Solubility characterization of airborne uranium from an in situ uranium processing plant.

Solubility profiles of uranium dusts in the Irigaray uranium processing plant were determined by performing in vitro solubility tests on breathing zone air samples conducted in all process areas of the processing plant. The dissolution rate of the uranium on the air samples was then determined over the next 28 d in a simulant solution of the extracellular airway lining fluid (Gamble's solution). Airborne uranium in the wet process areas of the processing plant was highly soluble, with 97% dissolving in a 0.3 d half-time and 3% with a half-time of 15.6 d. The airborne uranium dusts in the drum load out area were also soluble, with 97% dissolving with a T1/2 of 0.25 d and the remainder with a T1/2 of 20 d. Exhaust from the drier stack and areas of the processing plant that had only this airborne uranium was slightly more insoluble, with 46% dissolving with a T1/2 of 0.4 d and 53% with an 18 d half-time. These results compare well with x-ray diffraction analysis of the uranium samples and the bioassay program for the processing plant workers.