U[O.sub.2], Np[O.sub.2] and Pu[O.sub.2] preparation in aqueous nitrate solutions in the presence of hydrazine hydrate

It was established that heating to 90 °C of nitrate solutions of U, Np and Pu in the presence of hydrazine hydrate results in the formation of hydrated dioxides of these elements. On ignition under inert or reducing conditions in the temperature range of 280-800 °C hydrated uranium dioxide transmogrify into crystalline U[O.sub.2]. On ignition in air atmosphere U[O.sub.2] x n[H.sub.2]O turns into U[O.sub.3] at 440 °C and into [U.sub.3][O.sub.8] at 570-800 °C. It was shown that thermolysis of the solution containing a mixture of uranium, neptunium and plutonium nitrates at 90 °C in the presence of hydrazine hydrate allows one to prepare hydrated dioxides (U, Np, Pu)[O.sub.2] x n[H.sub.2]O which on heating to ~ 300 °C transmogrify into crystalline product of U[O.sub.2], Np[O.sub.2] and Pu[O.sub.2] solid solution. The technique of preparation of solid solutions of U and Pu dioxides is very promising as simple and effective method of production of MOX-fuel for. Keywords Uranium * Plutonium * Neptunium * Hydrazine hydrate * Denitration