Study on mechanism of the interaction between coolant and melt with high melting point

The high temperature melt interacts with the low temperature coolant is the important phenomenon in nuclear reactor severe accident, which has been experimentally and numerically studied for many years. However, the mechanisms involved in the thermal interaction of coolant and melt have not been figured out so far and there still exists a broad gap between the simulated results and the experimental data. Therefore, a new facility for intermediate-scaled fuel coolant interaction (FCI) experiments has been set up, mainly focusing on the impact factors and thermal interaction mechanism of coolant and melt. In the present study,a series of tests using simulant materials (304SS or Fe-Mo) have been carried out based on the new facility for FCI research. During the tests, the effects of initial mass, thermophysical properties of melt with high melting point and subcooling temperature on thermal interaction have been studied. Based on the analysis of debris characteristics and size distribution, it has been determined that the solidification of melt with high melting point is the significant impact factor which strongly influences the thermal interaction. Furthermore, interaction mechanisms have been discussed under different conditions. All the work is done for research on energy conversion process in the future. (authors)