Preparation of uranium oxides by reductive denitration of uranyl nitrate under microwave heating

Autoclave denitration of solid uranyl nitrate in the presence of hydrazine hydrate at 120°C under the action of microwave radiation (MWR) leads to the formation of uranium dioxide with simultaneous breakdown of excess hydrazine hydrate and nitrate ions. The reaction yields UO 2 when performed in an open system in a reducing medium and U 3 O 8 when performed under the conditions of contact with air. Thus, principles have been developed for a new, virtually waste-free procedure for the synthesis of uranium dioxide for the subsequent preparation of oxide nuclear fuel. The procedure is characterized by high rate and considerably reduced power consumption, compared to the similar process performed with convective heating.