June 7, 2021, Büyükeceli, Mersin province, Turkey. – Third tier of the internal containment shell installed at the Akkuyu NPP Unit 1 reactor building. The installation of a cylindrical structure weighing 322 tons took about a whole day.


The third tier of the internal containment shell is a welded metal structure consisting of 24 sections, each 11.5 m high, 5.8 m wide and weighing 13.4 tons. The sections were assembled into a single block 138 meters long in a circle. The structure was assembled near the Unit 1 reactor building. Upon completion of the assembly, the quality of all welded joints was confirmed by ultrasonic testing.


The installation of the third tier of the internal containment shell was carried out by one of the most powerful crawler cranes in the world using a specially developed technology, which requires the preservation of geometric parameters during installation - acceptable deviation from the intended diameter value is within the range of 5 mm.


After the third tier installation, the height of the reactor building increased by 11.6 meters and reached +28.55 meters. Further, specialists will have to do the joining of the second and third tiers, reinforcement and concreting of the shell. The walls will be 1.2 meters thick. In total, the internal containment shell will consist of four tiers and a dome. As soon as the installation of all elements is completed, the shell will be tested for tightness.


“Just a week ago, we installed the reactor pressure vessel of the first power unit and now we have passed another key stage of construction: the third tier of the inner containment has been installed in the design position,” First Deputy CEO - Director of the NPP under construction Sergei Butckikh noted. - We have picked up a good pace of implementation of the main stages of construction. The next key installation operations this summer will be performed at Unit 2 - the reactor shaft armored block, the second tier of the internal containment and the support truss installation are to be accomplished. We have completed the concreting of Unit 3 turbine building foundation, and the foundation slab of the reactor building will be ready soon.”


Akkuyu NPP reactor buildings will be equipped with a double containment shell. The outer containment shell is made from reinforced concrete and is designed to withstand any extreme external influences. The inner containment consists of a steel lining, which ensures the tightness of the reactor compartment, and special concrete. Internal containment shell is a localizing safety system of a nuclear power plant, it ensures the stability of the reactor compartment, serves as a support for pipeline penetrations and a polar crane, with the help of which the reactor maintenance operations are carried out at the NPP operation stage.