Thermal treatment of nuclear fuel-containing Magnox sludge radioactive waste

Magnesium aluminosilicate and magnesium borosilicate glass formulations were developed evaluated for the immobilisation of radioactive waste known as Magnox sludge. Glass compositions synthesised using two simplified bounding simulants, including corroded metallic uranium at loadings up to 50 wt.%. The glasses immobilising simulant formed generally homogenous fully amorphous glasses, while those wastes contained crystallites UO2 U3O8. Uranium speciation within was investigated by micro-focus X-ray absorption near edge spectroscopy it shown that characterised a slightly lower mean oxidation state than counterparts. This had an impact upon durability, higher states dissolved more readily. All material showed dissolution rates comparable with high level borosilicate-based melted temperature suitable modern vitrification technologies used in applications. These data highlight potential hazardous sludge or formulations, achieve >95 % reduction conditioned volume over current baseline plan.