Numerical Simulation of Flow Distribution in the Lower Plenum of NHR200-II

The type-II 200MW nuclear heating reactor (NHR200-II) designed by Tsinghua University is a novel pressurized water reactor, whose main specifications are as follows, the heat power is 200 MW, the design pressure of major loop is 10 MPa, the inlet and outlet temperature of coolant are 230 °C and 278 °C. In this paper, a quarter three-dimensional model of the lower plenum of the reactor pressure vessel is set up for analysis. The flow velocity distribution and the pressure distribution on the core supporting structure are calculated by method of three-dimensional numerical simulation. The results show that the lower part of the core produce symmetric vortex due to the existence of support structure. The production of the symmetric vortex, to some extent, increases the instability of the flow. On the other hand, the existence of the vortex is good for uniformity of flow distribution in the outlet holes. The flow rate in the flow channel of support structure is lower at the center and larger in the margin of core inlet. The results show that the maximum of the velocity in the flow channel is 5% higher than the minimum one.