Development of X-ray CT apparatus for the post-irradiation examination; Practical application of the CT images

not registered; not registered ; Matsumoto, Shinichiro

The X-ray CT apparatus for post-irradiation examination (PIE) was developed and installed in the Fuel Monitoring Facility (FMF). The apparatus started the common use for PIE in 1999. In this paper, the practical applicability of the CT image of this apparatus, based on the CT data of JOYO fuel subassembly (PFD512) is described. The results are as follows. (1)By the three-dimensional visualization of the CT images, the visibility to observation of the inside situation of the fuel assemblies was remarkably improved. (2)CT image analysis provides quantitative information such as the fuel pin rearrangements. It is expected as the data, which can reflect in the sub-channel analysis, etc. (3)By the CT data, it was confirmed that the information of the density variation of fuel pellets and ducts was obtained. Though the comparison with the destructive tests was necessity, this data is useful for evaluation when the swelling is big. (4)The apparatus measured fuel pellet center void diameters with an accuracy of about 0.1mm. This data is useful for confirming irradiation conditions and for selecting the position for optical macrograph observations. (5)The three-dimensional image provides fuel stack length and overall pin length without dismantling the fuel subassembly. The X-ray CT apparatus for PIE is useful for the early detection of fuel subassembly abnormalities and intermediate inspections of continuous irradiation rigs where dismantling is not permitted. The apparatus is also usefu1 for the selection of pins and observation positions in detailed destructive tests.