Browsing by Author "Hanga, Lusina Venomufenu"

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    Radionuclide analysis of soil samples taken from Outjo, Namibia
    (University of Namibia, 2020) Hanga, Lusina Venomufenu; Oyedele, James A.
    Naturally occurring radionuclides such as Uranium (238U), Thorium (232Th) and Potassium (40K), exist in the soil where they continuously disintegrate and emit ionising radiation which could pose health hazards to the inhabitants of a given location if the concentrations of the radionuclides are very high. In this work, the concentrations of the radionuclides 238U, 232Th and 40K in the soil samples taken from Outjo have been studied by gamma spectrometry. The town of Outjo was divided into ten geographical areas and five samples were collected across each area. These samples were dried under laboratory temperature, passed through a 2 mm mesh screen and sealed in 500 ml polythene bottles. The samples were analysed using a liquid nitrogen cooled High Purity Germanium (HPGe) detector (by Canberra). The Python Code was used to calculate the activity concentrations of- and Hazard indices due to- the radionuclides 238U, 232Th and 40K from the intensities of the gamma lines emitted. The results obtained show that the concentrations of radionuclides in the soils of the town of Outjo vary from 11. 7 ± 1.6 to 29. 8 ± 2.0 Bq kg-1 with an average of 20.5 ± 3.5 Bq kg-1 for 238U, 15.2 ± 1.8 to 58.3 ± 4.2 Bq kg-1 with an average of 31.4 ± 8.9 Bq kg-1 for 232Th and 206.2 ± 12.9 to 819.6 ± 31.9 Bq kg-1 with an average of 350.6 ± 124.6 Bq kg-1 for 40K. The average concentrations for 238U and 40K are lower than the worldwide averages of 35.0 Bq kg-1 and 400.0 Bq kg-1 respectively. In contrast, the average concentration for 232Th is slightly higher than the worldwide average of 30.0 Bq kg-1 . The average outdoor air absorbed dose rate due to terrestrial gamma rays at 1m above the ground was found to be 43.0 ± 10.6 nGyh-1 which is below the worldwide average value of 58.0 nGyh-1 . Also, the corresponding average effective dose was found to be 0.05 ± 0.01 mSvy-1 which is below the maximum permissible limit of 1.0 mSvy-1 . iii These results imply that the background radiation in the town is not high. The average values of Raeq and Hex are 92.4 ± 22.5 Bq kg-1 and 0.25 ± 0.06 which are below the recommended maximum limit of 370.0 Bq kg-1 and 1 respectively. Furthermore, the average values obtained for the other hazard parameters are all below the recommended maximum values, thus confirming that the town have normal background radiation so that radiation hazard is negligible in the town. All the results obtained in this study will contribute to the national baseline data of activity concentrations of radionuclides in the soils of Namibia
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    Radionuclide analysis of soil samples taken from Outjo, Namibia
    (University of Namibia, 2019) Hanga, Lusina Venomufenu
    Naturally occurring radionuclides such as Uranium (238U), Thorium (232Th) and Potassium (40K), exist in the soil where they continuously disintegrate and emit ionising radiation which could pose health hazards to the inhabitants of a given location if the concentrations of the radionuclides are very high. In this work, the concentrations of the radionuclides 238U, 232Th and 40K in the soil samples taken from Outjo have been studied by gamma spectrometry. The town of Outjo was divided into ten geographical areas and five samples were collected across each area. These samples were dried under laboratory temperature, passed through a 2 mm mesh screen and sealed in 500 ml polythene bottles. The samples were analysed using a liquid nitrogen cooled High Purity Germanium (HPGe) detector (by Canberra). The Python Code was used to calculate the activity concentrations of- and Hazard indices due tothe radionuclides 238U, 232Th and 40K from the intensities of the gamma lines emitted. The results obtained show that the concentrations of radionuclides in the soils of the town of Outjo vary from 11. 7 ± 1.6 to 29. 8 ± 2.0 Bq kg-1 with an average of 20.5 ± 3.5 Bq kg-1 for 238U, 15.2 ± 1.8 to 58.3 ± 4.2 Bq kg-1 with an average of 31.4 ± 8.9 Bq kg-1 for 232Th and 206.2 ± 12.9 to 819.6 ± 31.9 Bq kg-1 with an average of 350.6 ± 124.6 Bq kg-1 for 40K. The average concentrations for 238U and 40K are lower than the worldwide averages of 35.0 Bq kg-1 and 400.0 Bq kg-1 respectively. In contrast, the average concentration for 232Th is slightly higher than the worldwide average of 30.0Bq kg-1. The average outdoor air absorbed dose rate due to terrestrial gamma rays at 1m abovethe ground was found to be 43.0 ± 10.6 nGyh-1 which is below the worldwide averagevalue of 58.0 nGyh-1. Also, the corresponding average effective dose was found to be0.05 ± 0.01 mSvy-1 which is below the maximum permissible limit of 1.0 mSvy-1. These results imply that the background radiation in the town is not high. The average values of Raeq and Hex are 92.4 ± 22.5 Bq kg-1 and 0.25 ± 0.06 which are below the recommended maximum limit of 370.0 Bq kg-1 and 1 respectively. Furthermore, the average values obtained for the other hazard parameters are all below the recommended maximum values, thus confirming that the town have normal background radiation so that radiation hazard is negligible in the town. All the results obtained in this study will contribute to the national baseline data of activity concentrations of radionuclides in the soils of Namibia.