Numerical investigation of dissolution reaction between UO₂ and molten zry-4 using MPS method

Dissolution of UO2 by molten Zry-4 at high temperatures is an important chemical phenomenon affecting the fuel melting during reactor severe accidents. In this study, the dissolution model, based on the mass transfer and dissolution criteria, was development and incorporated into the Moving Particle Semi-implicit (MPS) method. To validate the dissolution model, the experiments of Pb (ball) and Sn (cylinder) reaction has been carried out and the dissolution process has also been simulated by the improved MPS code. The simulation results are agreement with the experimental results. The analyses on the dissolution of UO2 and molten Zry-4 were performed according to results by the improved MPS code. In this study, the influence factors of dissolution of UO2 and molten Zry-4, such as natural convection in the melt, have been discussed. The simulation results have been compared with the experimental results by some researchers. The results show that the natural convection of melting process has a significant influence on the dissolution behavior. If the natural convection happens, the penetration depths of chemical elements (U and O) become deeper, which could accelerate the progress of dissolution.