Data for FUMEX: Results from fuel behavior studies at the OECD Halden Reactor Project for model validation and development

Investigations of phenomena associated with extended or high burn-up are an important part of the fuel and materials testing programme carried out at the OECD Halden Reactor Project. The in-core studies comprise long term fuel rod behavior as well as the response to power ramps. Performance is assessed through measurements of fuel centre temperature, rod pressure, elongation of cladding and fuel stack, and cladding diameter changes obtained during full power reactor operation. Data from fuel behavior studies at the OECD Halden Reactor Project, provided for the IAEA co-ordinated research programme FUMEX, are used to elucidate short and long-term developments of fuel behavior. The examples comprise: fuel conductivity degradation manifested as a gradual temperature increase with burn-up; the influence of a combination of small gap/high fission gas release on fuel centre temperature (situation at high burn-up); fission gas release during normal operation and power ramps, and the possibility of a burn-up enhancement; PCMI reflected by cladding elongation, also for the case of a nominally open gap, and the change of interaction onset with burn-up. (author). 10 refs, 9 figs, 1 tab