Numerical analysis of sodium experiment for thermal stratification in upper plenum of fast reactor

高速炉上部プレナム温度成層化に関するナトリウム試験の数値解析

大野 修司  ; 大島 宏之; 菅原 章博*; 大木 裕*

Ohno, Shuji; Ohshima, Hiroyuki; Sugahara, Akihiro*; Oki, Hiroshi*

原子炉上部プレナム温度成層化現象の基本的解析手法の検証を目的として、ナトリウム試験の多次元数値解析を実施した。その結果、適切なメッシュサイズと高次差分スキームを採用した条件のもと、RANS乱流モデルを使ったCFD解析によって温度成層界面の上昇と温度勾配を良好に予測できることを明らかにした。

Multi-dimensional transient thermal hydraulic analyses for a sodium experiment are carried out in order to validate the applicability of basic simulation methods to a typical thermal stratification behavior in a reactor upper plenum region. Simulation predictability of the behavior is evaluated after the results of an existing experiment are reviewed and important fundamental characteristics of the behavior are quantified. The investigated results clarify that CFD codes provide good prediction for fundamental phenomena of steep temperature gradient and gradual rising behavior of the stratification interface under the condition of adopting appropriate mesh size, higher-order discretization scheme, and the RANS turbulence model.