Effectiveness of a Wet Scrubber in Reducing Radioactive Aerosol and Dust Concentrations in Underground Uranium Mines

The effect of a wet scrubber in controlling long-lived and short-lived radionuclides associated with airborne particulate matter in the submicron and respirable ranges was investigated during hard-rock crushing operations at a crusher plant located in an underground uranium mine. Dust-loaded air from crushing operations was fed to the wet scrubber via an intake plenum and ducting system. Measurements were made of long-lived radioactive dust concentration and radon progeny and thoron progeny concentrations. Mineral dust and radioactive dust-size distributions also were determined by means of eight-stage cascade impactors. Measurements were conducted preferentially at the crusher platform, the scrubber, and in an area adjacent to the crusher. The data show the wet scrubber was very efficient in reducing the concentration of long-lived radioactive dust and in removing radioactive particulate matter of size greater than about 2 µm. A modest reduction in radon progeny and thoron progeny concentration also was noticed during the operation of the wet scrubber. The data indicate the wet scrubber tested was very efficient in controlling long-lived radioactive dust concentrations in underground uranium mine operations.