Removal of Americium by Its Evaporation during Carbothermic Reduction of Plutonium Dioxide

The kinetic study of the reduction of U(VI) at the titanium electrode in nitric acid and hydrazine media was carried out at 25±0.5°C. Uranium (VI) is reduced through a totally irreversible process and kinetic parameters are affected by both the concentration of nitric acid and the electrolytic potential. An empirical equation to express the rate of the reduction of U(VI) was proposed and was confirmed to be in fairly good agreement with the amount of U(IV) produced by the controlled-potential electrolysis. The optimal condition for the preparation of U(IV) from U(VI) was found to be the electrolysis at -0.5V vs. Ag-AgC1/sat.KC1 in 1–2 M HNO₃ and 0.1–0.2_M hydrazine.