Assessment of natural radioactivity in soil samples collected around the thermal power plant area of Cuddalore district, Tamil Nadu

This study investigates the natural radioactivity levels of 238U, 232Th, and 40K in soil samples using a NaI (Tl) gamma-ray spectrometer. The primary objective was to determine the activity levels of radionuclides such as 238U, 232Th, and 40K in soil samples and to assess the related radiological risk. Based on these measurements, several radiological parameters, including radium equivalent activity (Raeq), outdoor absorbed dose rate (ADRout), annual effective dose equivalent (AEDEout), excess lifetime cancer risk (ELCRout), external hazard indices (Hex), and annual gonadal dose equivalent (AGDE), were calculated. Additionally, the effective radiation dose to specific body organs (Dorgan) was estimated to evaluate the potential biological impact of external gamma radiation exposure. The results indicate that the activity level of 238U slightly exceeds the world recommended limit of (35 Bq kg-1), while the calculated radiological variables such as ADRout (101 ± 13 nGy h-1), AEDEout (0.12 ± 0.02 mSv y-1), ELCRout (0.43 ± 0.08), and AGDE (366 ± 48 µSv y-1) were slightly higher than the internationally recommended safety limits. Multivariate statistical analysis was performed, helping to identify potential sources and interrelationships among the measured radionuclides and radiological variables.