Microwave sintering of simulated inert matrix fuel for generation IV nuclear reactors

Alternative processing methods are being considered for rapid sintering of inert matrix fuel (IMF) at low temperatures to minimize the loss of volatile actinides. Previous studies on microwave-hybrid sintering of the matrix material, 8mol.% yttria–zirconia (8YZ), showed rapid densification at lower temperatures when compared with a conventional process. The current study examines the applicability of dysprosia (Dy2O3) as a surrogate for americia (Am2O3) in investigating the microwave-hybrid sintering of a simulated IMF, 20wt.% Dy2O3 dispersed in 8mol.% yttria–zirconia (8YZ-20D). The results show that 8YZ-20D is sintered to 93% of its theoretical density (TD) at 1300°C with a soak time of 100min in a multimode microwave-hybrid furnace. A similar heating schedule in a conventional furnace resulted in 87% TD. The enhancement in densification of 8YZ-20D due to microwave-hybrid sintering did not alter any of the resulting microstructures. Based on these experiments, it was found that low-temperature microwave-hybrid sintering was suitable for fabricating IMF pellets.