Development of high resolution X-ray CT technique for irradiated fuel assembly

Ishimi, Akihiro ; Kodaka, Hideo; Katsuyama, Kozo ; Furuya, Hirotaka

In order to observe the structural change in the interior of irradiated fuel assembly, the non-destructive post irradiation examination technique using X-ray computer tomography (X-ray CT) was developed. In this X-ray CT system, the 12 MeV X-ray pulses were used in synchronization with the switch-in of the detector to minimize the effects of the ray emissions from the irradiated fuel assembly. This method was applied to a fuel assembly irradiated in the experimental fast reactor JOYO, and images were successfully obtained of transverse cross sections at different heights of fuel assembly along its axis for the first time in the world. This X-ray CT technique can substitute non-destructive PIEs for a number of destructive PIEs. This has a great advantage to enhance efficiency of PIE and greatly reduces radioactive wastes generated during PIE.