3D thermal hydraulic characteristics analysis of pool-type upper plenum for lead-cooled fast reactor with multi-scale coupling program

Abstract

The large space plenum of the lead-cooled reactor has complex three-dimensional thermal hydraulic phenomena such as thermal stratification and coolant mixing, which affects the safety performance of the reactor. In this paper, based on the multi-scale coupling program ATHLET-OpenFOAM, three-dimensional simulation of the hot pool for lead-cooled fast reactor M2LFR-1000 is carried out. Considering the axis symmetry of the hot pool model and reducing the amount of calculation, 1/8 model of the hot pool is selected to build the model by CFD, and the rest is simulated by system program ATHLET. The steady-state operation condition is first calculated by coupling program. Based on the calculation of steady-state condition, the main thermal parameters of M2LFR-1000 primary coolant system and the complex three-dimensional phenomena of the upper plenum under unprotected loss of flow accident (ULOF) are studied, and the results of multi-scale coupling calculation are compared with those of ATHLET alone. The results show that there is an obvious thermal stratification in the inner region and the outer region of the upper plenum in the early period of the accident, which slows down the speed of establishing natural circulation. During ULOF accident, there are obvious vortex flow changes in the inlet outer side and the outlet area of the upper plenum.