Laboratory Investigations In Support Of Fluid Bed Fluoride Volatility Processes

Experiments were carried out to determine the extent and rate of separation of mixtures of uranium hexafluoride and plutonium hexafluoride by selective thermal decomposition. Gaseous mixtures of uranium hexafluoride, plutonium hexafluoride, and helium were circulated for varying lengths of time through nickel vessels packed with nickel wool at temperatures of 150, 200, and 300 deg C. The initial ratios of uranium hexafluoride to plutonium hexafluoride in the mixtures were of the order of 10 to 1. The gas phase was analyzed for uranium and plutonium before and after circulation. The amounts of uranium and plutonium in the solid compounds deposited in the vessels were also determined. Passage of the mixtures through the hot vessels resulted in the removal of 99.5 to 99.9% of the plutonium. The solid product remaining in the vessels was plutonium tetrafluoride containing 0.09 to 1.3% uranium. The separation of plutonium hexafluoride from uranium hexafluoride by selective thermal decomposition is applicable to fluid bed fluoride volatility processes for the recovery of fissile material from reactor fuels.