Simulation of the Dissolution Kinetics of Zr02 by Molten Zircaloy-4 Between 2000 and 2400 degrees C

Abstract

A numerical simulationon of the dissolution kinetics of ZrO₂ by molten zircaloy-4 in the temperature range of 2000 - 2400 °C was made taking into account experimental laboratory determinations. The LISI code, already developed for the dissolution of UO₂ by molten zircaloy-4 was applied in the case under concern, due to the fact that several experimental features are common between those two processes. However, a significant difference is the physical appearance of the interface. This is described into the LISI model by the parameter S(T), where there are enclosed the phenomena at the interface. Whereas in the UO₂ dissolution the high value of the activation energy of the dissolution rate could be included in the temperature dependence of S(T), it was not sufficient to give a correct simulation in the dissolution of ZrO₂. In this latter case it was necessary to introduce some additional assumptions in the LISI model related with the oxygen concentration at the interface in the melt side. The proposed changes, together with the function S(T), allowed to obtain an acceptable agreement between numerical and experimental results.