Evaluation of Naturally Occurring Radioactive Materials (NORM) in the South Western Oil Wells of Iran

An investigation was carried out to find out the concentration of Naturally Occurring Radioactive Materials (NORMs) in an oil production unit, an evaporation pond, and a drilling site in the Khuzestan province, in south west Iran the 4th largest oil producing country in the world. The nuclides 232Th and 40K were determined in soil samples and 226Ra was analyzed in both soil and water. The 232Th ranged between 8.7 and 403 Bq kg−1, while the minimum concentration for 40K was much larger, i.e. 82 Bq kg−1 and its maximum concentration was 815 Bq kg−1. Soil samples indicated very low concentrations of 226Ra, typically between 10.6 and 42.1 Bq kg−1 with some exceptions of 282, 602, and even 1480 Bq kg−1. Also, the range for 226Ra in water was less from 0.1 to a maximum 30.3 Bq L−1. Results show that on average, NORM concentrations in these areas are lower in comparison with the usual concentration levels in typical oil and gas fields, but despite this fact, necessary measures have to be taken in order to minimize the environmental impact of radioactive materials.

► Samples of some oil wells in the SW of Iran are examined in order to evaluate their NORM content.
► Samples of Karoon-1 demonstrate the highest level of radioactivity for 226Ra and 232Th.
► 226Ra radioactivity concentration of 42% of these samples exceeds the NRC limits.