Welding work has begun on the main circulation pipeline, one of the key elements of the primary circuit of the reactor plant, at the second power unit of the Akkuyu NPP under construction in Turkey. The project is being implemented by the state corporation Rosatom in cooperation with the site operator Akkuyu Nuclear.
The installation and welding of the pipeline mean the actual unification of the reactor, steam generators, and main circulation pumps into a single closed heat exchange system. According to the press service, this is a high-tech operation, during which 32 welded joints will be made and about 260 tons of pipes and metal structures will be installed.
After welding is completed, each joint undergoes multi-level quality control using ultrasonic, capillary, and radiographic methods. This is followed by high-temperature heat treatment to relieve internal metal stresses, as well as the application of anti-corrosion cladding to the internal surfaces of the joints.
The main circulation pipeline is one of the most heavily loaded elements of the reactor plant. During operation, the primary circuit coolant will circulate through it at temperatures up to 330 °C and pressures of about 160 atmospheres. The total length of the pipeline exceeds 150 meters, with a wall thickness of about 70 mm, which places increased demands on the accuracy of installation and the quality of welding.
The company clarified that each weld has an individual marking and a fully traceable history of manufacturing, control, and acceptance. All operations are recorded in the executive documentation and stored throughout the entire life cycle of the power unit.