrical configuration enhances flow distribution uniformity, reducing the standard deviation of matching factor to 6.1%. Additionally, incorporating a flow distribution plate in the lower plenum more effectively suppresses vortex formation. Based on the above analysis, optimal parameters are determined, providing valuable guidance for the engineering optimization of solid-fuel molten salt reactors.