“…Thermal conditions such as heat transfer between fluid and structure are also affected by variation of two-phase flow conditions. Free surface behaviors of liquid sodium have been studied for fast breeder reactors (FBRs) [1][2][3][4][5]. Numerical simulations were performed in some studies to obtain the surface motion, where the motion of reactor tank was taken into account as the external acceleration term in fluid equations [1,2,4].…”