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吉田 啓之; 堀口 直樹; 阿部 豊*
Proceedings of 2015 US-Japan Seminar on Two-Phase Flow Dynamics, 10 Pages, 2015/05
From the viewpoint of protecting a containment and suppressing the diffusion of radioactive materials in accident of nuclear power plants, it is important to develop the device which allows a filtered venting of contaminated high pressure gas. In the filtered venting system that used in European reactors, so called Multi Venturi Scrubbers System is used to realize filtered venting without any power supply. This system is able to define to be composed of Venturi Scrubbers (VS) and a bubble column. In the VS, scrubbing of contaminated gas is promoted by both gas releases through the submerged VS and gas-liquid contact with splay flow. However, the scrubbing mechanism of the VS is understood insufficiently. Therefore, we started numerical and experimental study to understand the two-phase flow behavior in the VS. In this paper, we performed numerical simulations of two-phase flow behavior in the VS by the TPFIT. In the first step, we perform numerical simulations of supersonic flow by the TPFIT to validate the applicability of the TPFIT for high velocity flow in the VS. In the second step, numerical simulation of two-phase flow behavior in the VS including self-priming phenomena. As the results, dispersed flow in the VS was reproduced in the numerical simulation, as same as the visualization experiments.
上澤 伸一郎; 永武 拓; Jiao, L.; Liu, W.; 高瀬 和之; 吉田 啓之
no journal, ,
In order to evaluate the seawater effects on the thermal-hydraulic behavior in a severe accident like the Fukushima Daiichi NPS accident, we compared the thermal-hydraulic behavior of the pure water, the manmade seawater and the NaCl solution in an internally heated annulus. On conditions without boiling, the heat transfer of the manmade seawater and the NaCl solution can be estimated by Dittus-Boeltter equation, considering physical properties of salinity. On conditions with boiling, boiling curves of the manmade seawater and the NaCl solution were qualitatively coincident with Rohsenow equation, although superheating of the heated wall surface in these fluids was only a little lower than estimated values by the equation. Therefore, it was confirmed that the effects of the seawater on the heat transfer were small.
中村 秀夫; 新井 健司*; 及川 弘秀*; 藤井 正*; 梅澤 成光*; 大貫 晃*; 西 義久*; 阿部 豊*; 杉本 純*; 越塚 誠一*; et al.
no journal, ,
The Atomic Energy Society of Japan (AESJ) developed a New Thermal-Hydraulics Safety Evaluation Fundamental Technology Enhancement Strategy Roadmap (TH-RM) for LWR Safety Improvement considering lessons-learned from the Fukushima-Daiichi Accident. Joint efforts were made by three Sub-Working Groups (SWGs) of severe accident, safety assessment and fundamental technology. The safety assessment SWG pursued development of computer codes for safety assessment concerning reactor system response including severe accident. The fundamental technology SWG pursued safety improvement and risk reduction via enhancements in accident management (AM) measures, by referring a detailed state-of-the-art information on severe accident phenomena, countermeasures and research status given from the severe accident SWG. Important technical subjects were identified by going through accident scenario in both reactor and spent-fuel pool of PWR and BWR. Work description sheets were prepared for each of identified subjects. Detailed information to cope with influences from external hazards is also summarized. The developed TH-RM is described with examples, and future perspectives are discussed.