Patent Number: 062597590
Section: claims

1. An incore piping section maintenance system for performing a preventive-maintenance operation to a maintenance target portion in a reactor pressure vessel, comprising: a maintenance system main body fixed to the reactor pressure vessel in the vicinity of the maintenance target portion;  a moving means mounted to the maintenance system main body and movable with respect to the maintenance system main body;  a support means connected to the moving means and movable toward the maintenance target portion as the moving means moves with respect to the maintenance system main body, the support means including a laser de-sensitization treatment means to irradiate the maintenance target portion with a laser beam and seal means to keep an area around the maintenance target portion free of water;  a laser generation means for generating the laser beam; and  an optical transmission means guiding the laser beam to the laser desensitization treatment means. 2. The incore piping section maintenance system according to claim 1, wherein the laser de-sensitization treatment means includes an inspection monitoring means for monitoring the maintenance target portion. 3. The incore piping section maintenance system according to claim 1, wherein the laser de-sensitization treatment means includes a polishing means for polishing the maintenance target portion. 4. The incore piping section maintenance system according to claim 1, further comprising a cylinder member fixed to the maintenance system main body and an actuating rod extending from the cylinder member for pressing an inner wall of the reactor pressure vessel to fix the maintenance system main body to the reactor pressure vessel. 5. The incore piping section maintenance system according to claim 1, wherein the seal means include expandable seal members disposed around the laser desensitization treatment means and the area around the maintenance target portion between the expandable seal members is filled with a gas. 6. The incore piping section maintenance system according to claim 5, wherein the maintenance target portion is a pipe located in the reactor pressure vessel. 7. The incore piping section maintenance system according to claim 1, wherein the laser de-sensitization treatment means includes a maintenance target portion detector for detecting and confirming the maintenance target portion. 8. The incore piping section maintenance system according to claim 7, wherein the maintenance target portion detector is an ultrasonic flaw detector. 9. The incore piping section maintenance system according to claim 7, wherein the maintenance target portion detector is an ferrite indicator for distinguishing a difference in ferrite quantity between the maintenance target portion and a base material around the maintenance target portion. 10. The incore piping section maintenance system according to claim 9, wherein the maintenance target portion is a weld zone of a pipe located in the reactor pressure vessel.