Abstract
Eight samples of cement were collected from different commercial factories (Al-Koufa, Al-Basra, Al-Najaf and Kerkouk factories) located in Iraq. They were analyzed using a gamma ray spectroscopy system. The activity concentrations of <sup>226</sup>Ra, <sup>232</sup>Th and <sup>40</sup>K were ranged from 5.8 to 43.17 Bq kg<sup>-1</sup>, from 0.99 to 55.79 Bq kg<sup>-1</sup> and from 53.28 to 185.34 Bq kg<sup>-1</sup>, respectively. The potential radiological hazards were assessed by calculating the radium equivalent activity (Ra<sub>eq</sub>), the indoor absorbed gamma dose rate (D), the annual effective dose equivalent (AEDE), the alpha index (I<sub>α</sub>), the gamma index (I<sub>γ</sub>), and the external hazard (H<sub>ex</sub>) and internal hazard (H<sub>in</sub>) indices. The highest value of Ra<sub>eq</sub> is estimated of 101.36 Bq kg<sup>-1</sup>, which is significantly less than the upper limit of 370 Bq kg<sup>-1</sup>. The estimated maximum value of the absorbed gamma dose rate of 54.71 nGy h<sup>-1</sup> is within the world average value of 55 nGy h<sup>-1</sup>, and the annual effective dose equivalent in the studied samples were 0.05 (outdoor), 0.18 (indoor) mSv y<sup>-1</sup>, which is lower than the recommended limit reported in the UNSCEAR (2000). The values of the hazard indices were below the recommended levels; therefore, the study shows that the measured radioactivity for cement does not pose as significant source of radiation hazard and is safe for use in the construction of dwellings.
Highlights
The human population is always exposed to ionizing radiation due to background radiation
To assess the excess gamma radiation originating from building materials, several hazard indices have been suggested by a number of investigators; these calculations include the absorbed gamma dose rate in the indoor environment and the corresponding annual effective dose equivalent, the radium equivalent activity, the external and internal hazard indices, the alpha index and the gamma activity concentration
They were analysed by gamma-ray spectrometry system and ranged from 5.8 to 43.17 Bq kg-1, with an average value 24.25 Bq kg-1 for 226Ra, from 0.99 to 55.79 Bq kg-1, with an average value 25.41Bq kg-1 for 232Th and from 53.28 to 185.34 Bq kg-1, with an average value 93.17 Bq kg-1 for 40K
Summary
The human population is always exposed to ionizing radiation due to background radiation. The natural radioactivity in soil and building materials mainly comes from uranium (238U) series, thorium (232Th) series and a radioactive isotope of potassium (40K) (These radionuclides can be found almost in all types of rocks, sand, cement and gypsum from which building materials are produced) [1,2,3]. All of these natural sources of radioactivity can be sources of both internal and external radiation exposure. The potential radiological hazards associated with these materials were assessed by calculating the radium equivalent activity (Raeq), the indoor absorbed gamma dose rate (D), the annual effective dose equivalent (AEDE), the activity utilization index, the external hazard (Hex), the gamma index (Iγ), internal hazard (Hin) and the alpha index (Iα) indices
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