Estimation of natural radioactivity and radiological hazards in river sediments (sand) used as building materials in South Africa

This study presents an investigation into the natural radioactivity levels of ²³⁸U, ²³²Th, and ⁴⁰K using a thallium-doped sodium iodide (NaI(TI)) detector and associated radiological hazards in river sediments, specifically sand, which serves as a crucial building material in the KwaZulu-Natal Province of South Africa. The assessment aims to provide insights into potential radiological risks posed by the utilization of these sediments in construction activities. The mean activity concentrations of ²³⁸U, ²³²Th, and ⁴⁰K are 145.33, 38.67, and 362.67 Bq kg^-1, 124.64, 60.60, and 353.00 Bq kg^-1, 144.00, 48.80, and 371.00 Bq kg^-1, 92.95, 52.00, and 368.75 Bq kg^-1, 133.55, 45.60, and 324.40 Bq kg^-1, and 109.50, 52.50, 381.50 Bq kg^-1 for Umngeni River, Umsunduzi River, Ashburton Sarupen, Hammersdale, Kwanjobekazi, and Cator Ridge, respectively. The obtained values of the radiological hazard indices (radium equivalent activity, external hazard index, internal hazard index, and activity utilization index) were below the world average values reported for building materials. Therefore, the studied samples are radiologically safe for use as building materials in the study area because they may not constitute any severe radiological hazards to residents.