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Uchibori, Akihiro; Shiina, Yoshimi*; Watanabe, Akira*; Takata, Takashi*
Proceedings of 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-19) (Internet), 12 Pages, 2022/03
An unstructured mesh-based analysis method has been integrated into the sodium-water reaction analysis code, SERAPHIM, in our recent studies. In this study, numerical analysis of an experiment on sodium-water reaction in a tube bundle domain was performed to investigate the effect of the unstructured mesh. The unrealistic behavior appeared in the coarse structured mesh was improved by the unstructured mesh. The numerical result in the case of the unstructured mesh reproduced the peak value of the temperature in the reacting flow.
Uchibori, Akihiro; Watanabe, Akira*; Takata, Takashi; Ohshima, Hiroyuki
Nihon Kikai Gakkai Rombunshu (Internet), 84(859), p.17-00394_1 - 17-00394_6, 2018/03
For assessment of the wastage environment under tube failure accident in a steam generator of sodium-cooled fast reactors, a mechanistic computer code called SERAPHIM calculating compressible multicomponent multiphase flow with sodium-water chemical reaction has been developed. The original SERAPHIM code is based on the finite difference method. In this study, unstructured mesh-based numerical method was developed and introduced into the SERAPHIM code to advance a numerical accuracy for the complex-shaped domain including multiple heat transfer tubes. Validity of the unstructured mesh-based SERAPHIM code was investigated through the analysis of an underexpanded jet experiment. The calculated pressure profile showed good agreement with the experimental data. Numerical analysis of water vapor discharging into liquid sodium was also performed. It was demonstrated that the proposed numerical method could be applicable to evaluation of the sodium-water reaction phenomenon.
Muramatsu, Kazuhiro; Otani, Takayuki; Matsumoto, Hideki*; Takei, Toshifumi*; Doi, Shun*
JAERI-Data/Code 98-014, 35 Pages, 1998/03
JAERI-Data-Code-98-014.pdf:1.83MB
no abstracts in English
Parallel Computational Fluid Dynamics, p.561 - 568, 1998/00
no abstracts in English
JAERI-Data/Code 97-012, 20 Pages, 1997/03
JAERI-Data-Code-97-012.pdf:1.09MB
no abstracts in English
Motegi, Kosuke; Trianti, N.; Matsumoto, Toshinori; Sugiyama, Tomoyuki; Maruyama, Yu
no journal, ,
no abstracts in English
Hatayama, Sora*; Shimokawabe, Takashi*; Onodera, Naoyuki
no journal, ,
Computational fluid dynamics (CFD) is widely used as a fluid analysis technique. However, these have a problem that the calculation cost is very expensive and the execution time for reaching a steady-state is long. To solve this problem, we use convolutional neural networks (CNN), which is one of the deep learning methods, to predict CFD results. In this research, we provide the method and implementation of steady flow prediction using CNN with boundary exchange to predict the CFD results in a large area.
Uchibori, Akihiro; Shiina, Yoshimi*; Watanabe, Akira*; Takata, Takashi*
no journal, ,
A computational fluid dynamics code, SERAPHIM, for sodium-water reaction has been developed. An unstructured mesh-based analysis method was integrated into this code for a complex-shaped domain including multiple heat transfer tubes. In this study, both structured- and unstructured-mesh analyses of the experiment on sodium-water reaction in a tube bundle domain was performed to investigate. The analyses showed that non-physical flow behavior in the case of the coarse structured mesh was improved by the unstructured mesh.
Yamashita, Susumu
no journal, ,
Computational Fluid Dynamics (CFD) technology is used in many fields in the nuclear thermal hydraulics field, including optimal reactor design and prediction of thermal hydraulic fields in the reactor core and containment vessel during accident progression. In the planning lecture, titled Advances in Thermal-Hydraulic CFD Technology, the latest CFD technologies and their applications from plant manufacturers, universities, and research institutes will be presented. The author will present examples of the application of mechanistic CFD techniques developed by JAEA to reactor thermal hydraulics phenomena, such as the prediction of melt behavior during severe accidents and the prediction of bubble flow behavior inside a fuel assembly during steady-state operation. Through case studies, the current state of mechanistic CFD technology and its application to thermal-hydraulic phenomena in nuclear reactors will be discussed, as well as problems and future developments. The current status and problems of state-of-the-art CFD technology will be shared with participants, and future needs and prospects will be discussed.
Terada, Atsuhiko; Nagaishi, Ryuji; Thwe Thwe, A.; Ito, Tatsuya
no journal, ,
In the Development of Technologies for Containing, Transportation and Storage of Fuel Debris, efforts have been made to develop methods for evaluating the amount of hydrogen (H
) generated from lump-shaped debris, and we are now developing methods for powdered debris. As a new attempt, we started computational fluid dynamics (CFD) analysis to visually capture the state of powdered debris over time, such as movement and changes in a mixture of powdered debris and water. As this movement or change, we are currently conducting numerical analysis of two-phase systems, focusing on the growth and behavior of H bubbles in viscoelastic fluids (liquid and gas phases), as well as the structural changes (im-homogenization) over time within the mixture (liquid and solid phases) in relation to H bubbles (H pools) that are predicted to be generated during the radiolysis of water and retained in the mixture. In this report, oxides such as ceria and zirconia were used as debris simulants, and we will introduce the results of an analysis of the time-dependent im-homogenization of oxide powder inside water suspensions, as well as future challenges and developments.
Kaku, Eiji*; Okamoto, Koji*; Kondo, Masahiro*; Ozdemir, E.*; Shiba, Tomoki*; Sato, Ikken
no journal, ,
In this study aiming at contribution for safe decommissioning of Fukushima-Daiichi NPP, CFD (Computational Fluid Dynamics) method was applied and temperature distribution of Unit 3 was reproduced. This temperature distribution was then compared with the measured data obtained by TEPCO so that debris distribution can be estimated. Combined application of optimized tools and CFD method to resolve inverse problem determining best suited thermal balance within the containment vessel is a characteristic of this study.
Ishigaki, Masahiro; Abe, Satoshi; Shibamoto, Yasuteru; Yonomoto, Taisuke
no journal, ,
no abstracts in English
Matsubara, Shinichiro*; Murakami, Hisatomo*; Eto, Masao*; Kato, Atsushi; Yamamoto, Tomohiko
no journal, ,
A conceptual study on a 600 MWe-class sodium-cooled pool-type fast reactor was conducted to determine the basic concept of the plant prior to the conceptual design of the demonstration fast reactor. This study reports an overview of the main design evaluations related to the reactor structure.
