Summary

This paper presents an overview of the activities carried out in the framework of the SARNET project by the CIEMAT, INR, JRC/IE, GRS, UJV and VUJE partners involved in the validation of ASTEC on fission product (FP) release and transport experiments simulating severe accident conditions in the reactor circuit and containment. These activities were mainly devoted to the analysis of the Phébus experiments, FPT0, FPT1 and FPT2, which provided fundamental reference data for the severe accident research. The ELSA, SOPHAEROS, CPA and IODE modules were used respectively for FP release from the bundle, transport in the circuit, containment thermalhydraulics and aerosol behaviour, and finally iodine behaviour in containment. Studies on aerosol behaviour in the STORM experiments and iodine behaviour in the ThAI experiments are also summarized. In addition, integral ASTEC calculations were performed on the FPT1 and FPT2 Phébus experiments, using all FP modules in a coupled mode. Together with overview of the progress in the validation of main ASTEC modules, this paper also points out what are the needs for improvement of modelling in the future ASTEC V2 code versions. A