Actinide redistribution due to pore migration in hypostoichiometric mixed-oxide fuel pins

Abstract Redistribution of plutonium due to migration of pores in hypostoichiometric mixed-oxide fuel is analyzed. The unequal volatilities of the oxides of uranium and plutonium cause changes in the Pu/U ratio in the solid ahead of and in the wake of a moving pore. These elementary redistribution events of single pores are then combined to determine the gross redistribution in the fuel. For typical LMFBR fuel operating conditions, calculated redistribution due to pore migration is orders of magnitude smaller than that observed in irradiated pins.