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Fig. 2-13 Photographs of the components of the new tool

One of the remote-handling tasks in the maintenance of an experimental fusion reactor is the cutting and welding of the cooling pipes in the blanket modules. A cutting and welding tool has been developed, for use in the branching pipes (with inner diameter of 50 mm, and wall thickness of 3 mm) connected with the main laying pipes (with inner diameter of 100 mm, through minimum pipe-curvature radius of 400 mm). Many trial tests have been performed, and all of the results have been successful. The tool is composed of four parts: a welding/cutting head, a distance sensor, and two transportation units, A and B. The four parts are connected by signal lines and an optical fiber and move together. The transportation units A and B work like an inchworm, moving the tool inside a pipe at speeds of up to 50 cm/min. The distance sensor unit determines the position in the pipe, and fixes the welding/cutting head at the required position. Welding and cutting is then performed using a 2 kW laser beam sent along the optical fiber. If the tool malfunctions, it can be rescued by extraction. We expect that this technology will prove to be very useful for ITER, and for a wide range of other remote-handling assembly and maintenance tasks.

Reference M. Nakahira et al., Development of Remote Handling Tools and Equipment, Purazuma Kaku Yugo Gakkai-Shi, 73 (1), 54 (1997).

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