Measurements of radon exhalation from a South African gold mine tailings using sealed tube method

Abstract

To date, approximately 6000 tons of uranium has been disposed of onto tailings dams per year by gold mining activities in South Africa. These uranium bearing tailings dumps contain significant amounts of radium and are therefore possible sources of substantial amounts of radon gas. Due to the large sizes of these dams, measurements of the radon exhalation for the whole dam using established and conventional methods become time consuming and labour intensive. In this study, radon exhalation rates from a gold mine tailings dam around mining area of Odendalsrus were measured using passive “sealed tube” method and CR-39 gas etched track monitors known as Radon Gas Monitors (RGMs). Twenty samples were collected at the depths ranging from 90 cm to 1 m from the tailings for exhalation rate measurements. Radon exhalation rates from these samples were found to vary from 0.0410 ± 0.0042 Bq/m2 · s to 0.440 ± 0.045 Bq/m2 · s with a mean value of 0.102 ± 0.021 Bq/m2 · s and a standard deviation of 0.087 Bq/m2 · s. The results of these measurements show very high radon exhalation rate and radium content from one particular sample which requires further investigations.