Pre-disposal management of spent ion-exchange resins by Fenton oxidation treatment and conditioning in an alkali-activated matrix

The routine use of ion-exchange resins throughout the lifecycle of a nuclear facility poses significant issues regarding their safe and sustainable disposal at the end of their useful life. Effective strategies are thus required to overcome the challenging nature of this organic waste, aimed at minimizing volumes of the final waste forms, processing costs, and environmental impact. This work focuses on the pre-disposal management of spent mixed bed resins through the integration of a Fenton oxidative treatment process, an attractive environmentally friendly approach, and the successive encapsulation of the residues in an alkali-activated matrix. The successful treatment of a 20 g mix of cationic and anionic resins has led to a preliminary upscale of the process by using a surrogate waste (up to 200 g) loaded with representative activation and fission products contaminants. Some important process parameters were monitored, and the resulting residues were characterized. Finally, the obtained residues were encapsulated in an alkali-activated matrix with a loading factor up to 40 wt.%. Waste forms with residue loading factors up to 10 wt.% (corresponding to the conditioning of 0.6 kg of spent resin per kg of matrix) achieved preliminary compliance with waste acceptance criteria.