October 22, 2021, Büyükeceli, Mersin Province, Turkey. – The fourth tier of the internal containment shell (ICS) was installed in the reactor building of the first power unit of Akkuyu NPP. The internal containment is one of the main elements of the nuclear power plant's safety system. The ICS ensures protection of the reactor compartment and acts as a support for pipeline penetrations and the polar crane, which is used to carry out nuclear reactor maintenance operations at the NPP operation stage.


The ICS consists of steal liner, which ensures leak-tightness of the reactor compartment, and special concrete. The fourth tier of the IC is essentially a welded metal structure comprising 24 sections (two separate tiers, 12 sections in each tier). The sections, 11.3 meters long and over 4 meters high, are welded to each other and assembled to form a single cylindrical structure fitted with reinforcements and embedded parts. The total weight of the structure is 142 tons; it has a height of over 8 meters and a length along the circumference of 138 meters.


First Deputy Chief Executive Officer of AKKUYU NUCLEAR JSC, Director of the NPP under construction Sergei Butсkikh commented on the successful completion of installation of the 4th tier of the ICS: "The fourth tier of the internal containment of the first power unit has been installed in the design position. This is the last cylindrical tier of the IC; at further stages, elements of the dome part will be mounted. The complex engineering operation is the result of many months of work: it took 84 days to pre-assemble the tier from individual elements. Further, we will have to perform welding of the third and fourth tiers, and reinforcement and installation of embedded parts including elements of the transport lock and the personnel lock."


After the installation of the fourth tier, the height of Unit 1reactor building increased by more than 8 meters and reached 36.65 meters.


Installation of the ICS tier is a time-consuming process operation. It took 13 hours to install the fourth tier into the design position using the Liebherr LR 13000 heavy crawler crane.


Concurrently with the construction of the internal containment, work is being carried out in the reactor building for construction of external walls, the reactor shaft, floors, and the mounting of supporting structures for steam generators installation.


Rector buildings of Akkuyu NPP Power Units are equipped with double-layered containment. The external layer is built of reinforced concrete and designed to withstand any extreme external impacts, such as earthquakes with up to 9 magnitude, tsunami, hurricanes, and their combinations.