[en] In a highly irradiated wire spaced FBR fuel pin bundle, BDI (Bundle-Duct-Interaction) would occur and the significant bundle deformation due to BDI would be one of the life limiting factors of the bundle. Aiming at evaluating the bundle deformation behavior under the BDI condition, PNC has conducted the out of pile bundle compression tests. In these tests bundle cross sectional views are taken as CT images by applying the X-ray computer tomography (CT) technique. PNC has been developing a computer program which analyzes digital data of these CT images (CT image data) numerically and calculates the typical local parameters of bundle deformation status such as pin-to-duct clearance, pin-to-pin clearance etc. to be used for the evaluation of bundle deformation behavior and the validation of the bundle deformation analysis codes in PNC. The CT image analysis program is available in the PNC's Unix Workstation. This report describes the overview of this CT image analysis program, the methods of the CT image data analysis and sample results of this program. (J.P.N.)