Testing models for predicting the behaviour of radionuclides in aquatic systems.

The paper describes the main results of the international EMRAS model testing exercise for radionuclide transport in watershed-river and estuarine systems. The exercises included the following scenarios: multi-point source of (3)H discharge into the Loire River (France), radioactive contamination of the Dnieper-Southern Boug estuary (Ukraine), remobilisation of radionuclide contamination from the Pripyat River floodplain (Ukraine) following the Chernobyl accident, release of radionuclides into the Techa River (Russia) and behaviour of (226)Ra in the Huelva estuary (Spain).

Assessment, validation and intercomparison of operational models for predicting tritium migration from routine discharges of nuclear power plants: the case of Loire River.

During last decades, a number of projects have been launched to validate models for predicting the behaviour of radioactive substances in the environment. The project of the "Aquatic" working group of the project EMRAS (Environmental Modelling for Radiation Safety) organised by the International Atomic Energy Agency (IAEA) was based on the validation and assessment of models for predicting the behaviour of radionuclides in the aquatic ecosystems. The present paper describes a blind test of models aimed at assessing the dispersion of tritium releases in the Loire River (France), on a large domain ( approximately 350km) and on a period of six months, by comparing the results obtained by operational-to-experimental values of tritium concentration at Angers, a city along the Loire River.