Post-test calculations with ISAS-ITER system for ICE experiments

In the frame of the Safety and Environment tasks of the European Technology Program for ITER project one of the main issue is the validation of the computer codes and models used as reference for ITER safety analysis to obtain acceptance by licensing authorities. In the context of the fusion field facilities the data useful for validation are very limited because only few experimental machines are available as operating experience. To overcome this problem several integral and separate test experiments have been undertaken in the ITER program. The paper deals with the validation of the ISAS-ITER system for ITER safety analysis against the results obtained in the experimental campaign carried out during the year 2000 in the ICE (Ingress of Coolant Event) facility built in JAERI, Japan. ISAS-ITER links together the computer codes ATHENA (for thermal-hydraulic transient) and INTRA (for containment simulation). The experimental campaign investigated the discharge of water and steam from a pressurised container towards a vacuum vessel volume (VV) and a suppression tank. The VV represents the typical configuration of the plasma chamber, scaled respecting the geometrical dimensions of the ITER-FEAT design. Choked flow conditions, condensation, jet impingement and evaporation phenomena are involved in the tests reproducing different experimental conditions. ISAS-ITER post-test calculations, presented in the paper, show a quite good agreement with the ICE experimental data and the discussion of the results allows to detect the analytical model approximations that are the cause of the main discrepancies.