Assessment of state-of-art models for predicting tritium migration from routine discharges of Nuclear Power Plants: the case of the Loire River
Titre de la revue : Journal of Environmental Radioactivity
Volume : 99
N° : 2
Pagination : 367-382
Date de publication : 02/02/2008
During last decades, a number of projects have been launched to validate models for predicting the behaviour of radioactive substances in the environment. Some of these projects were dedicated to the prediction of the behaviour of the radionuclides in the fresh-water environment. Both the BIOMOVS (BIOspheric Model Validation Study; BIOMOVS, 1990) and the VAMP (VAlidation of Model Predictions; IAEA, 2000) projects stimulated intensive efforts at improving the reliability of the models aimed at predicting the migration of 137Cs in lakes and of 137Cs and 90Sr in rivers. The project EMRAS (Environmental Modelling for Radiation Safety, http://www-ns.iaea.org/projects/emras/), organised by the International Atomic Energy Agency (IAEA), continues some of the work of previous international programmes in the field of radioecological modelling (BIOMOVS II, 1996; BIOMASS, 2003). In particular, the working group "Aquatic" of the EMRAS project focused on the validation and assessment of models for predicting the behaviour of radionuclide in the aquatic ecosystem (Monte & al, 2006a; Monte & al., 2006b). The activities of the "Aquatic" working group were based on the extensive data sets of measured radionuclide concentrations in the components of fresh water ecosystems available following the Chernobyl and the Kysthyn accidents or from routine releases of radionuclides in the aquatic environment. In particular, the present work aims at assessing the performances of state-of-the-art models for predicting the migration of tritium through large rivers, an issue which were not afforded by the previous above-mentioned projects although several studies concerning the behaviour and the modelling of tritium in the environment were published in the international literature (Amiro, 1997; Raskob & Barry, 1997; Barry & al., 1999). As tritium does not interact with particulate matters in rivers, the results of this work can help at assessing the capabilities of state-of-the-art models to deal with the physical processes of convection and dispersion which drive the radionuclide transport in the aquatic system. The modelling exercise presented in this paper was performed for routine tritium releases of four nuclear power plants located along the Loire river. This exercise is a part of a more complete study on the evaluation of the increase of radionuclides in the downstream environment due to the releases of the nuclear power plant routines (Siclet, 2001; Siclet & al, 2002).