Evaluation of radiological risks due to natural radionuclides in the soil of Khanaqin district, Diyala, Iraq

Abstract This study aimed to evaluate the radiological impacts in Khanaqin, located in the Diyala Governorate, Iraq. The specific activities of natural radionuclides of 238 U, 232 Th, and 40 K in soil samples were investigated by collecting thirty composite soil samples from different locations in the area. Measurements were performed using a NaI(Tl) gamma-ray spectrometry system to acquire the data and analyses were conducted using the UCS-20 program. From the results, the average specific activities of 238 U, 232 Th, and 40 K were 25.15 ± 3.65 Bq kg −1 , 12.27 ± 2.28 Bq kg −1 , and 300.09 ± 14.50 Bq kg −1 , respectively. These results were lower than the global average recommended by UNSCEAR. The radiological risk criteria were estimated based on the specific activities of radionuclides to assess any radiological risks that may be associated with the soil of the study area under investigation. The radiological risk criteria included radium equivalent activity (Ra eq ), absorbed dose rate (D R ), annual effective dose (AEDE), annual gonadal equivalent dose (AGDE), excess lifetime cancer risk (ELCR), external hazard index (H ex ), internal hazard index (H in ), representative gamma index (I γ ) and effective dose rate to different body organs (D organ ). They were compared with the international safe limits. Overall, all the radiological risk criteria had values lower than the worldwide average recommended by UNSCEAR. This work employed statistical techniques to understand and explain the statistical characteristics of measured radionuclide-specific activities and the associated radiological risk criteria , including skewness, kurtosis, correlation coefficients, and K-means cluster analysis.