Development of numerical evaluation method for fluid dynamics effects on jet breakup phenomena in BWR lower plenum

BWR下部プレナム内ジェットブレイクアップ現象の流体力学的効果に関する数値評価手法の開発

鈴木 貴行; 吉田 啓之  ; 永瀬 文久 

Suzuki, Takayuki; Yoshida, Hiroyuki; Nagase, Fumihisa

The jet breakup phenomena of molten core during a severe accident are affected by the complicated structures, such as control rod guide tubes, instrument guide tubes and core support plate, in the lower plenum of Boiling Water Reactors (BWRs). Multi-phase computational fluid dynamics approach is considered to be the best way to estimate the jet breakup phenomena in the BWR lower plenum, and a simulation method has been developed based on interface tracking method code TPFIT (Two Phase Flow simulation code with Interface Tracking). The developing simulation method was applied to single/multi-channel experiments for verification and validation in this study. More specifically, numerical results from the simulation were compared to experimental results obtained by the multi-phase flow visualization technique with a high speed camera and the PIV method. As a consequence, the simulation method developed in this study was qualitatively validated for the jet breakup phenomena in the complicated structure.