Numerical simulation of boiling two-phase flow in a simulated subchannel of fuel assemblies excited by earthquake oscillation
地震動付加時の燃料集合体模擬サブチャンネル内沸騰二相流解析
三澤 丈治; 吉田 啓之 ; 高瀬 和之
Misawa, Takeharu; Yoshida, Hiroyuki; Takase, Kazuyuki
As a part of development of a thermal-structure coupling analysis method, we have performed evaluation of boiling two-phase flow in a nuclear reactor core under an earthquake condition by using three-dimensional two-fluid model code ACE-3D. The ACE-3D code was improved so that the boiling two-phase flow in a fuel assembly excited by earthquake acceleration can be calculated. The boiling two-phase flow behavior in 22 subchannels of the fuel assembly with the earthquake acceleration was analyzed numerically. The flow condition in the present analysis simulates the operating condition of current BWRs. The earthquake acceleration is simulated by the sine wave which oscillates in the horizontal and axial directions. As a result, it was confirmed that the time-averaged void fraction distribution in the horizontal direction under the earthquake condition is different from that under no oscillation case, and the region in 22 subchannels where the void fraction fluctuation is large moves from near wall to subchannel center. Finally, we could make sure that the improved ACE-3D code is able to predict the boiling two-phase flow characteristics in fuel assemblies excited by the earthquake acceleration.