2015 年 81 巻 823 号 p. 14-00460
For the safety design of a Sodium-cooled Fast Reactor, it is strongly required that the molten material which is released from a core region has to be solidified and cooled down in a reactor vessel by breaking up in the sodium coolant during a Core Disruptive Accident in terms of Post Accident Heat Removal. In this paper, in order to investigate the effects of the surface solidification on the jet breakup, the experimental results using a low melting point alloy and water are reported. The jet breakup behavior is observed with a high speed video camera, the front position of the jet and the jet breakup length are estimated with the visual observation results. In the high injection velocity conditions, it is found that the jet breakup is dominated by fragmentation induced by the surface instability due to the relative velocity even in the surface solidification condition. In addition, it is also found that the tendency of the jet breakup length is close to Epstein's correlation.
