Examinations on high burnup fuels to investigate fuel behavior under reactivity initiated accident conditions

The Japan Atomic Energy Agency (JAEA) investigates high burnup fuel behavior in reactivity initiated accidents (RIAs) using the Nuclear Safety Research Reactor (NSRR) and the Reactor Fuel Examination Facility (RFEF). RIA simulating pulse irradiation tests at the NSRR provide information on the fuel failure limit, fuel failure mode, post failure events which are required for the safety evaluation. Detailed examinations at the RFEF on the test fuel rods before and after the pulse irradiation tests provide knowledge on fuel cladding deformation, fission gas release, hydride precipitation states in the cladding and so on, which compliment the NSRR transient data and deduce the failure mechanism during an RIA