Measurements of Uncombined Radon Daughters in Uranium Mines

Abstract

Uncombined fractions of radon daughters were measured in several locations in each of 6 uranium mines with a diffusion-type sampler adapted from an instrument developed by Mercer. Simultaneous measurements were obtained of radon gas concentration, working level and particle concentration. Expressed in accordance with the ICRP definition of uncombined fraction, f, values obtained ranged from 0.002 to 0.12 with more than half being less than 0.03. The higher fractions were found in fresh ventilating air uncontaminated by diesel engines or dusty operations. An inverse relationship was noted between uncombined fraction and particle concentration, which ranged from 3 × 103 cc−1 near ventilation inlets to more than 107 cc−1 in main haulageways and working stopes.