Simulation of Liberation and Dispersion of Radon from Uranium Mill Tailings

• Type: Article in International Conference Proceedings Book
• Date: 2004

Authors

Maria de Lurdes (Author) FEUP; António Fiúza (Author) FEUP

Conference proceedings International

Title: Proceedings of the International Workshop on Environmental Contamination from Uranium Production Facilities and Remediation Measures

Pages: 63-70

International Workshop on Environmental Contamination from Uranium Production Facilities and Remediation Measures

Sacavém, Lisboa, February 2004

Indexing

ISI Web of Science

Scientific classification

FOS: Engineering and technology > Other engineering and technologies

CORDIS: Technological sciences > Engineering ; Physical sciences ; Natural sciences > Environmental science

Other information

Abstract (EN): Radon emissions from uranium mill tailings may constitute a major source of environmental contamination and consequently a potential health hazard to the nearby population. Radon-222 gas is generated from the radioactive decay of 226Ra present in the particles. When it is formed, radon is free to diffuse along the pores of the residues to the surface and escape to the atmosphere. A major concern in waste management and long term stabilization is to reduce radon emissions to near background levels. The common theoretical approach is to calculate the cover thickness that results in a radon flux lower than a stipulated and accepted value. The conceptual model is based on the principle of diffusion across a porous medium, which allows the mathematical description of the radon transport through the waste and the cover. The basic diffusion equations are used for estimating the theoretical values of the radon flux formed from the decay of the 226Ra content in the waste material. The algorithm incorporates the radon attenuation with an arbitrary cover system placed over the radioactive waste. Alternatively, the thickness can be estimated for a cover that allows a lower radon flux. Once the radon is released into the atmosphere it is available for atmospheric transport by the wind. Radon atmospheric dispersion is modelled using a modified Gaussian plume equation that estimates the average dispersion of radon released from a point source representative of one or more uniform area sources. The model considers the median release point between all the areas contaminated. The concentration available for the dispersion is calculated from the total flux released. The dispersion can be simulated for different wind directions, with different wind velocities, as well as in the dominant wind direction.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 8