Fission gas release of LWR-MOX fuel under RIA condition

Amaya, Masaki  

A pulse irradiation experiment using the NSRR under high temperature- high pressure condition was carried out on a mixed-oxide (MOX) fuel rod which was irradiated in a light water reactor up to high burnup, and fission gas release from MOX fuel pellet during reactivity-initiated accident (RIA) was investigated. From the puncture test result of the test rod after the pulse irradiation, fission gas release from fuel pellet was estimated as about 40%. Based on the EPMA results on a cross section of the test rod after the pulse irradiation, the fission gas release from plutonium-rich region (Pu spot) was estimated as about 12%. From the comparison between the measured and estimated values, it is suggested that fission gas released also from the region excluding Pu spot. Large cladding residual hoop strain was observed in the fuel rod after the pulse irradiation. It is likely that an increase of rod inner pressure due to fission gas release acts as a driving force of the deformation.