A description of a fuel-coolant thermal interaction model with application in the interpretation of experimental results

A coherent thermo- and hydrodynamic model to explain molten fuel-coolant interactions in the CORECT II experimental facility is described. The effects of heat losses to the surroundings, mass entrainment, two-phase frictional losses and non-condensable gases are taken into account for the coolant modelization, while a solidification-controlled fragmentation model is proposed for the fuel behavior. Interpretation of two significant experiments in the CORECT II facility permit verification of the consistency of the formulation for the behavior of the fuel-coolant couple. The interpretations allow a generalized interaction scenario in this facility to be proposed, illustrate the importance of understanding the mechanisms underlying the prefragmentation and mixing phase preceding the thermal interaction, and confirms the hypothesis that the process of solidification in the fuel is a major factor governing fuel fragmentation. (orig.)