Development of X-ray CT test apparatus for post irradiation examination. Post irradiation examination of irradiated 'JOYO' subassembly

The X-ray CT (Computerized Tomography) test apparatus has been developed as a non-destructive examination device for examining the internal condition of subassembly (Bundle Duct Interaction, etc) and for reflecting to soundness confirmation and fuel-life estimation, and installed in the extension facility of Fuel Monitoring Facility. In this report, the influence of gamma ray on CT image and post-irradiation examination faculties were evaluated in the case of fuel subassembly (PFD512) irradiated in 'JOYO'. (1) The CT and scanogram image of PFD512 (subassembly average burn up; 58,600 MWd/t) became possible to observe the internal state (arrangement of internal pins, distribution of the central void and crack) of irradiated subassembly. And it is not influenced by gamma rays emitted from an irradiated subassembly. (2) If the image ability of normal scan mode is evaluated in method defined by ASTM, the dimensional measurement accuracy is ±0.33 mm in the case of JOYO' subassembly. (author)