Fission Gas Release Grain Boundary Network Percolation Mechanistic Studies in Oxide Fuels Based on COMSOL Multiphysics Framework

Fission gas release was modeled by COMSOL Multiphysics in oxide fuels, whose theory is based on the effect of grain boundary network percolation. The model is contributed to the conventional Booth model. In this model, the fuel pellet microstructure adopts 2D axisymmetric geometry. The effect of different bubble growth and coalescence rates on the independent grain boundaries are investigated, such as bubble contact angle, resolution rate, and radial position. The modeled physical phenomena are similar to the existing experiments and can be observed in the fission gas release process. The fission gas release is sensitive to the variations of these parameters. Therefore, the parameters are essential to the fission gas release on the microscopic or macroscopic scales. The long-range percolation on the networked grain boundaries is also considered in this work, but it is not considered in the Booth model. The gas resolution on the grain boundaries is also taken into account. At last, this model’s results will be compared with the outcomes of the Booth model as well as the other models.