Liberation and Dispersion of Radon From a Waste Disposal

• Tipo: Artigo em Livro de Atas de Conferência Internacional
• Data: 2005

Autores

Maria Dinis (Autor) Outra; António Fiúza (Autor) FEUP

Ata de Conferência Internacional

Título: Advances in Air Pollution Modeling for Environmental Security

Páginas: 133-142

NATO Advanced Research Workshop on Advances in Air Pollution Modeling for Environmental Security

Borovetz, BULGARIA, MAY 08-12, 2004

Classificação Científica

FOS: Ciências da engenharia e tecnologias

CORDIS: Ciências Tecnológicas

Outras Informações

Resumo (PT): Radon emissions from a radioactive waste disposal may constitute a major source of environment contamination and subconsequently a potential health hazard to the nearby population. Gaseous Radon-222 is generated from the radioactive decay of Radium-226 present in the tails. When it is formed, radon is free to diffuse along the pores of the residues to the surface and escape to the atmosphere. Waste management and long term stabilisation has a major concern in reducing radon emissions to near-background levels. The common theoretical approach is done by calculating the cover thickness that allows a radon flux inferior to a stipulated and accepted value. The fundamentals of the conceptual model are based in the principles 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 Radium-226 contained in the waste material. The algorithm incorporates the radon attenuation originated by an arbitrary cover system placed over the radioactive waste disposal. As an alternative, the thickness of the cover that allows a radon flux inferior to the acceptable one can be estimated. Once the Radon is released into the atmosphere, it is available for atmospheric transport by the wind. Radon atmospheric dispersion is modelled by a modified Gaussian plume equation, which estimates the average dispersion of radon released from a point source representative of one or several uniform area sources. The model considers the medium point release between all the areas contaminated. The concentration available for the dispersion is calculated from the total flux released. The dispersion can be simulated in different wind directions, with different wind velocities, as well as in the dominant wind.

Abstract (EN): Radon emissions from a radioactive waste disposal may constitute a major source of environment contamination and subconsequently a potential health hazard to the nearby population. Gaseous Radon-222 is generated from the radioactive decay of Radium-226 present in the tails. When it is formed, radon is free to diffuse along the pores of the residues to the surface and escape to the atmosphere. Waste management and long term stabilisation has a major concern in reducing radon emissions to near-background levels. The common theoretical approach is done by calculating the cover thickness that allows a radon flux inferior to a stipulated and accepted value. The fundamentals of the conceptual model are based in the principles 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 Radium-226 contained in the waste material. The algorithm incorporates the radon attenuation originated by an arbitrary cover system placed over the radioactive waste disposal. As an alternative, the thickness of the cover that allows a radon flux inferior to the acceptable one can be estimated. Once the Radon is released into the atmosphere, it is available for atmospheric transport by the wind. Radon atmospheric dispersion is modelled by a modified Gaussian plume equation, which estimates the average dispersion of radon released from a point source representative of one or several uniform area sources. The model considers the medium point release between all the areas contaminated. The concentration available for the dispersion is calculated from the total flux released. The dispersion can be simulated in different wind directions, with different wind velocities, as well as in the dominant wind

Idioma: Português

Tipo (Avaliação Docente): Científica