A Radiological Survey in Tailings: A Case Study of Rosterman Gold Mine, Western Kenya

Abstract

Thirty samples of tailing waste weighing 200 g were randomly collected from both active and inactive tunnels at the Rosterman gold mine site in western Kenya. The average activity concentration of the radionuclides (40K, 232Th and 238U) analyzed by the gamma-ray spectrometry in the tailing samples was 260 ± 14.29 Bq/Kg for 40K, 118 ± 8.25 Bq/Kg for 232Th and 81 ± 3.63 Bq/Kg for 238U. The corresponding radiological parameters for all the collected thirty tailing waste samples were determined from the specific mean activity concentrations. The average dose rate for all the samples was 54 nGy/h. The average radium equivalent value was 262 ± 12.04 Bq/Kg with a range of 154 ± 6.42 Bq/Kg to 350 ± 10.24 Bq/Kg. The average values of external and internal indices were 0.6 ± 0.03 mSv/y and 0.7 ± 0.04 mSv/y respectively. The average indoor and outdoor annual effective dose rates that were determined for this study were 0.3 ± 0.02 and 0.2 ± 0.01 respectively. Therefore, the tailing samples recorded doses and radiological indices below the world average permissible values. This implies that the radiation exposure to the miners and general public due to tailing wastes at Rosterman gold mine poses no significant health risk.