Supercritical kinetic analysis in simplified system of fuel debris using integral kinetic model

• Kinetic analysis in simplified weakly coupled fuel debris system was performed.
• The integral kinetic model was used to simulate criticality accidents.
• The fission power and released energy during simulated accident were obtained.
• Coupling between debris regions and its effect on the fission power was obtained.

Preliminary prompt supercritical kinetic analyses in a simplified coupled system of fuel debris designed to roughly resemble a melted core of a nuclear reactor were performed using an integral kinetic model. The integral kinetic model, which can describe region- and time-dependent fission rate in a coupled system of arbitrary geometry, was used because the fuel debris system is weakly coupled in terms of neutronics. The results revealed some important characteristics of coupled systems, such as the coupling between debris regions and the effect of the coupling on the fission rate and released energy in each debris region during the simulated criticality accident. In brief, this study showed that the integral kinetic model can be applied to supercritical kinetic analysis in fuel debris systems and also that it can be a useful tool for investigating the effect of the coupling on consequences of a supercritical accident.