Anisotropic growth and volumetric expansion of individual alumina crystal have been demonstrated to occur as a result of neutron irradiation. In the case of a simple alumina polycrystal, the anisotropic growth has been found to generate internal or micro stresses in polycrystalline alumina leading to microcrackings. When alumina is incorporated into complex composite structures, such as niobium and alumina in a trilayer concentric cylinder, the differential swelling of the components may lead to complex configurational or macro stresses in the system. Both the micro and macro stress generation processes were modeled using a stress compliance method based on the ANSYS finite element code. The effects of irradiation conditions and operation temperature were examined. Additional relaxation due to long term thermal creep and effect of irradiation enhanced creep were also included. The overall governing equation of the internal stress generation process was solved by numerical integration. The critical failure modes of the sheath insulator were illustrated based on the numerical calculation results.