Radioatividade natural de solos na envolvente da antiga central termoelétrica de Sines: impactes da combustão de carvão

ABSTRACT: For 36 years, the coal combustion in Sines thermal power plant generated a complex mixture of gases and particles that were partially emitted into the atmosphere and the environment. The determination of radiological parameters in soils surrounding the power plant reveals that soils in the southern area have higher activity concentration of natural radionuclides (40K, 232Th, and 238U), as well as higher exhalation rates and emanation coefficients of 222Rn and 220Rn than those located at north. The higher values of radiological parameters in the southern area are explained by dispersion of gases and particles driven by the preferential direction of winds and the proximity to storage facilitates of coal and products derived from combustion. The higher exhalation rates and low emanation coefficients of thoron indicates that K and Th may be accumulated and encapsulated in the mineral fraction of ash particles while U, preferentially bounded to organic matter, was mobilized during coal combustion. The results do not indicate a significant radiological risk, although it is higher in the southern area.