Y.M. MUSSA, E. MENGISTU, D. AYALEW, B.S. GOSHU#
Department of Physics, Dire Dawa University, Ethiopia
The purpose of this work is to the assess the natural radioactivity levels and radiation hazard of ancient Harar city, Jugal. The soil samples were taken from ten different sites around the Jugal. Estimation of background radiation was carried out using HPGe gamma-ray spectrometry. The specific activity of 40K, 238U and 232Th in soil samples were obtained in the range between 254.64±11.614 Bq/kg to 330.83 ±14,73 Bq/kg, 12.84±0.952 Bq/kg to 30.22±2.135 Bq/kg and 34.25±2.47 Bq/kg to 124.91±8.622 Bq/kg, with the average value of 261.63±11.00 Bq/kg, 17.26±2.07 Bq/kg and 77.92±5.80 Bq/kg respectively. The radium equivalent activity, absorbed dose rate, annual effective dose estimated ranged from 83.22 Bq/kg to 234.32 Bq/kg, 38.165 to 103.202 nGy/h, 0.187 to 0.506 mSv/y, respectively. The internal and external hazard indices, gamma index estimated ranged from 0.292 to 0.817 and 0.261 to 0.714, 0.225 to 0.633, respectively. The annual gonad dose equivalent 269.57 μSv/y to 719.38 μSv/y, respectively. The results of soil examined in the ancient city show no significant radiological hazard arise from the soil.
Key words: Specific radioactivity, radionuclides, groundwater, well, radium equivalent, HPGe gamma-ray spectroscopy, radiological hazard.
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