The Thermal-hydraulic behavior of seawater in an internally heated annulus

二重管流路内の海水の熱流体挙動

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

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

The progress of the 2011 Fukushima Daiichi nuclear disaster has been calculated by severe accident analysis codes to understand the current status of the reactors. However, effects of seawater are not considered in these calculations, although the seawater has been attempted to inject into the reactors to cool down the nuclear fuels. In the present study, we evaluated the thermal-hydraulic behavior of the pure water, the manmade seawater and the NaCl solution in the internally heated annulus with the measurement of temperature, boiling behavior, velocity distributions and deposition of crystals, in order to inform about the effect of the seawater. From the experiment, considering physical properties and inlet velocity of fluid, the heat transfer coefficients in the manmade seawater and the NaCl solution are the same values with that in the pure water in the single phase condition. However, in the boiling condition, the heat transfer coefficients in the manmade seawater and the NaCl solution are more largely increased than that in the pure water with increasing the input heat flux. The difference of the heat transfer is concerned with the difference of the boiling behavior and the velocity distributions in each fluid. As one of the causes of the difference of boiling behavior and velocity distribution, the deposition of crystals is considered. In fact, the deposition of crystals of CaCO was observe in the internally heated annulus with the manmade seawater.