Approaches to simulate destruction of a fuel rod with different fuel types

Abstract

Due to the revival of interest to the development of fast reactors cooled by liquid metals, the theoretical research for improving their safety is actual. A detailed calculation of all stages of an accident from the beginning to the end requires knowledge of the laws for modelling physical processes occurring in the reactor in case of emergency. The most serious are accidents with core destruction. Simulation of a severe accident in a nuclear reactor is the key element in safety analysis of nuclear power plants. Destruction of fuel rods is one of the most important processes during core degradation that should be calculated. For different types of fuels the mechanisms of the degradation are different too. For example, oxide and metallic fuels usually melt congruently at high temperature, but nitride fuel dissociates. The main objective of the proposed research is to develop models and numerical algorithms for calculation of the destruction of fuel rods with oxide, metallic and nitride fuels. The models of destruction and some calculation results are presented in the paper. The processes are investigated for the first phase of severe accidents, covering the period from the onset of fuel-rod melting to the melt escape from the core center.