Evaluation of seawater effects on thermal-hydraulic behavior for severe accident conditions, 1; Outline of the research project

シビアアクシデントにおける海水の熱水力挙動への影響評価,1; 研究計画の概要

吉田 啓之  ; 上澤 伸一郎  ; 永武 拓 ; Jiao, L.; Liu, W.; 高瀬 和之

Yoshida, Hiroyuki; Uesawa, Shinichiro; Nagatake, Taku; Jiao, L.; Liu, W.; Takase, Kazuyuki

In the Fukushima Daiichi Nuclear Power Plant accident, seawater was injected into the reactor to cool down the nuclear fuels. The injection of the seawater may change the thermal-hydraulic characteristics. Therefore, the thermal hydraulic behavior of seawater has to be evaluated to consider the current status of Fukushima Daiiichi Nuclear Power Plants. However, there is little information about the thermal-hydraulic characteristics of seawater. In order to understand the effects of the seawater on the thermal hydraulic behaviors, a research project was started in Japan Atomic Energy Agency. In this research project, we performed two-different type experiments, one is a heat transfer and visualization experiment by using an internally heated annulus, the other is a heat transfer experiment by using a degraded core simulated test section. In this paper, the outline of the research project and examples of results are reported. For single phase flow conditions, heat transfer coefficients of evaluated by the existing correlation and thermal properties of the artificial seawater almost agreed with the experimental results. For two-phase flow conditions, the results of the artificial seawater were different from that of pure water and the NaCl solution. In the artificial seawater, small solid depositions were observed, and it was considered that these solid depositions affected the thermal hydraulic behavior of the artificial seawater.