PHASE SEGREGATION MODEL AND MOLTEN POOL THERMAL-HYDRAULICS DURING MOLTEN CORE-CONCRETE INTERACTION

A new model for melt thermal-hydraulics during molten core concrete in teraction (MCCI) is presented. This model assumes that phase segregati ons occur in the melt, leading to a crust formation composed of refrac tory materials (UO2-ZrO2). The interface temperature between this crus t and the liquid melt is linked to the solid fraction and is calculate d on the basis of a thermal equilibrium assumption. The solid fraction is also controlled by conduction heat transfer through the solid crus t. It is shown that the temperatures measured in the ACE experiments a re recalculated within a maximum deviation of 10% (when referenced to the solidus temperature) without any adjustment. Other important conse quences for this new approach are outlined: for physical properties, p hysico-chemical interactions, fission products behavior, mixing with s acrificial materials, and crust stabilities.