Diffusion reaction behaviors of U-Mo/Al dispersion fuel

Abstract

The uranium (U)-molybdenum (Mo)/aluminum (Al) dispersion fuel that is currently under development for high-performance research reactors has shown complicated diffusion reaction behavior between the U-Mo particles and the Al matrix. Diffusion reactions in U-Mo/Al dispersion fuels were characterized by out-of-pile annealing tests and in-pile irradiation tests in the HANARO research reactor. The effect of the addition of a third element such as silicon (Si), Al, or zirconium (Zr) to U-Mo fuel, and the addition of Si to the Al matrix on the diffusion reaction were also investigated. The growth rate and activation energy for the reaction phases of U-Mo/ Al dispersion fuels were obtained. The effect of alloying a small amount of a third element in U-Mo and of Si in the Al matrix on diffusion reaction kinetics was negligible in annealing tests conducted at similar to 550 degrees C. gamma phase stability in the U-Mo alloy was enhanced by the addition of 0.1 to 0.2 wt.% Si. The Si accumulated in the interdiffusion layer of U-Mo/Al-Si dispersion fuel annealed at similar to 550 degrees C, whereas Zr migration to the interdiffusion layer of U-Mo-Zr/Al was negligible.