Radiometric Assessment and Radiological Hazard Evaluation of Soil around the Mymensingh 210 MW Combined Cycle Power Plant, Bangladesh

Abstract

This study explores the distribution and radiological impact of transporting naturally occurring radioactive materials (NORMs) in soils collected from the vicinity of the Mymensingh 210 MW Combined (heavy fuel oil/gas) Cycle Power Plant in Bangladesh. Twenty-five soil samples were systematically collected at radial distances of 250, 500, and 1000 m from the power plant to assess the spatial variation in radioactivity levels. The measured activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K ranged from 18 ± 1 to 34  ±  3, from 23 ± 2 to 60 ± 5, and from 340 ± 29 to 550 ± 35 Bq/kg, respectively. Although the ²²⁶Ra level did not exceed global average values, high levels of ²³²Th and ⁴⁰K, exceeding world average values, were revealed. Contrary to expectations of a gradual decrease in the radionuclide concentrations with increasing distance from the power station, their levels actually varied nonmonotonically. The results obtained can be explained by high variability of geological background conditions, mobility of radionuclides, and human impact on the environment. While radium equivalent activity and general hazard index were within international safety standards, some samples exceeded these values, which could lead to a potential threat to public health. Multivariate statistics analysis showed that ²²⁶Ra and ²³²Th were the main factors causing radiological hazard in the research area, whereas ⁴⁰K showed completely different behavior and formed a special cluster due to the presence of other geochemical processes related to its formation.