Assessment of natural radioactivity and associated radiation hazards of some used engine oil samples

Abstract

To assess the natural radioactivity and associated radiation hazards of used and unused engine oil in the environmental, some samples have been collected from fuel station and local markets in Baghdad city of Iraq. The specific activities of 238U, 232Th, 40K and 235U were measured by using a gamma ray spectrometer based on a high purity germanium (HPGE) detector. The results showed that the activities concentration of Ra-226 (238U series), 232Th, 40K and 235U were (0.59-18.41) Bq/L and average (10.15) Bq/L, (0.00-35.47) Bq/L and average (14.87) Bq/L , (14.16-245.27) Bq/L and average (88.97) Bq/L,(0.03-0.85) Bq/L and average (0.47) Bq/L, respectively. The hazard indices have been calculated in the present work which include (radium equivalent activity (Raeq), absorbed dose rate in Air (AD),annual effective dose equivalent (A.E.D) which include indoor and outdoor effective dose rate, activity concentration Index (Iγ), external hazard index (Hext) and internal hazard index (Hint)), respectively. For the used engine oil samples, the highest values of (Raeq (Bq/l), AD (nGy/h) , A.E.Din(mSv/y) , A.E.Dout (mSv/y) , Iγ, Hext, Hint ) which were equal to (52.57, 24.18, 0.12, 0.03, 0.38, 0.19, 0.14), respectively , for Iraqi used engine oil sample, while the lowest values of (Raeq (Bq/l), AD (nGy/h) , A.E.Din (mSv/y) , A.E.Dout (mSv/y) , Iγ,Hext, Hint ) was found in (U.A.E) sample which was equal to (5.21, 2.49, 0.01, 0.003, 0.04, 0.03, 0.01), respectively. While the unused engine oil samples, the highest values of (Raeq (Bq/l), AD (nGy/h) , A.E.Din (mSv/y) , A.E.Dout (mSv/y) , Iγ, Hext, Hint ) which were equal to (70.21, 33.03, 0.16, 0.04, 0.52, 0.24, 0.19), respectively ,for Iraqi unused engine oil sample, while the lowest values of (Raeq (Bq/l), AD (nGy/h) , A.E.Din (mSv/y) , A.E.Dout (mSv/y) , Iγ, Hext, Hint ) were found in (U.A.E) sample which were equal to (27.73, 13.12, 0.06, 0.02, 0.20, 0.11, 0.08), respectively. The results comparison with worldwide average and it is found that the levels of radiation and radiation hazards indices values were within the permissible limits globally , the study showed that the used and unused engine oil are safe radiological and does not constitute a danger to the environmental.