Fabrication of stoichiometric U₃Si₂ fuel pellets

Uranium silicide, U₃Si₂, is an accident tolerant fuel type which is gaining momentum as a replacement fuel for uranium dioxide (UO₂). Idaho National Laboratories has been fabricating phase pure U₃Si₂ fuel pellets for use in various irradiation and material characterization experiments. Stoichiometric U₃Si₂ fuel pellets were fabricated using a powder metallurgy and arc melting technique. The use of the stoichiometric ratio to alloy uranium and silicon, and sintering in a vacuum environment allowed for the fabrication of high density (>94% theoretical density), phase pure pellets, greater than 94% U₃Si₂. Silicon volatilization was not observed in the as-sintered microstructure, which has been verified through XRD and SEM, thus eliminating the need to alloy a substoichiometric U/Si ratio. •Stoichiometric ratio of U to Si used to form U₃Si₂ phase.•Decrease in secondary phases present confirm absence of silicon volatilization.•Analysis via XRD and SEM confirm the phase purity of the U₃Si₂ fuel pellets.