An investigation into radiation exposures in underground non-uranium mines in Western Australia

Abstract

A preliminary investigation into the radiological conditions in underground non-uranium mines in Western Australia has been undertaken. Measurements of radon concentration by passive track etch monitors and absorbed gamma dose-rate by thermoluminescent dosimetry were undertaken in 27 mines. These mines employed 2173 workers which represented nearly 80% of the underground workforce at the time of the survey. Radon progeny concentration by both grab sampling and automatic devices were undertaken at selected mines. Radiological conditions in all surveyed underground workplaces were such that it was estimated that most underground workers should not exceed an annual effective dose of 5 mSv. The average annual effective dose across all mines was estimated to be 1.4±1.0 mSv, ranging from 0.4 mSv for a nickel mine to 4.2 mSv for a coal mine. Radon progeny exposure contributed approximately 70% of the total effective dose. The estimated average annual effective dose in three coal mines (employing 297 workers) was 2.9±1.5 mSv. On the basis of this preliminary investigation it was concluded that no regulatory controls are specifically required to limit radiation exposures in Western Australia underground mines.