Natural radioactivity and concomitant radiological risks in sediments of the Padma river near Rooppur Nuclear Power Plant of Bangladesh: Pre-operational status

In this study, natural radioactivity levels in sediments of the Padma River and concomitant radiological risks were assessed. Sediment samples were collected from the Padma River near the under-construction Rooppur Nuclear Power Plant (RNPP) of Bangladesh and analyzed for 226Ra, 232Th, and 40K radioactivity levels using a gamma-ray spectrometry system. The activity concentrations (Bq kg-1) of 226Ra, 232Th, and 40K in sediments of the Padma River varied from 45.6 +/- 6.7 to 119 +/- 11 with average 73.2 +/- 17.4; 49.8 +/- 6.9 to 137 +/- 11 with average 86.6 +/- 20.3, and 540 +/- 23 to 1,032 +/- 32 with average 782 +/- 146, respectively. This study indicates that activity concentrations of these radionuclides in the Padma River sediments are relatively higher than the world average values. Among the seven radiological hazard indices determined, four of them: radium equivalent activity, annual effective dose rate, and external and internal hazard indices are within their international guideline values. However, values of absorbed dose rate, gamma representative level index, and excess lifetime cancer risk are considerably higher at all sampling points, suggesting radiological risks for the river environment. The statistical analyses revealed a strong correlation between 238U and 232Th radionuclides. The spatial distribution of activity concentrations and radiological hazard indices for the studied area will serve as a documented radiological reference for the Padma River near RNPP. This study recommends routine monitoring of the radionuclides in the surrounding regions of RNPP to assess any post-operational environmental impact due to radionuclide contamination.