Introduction: Considering the risk of radiation, the measurement of the natural radiation sources seems to be necessary. In this study, the concentrations of the natural radionuclides, namely ²²⁶Ra, ²³²Th, and ⁴⁰K, were measured in the soil samples taken from different locations of Golestan, Iran. The measurement results can also be used as a baseline to evaluate the impact of non-nuclear activities and the routine releases of nuclear installations.
Materials and Methods: A total of 42 soil samples were collected. The samples were sealed for at least three weeks to ensure the secular equilibrium between ²²⁶Ra and ²³²Th and their respective radioactive progenies. The activity concentrations of natural radionuclides in soil samples were measured using a shielded HPGe detector.
Results: The average activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K were 23, 31, and 453 Bq.kg^-1, respectively. To assess the radiological hazards, the Ra equivalent activity as well as the external and internal hazard indices were estimated. Radium equivalent varied within the range of 58.4-142.6 Bq.kg^-1 with a mean value of 102.4 Bq.kg^-1. The estimated mean values of H_ex and H_in (0.28 and 0.34, respectively) in the area under investigation were lower than unity as desirable. Therefore, it did not pose any health risks to the population of the area.
Conclusion: The results of this study were compared with those of other studies carried out in other countries. As the findings of the present study indicated, the health-related risks causing by the naturally accruing radionuclides was very low in the investigated area.