IN- AND EX-VESSEL CORIUM STUDIES AT JRC-ITU, KARLSRUHE

This article gives an overview of the severe accident research as part of the reactor safety programme at JRC-ITU Karlsruhe. ITU has been examining the high temperature properties of U-Zr-Fe-O materials fabricated in the institute using a laser heating and pyrometry system to observe the various melting transitions. It has also examined selected ex-vessel compositions. The paper then describes samples taken from major severe accident studies including the melted material from TMI-2 and degraded bundles from the French IRSN Phébus PF project. The comparison of the small and large-scale studies illustrate how the similar processes are observed and how the small scale testing can help understanding of reactor core degradation. In particular the oxidation conditions during the accident can greatly effect the mechanism and extent of the core's collapse.JRC.G.I.3-Nuclear Fuel Safet