Presentation of evolutions of the CERES platform used to evaluate the consequences of the emissions of pollutants in the environment

The Radiological and Chemical Impact Laboratory (LIRC) of the French Atomic Energy Commission (CEA) is in charge of the development of modelling tools to evaluate the consequences on human health of releases of radionuclides or toxic chemicals in the environment, for emergency planning and for safety evaluation. In this context, the laboratory has developed the CERES application (Code d'Evaluations Rapides Environnementales et Sanitaires), in order that all impact calculations relative to CEA installations will be done using the same tools and methods. It is used to evaluate the consequences on human health of releases of isotopes in the environment, either for emergency planning or for safety evaluation. Various types of emissions can be simulated: atmospheric accidental emission, atmospheric emission during normal operation or emission in liquid media under normal operation. This application is used for emergency situations planning and for the realization of assessment calculations within a regulatory framework, for example in the safety documents relative to nuclear installations. It helps to evaluate either the consequences of accidental situations supposed to occur on installations or the impact of routine releases from single installations or nuclear sites on their near environment. A specific module is used to evaluate the dispersion and impact of tritium release and in normal situations for C-14 release. The ERASTEM module helps to estimate the release to environment in case of accidental situation on nuclear reactor. Two versions exist, one devoted to radiological impact evaluations, the other one devoted to toxic impact. This platform is used on every CEA site, either for emergency situation and impact studies on human health. Recent evolutions of these platforms follow demands expressed in CEA user's group. According to radiological version, these evolutions mainly concern the implementation of isotopes and the evaluation of atmospheric dispersion and consequences of routine releases of short duration (i.e less than 1 year). A new version for the evaluation of impact of radon release has also been implemented. The impact of mud from water treatment station is also taken into account. For toxic releases, a work is in progress to simulate transfer in food chain and consequence of release of organic substances. An important work is also necessary to keep the database of substance characteristics up to date, mainly according toxicity reference values for chronic releases. This platform is validated through inter comparison exercises between codes. Results obtained for atmospheric releases, in accidental and normal situations, have been compared to results obtained with assessment codes developed by the French Support to Nuclear Safety (IRSN). Nevertheless we must keep in mind that these platforms are only helps to evaluate the safety of installations. Results are sensitive to input data, especially releases in the environment, even if tests are implemented to limit input errors. The correct use of these tools is linked to user formation and knowledge of installations and process. Document available in abstract form only. (authors)