| 摘要 |
<p>Plutonium and fission products are separated from irradiated uranium-containing nuclear fuel by contacting a nitric acid solution of the fuel with a strong base quaternary amine type anion exchange resin to remove plutonium, and then evaporating to dryness the solution of uranium and fission products, and fluorinating the residue, fission product fluorides being separated by fractionation from uranium hexafluoride. The process is described in detail with reference to a diagrammatic flow sheet. Spent UO2 fuel is dissolved in strong HNO3, the acidity adjusted to 6-8 molar, and the solution passed through a bed of the resin which retains the Pu; the resin is washed with strong HNO3, and the Pu eluted with 0.4 to 0.8 molar HNO3. Pu is absorbed from this solution on to a second anion exchange resin bed, which is washed and eluted to yield a solution of Pu nitrate free from fission products. The effluent from the first resin bed containing U and fission products is evaporated and the residue calcined, nitric acid being recovered. The calcined oxides are fluorinated by treatment as a fluidized bed with F2 at 300-600 DEG C.; a preliminary treatment with HF at 250-350 DEG C. may be given. Solid fission product fluorides are removed and UF6 and volatile fission product fluorides are separated by fractionation or by sorption on a bed of sodium fluoride. Instead of oxide fuels, metallic, carbide, nitride, or silicide fuels may be treated.</p> |
