Investigations on boron carbide oxidation for nuclear reactors safety-General modelling for ICARE/CATHARE code applications

摘要

The present paper deals with the problem of boron carbide pellet oxidation which might occur during a severe accident. A basic correlation, involving global variables, has been developed for the simulation of boron carbide oxidation with the ICARE/CATHARE code. This modelling has been based on available experimental data, including the VERDI separate effects experiments performed by IRSN at low pressures and high temperatures. According to the agreement between the measured and the calculated bundle temperatures as well as hydrogen release and oxidized B_4C, the ICARE/CATHARE code simulates rather well QUENCH experiments involving B_4C control rod degradation, Zircaloy oxidation under starvation and cooling with steam. Based on simulations results, it has been noticed that the B4C degradation has a slight direct effect on global bundle degradation but a non-negligible influence on Zircaloy oxidation through power release, material melting and flowing down.