An efficient numerical method for intergranular fission gas evolution under transient with piecewise boundary resolution

It is theoretically found that the boundary gas concentration could decline under transient due to the intergranular resolution. An efficient numerical method is first developed for the case before saturation. After the saturation of the grain boundary, a rate-release equation is applied not only to ensure no return of the gas released, but also ensure the gas conservation in the grain boundary. Accordingly, an efficient predict-correct algorithm for the intergranular gas concentration is invented for arbitrary power transient. Our numerical method has been validated by the analytical solution and the finite element solution. It demonstrates both high efficiency as well as high accuracy.