Latest laser working technology in nuclear power field

By utilizing the laser beam with relatively even phase, high energy density can be obtained, and the industrial expectation as a high performance heat energy source for material processing is high. Laser working has been put to practical use in various industries. By the increase of the power output of laser oscillators, the new utilization technologies of laser working has been advanced rapidly also in heavy industry field. As the typical examples of the practical use in nuclear power field, the welding of control cluster guide tubes and the welding of vibration stoppers for steam generator heating tubes in production processes, and the repair welding of steam generator heating tubes and the preventive maintenance technology by cladding on the internal surfaces of small bore pipes as the practical use in existing plants are briefly reported. Recently, the advance of laser oscillators is remarkable, and 25 kW CO2 laser and 4 kW YAG laser have appeared. As the new laser working technologies being developed, the underwater welding using large power YAG lasers, the laser cladding using powder-containing wires, the laser cutting of thick stainless steel and the stress relaxation technology by laser peening are described. (K.I.)