“…According to the previous study [9], it can be obtained that the thermal effects at the increasing stage of burnup are relatively weak in normal operation, so in this study the real thermal effects at the increasing stage of burnup are ignored. In the previous studies [10][11][12], in considering the similarity between the irradiation swelling and the thermal expansion, the irradiation swelling of the fuel particles was simulated with the method of virtual temperature increase. While the irradiation growth of the cladding, which shows elongation in one direction and shrinking in other two directions, can be modeled with the method of virtual anisotropic thermal expansion.…”