Development of the simplified boiling model applied for the large scale simulation

Ono, Ayako ; Yamashita, Susumu   ; Sakashita, Hiroto*; Suzuki, Takayuki*; Yoshida, Hiroyuki  

JAEA is implementing a simulation of a two-phase flow in the reactor core by TPFIT and JUPITER which are developed by JAEA based on the surface tracking method. However, it is impossible to simulate a boiling on the heating surface in the large-scale domain by this type of simulation method since the simulation of boiling based on the surface tracking method needs the fine mesh which sufficiently resolves the initiation of boiling. Therefore, JAEA started to develop the simplified boiling model applied for the two-phase flow in the fuel assemblies. In this study, the simulation results of the convection boiling on vertical heating surface and the comparison between the simulation results and experimental results are shown.