Oyedele J A, Shimboyo S
Department of Physics, University of Namibia, Private Bag 13301, Windhoek, Namibia.
Radiat Prot Dosimetry. 2013 Sep;156(3):343-8. doi: 10.1093/rpd/nct081. Epub 2013 Apr 2.
The activity concentrations of (238)U, (232)Th and (40)K in soil samples taken from four major towns across southern Namibia have been determined by gamma spectroscopy and used to calculate the mean dose rate, radium equivalent activity (Raeq) and external hazard index (Hex) for each town. The average concentrations of radionuclides in the towns vary from 10.7±3.1 to 35.6±8.4 Bq kg(-1) for (238)U, 12.3±4.9 to 77.8±20.9 Bq kg(-1) for (232)Th and 248.0±35.6 to 734.6±61.4 Bq kg(-1) for (40)K. These values are within the range of concentrations reported in some countries but most of the values for (232)Th and (40)K are above the worldwide averages. However, the mean effective dose rate of 0.08±0.03 mSv y(-1) and the mean values of Raeq and Hex for the region are below their respective permissible limits, thus indicating that radiation hazard is negligible in the region.
已通过伽马能谱法测定了从纳米比亚南部四个主要城镇采集的土壤样品中（238）U、（232）Th和（40）K的活度浓度，并用于计算每个城镇的平均剂量率、镭当量活度（Raeq）和外照射危害指数（Hex）。各城镇放射性核素的平均浓度范围为：（238）U为10.7±3.1至35.6±8.4 Bq kg-1，（232）Th为12.3±4.9至77.8±20.9 Bq kg-1，（40）K为248.0±35.6至734.6±61.4 Bq kg-1。这些值在一些国家报告的浓度范围内，但（232）Th和（40）K的大多数值高于全球平均值。然而，该地区的平均有效剂量率为0.08±0.03 mSv y-1，Raeq和Hex的平均值低于各自的允许限值，因此表明该地区的辐射危害可忽略不计。
