June 1, 2021, Büyükeceli, Mersin province, Turkey. Unit 1 reactor pressure vessel (RPV) installation is completed at the Akkuyu NPP construction site. This is one of the key stages in the main equipment assembly. Prior to RPV installation, 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 installation required special preparation of the on-site roads in order to transport the RPV to Unit 1 construction area. After filling and leveling the roads along the entire route, a special wheeled platform freely passed the way from the equipment temporary storage site to Unit 1 building site. Then, using a Liebherr LR 13000 self-propelled crawler crane with a lifting capacity of up to 3 thousand tons, the RPV with a mass of 330 tons, diameter of 4.5 meters and height of 12 meters was set to the upright position, lifted above the reactor compartment and installed in its regular place in the reactor shaft.
“The installation of the reactor pressure vessel of Unit 1 is one of the main events within this year. On April 21, 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. I would like to note the impeccable work of the installation team and the operators of the lifting equipment. The installation of the vessel must be performed with pinpoint accuracy: the maximum permissible horizontal deviation does not exceed a tenth of a millimeter. Completing of the RPV installation will allow us to continue work on the reactor shaft construction”, - said Sergei Butckikh, First Deputy CEO of Akkuyu Nuclear JSC and Director of NPP under construction.
The progress of installation was controlled by representatives of the Nuclear Regulatory Authority of Turkey (NDK), the French Assystem engineering group as the independent construction control organization, OKB Gidropress (designer of the Akkuyu NPP reactor plant) and AEM-Technologies - the manufacturer of the reactor vessel.
The RPV installation was carried out under the Open Top technology, through the uncovered top of the cylindrical part of the reactor building. It enables to combine construction and installation operations in the best way possible and thus to start the equipment installation and pipelines assembly before the completion of the floors concreting. The technology has successfully proven itself at many NPP construction projects in China, Japan, Bulgaria and Russia, including the construction of the Leningrad NPP-2 power units with VVER-1200 reactors. Open Top technology is to be implied for installation of steam generators, pressure compensators, main circulation pumps and other main technological equipment of Akkuyu NPP reactor buildings.
After the RPV installation, construction workers will proceed with concreting the reactor shaft, install bearings for the main circulation pipeline (MCP) components and steam generators. After the installation of steam generators and casings of the reactor coolant pump set, it will be possible to start welding of the MCP, which connects the main equipment of the NPP primary circuit.
The RPV for Unit 1 was delivered to the Akkuyu NPP construction site by sea in November, 2020. After unloading the vessel at the Eastern Cargo Terminal, the RPV was transported to the storage site, where it underwent the incoming inspection procedure that confirmed the integrity and high quality of the vessel manufacturing.