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Application of in-situ gamma-ray spectrometry in the determinationof activity concentrations of 40K, 238Uand 232Th and mean annual effective dose rate levels in southeastern cities in Nigeria

Published online by Cambridge University Press:  01 December 2005

N. N. Jibiri
Affiliation:
Radiation and Health Physics Research Laboratory, Department of Physics, University of Ibadan, Ibadan, Nigeria
I. P. Farai
Affiliation:
Radiation and Health Physics Research Laboratory, Department of Physics, University of Ibadan, Ibadan, Nigeria
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Abstract

A low cost in-situ gamma-ray spectrometric method for rapid assessment of radiation exposure, identification of radionuclides and detection of changes in environmental radioactivity has been employed in the determination of the natural gamma radiation dose levels in six major cities of the southeastern region of Nigeria. The soil radioactivity concentrations of the primordial radionuclides; 40K, 238U and 232Th were determined and have been related to the γ-dose rates in the cities. The activity concentration of 40K across the region ranged between 0.021 and 0.200 kBq kg–1; 238U was between 0.001 and 0.066 kBq kg–1 while that of 232Th ranged between 0.015 and 0.103 kBq kg–1. The total γ-absorbed dose rates in air in the region ranged between 0.016 and 0.090 μGy h–1 with a mean of 0.039 ± 0.018 μGy h–1. The mean of the annual outdoor effective dose due to the terrestrial gamma radiation for the region was calculated as 50 μSv y–1 representing 66% of the world average value.

Type
Other
Copyright
© EDP Sciences, 2005

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