Article published by EDP Sciences and available at http://www.edpsciences.org/radiopro C. ROMMENS et al dispersion of gases and aerosois into the environment (ahnosphere contamination and ground deposition), their transfer in the biosphere (soils, plants and animals) and their impact to a memher of the public (individual effective and equivalent doses, external exposure to the plume and to the deposits, interna1 exposure hy inhalation and ingestion). FOCON96 uses ergonomic windows and proposes many capahilities (modnlar architecture, default values, choice of libraries, acces to al1 the parameters of the models, listing of resniîs, management of resnlt iïies, calculations made directly, etc.). In the European context, an intercomparison with the PC-CREAM code, developped hy the National Radiologid Protection Board, has shown the coherence of the results of the two codes. A comparison of the windows and capabilities has shown that FOCON96 was easier to use. FOCON96 is not adapted to calculate the doses received dnring one particnlar year that are due to the discharges of a facility in operation for a long period of t h e . An evolution of the software will he considered if this kind of assessment is generalized.

Dans son rapport remis aux ministres en 1999, le GRNC a indiqué la nécessité de mener des compléments d'études afin de combler certaines lacunes dans la connaissance de paramètres radiologiques. Le GRNC a également recommandé de prendre en compte des aspects autres que radiologiques. Suite a ces recommandations, les ministres de la Santé et de l'Environnement ont confié au GRNC une deuxième rnisîion portant sur l'étude des incertitudes associées aux résultats de la première mission, et la prise en compte des rejets chimiques. De plus, à la faveur de diverses études publiées récemment par I'IRSN, des informations sur des concentrations de radionucléides peu étudiés jwqu'alors ont été obtenues et des paramètres ont été précisés. Des informations totalement nouvelles ont été acquises comme celles sur le chlore-36. Dans le présent texte les apports scientifiques obtenus depuis la publication du rapport GRNC sont résumés. RÉSUMÉABSTRACT Updating of scientific data following the Nord-Cotentin Radioecology Group (GRNC) recommendations expressed in 1999.In its report submitted to the ministers in 1999, the GRNC indicated the need to carry out further studies sa that some gaps in the knowledge of radiological parameters are filled, and recommended ta take into acconnt aspects other than the radiological ones. Further ta these recommendations, the ministers of State of Health and Environment assigned the GRNC the responsihilitg of a second mission (study of uncertainties on the first mission results, and consideration of chemical releases). Then, about the radiological data used, thanks to various studies recently puhlished hy the IRSN, information concerning radionuclide concentrations, not much studied until then, has heen ohtained and parameters have been specified.Completely new information has heen acquired as chlorine-36 information. In the present text are summarized the scientific contributions ohtained since the GRNC report publication.i IRSN. B.P. IO. 50130 Cherhourg~OcteviIIr. France.