抄録
An X-ray computed tomography scanner (CT scanner) has been developed recently to inspect the inside of materials, such as ceramics, plastics, rubbers and light metals. The advantage of the CT scanner is that sensitivity of detection is about an order of magnitude higher than that of an ordinary radiography. For the purpose of investigating the ability of a CT scanner in nuclear grade graphite, some tomograms of graphite with artificial defects were tested using a CT scanner. Both a slit of 0.1mm in width and a hole of 0.2 mm in diameter could be detected by a CT scanner. The detecting limitation of defects was found to be dependent on the configuration of defects or the type of graphite. The configuration of macro- and micro-cracks, pores generated by oxidation were also confirmed from the tomogram. However, the accurate dimension of those defects could not be obtained from the tomogram. The distribution of density in graphite generated by oxidation could be obtained nondestructively using the distribution of CT values.
