RESUMO
In the present study, thoron exhalation flux density were measured in the soil samples collected around the Indian station namely Bharati (69° 24.41' S, 76° 11.72' E) and its nearby islands in the Larsemann hills region of Antarctica. Further, dependency of thoron mass emanation rate and emanation coefficient on the soil grain size was studied by segregating the soil samples into four different grain size groups: 50-100 µm, 100-200 µm, 200-500 µm and 500-1000 µm which showed that both of them follow a decreasing trend with increase in grain size. A comparison of measured mass emanation rate between different soil samples showed that it had a larger variation for the smaller grain size which eventually decreased as grain size increased while emanation coefficient was observed to be nearly constant for all the grain size groups. The variation in emanation coefficient with respect to mean grain size has been investigated and an empirical exponential model has been proposed for predicting emanation coefficient for different grain sizes.
Assuntos
Monitoramento de Radiação , Solo , Regiões Antárticas , Expiração , RadônioRESUMO
Zeolites are important additives materials which are widely used in different industries such as construction, paper, paint, agriculture, textile, and fertilizer. In this study, radiometric characterization of natural zeolite samples collected from four zeolite open quarries in Western Anatolia in Turkey were determined using a gamma-ray spectrometry with high purity germanium detector. The radiological risks due to the use of zeolite samples as raw materials in cement and concrete production was assessed for adult people by estimating activity concentration index and annual effective dose due to external exposure in indoor. Also, annual effective radiation dose in outdoor and the corresponding lifetime cancer risk were estimated for quarry workers. Average activity concentrations of 226Ra, 232Th and 40K measured in seventy-seven zeolite samples were found as 85⯱â¯4, 129⯱â¯2 and 1030⯱â¯24 Bq kg-1, respectively. The radon emanation factor and radon mass exhalation rate of zeolite samples varied from 1 to 9% with an average of 4% and 1.8-15.1 µBq kg-1 s-1 with an average of 7.2⯱â¯0.3 µBq kg-1 s-1, respectively. The data were compared with criteria or limit values. The results revealed that usage of the examined zeolite samples as building raw materials would not cause any significant radiological risk.
RESUMO
Natural radionuclides are released into the environment together with fly ash from the coal-burning power plant and cause an increase in the natural radioactivity in environmental samples. The study concerns to the evaluation the influence of Kangal lignite-burning power plant (LBPP) with a power of 457 MWe, which has been in operation since 1989, on natural radionuclide a concentration in surface soil samples around it. Activity concentrations of natural radionuclides (226Ra, 232Th, 40K and 222Rn) in the soil samples, and emanation coefficient (EC) and mass (ERM) and surface (ERS) exhalation rate of radon were determined by using a gamma-ray spectrometer with an HPGe detector. The average values of 226Ra, 232Th, 40K and 222Rn, EC, ERM and ERS were found as 37±5, 17±3, 222±30Bqkg-1 and 9±1kBqm-3, 12%, 12.1 µBq kg-1 s-1 and 7.1mBqm-2 s-1, respectively. Absorbed gamma dose rate in outdoor air and the corresponding effective dose rate from external exposure and excess lifetime cancer risk were estimated to evaluate radiological hazards for human population. The results revealed that the Kangal LBPP has caused a small increment in 226Ra concentration in the studied area. No influence was observed for 232Th and 40K.