Radiological impact of the operation of two Steam Power Plants on the activity levels of 232Th, 226Ra and 40K in the sediments at Semarang and Cirebon, Indonesia

Abstract The radiological concentration and distribution of natural radionuclides of 232Th, 226Ra, and 40K in the surface sediments of two steam power plants (SPP) vicinity were investigated. Sediment samples were analyzed for radionuclides, organic matter, and grain size composition. The average concentration activity for 232Th, 226Ra and 40K in Semarang are 71.485 Bq·kg−1; 29.645 Bq·kg−1 and 570.459 Bq·kg−1 and in Cirebon 90.593 Bq·kg−1; 41.709 Bq·kg−1 and 725.788 Bq·kg−1, respectively. According to the Indonesian standards concentrations are still below the recommended values. The radionuclide concentration levels were influenced more by proximity to coal resources, than other factors such as organic content,sediment texture, and hydrodynamic processes. These data can be considered baseline data in this region and used as reference or baseline information. Thus, the data obtained in this study did not show any significant radiological health risk to the ecosystem in nearby areas of two SPP. Radiological parameters such as absorbed dose rate (Din), activity utilization index (AUI), annual effective dose equivalent (AEDEin), annual gonadal dose equivalent (AGDE), radium equivalent activity (Raeq), and hazard indices (Hex, Hin) showed some excess values when compared to standards.However, they were still comparable to values from other parts of the world.