A transportation airlock has been installed into the design position at unit 1 of the Akkuyu NPP under construction in Türkiye. The airlock will insulate the inner compartments from the environment, and ensure safe transportation of nuclear materials and equipment into the reactor compartment. It was installed using a caterpillar crane.

The transportation airlock is a heavy and large-sized component comprising a 14-metre cylindrical chamber that is closed from both sides. Alternating opening of the gates ensures that the reactor compartment is sealed. The 260-tonne housing has a seven metre diameter. Using the transportation airlock Akkuyu NPP specialists will be able to deliver the high-tech equipment that is required for operation and maintenance of the reactor plant. This includes steam generators, the upper reactor unit, the reactor coolant pump, primary circuit pipelines and other products.

During NPP operation, containers with used fuel, fresh fuel casks and transport-and-handling equipment will pass through the airlock. The product is equipped with a special access control system to ensure that only authorised personnel can enter the inner compartments. Ionising radiation detectors are also installed inside to maintain reliable and safe operation. Rosatom said the airlock can be used for maintenance and repair of the equipment, which will save money and ensure more efficient operation of Akkuyu NPP.

"We have completed yet another important process operation and are one step closer to completion of containment installation in the reactor building of unit 1,” said Sergei Butskikh, First Deputy General Director of project company Akkuyu Nukleer and Director of the Akkuyu NPP project under construction. “It is a result of well-coordinated and labour-intensive work of Russian and Turkish specialists of the Akkuyu NPP project. In the coming days, we are going to start stressing the containment prestressing system. It comprises particularly strong metal ropes which exponentially improve the strength of the reactor's inner containment."

Rosatom has also completed installation of horizontal steam-heater separators (SPPs – Separatorov ParoPeregrevatelii) at unit 1. SPPs, part of the auxiliary systems of the steam turbine unit, are used to maintain the temperature and humidity parameters of the steam rotating the turbine rotor blades. The principle of operation of the SPP is based on centrifugal acceleration, which allows the separation of steam and water. When circulating through the separator, the steam-water mixture, large particles of water settle on the walls of the separator and partitions, and are then removed through the drainpipe. Internal parts in contact with wet steam are made of ferritic stainless steel, which eliminates erosive and corrosive wear. Each 317-tonne component is 22 metres long with a diameter of 4.5 metres.

Especially for the Akkuyu NPP, an enterprise of the Rosatom State Corporation manufactured horizontal SPPs. Previously, such equipment was manufactured only in a vertical version. An optimised modification of the SPP made it possible to combine two devices of a traditional design in one housing enabling their number to be reduced from four to two. Also, Russian manufacturers have almost halved the metal used in the SPPs, while generally increasing their efficiency, reliability and cost-effectiveness.

“The innovative horizontal layout of the SPPs allowed us to significantly reduce their installation time,” said Sergey Butskikh. “Installation of devices is an important stage in the assembly of components of a turbine installation, it will be followed by the installation of instrumentation and automation, as well as steam and pipelines, and then preparation of the turbine installation for testing.”

Akkuyu, Türkiye's first NPP, will eventually host four Russian-designed VVER-1200 reactors. The pouring of first concrete for unit 1 took place in April 2018, for unit 2 in June 2020, for unit 3 in March 2021, and for unit 4 in July 2022. Completion of unit 1 is expected in the third quarter of 2023. Rosatom is constructing the reactors according to a build-own-operate model. To date, the project is fully funded by the Russian side. However, Rosatom has the right to sell a share of up to 49% in the project to other investors.

Image (top): The transportation airlock in place at Akkuyu 1 (courtesy of Akkuyu Nukleer)

Image (bottom): Installation of the horizontal steam-heater separators which are used to maintain the temperature and humidity parameters of the steam rotating the turbine rotor blades (courtesy of Akkuyu Nukleer)