Method for purifying actinides which are in low oxidation states

Abstract

A method is provided for purifying actinides which are present in a low oxidation state in aqueous solution. The actinides are purified of fission products by extracting the actinides from aqueous solution while confining the fission products to the aqueous solution. The actinides that are purified are selected from the group of uranium (IV), neptunium (IV) and plutonium (III). An aqueous nitric acid solution containing the actinides, hydrazine nitrate or hydroxyl ammonium nitrate, as well as fission products is initially subjected to an electrolysis voltage. If Pu (III) is involved, the electrolysis voltage is below the voltage at which oxygen develops at the anode and anodically oxidizes the Pu (III) to Pu (IV). The Pu (IV) which is formed is transferred by means of an organic extraction agent from the aqueous solution to an organic phase. The organic phase is then separated and used for the plutonium recovery process. If U (IV) and/or Np (IV) are involved, the aqueous nitric acid solution is initially subjected to an electrolysis voltage in the vicinity of the voltage at which oxygen develops at the anode or higher to anodically oxidize the U (IV) to U (VI) and the Np (IV) to Np (VI). The U (VI) and/or Np (VI) which is formed is transferred by means of an organic extraction agent from the aqueous phase to the organic phase. The organic phase is then separated and used for the uranium or neptunium recovery process.