The importance of monitoring radioactivity in surface waters downstream from nuclear power plants

Radioactivity monitoring in the Republic of Serbia is defined by Law on Radiation and Nuclear Safety and Security (Official Gazette of RS, No. 95/2018 and 10/2019), along with a series of Rulebooks, including the Rulebook for Establishing Programme of Systematic Environmental Radioactivity Examination (Official Gazette of RS, No. 100/2010), and Rulebook on Radioactivity Monitoring (Official Gazette of RS, No. 97/2011). In accordance with these regulations, in Serbia regular and systematic sampling of various environmental matrices, including air, precipitation, soil, vegetation, foodstuffs, drinking water, surface waters are conducts. Surface water monitoring plays a critical role in Serbia’s radiological surveillance system due to the country’s geographical position downstream from two operational nuclear power plants: Nuclear Power Plant Krško in Slovenia, and Nuclear Power Plant Paks in Hungary. In the event of a radiological incident, these upstream facilities could impact major rivers flowing through Serbia, primarily the Sava and the Danube River Basin. The radioactivity monitoring program focuses on measuring the concentrations of naturally occurred radionuclides as well as artificial such as Cs-137, Sr-90, and tritium. Additionally, following the signing of the Agreement between the Government of the Republic of Serbia and the Government of Hungary on Cooperation in the Field of Sustainable Management of Transboundary Waters and River Basins of Common Interest, radioactivity monitoring has been established in the Danube River at the transboundary section with Hungary, specifically at monitoring stations located in Bezdan (Serbia) and Mohács (Hungary). This monitoring represents a key component of transboundary water quality control and plays an important role in the early detection of potential radiological impacts originating upstream, including those associated with the operation of nuclear power plants such as Paks in Hungary. Monitoring radioactivity in surface waters is of critical importance for environmental protection and public health, particularly in terms of detecting artificial radionuclides. Nuclear power plants, which are primarily located on major rivers, present potential sources of radioactive contamination, especially in the event of accidents or contamination during cooling processes. Artificial radionuclides such as Cs-137 and Sr-90, can have long-term ecological and health impacts. Therefore, early detection of these radionuclides in aquatic ecosystems is essential. Given that rivers serve as the primary watercourses for the cooling systems of nuclear plants, there is a real risk of these pollutants being transferred into broader ecological systems. An effective surface water monitoring system, which includes analyses for artificial radionuclides, enables timely detection and the implementation of preventive measures to mitigate the risk of long-term environmental and health consequences.