Browsing by Author "Asefa, Zewdineh"

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    Effective Radiation Dose From Indoor Rn-220 Concentration
    (Addis Ababa University, 2017-10-03) Asefa, Zewdineh; Tesfaye, Tilahun (PhD)
    Equilibrium equivalent concentration of thoron (EECTh)were measured in theNuclear Physics laboratory of the Addis AbabaUniversity over a period of 21 days in the months of April andMay 2017. The laboratory is located in the first floor of the Department’s building. The method, used in this work, is based on gross beta counting of filtered aerosol samples counted over successive time intervals using an end-windowGeiger- Müller detection system. i.e., grab sampling of air followed by absolute beta counting was used to determine thoron concentration. The gross beta-count was then fitted to a mathematical model using least-square fitting method. The concentrations of the radon and thoron daughter products were determined from the best fit. Equilibrium Equivalent Concentrations of Radon and Thoron were calculated from the concentrations of the progeny. This EEC was used to determine the effective indoor inhalation dose due to thoron. It was found that the effective annual effective doses for thoron inhalation by the inhabitantswere found to vary in the range (0.06 - 0.20mSv/y) with a mean of 0.1 mSv y . These results are close to the maximum permissible dose (0.1mSv/y) to the public due to thoron progeny recommended by (ICRP, 1990). xi