Abstract

Mining and milling processes could cause potential radiological exposures to the public. The objective of this study was to estimate the off-site radiological doses expected to be received by the public as a result of uranium mining and milling activities at Mkuju River Project in the United Republic of Tanzania. MILDOS-AREA was used to estimate off-site doses along with RESRAD-OFFSITE for comparison and verification. Since the mining has not yet started, the conceptual scenario was chosen. Using the concept of the most exposed individual, the location of the nearest residence (receptor) was chosen at 2.5 km from the site with other receptors being the fence boundary and grazing area being at 1.0 and 1.8 km, respectively. Yellowcake stack (point source), ore pad and two tailing piles where each had an area of 2.5 × 10⁵ m² were chosen to be the source of radiological contamination. The radiological source term was obtained from the concentration of ²²⁶Ra and ²³²Th in soil obtained from the previous studies of environmental impact assessments. Meteorological and site-specific data were used for this analysis. The estimated total effective dose equivalent (TEDE) for the nearest residence which was calculated by MILDOSE-AREA ranged from 2.5 × 10⁻² to 4.45 × 10⁻² mSv/y during the operation of 13 y. The result of RESRAD-OFFSITE ranged from 7.19 × 10⁻² mSv/y for the first year to 7.43 × 10⁻² mSv/y in the final year. This implied all the estimated TEDEs were below the dose limit and dose constraint of 1 and 0.3 mSv/y, respectively, as suggested by the International Atomic Energy Agency. Hence, it was found that there was no potential radiological concern of uranium mining at Mkuju River Project. It was found that using MILDOS-AREA it is possible to estimate dose at different distances from the facility. Therefore, this study apart from estimating the off-site doses, it can be used for planning of public and social premises before the commencement of the project. That is the distance from the facility where the public should be located as well as other locations for social activities.

中文翻译：

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铀矿开采和铣削设施的运营对公众的潜在环境危害

摘要

采矿和制粉过程可能导致对公众的潜在放射暴露。这项研究的目的是评估坦桑尼亚联合共和国姆库尤河项目铀矿开采和制粉活动将使公众预期获得的场外放射剂量。MILDOS-AREA与RESRAD-OFFSITE一起用于估算异地剂量，以进行比较和验证。由于尚未开始开采，因此选择了概念方案。使用暴露程度最高的个体的概念，选择离该地点最近的住所（受体）的位置在距该地点2.5公里处，其他受体分别是围栏边界和放牧区，分别在1.0公里和1.8公里处。黄饼堆（点源），矿垫和两个尾矿堆，每个堆场的面积为2.5×10 ⁵选择 m ²作为放射污染源。放射源术语是从先前的环境影响评估研究中获得的土壤中²²⁶ Ra和²³² Th的浓度获得的。气象和特定地点的数据用于此分析。由MILDOSE-AREA计算得出的最接近居住地的估计总有效剂量当量（TEDE） 在13 y的操作范围内为2.5×10 ^-2至4.45×10 ^-2 mSv / y。RESRAD-OFFSITE的结果范围从 第一年的7.19×10 ^-2 mSv / y到7.43×10 ^-2 最后一年的mSv / y。这意味着所有估计的TEDE分别低于国际原子能机构的建议的剂量极限和剂量限制（分别为1和0.3 mSv / y）。因此，发现在姆库朱河项目中铀矿开采没有潜在的放射性问题。发现使用MILDOS-AREA可以估计距设施不同距离的剂量。因此，该研究除了可以估算异地剂量外，还可以在项目开始之前用于公共和社会场所的规划。那是距公众应所在的设施以及其他社交活动场所的距离。