Novel surface chemical treatment to improve the quality of sintered UO2 pellets

Sintering of UO2 to form pellets is aided when UO2 powders with high O/U ratios are used. A novel surface chemical treatment technique has been developed to deliberately oxidise a fraction of surface uranium in UO2 powder to hexavalent state. Controlled surface oxidation is achieved by a solid state reaction using ethylene diamine carbamate (EDC) and hydrogen peroxide vapour. EDC catalyses the oxidation of uranium by hydrogen peroxide and subsequently forms a surface complex with uranyl ions, which acts as a binder. Using UO2 powders of varying qualities (produced in Nuclear Fuel Complex, Hyderabad), it has been demonstrated, both on laboratory and pilot-plant-scale, that, the newly developed surface chemical treatment improves the quality of the sintered UO2 pellets and increases its grinding recovery. (author). 12 refs., 3 tabs