Fragmentation of molten metal drop caused in sodium with instantaneous contact interface temperature below its melting point

In order to clearly understand the fragmentation originating from the coolant entrapped within the melt, a series of experiments dropping a molten copper drop into a sodium pool was conducted under the condition that the instantaneous contact interface temperatures between the molten copper drop and the sodium were below the melting point of copper. An effective fragmentation originating from the coolant entrapped within the molten copper drop was observed even under the condition that the molten drop was easily solidified for the contact with the sodium. In addition, it was found that the degree of fragmentation was not strongly affected by the condition whether the instantaneous contact interface temperature between the molten copper and sodium was higher than the melting point or not. (author)