Critical element development of internal-access pipe welding/cutting equipment

In D-T burning reactors such as Fusion Experimental Reactor (FER), internal access welding/cutting of cooling pipe for in-vessel components, such as the divertor is inevitably required because of spatial constraints due to the nuclear shield and the available port opening space. For this purpose, internal-access pipe welding/cutting using a CO/sub 2/ laser beam is being developed. A welding/cutting processing head with a 10 kW CO/sub 2/ laser beam has been fabricated and the basic feasibility has been successfully demonstrated for studies of the internal-access pipe welding/cutting concept using a 100-A stainless steel pipe with 6.3 mm thickness. In this study, the optimum focal point of the laser beam, laser beam power and travel speed of the head have been investigated together with the adjusting mechanism for the relative distance between the head and the pipe wall.