Volume 13 (ISTJN)

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http://hdl.handle.net/11070/2619

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Browsing Volume 13 (ISTJN) by Subject "Radioactivity"

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    Assessment of natural radioactivity levels and radiation hazards in shore sediments from the Zambezi River, Namibia
    (University of Namibia, 2019) Amwaalanga, Maria N.; Onjefu, Sylvanus A.; Zivuku, Munyaradzi; Hamunyela, Roswita H.
    In this study, the radioactivity concentrations and the potential health hazards of primordial radionuclides; 238U, 232Th and 40K were measured using a gamma ray spectrometer in 30 soil samples collected from the Zambezi River, Namibia. The average activity concentrations for 238U, 232Th and 40K was found to be 18.91 Bq/kg, 15.58 Bq/kg and 79.17 Bq/kg respectively. The activity concentrations of the measured radionuclides were used to calculate the radiological hazards in soil samples i.e. absorbed dose rate, annual effective dose equivalent, radium equivalent activity and hazard indices (Hex and Hin). From the values obtained, all the radiological hazard parameters were within the world acceptable average values. However, the mean annual effective outdoor and indoor dose equivalent was found to be 0.26 mSv/y and 1.05 mSv/y, respectively, which both exceed the recommended world average United Nations Scientific Committee on Effects of Atomic Radiation (UNSCEAR) values of 0.07 mSv/y for outdoor and 0.45 mSv/y for indoor.
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    Measurement of natural radioactivity and dose rate assessment of terrestrial gamma radiation in the soils of Karibib and Okahandja, Namibia
    (University of Namibia, 2019) Midzi, Wilfred; Oyedele, James; Shimboyo, Simon A.; Taapopi, Erastus E.
    The activity concentrations of the naturally occurring radionuclides 238U, 232Th and 40K in soil samples taken from the towns of Okahandja and Karibib in Namibia have been determined by gamma-ray spectroscopy using an HPGe detector. The average activity concentrations of 238U, 232Th and 40K in Karibib are 29.4±5.8Bq/kg, 49.0±8.6Bq/kg, and 824.3±153.5Bq/kg while they are 40.9±8.6Bq/kg, 57.9±19.4Bq/kg, and 562.4±125.4Bq/kg respectively in Okahandja. Most of these values are much higher than the corresponding worldwide average values. These activity concentrations were used to calculate different radiological parameters in order to evaluate the associated health hazard. The value of 9.5×10−2 mSv/y obtained for the mean effective dose rate in both towns is far below the permissible limit of 1.0mSv/y recommended by the ICRP and implies that there is no significant radiation hazard in the towns. Also, the values of 163.0Bq/kg and 167.1Bq/kg obtained for the average radium equivalent activity (Raeq) in the towns and the corresponding values obtained for the average external hazard index (Hex) are much below their maximum permissible limits thus confirming that radiological hazard is negligible in the towns.