Melting and ceramic routes to Synroc

Abstract

Synroc formulations incorporating different simulated high-level wastes from reprocessing of spent nuclear fuel were melted at ~1400oC in a cold-crucible furnace. The samples were characterised and compared to equivalent materials made by the reference Synroc production method of subsolidus hot-pressing. The melted materials had essentially the same major phases, but much larger grain sizes. Minor phases were different, largely because of the different redox conditions prevailing in each case; whereas elements such as Mo, Fe and Ni exist as metals in the ceramic, they were present as ionic species in the melted materials.