Abstract
Laser peening is a process that introduces residual compressive stress on a metal surface by irradiating laser pulses underwater without any surface preparations. The process utilizes the impulsive effect of high-pressure plasma generated by ablative interaction of each laser pulse with material. A laser peening system, which delivers laser pulses with mirrors or through an optical fiber, was developed and has been applied to preventive maintenance against stress corrosion cracking (SCC) in nuclear power reactors since 1999. The system is composed of laser oscillators, a beam delivery system, a laser irradiation head, remote handling equipment and a monitor/control system. Beam delivery with mirrors was accomplished through alignment/tracking functions with sufficient accuracy. Reliable fiber-delivery was attained by the development of a novel input coupling optics and irradiation heads with automated focusing. The remote delivery of intense laser pulses opens up the possibility of new applications of laser technology.
