UNDERWATER WELDING FOR RESTORATION TUBING FOR NUCLEAR POWER GENERATION

摘要

PROBLEM TO BE SOLVED: To discover a crack at tubing to repair it in light water, in reference to risk of cracks occurring in a cooling pipe at a nuclear-power plant due to vibration of earthquake, and radioactivity flowing out into sea, in view of the fact that the number of cooling pipes is about 10,000; even one of them shows a crack, water contaminated with radioactivity is leaked out to sea water; and stopping of sea water pouring causes a nuclear reactor run-away to occur.SOLUTION: A synthetic silica glass incident window for feeding Nd/YAG laser beam to a steam condenser in which tubing to be repaired is stored or to an outer wall of a water steam generating unit is installed, a reflection mirror or a concave-surface mirror covered with a plurality of protective films capable of flapping in light water or water within the steam condenser and the water steam generating unit is arranged and the laser beam is applied uniformly for scanning or concentrated at a damaged location and then a laser underwater welding is carried out in real time.SELECTED DRAWING: Figure 6