Neutron Irradiation of U3Si5 and Al43Mo4U6 Compounds. First Results

In the framework of U(Mo) alloys qualification used as nuclear fuel for research reactors, post-irradiation experiments have shown that the porosity and swelling phenomena observed due to irradiation on dispersed fuel elements are associated to a poor behavior of the interaction layer grown by interdiffusion during fabrication and/or irradiation between U(Mo) particles and the matrix. Fission induced amorphization of some of the phases that form the interaction layer, has been proposed as one explanation to understand the failure. Out of pile diffusion couples experiments have shown that the phases UAl3, UAl4, Al20Mo2U and Al43Mo4U6 form the interaction layer when pure Al is used as matrix while U(Al,Si)3, U3Si5, USi2, USi2-x, Al20Mo2U and Al43Mo4U6 are identified when Al(Si) is used instead of Al. The objective of this investigation is to study, independently, the behavior of each phase under neutron irradiation focusing on a possible amorphization. In this work, powders of U3Si5 and Al43Mo4U6 compounds were irradiated at RA1 reactor (Argentina). Samples were analyzed by optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, wavelength dispersive spectroscopy and X-ray diffraction.