Failure behavior of LWR fuel cladding under accident conditions; Key observations from fuel safety research program at JAEA

Nagase, Fumihisa ; Sugiyama, Tomoyuki ; Amaya, Masaki  ; Udagawa, Yutaka  ; Fukuda, Takuji; Mihara, Takeshi  

The Japan Atomic Energy Agency (JAEA) performs the comprehensive research program to better understand behavior of high burnup fuels under accident conditions. The high burnup fuel cladding fails by mechanical interaction with fuel pellets under RIA conditions. The failure threshold reduces with increasing burnup. The information has been accumulated on failure mechanism from mechanical property tests and computer code analysis as well as on the failure threshold from the NSRR experiments. Regarding fuel behavior in a LOCA, JAEA has obtained data on oxidation kinetics and fracture threshold and evaluated the high burnup effects. JAEA continues researches for clarifying fuel failure mechanism and improving safety evaluation methodologies.