Radiological Hazard Assessment of Soil at North Oil Company Using Spatial Distribution and Monte Carlo Simulation in Kirkuk Governorate, Iraq

This study investigates natural radioactivity levels of ²³⁸U, ²³²Th, and ⁴⁰K in soil samples from the North Oil Company (NOC) area in Kirkuk, Iraq, and assesses associated radiological hazards. The activity concentrations were measured using gamma spectrometry with NaI(Tl) and were found to be 28.51 ± 1.42, 20.22 ± 1.01, and 331.51 ± 16.73 Bq kg⁻¹ for ²³⁸U, ²³²Th, and ⁴⁰K, respectively, which are all lower than the global average. The radiological hazard indices include radium equivalent activity (Ra_eq), absorbed dose rate (ADR), annual effective dose equivalent (AEDE), and excess lifetime cancer risk (ELCR). All indices were within acceptable limits. The geo-accumulation index (I_geo) indicated little contamination, with most values negative, indicating little or no anthropogenic effect. The kriging interpolation indicated localized hotspots in the spatial distribution, whereas Moran's index test indicated random spatial patterns. The Monte Carlo Simulation indicated uncertainties with the ELCR, but the average value of 1.88 × 10^{- 4} is considered slightly elevated. The multivariate statistical analyses, including Spearman correlation and cluster analysis, showed links between radionuclides and risk indices. The study showed that the current radiological risks in the NOC area are low, but require monitoring due to oil extraction activities potentially impacting people. This study provides fundamental knowledge that can be applied to evaluating the environment and public health aspects surrounding oil production.