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

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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.