Glass ceramics containment matrix for insoluble residues coming from spent fuel reprocessing

Abstract Spent fuel reprocessing by hydrometallurgical process generates insoluble residues waste streams called fines solution. Considering their radioactivity, fines solution could be considered as Intermediate Level Waste. This waste stream is usually mixed with fission products stream before vitrification. Thus fines are incorporated in glass matrix designed for High Level Waste. The withdrawal of fines from high level glass could decrease the volume of high level waste after conditioning. It could also decrease the reaction time between high level waste and additives to obtain a homogeneous melt and then increase the vitrification process capacity. Separated conditioning of fines in glass matrices has been tested. The fines content targeted value is 16 wt%. To achieve this objective, two types of glass ceramic formulations have been tested. 700 g of the two selected glass ceramics have been prepared using simulated fines. Additives used were ground glass. Melting is achieved at 1100 °C. According to the type of glass ceramic, reducing or oxidizing conditions have been performed during melting. Due to their composition and the melting redox conditions, different phases have been observed. These crystalline phases are typically RuO 2 , metallic Ru, metallic Pd, MoO 2 and CaMoO 4 . In view of melting these matrices in an in can process the corrosiveness of one of the most oxidizing borosilicate glass ceramic formulation has been tested. This one has been remelted at 1100 °C in inconel 601 pot for 3 days. The oxygen fugacity measurement performed in the remelted glass leads to an oxidizing value, indicating that no significant reaction occurred between the inconel pot and the glass melt had occurred.