of Nuclear Installations Flavio Parozzi*; Sandro Paci** ICONE14 14th International Conference on Nuclear Engineering Miami Florida, 17-20 Luglio 2006 * CESI RICERCA ** UNIVERSITA’ DI PISA ECART can simulate the thermal-hydraulic behavior of LWR and GCR plants under severe accident conditions together with the transport of radiotoxic substances. This tool is still under improvement and assessment for new applications in non-nuclear risk studies, new advanced and fusion reactors. As regards accidents with fires within closed environments, specific models can simulate both thermal and chemical processes, accounting for combustion of gases and solids, as well as pool fires. The radiative heat transfer and the action of water sprays on atmosphere cooling and aerosol removal are properly taken into account, as verified by comparing the code predictions to full-scale experiments and to the consequences of fire accidents really occurred. About its application on tokamak fusion plants, a large validation activity is underway, mainly based on the analyses of ad hoc experimental programs or code benchmark promoted inside EURATOM Fusion Technology Programme. The correct simulation of the main phenomena occurring in ICE and STARDUST facilities, as well as the comparison with the results of codes employed in the fusion safety studies, demonstrates the applicability of ECART models in performing a realistic prediction of the whole incidental sequence, accounting both thermal- hydraulics and dust transport also inside fusion plants.