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Kawabe, Tomosaburo*; Sano, Yoshihiko*; Kuwahara, Fujio*; Uesawa, Shinichiro; Yoshida, Hiroyuki
Dai-63-Kai Nihon Dennetsu Shimpojiumu Koen Rombunshu (Internet), 1 Pages, 2026/05
To estimate the thermal behavior of fuel debris inside the Primary Containment Vessels (PCVs) of TEPCO's Fukushima Daiichi Nuclear Power Station, a simulation method has been developed using the JUPITER code with porous medium models. However, it has been found that the selection of models and parameters according to the internal structure of the porous media significantly affects the accuracy of simulation results, highlighting the need for appropriate model selection strategies. In this study, we focus on packed beds with particles as one form of porous media and investigate a methodology for determining model parameters that characterize their flow behavior. Systematic knowledge of packed beds with heterogeneous particle size ratios and packing structures remains limited, and comprehensive organization accounting for structural differences has not yet been fully established. Therefore, numerical simulations were employed to evaluate the permeability and Forchheimer coefficient of packed beds with different particle size ratios and packing structures. Based on the obtained results, a method for appropriately determining these parameters according to the structural characteristics of packed beds is proposed, and insights are provided that contribute to improving the accuracy of flow analysis models in porous media.
Sano, Yoshihiko*; Ota, Kensuke*; Kuwahara, Fujio*; Uesawa, Shinichiro; Yoshida, Hiroyuki
Nihon Kikai Gakkai Netsu Kogaku Konfuarensu 2025 Koen Rombunshu, 1 Pages, 2025/10
To estimate the thermal behavior of fuel debris inside the Primary Containment Vessels (PCVs) of TEPCO's Fukushima Daiichi nuclear power station, a simulation method has been developed using the JUPITER code with porous medium models. However, it has been found that the selection of models and parameters according to the internal structure of the porous media significantly affects the accuracy of simulation results, highlighting the need for appropriate model selection strategies. In this study, we investigated methods for calculating macroscopic model constants that characterize flow behavior in porous media. These properties are influenced not only by the volume ratio of solid and gas phases but also by the structural features of the porous media. Focusing on packed beds composed of particles with varying diameters, we conducted numerical simulations to evaluate permeability and Forchheimer coefficient across diverse structural configurations. Based on the results, we propose a method for appropriately determining these parameters according to the structure of the packed bed, thereby contributing to the improvement of the porous media heat transfer and flow model.
Ito, Koki*; Sano, Yoshihiko*; Kuwahara, Fujio*; Uesawa, Shinichiro; Yoshida, Hiroyuki
no journal, ,
To estimate the thermal behavior of fuel debris in the primary containment vessel of the Fukushima Daiichi Nuclear Power Station, we have developed a numerical simulation method for analyzing the thermal behavior of fuel debris during air cooling. Since fuel debris is assumed to be a porous material, by using a porous medium model, the numerical simulation was conducted to simulate the natural convection in a closed vessel with porous materials. The simulation was validated by comparing it with the experiment in JAEA.