The impact of nuclear power stations and of a fuel reprocessing plant on the Rhone river and its prodelta

The Rhone, with its 6 nuclear sites (17 reactors of various types and a fuel reprocessing unit), presents a relevant example for comparing the impact of these various installations on the aquatic ecosystem. Artificial radioactivity (γ emitters, Pu, 3H, 90Sr...) and natural radioactivity are monitored in sediments and various living organisms in the river and its prodelta. A summary of the radioecological procedure is given and illustrated with examples selected from results obtained over the last fifteen years (data resulting from about 7500 samples taken up- and downstream of the installations and in the prodelta). The evolution of results obtained during this period by γ spectrometry on fish up- and downstream of the nuclear power station at Bugey and the Marcoule fuel reprocessing unit is presented. The role of aquatic vegetation as indicator of radiocontamination is also illustrated. The evolution in the concentration levels of γ emitting artificial radionuclides in sediments and mussels in the prodelta is commented on in order to show the global radioecological impact of the Rhone in the Mediterranean sea. The analyses presented show that it is possible to quantify the influence of each source term on the total artificial radioactivity of the compartments of the ecosystem. The source terms are atmospheric fallout from early nuclear weapon tests and of the Chernobyl accident, and liquid wastes of various composition from nuclear installations