Studies on hydrodynamic deformation and fragmentation of melt jet injected into water pool using level set method

The molten core material (corium) that can be formed during severe accident scenarios in light water reactors (LWRs) can drop in the water pool and form a "melt jet" (hereafter referred to as "jet") flow. We presented a numerical model to study the hydrodynamic deformation and fragmentation of a jet in the water pool using the Level Set (LS) method, despite that previous investigations had employed the widely used Volume-Of-Fluid (VOF) method. The effects of jet inlet speed, diameter and surface tension on the jet breakup length were studied and the results were in good agreement with previously performed experiments and with results obtained using the VOF method. The dimensionless jet breakup length was found to generally decrease with increasing jet inlet speed and increase with increasing jet diameter. In conclusion, the present model could successfully simulate the jet breakup in melt coolant interactions, and the results demonstrated a promising use of the LS method.