Modelling of Zr-O and U-Zr-O melts oxidation and new crucible tests

Abstract

This report summarises the results of task WP7.2 of the European COLOSS Project conducted within the 5 t h Framework Programme on Nuclear Fission Safety. The objective of this multi-partner task is the development of models regarding the oxidation of U-O-Zr mixtures, in particular: Models that can adequately simulate the oxidation of U-O-Zr mixtures and related H 2 production during the core degradation phase of a severe accident. Models that can be integrated in SA codes. In order to modelling of Zr-O and U-Zr-O melts oxidation, it was agreed to use available FZK data on post-test examinations of molten materials oxidation in the CORA and QUENCH bundle tests, as well as new FZK tests (described in the Part I) on ZrO 2 crucible dissolution by molten Zry. These single effect tests were specially designed for the investigation of long-term behaviour during the melt oxidation stage. On this base, a new model (Part II of the report) for oxidation of molten Zr-O and U-Zr-O mixtures in steam was developed, in order to analyse and explain the H 2 peak production during the quenching of degraded rods.