Proposal of thermal fragmentation models for numerical study of FCI

Thermal fragmentation mechanisms have been studied for many years, but the fragmentation models, triggered by boiling effect and surface solidification effect, are not available for numerical simulation tools. In this study, based on the understanding of the thermal fragmentation mechanisms, a thermal fragmentation model is proposed for the simulation tools. In this model Taylor instability is proposed to be the mechanisms for the thermal fragmentation of a melt droplet induced by external pressure pulse, boiling effect and surface solidification effect. The vapor film collapse model and the surface solidification model are developed to estimate the generated pressure pulse for different triggering event. Based on the triggering event of each fragmentation mechanism, simplified fragmentation correlations are proposed. The proposed fragmentation correlations are verified by simulating the MIXA and KROTOS experiments, respectively. (author)