Fabrication of stoichiometric U3Si2 fuel pellets

Abstract

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. Method name: Fuel fabrication via powder metallurgy, Keywords: Uranium silicide (U3Si2), XRD, accident tolerant fuel