PIE results on MOX fuel irradiated in MIHAMA Unit 1

This paper describes the results of the post-irradiation examination (PIE) on the MOX fuel rods irradiated in the Japanese commercial PWR, MIHAMA Unit 1. The objective of the PIE is not only to confirm the fuel integrity but also to build up the irradiation data base for MOX fuel design. After three cycles irradiation up to the assembly burnup of 23 GWd/t, they were examined at the site and further PIE was carried out on eight MOX fuel rods at a hot laboratory. The non-destructive test results of PIE proved the integrity of the MOX fuel rods up to the burnup of about 25GWd/t, and revealed the similar irradiation behaviour of dimensional change with the standards UO2 fuel rods. Results of the following destructive tests also revealed the similar irradiation behaviour of FGR, fuel pellet dimensional change and cladding oxidation with the standard UO2 fuel, and confirmed no abnormality in microstructure changes of fuel pellets. (author)