Numerical investigation of oxidation and dissolution behavior in the fuel cladding using MPS-CV method

Abstract The Moving Particle Semi-implicit-Controlled Volume (MPS-CV) method, based on the MPS method and Finite Volume Method (FVM), is a particle-grid coupling method. In this method, the particle interaction models in the MPS method are used to discretize and solve the momentum equation. For the eutectic reaction model, the FVM is used to solve the mass transfer equation if the particle locates at the boundary or the interface between different substances. In contrast, the particle interaction models are still used to discretize and solve the remaining particles' mass transfer equations. Therefore, it has advantages in describing fluid interfaces with large deformation and phase transition problems. Simultaneously, the MPS-CV method avoids the apparent error in calculating the mass transfer equation of boundary and interface between different substances due to the truncation of support domain in that area particles while using particle interaction models in the MPS method. In this study, the simulation of one-dimensional mass transfer and phase transition was used to verify the MPS-CV method, and the results were compared with those obtained by the MPS method. It showed that the MPS-CV method could get more accurate results in the calculation than the MPS method. Then the cladding oxidation mechanism at 1300 ~ 1800 K and the dissolution behavior between ZrO2 and molten zirconium at 2373 ~ 2573 K were analyzed using the MPS-CV method. The results indicated that the change of oxygen content obeyed parabolic laws. So did the oxide and α-Zr(O) layers' growth rates in cladding oxidation. And compared with the fixed parabolic relations used in commercial codes, the MPS-CV method can obtain the corresponding relationships according to different reaction conditions. The dissolution between ZrO2 and molten zirconium at high temperatures showed a parabolic pattern in the early stage. In the later stage of the reaction, the oxygen in the melt gradually reached saturation, and the solid ZrO2 did not continue to melt. The simulation results of the molten zirconium with the same volume but different contact areas with ZrO2 crucible showed that the larger the contact area was, the higher the growth rate of oxygen content in the melting the early stage of the reaction was. And it also showed that the larger the contact area was, the less dissolution volume of the ZrO2 crucible was.