Thermal and hydrodynamic fragmentation of continuous molten copper droplets penetrating into sodium pool

Abstract

To fully investigate the hydrodynamic and thermal fragmentation mechanism of the molten metallic fuels, the experiments of dropping 20–100 g continuous molten copper droplets into sodium were conducted with high ambient Weber number (477<Wea<566), as the supplement of the previous continuous copper droplets experiments with relatively low Wea (87<Wea<339). It is found that the fragmentation changes sharply under the low thermal and hydrodynamic conditions, and changes slowly under the relatively high thermal and hydrodynamic conditions. For the continuous copper droplets, the effect of mass is negligible on the fragmentation degree. The comparisons show that fragments of continuous droplets tend to have a smaller dimensionless mass median diameter (Dm/D0) value than that of single droplet fragments and have a larger Dm/D0 value than that of copper jet fragments under the similar conditions. The empirical correlations, which take the thermal and hydrodynamic effects into consideration, are proposed to calculate the Dm/D0 values of the continuous copper droplets, single copper droplet and copper jet fragments. These results are helpful for predicting the fragment size and termination in CDAs and promising to the development of the core safety codes and the design of reactor core in SFRs.