SUBMICRON-SIZED AEROSOL AND RADON PROGENY MEASUREMENTS IN A URANIUM-MINE

Submicron-sized aerosol was studied at one place in a uranium mine for 4 days, during an intercomparison campaign mostly devoted to radon measurement. The instruments used for measuring particle size and number concentration were an Electrical Aerosol size Analyser (EAA) and a Differential Mobility Particle Sizer (DMPS), both from the TSI company. In addition radon progeny particle size distributions were measured using a prototype instrument, called SDI and developed by the authors which is a combination of a cascade impactor associated in series with a granular bed diffusion battery. Particle size and number concentration were measured every 15 min by the EAA and simultaneous samplings were made with the DMPS and the SDI. During the 4 day campaign the number-weighted mean diameters and the geometric standard deviations measured by EAA ranged, respectively, from 0.05 to 0.1 mum and from 1.8 to 2. A good agreement was observed between the results obtained with the DMPS and the EAA. From the SDI samples, radon progeny particle-size distributions were measured and the global activity-weighted mean diameters ranged typically from 0.10 to 0.20 mum. Using the aerosol size distribution measured with DMPS, radon progeny particle size distributions were calculated by applying the attachment theory. The global activity-weighted mean diameters determined by this calculation were in good agreement with those measured with the SDI.