Thermal hydraulic analysis of KSNP steam generator for off-design conditions

The three dimensional thermal hydraulic analysis of KSNP steam generator for off-design conditions has been carried out by using ATHOS3 code. Four off-design parameters such as the reactor coolant temperature of 10 , the reactor thermal power of 5%, the steam generator tube plugging of 8%, and the feedwater temperature of 10 are considered. Algebraic slip model is used for the two-phase flow analysis in the secondary side of steam generator. The void fraction increases with the increase of reactor thermal power or tube plugging rate, and the decrease of reactor coolant temperature. The vertical mixture velocity of steam and liquid shows the sae trend to the void fraction and increases in general as the steam pressure decreases. The maximum hydrodynamic load based on normal gap velocity on the tube of 41R-83C around the central cavity increases about 14% as the reactor coolant temperature of 10 decreases. Also the maximum hydrodynamic load increases about 15% on the tube with the increase of 5% in reactor thermal power