Mustapha A O, Mbuzukongira P, Mangala M J
Department of Physics, University of Nairobi, PO Box 30197, Nairobi, Kenya.
J Radiol Prot. 2007 Jun;27(2):187-95. doi: 10.1088/0952-4746/27/2/005. Epub 2007 May 24.
Artisans in Masisi and other parts of the North Kivu province in the eastern Democratic Republic of Congo (DRC) mine columbite-tantalite mineral ores (also called 'coltan') for the tantalum content. The potential occupational radiation exposures in the course of this operation, due to the presence of naturally occurring radioactive material (NORM), have been investigated in this screening survey. Activity concentrations of the naturally occurring radionuclides in samples of coltan were measured using gamma-ray spectrometry. The average values in Bq g(-1) are 10.75 +/- 5.11 for (238)U, 7.06 +/- 3.39 for (226)Ra, 1.75 +/- 0.85 for (232)Th, and 1.63 +/- 0.52 for (40)K. Based on these values and the working scenarios involved in artisanal coltan mining, the occupational doses that may accrue from a variety of exposure pathways were determined by model calculations. The results, assuming conservative dust load and dilution factors, indicate that grinding and sieving coltan can give rise to high occupational doses, up to 18 mSv per annum on average.
刚果民主共和国（DRC）东部北基伍省马西西及其他地区的工匠开采钶钽铁矿矿石（也称为“钶钽铁矿”）以获取钽含量。在这项筛查调查中，对该作业过程中由于天然存在的放射性物质（NORM）而可能产生的职业辐射暴露进行了调查。使用伽马射线能谱法测量了钶钽铁矿样品中天然存在的放射性核素的活度浓度。以Bq g(-1)为单位的平均值分别为：(238)U为10.75±5.11、(226)Ra为7.06±3.39、(232)Th为1.75±0.85、(40)K为1.63±0.52。基于这些值以及个体手工钶钽铁矿开采所涉及的工作场景，通过模型计算确定了各种暴露途径可能产生的职业剂量。结果表明，假设粉尘负荷和稀释因子保守，研磨和筛选钶钽铁矿可导致高职业剂量，平均每年高达18 mSv。
