Flash sintering of UO2 pellets for nuclear fuel and wasteform applications
R. W. Harrison, J.G. Morgan, Jennifer Buckley, S. Bostanchi, David Pearmain, T. Abram, D.T. Goddard, N. Barron
Abstract
Flash sintering (FS) has been shown to enhance the sintering kinetics in UO 2 . Using a bespoke AC-FS furnace, high density UO 2 pellets, >95 % theoretical density (TD) have been produced followed by scale up and Gd 2 O 3 doping trials. Increasing furnace temperature during FS increases pellet density to a plateau, however, increasing hold time and maximum current both increased the density of UO 2 samples to >95 % TD and grain size to ∼4 µm, close to conventional sintering (CS). The optimised FS program reduced sintering temperature and cycle time by ∼50 % compared to CS. Scale up trials showed >96 %TD pellets could be achieved for 11.3 and 14.125 mm diameter green bodies, demonstrating typical fuel pellet diameters are feasible with FS. Gd doping experiments showed with 1 wt% Gd 2 O 3 addition, a ∼92 %TD pellet with ∼2 µm grain size was obtainable, highlighting further optimisation is required for mixed oxide (MOx) materials.