Preliminary assessment of surface inspection using visual imaging sensors for DEMO service weld seam

Maintenance of DEMO breeding blanket includes the removal and replacement of plasma facing components. Due to the components having an active cooling loop, multiple coolant pipes need to be removed to allow access to the tokamak. The connection then needs to be reconnected using the replacement components. To fulfill the safety requirements, the welded connection needs to be inspected and approved for operation. Due to the space restriction of DEMO vacuum vessel, both the welding procedure and the subsequent inspection procedure must be conducted from inside the pipe bore. One of the methods currently under development in DEMO remote maintenance work package is visual inspection method designed to inspect the surface of the pipe weld seam as an alternative inspection method. This study presents the comparison between stereo RGB cameras and laser triangulation-based system for use in demo service joining. This includes the comparison between the visual inspection systems for their capability to detect the pipe weld seam, detect any pipe weld defect if present and quantify the size of the pipe defect. With the result from each visual inspection system, a comparative advantage and disadvantage analysis of each sensor is carried out and the result of the analysis is then used for further development and integration of the inspection system into the overall cut and weld concept.