Computational study of thermal striping in an upper plenum of KALIMER

A computational study of thermal striping in an upper plenum of KALIMER (Korea Advanced Liquid Metal Reactor) was performed. The primary objective of the present study was to find the distribution of amplitude of temperature fluctuation in the hot pool of KALIMER. The computations were performed using the CFX-4 code with the differential stress and flux turbulence model and the Van-Leer convection scheme. Two cases with different outlet velocity of the control rod fuel assemblies are considered. The distributions of the velocity vector, temperature and temperature fluctuation were obtained from the calculation. In order to understand the amplitude of temperature fluctuation at the bottom wall of the UIS (Upper Internal Structure) quantitatively, the amplitude of the fluctuation of temperature in the radial and angular directions were investigated. It was found that the amplitude of temperature fluctuation at the UIS bottom plate was largely dependent on the magnitude of outlet velocity of the control rod fuel assemblies. Since thermal striping is dependent on the amplitude of temperature fluctuations and frequency, the region of UIS bottom edge need to be analyzed with a detailed unsteady calculation