Fluidized-Bed Fluorination of UO₂-PuO₂-Fission Product Pellets with Brf₅ and Fluorine. Part I: The Fluorination of Uranium, Neptunium, and Plutonium

Fluorination of simulated thermal reactor fuel containing UO₂, PuO₂, and oxides of elements formed in fission has been studied in a 2-in.-diam reactor containing a fluidized bed of alumina. After oxidation at 450°C pulverized the fuel pellets, the uranium was selectively fluorinated to UF₆ with 10 vol% BrF₅ at 200 to 400°C. Plutonium which remained in the fluidized bed as PuF₄ was subsequently converted to PuF₆ with 90 val% fluorine at 300 to 550°C. Volatile NpF₆ was formed during fluorination with both BrF₅ and fluorine and was distributed equally between the UF₆ and the PuF₆ products. The uranium was fluorinated at high rates with reasonably high utilization of BrF₅. The temperature used to fluorinate uranium with BrF₅ and plutonium with fluorine affected the extent of removal of plutonium from the fluidized bed. When fluorination is carried out at 250 to 350°C for uranium and 300 to 550°C for plutonium, ∼3% of the plutonium charged remains in the fluidized bed. Plutonium losses can be reduced by reuse of the alumina bed to process several batches of fuel.