Study on Underwater Remotely Operated Welding System in Nuclear Power Stations Repair

Underwater welding repair in nuclear power stations is usually carried out by diving welders, with features of great dangers and uncertainty of joint quality. An innovative automated underwater local dry MIG welding system is developed, and may be applied to take the place of underwater welders in nuclear power plants repair. Underwater welding test chamber is built to simulate 30 meters water depth, the chamber is a large vertical pressure vessel with a hydraulic driven cover and three viewing systems, to obtain images from surface, welding arc and underwater. Remotely eperated underwater welding equipment is a three-dimentional platform, also driven by hydraulic servo valves, to realize travelling, oscillation, and vertical adjustment needed by welding. Argon is transferred into the shielding cup, to drive water from the cup bottom and build a local dry space around the welding gun. Welding test of 304 stainless steel under 15 meters water depth are carried out, perfect NDT and mechanical test results are obtained. The remotely operated underwater welding technologies will contribute to the progress of nuclear power plants repair.