The welding of the main coolant pipeline at the Turkish site was completed in 73 days and included 32 pipeline joints, which all underwent a high-temperature treatment, with special surfacing applied on the internal surface of the joints to protect against corrosion.
The process involved engineers, welders, fitters, pipe cutters, flaw detection and heat treatment specialists and quality control service employees. Ultrasonic and radiographic testing were among the methods used to check the joints.
The total length of the main coolant pipeline reaches 150 metres, with a wall thickness of 70 millimetres. During operation, pressurised water will circulate at temperatures of about 330 degrees Celsius. The primary circuit coolant transfers thermal energy through the heat exchanging surfaces of steam generators to water in the secondary circuit, where steam is generated for the turbine generator operation.
(Image: Rosatom)
Sergei Butckikh, CEO of Akkuyu Nuclear JSC, said: “Welding of the main coolant pipeline is one of the most critical process operations during the power unit construction. Quality was the main criterion at every stage. Having completed welding of the main coolant pipeline, we formed the unit’s primary circuit and created conditions for further piping installation on the equipment of the reactor plant and preparation of start-up and adjustment works.”
Background
Rosatom is building four VVER-1200 reactors at Akkuyu in Turkey under a so-called BOO (build-own-operate) model. According to the terms of the 2010 Intergovernmental Agreement between the Russian Federation and the Republic of Turkey, the aim was for the commissioning of the first power unit of the nuclear power plant to take place within seven years from receipt of all permits for the construction of the unit.
All four units at the site are under construction (Image: Akkuyu NPP)
The licence for the construction of the first unit was issued in 2018, with construction work beginning that year. The first steam generators were shipped to the site – for unit 1 – in August 2020. Nuclear fuel was delivered to the site in April 2023. The aim is for unit 1 to begin supplying Turkey’s energy system during 2026.
When the 4,800 MWe plant is completed, it is expected to meet about 10% of Turkey’s electricity needs.
Turkey has plans for a second nuclear power plant, at Sinop, and has also been in talks with China about plans for a third plant, in the Thrace region in the country’s north-west.
The country is also developing plans for small modular reactors, with the aim of adding 5 GWe of capacity by 2050 – which would mean the equivalent of at least 16 individual SMRs.
