Characterization of long-lived radioactive dust in uranium mill operations

The characteristics of long-lived radioactive dust clouds generated in several mechanical and physiochemical operations in a uranium mill have been investigated. The study consisted of the determination of dust size distribution and of the size distribution of radionuclides associated with particulate matter in the size range less than 0.1 to 26 microns. Experiments were conducted by using two different types of cascade impactors operating at different sampling flow rates. Radionuclide identification was done by using alpha-spectrometry. Long- and short-lived radionuclides were identified in dust samples. The characteristics of the dust clouds depended on the mill operation, such as crushing (vibrating grizzly, jaw crusher, cone crusher); screening; ore transportation; grinding; acid leaching; counter-current decantation; yellow cake precipitation and drying; and yellow cake packaging. In addition, other dust and radioactivity measurements have been carried out.