Method of removing americium from plutonium oxides

Purpose: To remove most portions of americium from plutonium oxides in a solid state as they are without dissolving them. Method: Carbon or graphite powder or hydrocarbon is added to plutonium oxide or plutonium/uranium mixed oxide powder at 0.5 to 4.0 molar ratio based on the plutonium oxides and then kneaded. The mixture is placed in a crusible and, when heated at a temperature from 1200 to 1500 deg C in a vacuum heating furnace, most portions of americium are evaporated in 2 - 6 hours after reaching the predetermined temperature. Then, when the evacuation is stopped and the heating is further continued after returning to the atmospheric or oxygen atmosphere, excess carbon can be converted into carbon dioxide and monoxide to leave plutonium oxides or plutonium/uranium mixed oxides. (Takahashi, M.)