Determination of the Contribution of Long-Lived Dust to the Committed Dose Equivalent Received by Uranium Mine and Mill Workers in the Elliot Lake Area. Volume 1 - Report

摘要

This study was aimed at determining the physical characteristics of airborne long lived dust and their dosimetric implications. In the first part of this study, the physical characteristics of alpha-emitting long-lived dust present in uranium mine and mill atmospheres were investigated. In total, 91 air samples were taken on open face filters for the determination of gross alpha activity parameters (concentration and radionuclide make-up), and 43 air samples were taken using a Cascade Impactor for the determination of the aerosol size distribution and of the radionuclide make-up per class of particle dimension. It was found that airborne long-lived dust presents a wide range of Activity Median Aerodynamic Diameters (AMAD), usually with large dispersion parameters (Standard Geometric Deviation). In underground locations, AMADs range from 5 to 10 micrometers, whereas in mills AMADs are close to 7 micrometers. From the radionuclide make-up of long-lived aerosols, their AMAD and the ICRP 30 lung dosimetry model, it was found that the DAC in underground locations ranges between 1290 mBq.m sup -3 and 1640 mBq.m sup -3 of alpha activity. In mill workplaces, the DAC is 2360 mBq.m sup -3 of alpha activity. Due to the extreme variability of air concentration and dimension of alpha-emitting long-lived dust in uranium mines and mills, and should individual exposures need to be assessed, the use of a continuous personal monitor should be considered. (Atomindex citation 19:035478)