The R&D Workshop ASK of Uralatomenergoremont (a subdivision of the branch of Atomenergoremont, specialising in the manufacture of robotic systems) has created a unique robotic arm for jamming defective steam generator pipes. It has already been tested in the presence of representatives of nuclear uitility Rosenergoatom and OKB Hydraulic, who confirmed that the robot meets technical specifications and can be used in the repair of NPPs this summer.
During the operation of the steam generator, the heat exchange tubes , the wall thickness of which is 1.5 mm, have to withstand extreme operating conditions - pressure of 160 atmospheres and a temperature of 300 degrees Celsius. As a result, defects can form on the tubes. If the tubes have an unacceptable defect, they have to be shut down. Jamming is a process in which experts insert a plug in the faulty pipe repair and then welded it to block the water outlet. Previously, to close the pipes, specialists from the repair company had to climb into the steam generator and manually performed the welding.
The robotic arm, ASK 565.00, which took two years to develop, muffles pipes based on the results of an automated eddy current inspection of the pipes, obtained by the robotic ASK 183. The device can undertake up to 40 plugs per hour, with an average time per tube of 2 minutes. The robot is highly accurate and the manipulator sees the entire grid of tubes inside the steam generator at the same time, and not individual sectors, so it does not require repeated reinstallation. Another advantage of the robot is its small size: it can be carried in two suitcases. At the work site, three specialists are needed to install it into the steam generator, and then the operator interacts with it remotely using the control panel.
The manipulator is ready for operation at NPPs with VVER-1200 and VVER-1000 reactors. In the future, a program will be developed and the design will be improved to work with VVER-TOI reactors. “As of today, the manipulator can be used at NPPs under construction and in operation, if defects are revealed during the inspection.” said Maxim Gorbov, head of the ASK R&D department at Uralatomenergoremont. “Now we are working on obtaining a patent, and we want to further advance the technology beyond the nuclear industry. For example, in petrochemistry, to work with equipment for heat exchangers.”