Overview of recent and ongoing extended burnup studies at the OECD Halden Reactor Project

The OECD Halden boiling water reactor is a useful tool for providing well qualified in-reactor data from instrumented fuel rods. Recent experimental studies have included much work that relates to the behaviour of fuel rods at extended burnup. Temperature and fission gas release data have been obtained to burnups in excess of 35 MW·d/kg UO2; mechanical data on cladding and fuel elongation, cladding diameter and ridging, and fuel-cladding gap condition have also been obtained. In addition to providing direct measurements of conditions, a considerable amount of work has also been carried out to provide an understanding of what the measurements mean. (author)