Occupational Natural Radiation Exposure at the Uranium Deposit of Kitongo, Cameroon

Abstract

Soil samples were collected around the uranium deposit of Kitongo to determine activity concentrations of 238U, 232Th and 40K using a NaI(Tl) detector. Ambient dose equivalent rates were measured using a survey meter. 222Rn-220Rn discriminative measurements were performed using passive type monitors. The activity concentrations of 238U, 232Th and 40K ranged from 20±5 to 337±78 Bq kg−1, 14±4 to 53±13 Bq kg−1 and from 21±4 to 897±190 Bq kg−1 respectively, with the average values of 99±24, 27±4 and 592±125 Bq kg−1, respectively. Ambient dose equivalent rates ranged from 0.05 µSv h−1 to 6.20 µSv h−1. Higher values were recorded inside the two galleries of the uranium deposit. The maximum dose to prospective miners was calculated to be 15.2 mSv y−1. In case of the miner staying permanently inside the galleries, the external dose received would vary from 32 to 54 mSv y−1 with an average of 43 mSv y−1. Radon concentrations ranged from 416±13 to 523±14 Bq m−3 with the average value of 486±14 Bq m−3. Occupational inhalation dose ranged from 2.8 to 3.5 mSv y−1 with an average value of 3.2 mSv y−1.