Development of numerical simulation method of natural convection around heated porous medium by using JUPITER

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

Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 9 Pages, 2023/05

For contaminated water management in decommissioning Fukushima Daiichi Nuclear Power Stations, reduction in water injection, intermittent injection water and air cooling are considered. However, since there are uncertainties of fuel debris in the PCV, it is necessary to examine and evaluate optimal cooling methods according to the distribution state of the fuel debris and the progress of the fuel debris retrieval work in advance. We have developed 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. Since a large-scale thermal-hydraulics analysis of natural convection is necessary for the method, JUPITER developed independently by JAEA is used. It is however difficult to perform the large-scale thermal-hydraulics analysis with JUPITER by modeling the internal structure of the debris which may consist of a porous medium. Therefore, it is possible to analyze the heat transfer of the porous medium by adding porous models to JUPITER. In this study, we report the validation of JUPITER applied the porous model and discuss which heat transfer models are most effective in porous models such as series, parallel and geometric mean models. To obtain validation data of JUPITER for the natural convective heat transfer analysis around the porous medium, we performed the heat transfer and the flow visualization experiments of the natural convection in the experimental system including the porous medium. In the comparison between the experiment and the numerical analysis with each model, the numerical result with the geometric mean model was the closest of the models to the experimental results. However, the numerical results of the temperature and the velocity were overestimated for those experimental results. In particular, the temperature near the interface between the porous medium and air was more overestimated.

Report of summer holiday practical training 2018; Feasibility study on nuclear battery using HTTR core; Feasibility study for nuclear design

Ishitsuka, Etsuo; Matsunaka, Kazuaki*; Ishida, Hiroki*; Ho, H. Q.; Ishii, Toshiaki; Hamamoto, Shimpei; Takamatsu, Kuniyoshi; Kenzhina, I.*; Chikhray, Y.*; Kondo, Atsushi*; et al.

JAEA-Technology 2019-008, 12 Pages, 2019/07

JAEA-Technology-2019-008.pdf:2.37MB

As a summer holiday practical training 2018, the feasibility study for nuclear design of a nuclear battery using HTTR core was carried out. As a result, it is become clear that the continuous operations for about 30 years at 2 MW, about 25 years at 3 MW, about 18 years at 4 MW, about 15 years at 5 MW are possible. As an image of thermal design, the image of the nuclear battery consisting a cooling system with natural convection and a power generation system with no moving equipment is proposed. Further feasibility study to confirm the feasibility of nuclear battery will be carried out in training of next fiscal year.

Study on natural convection heat transfer in vertical annular space of a double coaxial cylinder

Inaba, Yoshitomo; Takeda, Tetsuaki

JAERI-Research 2000-062, 73 Pages, 2001/02

JAERI-Research-2000-062.pdf:2.83MB

no abstracts in English

Heat transfer by natural convection in a half-sphere heated from below

;

Journal of Nuclear Science and Technology, 23(6), p.568 - 570, 1986/00

https://doi.org/10.3327/jnst.23.568

no abstracts in English

Development of numerical simulation method to evaluate heat transfer of fuel debris in air cooling, 6; Effect of effective thermal conductivity model in analysis of thermal behavior in PCV

Uesawa, Shinichiro; Ono, Ayako; Yamashita, Susumu; Yoshida, Hiroyuki

no journal, , 

To evaluate the thermal behavior of fuel debris of porous media in PCVs of TEPCO's Fukushima Daiichi Nuclear Power Station for air cooling, JAEA has developed a numerical simulation method with JUPITER. In this presentation, we report the numerical simulation results of the thermal behavior in the PCV considering three effective thermal conductivity models for fuel debris. The results showed the temperature and the velocity distributions and the heat removal amount from the fuel debris were different for each model. It is important to understand the internal structure of the fuel debris and choose the appropriate effective thermal conductivity model for the analysis of the thermal behavior because the model affects the simulation results.