The reactor pressure vessel (RPV) has been installed at unit 1 of the Akkuyu nuclear power plant under construction in Turkey. Russian state nuclear corporation Rosatom, which is constructing four VVER-1200 reactors at the site in Mersin province, described the milestone as "one of the key stages in the main equipment assembly".

The RPV for Akkuyu 1 is lifted into place within the reactor building (Image: Rosatom)

Prior to the installation of the RPV, the core catcher was mounted at unit 1, concreting of the support and thrust trusses was carried out, and dry shielding and thermal insulation of the reactor vessel cylindrical part were installed. Shortly before the RPV installation, the support ring carrying the main weight load of the vessel was installed.

The vessel - weighing 330 tonnes, 4.5 metre in diameter and 12 metres in height - was installed within the reactor building of unit 1 using a Liebherr LR 13000 self-propelled crawler crane with a lifting capacity of up to 3000 tonnes. The component was lifted above the reactor compartment and installed in the reactor shaft.

"The installation of the reactor pressure vessel of Unit 1 is one of the main events within this year. On 21 April, we mounted a support ring on which the reactor vessel is installed. It is a structural element of the reactor plant, designed to secure the vessel, keep it from horizontal and vertical displacements when exposed to loads. And now the reactor vessel has been installed in the design position," said Sergei Butckikh, first deputy CEO of Akkuyu Nuclear JSC and director of the Akkuyu plant. "Completing of the RPV installation will allow us to continue work on the reactor shaft construction."

Rosatom noted the installation of the RPV was carried out under the "Open Top" construction method, through the uncovered top of the cylindrical part of the reactor building. This enables construction and installation operations to be carried out simultaneously, allowing the start of equipment installation and pipeline assembly before the completion of concreting of the floors. It said this technology has successfully proven itself at nuclear power plant construction projects in China, Japan, Bulgaria and Russia, including the construction of the Leningrad II units, which feature VVER-1200 reactors. Open Top technology will be used for installation of steam generators, pressure compensators, main circulation pumps and other main technological equipment in the reactor buildings of the Akkuyu plant.

Following the installation of unit 1's RPV, construction workers will now proceed with concreting the reactor shaft, installing bearings for the main circulation pipeline components and steam generators. After the installation of the steam generators and casings of the reactor coolant pump set, it will be possible to start welding the main circulation pipeline, which connects the main equipment of the unit's primary circuit.

The 4800 MWe Akkuyu plant is expected to meet about 10% of Turkey's electricity needs. Turkey aims to bring unit 1 online in 2023, the centenary of its foundation as a republic.

Researched and written by World Nuclear News