Effect of High Si Content on U₃Si₂ Fuel Microstructure

The development of U₃Si₂ as an accident-tolerant nuclear fuel has gained research interest because of its promising high uranium density and improved thermal properties. In the present study, three samples of U₃Si₂ fuel with varying silicon content have been fabricated by a conventional powder metallurgical route. Microstructural characterization via scanning and transmission electron microscopy reveals the presence of other stoichiometry of uranium silicide such as USi and UO₂ in both samples. The detailed phase analysis by x-ray diffraction shows the presence of secondary phases, such as USi, U₃Si, and UO₂. The samples with higher concentrations of silicon content of 7.5 wt.% display additional elemental Si. These samples also possess an increased amount of the USi phase as compared to that in the conventional sample with 7.3 wt.% silicon. The optimization of U₃Si₂ fuel performance through the understanding of the role of Si content on its microstructure has been discussed.