Evaluation of seawater effects on thermal-hydraulic behavior for severe accident conditions, 2; Heat transfer and flow visualization experiment by using internally heated annulus

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,2; 二重管を用いた熱伝達流動可視化試験

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

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

To understand the current status of the TEPCO's Fukushima Daiichi Nuclear Power Station, the progress of the accident has been calculated by severe accident analysis codes, for example, MAAP, SAMPSON and so on. However, effects of seawater are not considered in these calculations, although the seawater was attempted to inject into the reactors to cool down the nuclear fuels. In the present study, the objective is to understand the basic physical effect of the seawater on the thermal-hydraulic behavior without boiling. We measured and compared the thermal-hydraulic behavior in pure water, NaCl solution and artificial seawater with the concentration of 3.5wt% in a heat transfer and flow visualization experiment by using an internally heated annulus. Above Re = 2300 [-], the correlations between Nusselt number and Reynolds number in the NaCl solution and the artificial seawater were the same with that in the pure water. Moreover, the correlation can be predicted by Dittus-Boelter equation. Below Re = 2300 [-], the Nusselt numbers of each fluid correlated with the Rayleigh number. Therefore, considering physical properties of the NaCl solution and the artificial seawater, the thermal-hydraulics behavior without boiling in the NaCl solution and the artificial seawater was not different from the behavior in the pure water.