Document Type : Original Paper
Radiation Applications Research School, Nuclear Science and Technology Research Institute, Tehran, Iran
Physics Department, Toosi University of Technology, Tehran, Iran
Introduction: This paper aimed to outline the procedure for determining the activity concentrations of naturally occurring radionuclides (i.e., 226Ra, 232Th, and 40K) in surface soil samples collected from Mazandaran province, Iran.
Material and Methods: In total, 61 samples were collected between longitude 50˚ 34′ and 54˚ 10′ east and latitude 35˚ 47′ and 36˚ 35′ north from uncultivated locations of Mazandaran province, Iran. The measurements were performed by the gamma spectrometry system using a High Purity Germanium detector.
Results: The mean levels of 226Ra, 232Th, and 40K were found to be 20 Bqkg-1 (without considering high-level areas), 33 Bqkg-1, and 421 Bqkg-1, respectively. The results were compared with those of different countries across the world. The radiological hazard to the natural radioactivity was assessed by calculating the absorbed dose rate, the radium equivalent activity, the external and internal hazard indices, and the outdoor and indoor annual effective dose rate. The mean radium equivalent without considering three high-level areas was estimated at 100.8 Bqkg-1.
Conclusion: Results indicated that no radiological risk may threat the residents of the areas under study, except for regions near the hot spring in Sadat Shahr and Lavich, Iran. Without considering high-level areas, the mean radium equivalent activity was 100.8 Bqkg-1 that was about 73% lower than the permissible maximum. Moreover, internal and external hazard indices were less than the unit. The mean absorbed dose rate, as well as the outdoor and indoor annual effective dose rates were 48.56 nGyh-1, 238.4 µSv y-1, and 292.6 µSv y-1, respectively.