A panoramic image stitching method for nuclear fuel assemblies

The fuel assembly (FA) is the core component of the nuclear reactor, and inaccurate inspection of FA bending and deformation can cause severe disasters in nuclear power plant reactors. It is an important task to restore a panoramic image of the FA from the video collected by the orthogonal visual inspection system. It can provide a more intuitive qualitative observation. Meanwhile, it is conducive to the estimation of deformation. This paper proposes a panoramic image stitching method for nuclear FA, which classifies video frames into grid images (GI) and non-grid images (NGI). It utilizes the speed of GI frames to estimate the speed of NGI frames. The horizontal offset and vertical offset between frames are estimated in two steps. The high-quality panoramic image can be obtained by image fusion. The experimental results indicate that the proposed method can achieve the panoramic image stitching of simulated samples and actual FAs with a deformation estimation accuracy of 0.3 mm. The proposed method has been verified and used in actual nuclear power plant reactor maintenance.