CFD investigation of ballooning effects for dispersed droplet flow during LOCA

This study investigates the impact of cladding ballooning on dispersed droplet flow during Loss of Coolant Accidents (LOCA), integrating experimental insights from COAL and MASCARA campaigns with advanced CFD simulations using Neptune_CFD. The work validates carrier gas flow, analyzes droplet dynamics in highly blocked subchannels, and assesses peak cladding temperature behavior under disperse droplet conditions. Handling complex balloons with a discrete forcing Immersed Boundary Methods (IBM), results highlight the critical influence of blockage ratio, blockage length, and droplet size on flow redistribution and hotspot formation. By combining detailed experiments with multiphase modeling, the study could advance understanding of coolability margins in ballooned fuel assemblies and supports the development of more predictive multiscale safety codes.