Welding of main circulation pipeline completed for Unit 2 of Turkey's Akkuyu NPP

On August 27, welding of the main circulation pipeline was completed for Unit 2 of Turkey's Akkuyu Nuclear Power Plant. The pipeline connects the reactor, steam generators, and main circulation pumps, and is one of the key components forming the primary circuit system of the reactor facility.

The welding work lasted 73 days and involved welding 32 pipe joints. Engineering technicians, welders, fitters, pipe cutters, non-destructive testing personnel, heat treatment personnel, and quality inspection personnel participated in the relevant operations. During construction, each process step proceeded according to the established technological workflow, and welded joints had to pass inspection before moving to the next stage.

According to reports, all welded joints underwent high-temperature heat treatment to relieve internal stress in the metal and ensure compliance with design performance requirements. A special protective coating was also applied to the inner surfaces of the joints to reduce the risk of corrosion. After welding was completed, comprehensive inspections of weld quality were carried out on site using ultrasonic testing, penetrant testing, and radiographic testing methods.

Sergey Butskikh, General Director of Akkuyu Nuclear JSC, stated that main circulation pipeline welding is one of the key processes with high technical requirements in nuclear power plant construction. With the completion of this work for Unit 2, the primary circuit system is now ready for subsequent reactor equipment piping installation and commissioning preparation work.

The main circulation pipeline performs the function of reactor coolant circulation. During unit operation, deionized water will circulate between the reactor, steam generators, and main circulation pumps, and transfer reactor thermal energy to the secondary circuit water through the steam generator heat exchange surfaces, generating steam to drive the turbine generator. The pipeline operates under severe conditions, with internal coolant temperatures reaching up to 330 degrees Celsius and pressure of approximately 160 atmospheres, thus imposing high requirements on installation quality and welded joint reliability. The total length of the main circulation pipeline for Unit 2 exceeds 150 meters, with a wall thickness of 70 millimeters.

Akkuyu NPP is Turkey's first nuclear power plant, constructed with the participation of Russia's Rosatom. The project plans to build four VVER Generation 3+ reactor units of Russian design, with each unit having an installed capacity of 1,200 megawatts. The project is being implemented under the "Build-Own-Operate" (BOO) model.