新疆某地浸铀矿山氡的析出特征及辐射剂量分析

发布时间：2018-05-04 05:01

本文选题：地浸铀矿 + 氡析出　；参考：《南华大学》2016年硕士论文

【摘要】：地浸采铀技术与传统铀矿开采相比,减少了地面污染的尾矿坝和废石场,具有明显的环保优势,但对环境的影响有其自身的特性,其中地浸采铀过程中氡气析出所致的辐射影响不可忽视,给铀矿工作人员和周围公众带来潜在的辐射风险,照射途径为空气吸入内照射,形成长期的放射性危害。因此,研究地浸铀矿氡的析出特征,并分析所致的辐射剂量程度,为地浸铀矿氡析出辐射防护提供科学依据,对保护环境、人员健康具有重要的意义。本文以新疆某地浸铀矿为研究对象,对地浸铀矿进行环境空气中氡浓度、氡析出率调查和监测,掌握氡的析出特征,并采用UAIR-FINE软件模拟得到了集液池、蒸发池所致周围20km范围内各子区的氡浓度贡献值分布、公众个人剂量分布、公众集体剂量以及5km范围内的公众个人剂量等值线,分析氡析出对工作人员和周围公众的影响。主要研究结论如下:(1)氡监测结果表明,监测值均在有关标准约束值以下,水冶车间二楼氡浓度明显高于其他楼层,最高达438Bq/m3,主要是吸附塔内液体在二楼的流量和含铀溶液均最多,容易导致氡气析出;集液池是地浸铀矿山氡气析出的主要污染源项,并且温度升高会促进浸出液表面氡的析出;通过偏安全估算,地浸铀矿山氡析出量远小于传统铀矿山。(2)估算水冶车间工作人员的最大个人辐射剂量为2.01mSv/a,低于国家标准限值,对工作人员影响不大。(3)氡浓度及剂量分布结果表明,同一个方位下,随着距离的增加,氡浓度贡献值逐渐减小,且在5km内,浓度下降梯度较大;受风频影响,公众剂量等值线在西方向、西北方向比较分散,下降梯度较小;集液池、蒸发池位于盛行风向的下风向,距离较近的居民点位于上风向,并且下风向的居民点均位于10km以外,铀矿合理的地理规划布局减轻了污染源项对公众的影响。所致氡浓度贡献值、公众个人剂量最大值均出现在集液池的W方位,而所致关键居民点的公众个人剂量最大值位于集液池的E方位、2km~3km的子区,位于A村,为0.00171mSv/a;所致周围20km范围内的公众集体剂量为4.55×10-3人·Sv/a,均低于各项标准限值,对公众影响较小,符合辐射防护要求。(4)针对地浸铀矿的特点提出了合理的氡析出辐射防护建议。
[Abstract]:Compared with traditional uranium mining, in-situ leaching uranium mining technology has obvious advantages of environmental protection, but has its own characteristics of environmental impact, which reduces the surface pollution of tailings dams and waste quarries. The radiation effect caused by radon precipitation during in-situ uranium leaching can not be ignored, which brings potential radiation risk to uranium mine workers and the surrounding public. The way of exposure is air inhalation internal irradiation, which forms long-term radiation hazard. Therefore, it is of great significance to study the characteristics of radon exhalation in in-situ leaching uranium mine and analyze the radiation dose level, which provides a scientific basis for the radiation protection of radon exhalation in in-situ leaching uranium mine and is of great significance to the protection of environment and the health of personnel. In this paper, the concentration of radon in ambient air and radon exhalation rate are investigated and monitored, the characteristics of radon exhalation are grasped, and the liquid collecting tank is obtained by UAIR-FINE software simulation. The distribution of radon concentration contribution value, public individual dose distribution, public collective dose and public personal dose isoline caused by the evaporation pool in the 20km area around the evaporator were analyzed. The effects of radon emission on the workers and the surrounding public were analyzed. The main conclusions are as follows: (1) the radon monitoring results show that the monitoring values are below the relevant standard constraint values, and the radon concentration on the second floor of the hydrometallurgical workshop is obviously higher than that on the other floors. The maximum is 438Bq / m3, mainly because the liquid in the adsorption tower has the most liquid flow on the second floor and the uranium-containing solution, and the liquid collecting tank is the main source of radon precipitation in the uranium mine mountain, and the increase of temperature will promote the radon release on the surface of leaching solution. Based on the partial safety estimation, radon emission from in-situ leaching uranium mine is much smaller than that from traditional uranium mine.) the maximum personal radiation dose of workers in hydrometallurgical workshop is estimated to be 2.01mSv / a, which is lower than the national standard limit. The results of radon concentration and dose distribution showed that under the same azimuth, the radon concentration contribution value gradually decreased with the increase of distance, and in 5km, the decrease gradient of radon concentration was larger, which was influenced by wind frequency. The isoline of the public dose is scattered in the west direction and the northwest direction, and the descending gradient is smaller; the liquid collecting pool and evaporation pool are located in the downwind direction of prevailing wind direction, and the nearby residential areas are located in the upper wind direction, and all the downwind settlement areas are located outside of 10km. The rational geographical layout of uranium mine mitigates the impact of pollution sources on the public. The maximum value of the individual dose of radon concentration was found in the W direction of the liquid collecting pool, while the maximum value of the individual dose in the key residential area was located in the sub-area of 2km / 3km in E azimuth of the liquid collecting pool and located in village A. For 0.00171 mSv / a, the collective dose in the range of 20km is 4.55 脳 10 ~ (-3) person, which is below the standard limit, and has little influence on the public, and meets the requirements of radiation protection.) in view of the characteristics of in-situ uranium leaching, the paper puts forward reasonable suggestions for the radiation protection of radon exhalation.
【学位授予单位】：南华大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TD868

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