Effectiveness of the metal coating on U–7Mo dispersion fuel in Al during irradiation

Abstract The effectiveness of a transition metal coating layer as a diffusion barrier between the UMo and matrix Al was examined. The samples were cut from KAERI-made U–Mo/Al dispersion miniplates containing 8 gU/cm3 fuel meat. Mo, W and Zr were included as coating candidates. A physical vapor deposition (PVD) method was used to produce about a 0.2-μm thick coating layer on the UMo. An Al protection coating layer was subsequently applied to protect the main coating layer. The samples were irradiated at the ATLAS facility in Argonne National laboratory with 84-MeV Xe26+ ions, with the beam current of 200 particles nano ampere (pnA), to achieve a final dose of 2.7ⅹ1017 ions/cm2. Post-irradiation examinations included focused ion beam (FIB), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Among the coating metals, Mo showed the highest survival during the fuel plate fabrication and endurance during irradiation, which was consistent with the pre-irradiation thermodynamics evaluation. This result also emphasized the importance of the Al protection layer.