| 摘要 |
<p>1,206,775. Neptunium recovery. GENERAL ELECTRIC CO. 30 Oct., 1967 [17 Nov., 1966], No. 49266/67. Heading G6R. Neptunium (Np) is recovered from an aqueous solution containing Np and plutonium (Pu) by reducing the Pu to the Pu (III) state at an acid concentration of 2M or less, oxidizing the Pu to the Pu (IV) state and Np to a valency greater than IV by increasing the acid concentration to at least 4M, contacting the solution with an anion exchange resin to remove Pu, and recovering Np from the purified solution. The original aqueous solution containing uranium, Pu, and Np may be obtained by extraction with a dilute acid of an organic solvent extract of an acid solution of used UO 2 nuclear fuel. Reduction of the Pu in the solution to Pu (III), and of Np to Np (IV), is effected with hydroxylamine nitrate, aminoguanidine, ferrous ion, semicarbazide, or ascorbic acid. The solution is then mixed with boiling 7M nitric acid which destroys the reducing agent and oxidizes Pu to Pu (IV) and Np to a valency greater than IV. Pu is adsorbed on an anion exchange resin and the effluent solution again contacted with a reducing agent (e.g. a mixture of ferrous ion and hydrazine) to reduce the Np to the Np (IV) state. The Np is separated from uranium by adsorption on a second anion exchange resin bed, the effluent solution being evaporated to dryness and treated with fluorine to form UF 6 , free from residual fission products. The ion exchange separation steps may be carried out in semi-continuous movable bed equipment. Elution of Pu and Np from the resin beds is effected with dilute nitric acid, followed by concentration of the eluates. Specification 1,206,776 is referred to.</p> |
