An advanced model for grain face diffusion transport in irradiated UO2 fuel. Part 2: Model implementation and validation

The advanced model for intergranular diffusion transport in irradiated UO2 fuel described in Part 1 is numerically realized. The important model parameters are specified and improvement of the model for the irradiation induced re-solution of gas atoms from the intergranular bubbles is carried out. Implementation of the model in the MFPR code and numerical treatment of various available data on gas release from irradiated fuel and grain face microstructure show a satisfactory agreement of the code predictions with experimental observations. In particular, the main model prediction concerning the onset of gas release from fuel at very low grain face bubble coverage, below the saturation value manifested by formation of bubble network on grain faces, was confirmed by calculations.