Investigation of point defects diffusion in bcc uranium and U-Mo alloys

We present results of investigation of point defects formation and diffusion in pure gamma-U and gamma-U-Mo fuel alloys. The study was performed using molecular dynamics simulation with the different interatomic potentials. The point defects formation and migration energies were estimated for bcc gamma-U and U9 wt.%Mo alloy. The calculated diffusivities of atoms via defects are provided for pure gamma-U and for the alloy components. Analysis of simulation results shows that self-interstitial atoms play a leading role in the self-diffusion processes in the materials studied. This fact can explain a remarkably high self-diffusion mobility observed experimentally for gamma-U. The self-diffusion coefficients in gamma-U calculated in this assumption agree with the data measured experimentally. It is shown that alloying of gamma-U with Mo increase formation energy for self-interstitial atoms and decelerate their mobility. These changes lead to decrease of self-diffusion coefficients in U-Mo alloy compared to pure U. (C) 2014 Elsevier B.V. All rights reserved.