Simulation of Grain Growth and Pore Migration in a Thermal Gradient

The Potts Monte Carlo simulation was used to simulate microstructural evolution in uranium dioxide fuel rods. During service, grain growth, pore migration, and thermal segregation of the pores and UO 2 occur in the rods in a thermal gradient. In this investigation, we developed a model which simulates simultaneous grain growth, pore migration, and thermal segregation of the pores and UO 2 in a temperature gradient. Grain growth in a thermal gradient was simulated using the Monte Carlo Potts model technique developed by Anderson, Srolovitz, and co-workers. Pore migration was simulated using conserved dynamics with minimum-energy exchanges at a finite temperature. A temperature gradient was introduced into the model via interfacial mobility gradient. Finally, thermal segregation of the pores and UO 2 was achieved by introducing a heat of migration term, ΔE t , which biased the motion of porosity to the high-temperature region. The development of this model is described and the incorporation of the proper physics of pore migration and thermal segregation is discussed.