Fluidized-Bed Fluorination of UO₂-PuO₂ Fission-Product Fuel Pellets with Fluorine

Fluorination of uranium and plutonium oxides to the volatile hexafluorides, UF₆ and PuF₆, is a major step for the fluidized-bed volatility processing of spent Zircaloy-clad UO₂-PuO₂ power reactor fuel. This step was studied in a 2-in.-diam reactor using 0.3- to 1.2-kg charges of simulated spent fuel pellets containing UO₂, PuO₂, and nonradioactive oxides of elements that would be formed in fission. Retention of uranium and plutonium by the fluidized bed of inert alumina, which is discarded after serving as a heat-transfer medium, was minimized and amounted to only 0.02% of the uranium and 3.5% of the plutonium in a 0.65-kg pellet charge. The total plutonium retention was reduced to ∼ 1% of the plutonium charge by using a single 1.2-kg bed of alumina to process three charges (1.95 kg) of fuel pellets.