植被覆盖对铀尾矿库氡大气扩散影响的数值模拟  

Numerical simulation of the influence of vegetation-covered area on the atmospheric diffusion of radon emanating from the uranium tailings impoundment

作　　者：谢清芳[1] 彭小勇[1] 万芬[1] 黄帅[1] 张欣[1] 

机构地区：[1]南华大学城市建设学院,湖南衡阳421001

出　　处：《安全与环境学报》2013年第6期264-268,共5页Journal of Safety and Environment

基　　金：国家自然科学基金项目(11075072)

摘　　要：以平行于来流方向和垂直于来流方向建造的平地型铀尾库为研究对象,采用计算流体力学软件Fluent对氡大气扩散进行数模拟,研究了风速为0.5 m/s时滩面植被覆盖对铀尾矿库下风向氡的迁移规律和浓度分布的影响,并对比分析了两种建造方向对氡扩范围的影响。结果表明,随铀尾矿库下风向距离和植被覆盖面积加,铀尾矿库下风向的氡浓度不断下降。植被覆盖面积相同时,建方向平行于来流的铀尾矿库下风向的局部氡浓度明显高于建造方垂直于来流的,并且氡污染距离较远。建造方向一定时,随植被覆面积增大,局部氡浓度不断增加,但随距离增加,氡污染程度不断弱。The paper is to introduce a numerical simulation model of the influence of the vegetationcovered area on the atmospheric diffu sion of radon emanating from the uranium tailings impoundment by using a fluid mechanics software. In the paper, what we have chosenas our research object is the three kinds of vegetation areas under the conditions of the uranium tailings impoundment emerged in the airflow direction or that in the perpendicular direction. The vegetation area given is supposed to be a porous medium model, whose porosity can be taken as 0.8. The vegetation coverage mentioned in this paper refers to that on the sandbeach surface under the influence of the mi gration regulation and concentration distribution of radon emanating from the uranium tailings impoundment when the wind speed is sup posed to be 0.5 m/s. The results of our simulation show that the radon concentration tends to decrease constantly with the increase of the vegetation coverage and the migration distance. On the basis of the same vegetation coverage condition, as compared with that of ura nium tailings impoundment formed in the perpendicular direction, the local radon concentration of the condition that is formed in the airflow direction is obviously higher, though the radon pollution distance is greater but its diffusion range is limited. With the increase of vegeta tion coverage, the local radon concentration tends to increase con stantly both in the condition when the railings impoundment resulted in the airflow direction or in the perpendicular direction. When urani um tailings impoundment emerged in the airflow direction, the radon concentration of uranium railings impoundment covering the three fourth of the beach area covered by the vegetation turned out to be higher than that of the rest part of the beach area that was also cov ered by vegetation, and there exists a maximum difference about 19%.

关 键 词：环境工程学 铀尾矿库 数值模拟 植被 氡浓度 大气扩散 

分 类 号：TL752.2[核科学技术—辐射防护及环境保护]