A Numerical simulation method to evaluate heat transfer of fuel debris in air cooling by JUPITER, 2; Validation of porous model for natural convective heat transfer

JUPITERを用いた空冷における燃料デブリの熱伝達評価の数値シミュレーション手法, 2; 自然対流熱伝達におけるポーラスモデルの妥当性検証

上澤 伸一郎  ; 山下 晋   ; 柴田 光彦 ; 吉田 啓之  

Uesawa, Shinichiro; Yamashita, Susumu; Shibata, Mitsuhiko; Yoshida, Hiroyuki

Various types of cooling of fuel debris such as reduction in the amount of water injection, intermittent injection water and air cooling are considered for contaminated water management in the decommissioning of Fukushima Daiichi Nuclear Power Station (NPS). As a method for estimating the thermal behavior of fuel debris in the preliminary containment vessel (PCV) of Fukushima Daiichi NPS, JAEA develops a method for estimating the thermal behavior in the air cooling, including the influence of the position, heat generation, and the porosity of fuel debris by JUPITER added a porous model. In order to validate the natural convective heat transfer analysis with porous bodies by the JUPITER added the porous model, the heat transfer and the flow visualization experiments of air natural convection with a porous body was performed in this study. The temperature distributions of the heat transfer surface, the natural convection area and the porous body were measured with thermocouples. In addition, the flow visualization was performed by a particle image velocimetry (PIV). We compared the temperature and flow results between the experiment and the numerical analysis. The temperature distributions at the central axis were generally agreed on the condition without the porous body. As for with the porous body, the tendency to increase the temperature inside the porous body was reproduced as in the analysis, but quantitative differences were observed. For the flow distribution of the test vessel, flow along the experimental vessel wall to form a vortex was observed in the experiment. On the other hand, an upward flow occurred from the center of the heating surface, and the flow was separated by the ceiling to form two vortices in the numerical analysis. The difference between the analysis and the experiment indicates that discussions for various thermal conductivity models to porous bodies is necessary.