Fluidized-Bed Fluorination of UO₂-PUO₂-Fission Product Pellets with BrF₅ and Fluorine. Part II: Process Considerations

The fluorination step in a fluidized-bed fluoride volatility process has been studied in a 2-in.-diam reactor using BrF₅ and fluorine as fluorinating agents and sintered alumina as the fluidized bed. Fuel pellets containing UO₂, PUO₂, and nonradioactive fission product oxides were pulverized by oxidation before uranium was selectively fluorinated with dilute BrF₅; plutonium was then fluorinated with concentrated recycled fluorine. Fission product elements added to the system simulated burnups of 10 000 and 30 000 MWd/ton. Several aspects of the fluoride volatility process are discussed: effect of variations in process parameters on residual plutonium in the bed, distribution of selected fission products and ¹⁰⁶Ru tracer, demonstration of reduced plutonium losses by reuse of a single alumina bed to process three batches of pellets at each of the simulated burnups of 10 000 and 30 000 MWd/ton, plutonium inventory in the reactor, and sampling the fuel charge for material balance and accountability. A processing step for a hybrid process incorporating leaching of the fluidized bed with nitric acid after uranium fluorination with BrF₅ was also demonstrated.