| Abstract Scope |
Uranium molybdenum (U-Mo) fuels are being evaluated for use in alternate light water reactors (LWRs), research and test reactors (RTRs) and advanced fast reactors for their high fuel efficiency and the superior irradiation stability of their predominant γ-phase. At the operating temperatures of LWRs and RTRs, the γ-phase alternates between decomposing into the α+γ' phases and reverting back into the γ-phase, depending upon the fission rate density of the irradiation. The latter reaction, also called phase reversal, is desirable as neither the α nor the γ' phases are as resistant to anisotropic fuel swelling as the γ-phase. While phase reversal has been theorized to proceed via the displacement spike mechanism, the factors affecting the kinetics of the reaction are not well understood. In this study, molecular dynamics simulations are performed using LAMMPS to investigate the phase reversal behavior of the γ’-phase upon exposure to neutron irradiation. The phase fractions of the γ^'-phase and the reverted γ-phase are obtained as a function of irradiation temperature, dose, and dose rate via Rietveld refinement of computed x-ray diffraction spectra. This study provides valuable insights into the nature of phase reversal and the displacement spike mechanism occurring in the γ' intermetallic phase. |