title: Radon dispersion modeling and dose assessment for uranium mine ventilation shaft exhausts under neutral atmospheric stability.
abstract: In the present study, the roles of atmospheric wind profiles in the neutral atmosphere and surface roughness parameters in a complex terrain were examined to determine their impacts on radon ((222)Rn) dispersion from an actual uranium mine ventilation shaft. Simulations were completed on (222)Rn dispersion extending from the shaft to a vulnerable distance, near the location of an occupied farmhouse. The eight dispersion scenarios for the ventilation shaft source included four downwind velocities (0.5, 1.0, 2.0 and 4.0 m s(-1)) and two underlying surface roughness characteristics (0.1 m and 1.0 m). (222)Rn distributions and elevated pollution regions were identified. Effective dose estimation methods involving a historical weighting of wind speeds in the direction of interest coupled to the complex dispersion model were proposed. Using this approach, the radiation effects on the residents assumed to be outside at the location of the farm house 250 m downwind from the ventilation shaft outlet were computed. The maximum effective dose rate calculated for the residents at the outside of the farm house was 2.2 mSv y(-1), which is less than the low limit action level of 3-10 mSv y(-1) recommended by the International Commission on Radiological Protection (ICRP) occupational exposure action level for radon.
authors.affiliation: School of Energy Science and Engineering, Central South University, Changsha 410083, China; School of Urban Construction, University of South China, Hengyang 421001, China. Electronic address: nhxiedong@126.com.
authors.forename: Dong
authors.initials: D
authors.lastname: Xie
authors.affiliation: School of Civil Engineering, University of Hunan Technology, Zhuzhou 412007, China.
authors.forename: Hanqing
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109-2104, USA.
authors.forename: Kimberlee J
authors.initials: KJ
authors.lastname: Kearfott
authors.affiliation: School of Urban Construction, University of South China, Hengyang 421001, China.
authors.forename: Zehua
authors.initials: Z
authors.lastname: Liu
authors.affiliation: School of Urban Construction, University of South China, Hengyang 421001, China.
authors.forename: Shunquan
authors.initials: S
authors.lastname: Mo
mesh_terms: D000383:Agriculture; D000396:Air Pollutants, Radioactive / Q000032:analysis*; D001272:Atmosphere; D004781:Environmental Exposure / Q000032:analysis; D006801:Humans; D008906:Mining; D008962:Models, Theoretical; D016273:Occupational Exposure / Q000517:prevention & control; D011829:Radiation Dosage; D011886:Radon / Q000032:analysis*; D014501:Uranium; D014691:Ventilation; D014919:Wind
chemical_list: D000396:Air Pollutants, Radioactive; D014501:Uranium; D011886:Radon
keywords: (222)Rn release; Atmospheric dispersion; Numerical modeling; Radiation dose evaluation