The paper presents results and interpretation of long-term monitoring of occurrence and behaviour of radioisotopes 3H, 90Sr and 137Cs in surface water in the vicinity of the Temelín Nuclear Power Plant. 3H, 90Sr and 137Cs originate predominantly from residual contamination due to atmospheric nuclear weapons tests and the Chernobyl disaster in the last century. The basic evaluated radioecological characteristics can be used in assessing the long-term kinetics of decline and behaviour of radionuclides and their potential release into the environment.
A very slow decline in 3H concentration at unaffected sites was observed. At sites downstream from the power plant the 3H concentrations were significantly higher, an evident impact of the power plant operation.
A decline in 90Sr and 137Cs concentrations was observed in all the monitored sites.