Since the time of the first loss-of-coolant accident (LOCA) experiments, which were largely conducted with fresh fuel, changes in fuel design, the introduction of new cladding materials and in particular the move to high burn-up have generated a need to re-examine the LOCA safety criteria and to verify their continued validity. As part of international efforts to this end, the OECD Halden Reactor Project (HRP) implemented a LOCA test series. The fourth test in this series, using a commercially irradiated segment with 92 MWd/kg burn-up, exhibited strong fuel fragmentation and dispersal upon ballooning and burst at 790°C. The fact that fuel dispersal could occur at cladding temperatures far lower than the temperature entailed by the current 1 200°C/17% ECR limit caused concern. The CSNI therfore posed a question to the NEA’s Working Group on Fuel Safety (WGFS): How could the Halden LOCA tests affect regulation?
This report provides a summary of the WGFS members’ evaluation related to this task.