Recovery of plutonium

摘要

839,191. Separation of plutonium and neptunium. UNITED KINGDOM ATOMIC ENERGY AUTHORITY. Dec. 4, 1945 [Nov. 30, 1944], No. 32815/45. Drawings to Specification. Class 39(4). Plutonium is separated from fission products by precipitating the plutonium in its higher oxidation state as an alkali metal plutonyl acetate. When the plutonium content of the solution treated is small, the corresponding uranyl salt may be precipitated at the same time, or added to the solution, and this salt acts as a carrier for the plutonium ; the fission products remain in solution. Plutonium and uranium may be separated by reducing the plutonium so that it does not precipitate and then precipitating the alkali metal uranyl acetate. A suitable oxidising agent is a dichromate and suitable reducing agents are sulphur dioxide, sodium bisulphite, hydroxylamine, or hydrogen peroxide. In examples, solutions of uranyl nitrate containing plutonium and fission products are treated as follows:- (1) the solution is oxidised with sodium dichromate, and sodium acetate added to precipitate uranium and plutonium ; the precipitate is washed, dissolved in nitric acid, the solution reduced with sodium bisulphite, and uranium precipitated by adding sodium acetate, leaving plutonium in solution ; (2) the solution is reduced with hydroxylamine hydrochloride, and sodium acetate is then added to precipitate uranium; the filtrate containing plutonium and fission products is oxidised with sodium dichromate, a small amount of uranyl nitrate added and uranium and plutonium precipitated by treatment with sodium nitrate and sodium acetate ; the precipitate is removed, redissolved, and the process repeated; finally the plutonium may be precipitated as the complex acetate without uranium or alternatively may be recovered by evaporating the solution of reduced plutonium or by precipitating as phosphate or fluoride; (3) as in Example (1) except that hydroxylamine hydrochloride is used as reducing agent. Plutonium and neptunium are separated from one another by dissolving irradiated uranium in nitric acid, reducing plutonium and neptunium with sulphur dioxide, adding potassium bromate to oxidise neptunium but not plutonium, and precipitating sodium uranyl acetate, neptunium being carried down, leaving plutonium in solution.