Indústrias Nucleares do Brasil-INB, Rodovia. Presidente Dutra Km 330, Engenheiro Passos, Resende, RJ, 27555-000, Brazil.
Universidade Federal do Rio de Janeiro-UFRJ, Rio de Janeiro, 21941-972, Brazil.
Environ Sci Pollut Res Int. 2020 Oct;27(29):36704-36717. doi: 10.1007/s11356-020-09672-6. Epub 2020 Jun 20.
A mine in an area of naturally occurring radioactive materials (NORM), characterized by acid mine drainage, generates effluents with natural radionuclide concentrations, usually above the limits authorized by the regulator. The plant exploiting NORM controls the water quality and discharges it into the aquatic environment after meeting technical requirements. Downstream, water usage is unrestricted. In order to reach activity concentrations in the released effluents below the authorized values, the facility applies a chemical treatment to the effluent. Then, to ensure the effectiveness of the treatment, the facility performs sampling of treated effluent and determines the activity concentration of natural radionuclides (U, Ra, and Pb from the uranium series and Th and Ra from the thorium series). In the current study, the proportion and distribution of these radionuclides between the soluble and particulate fractions were determined. The measured activity concentrations were compared with the values proposed by the World Health Organization and Brazilian legislation, as well as other authorities, as regards the potable use from the radioprotection point of view. It was observed that the radionuclides are not in secular equilibrium. The fractions contribute differently to the total release of radionuclide, and there is no linear relationship between the fractions. The average activity concentrations did not result in radiological restrictions to water use, and the committed effective dose due to ingestion was estimated at 0.06 mSv y. Therefore, there is no radiological restriction to water use, since the dose which was found was below the constraint value for the public.
一个位于自然放射性物质（NORM）区域的矿山，其特征是酸性矿山排水，产生的废水含有天然放射性核素浓度，通常高于监管机构规定的限值。开采 NORM 的工厂控制水质，并在满足技术要求后将其排放到水生环境中。下游，水的使用不受限制。为了使释放废水中的活度浓度低于授权值，该工厂对废水进行化学处理。然后，为了确保处理的有效性，工厂对处理后的废水进行采样，并确定天然放射性核素（铀系中的 U、Ra 和 Pb，以及钍系中的 Th 和 Ra）的活度浓度。在当前的研究中，确定了这些放射性核素在可溶和颗粒部分之间的比例和分布。所测量的活度浓度与世界卫生组织和巴西法规以及其他当局提出的值进行了比较，从辐射防护的角度来看，这些值涉及饮用水的使用。结果表明，放射性核素未达到长期平衡。各部分对放射性核素的总释放量的贡献不同，且各部分之间不存在线性关系。平均活度浓度不会对水的使用造成放射性限制，由于摄入造成的预计有效剂量为 0.06 mSv y。因此，水的使用不受放射性限制，因为发现的剂量低于公众的约束值。
