September 28, 2021, Büyükeceli, Mersin Province, Turkey. – At the construction site of the reactor compartment of the Akkuyu NPP second power unit, nuclear reactor shaft construction work is underway. The main elements of the shaft structure including the support truss, the thrust truss, the reactor's dry shielding, and the thermal insulation of the cylindrical part of the reactor pressure vessel have already been installed in the design position.


Installation of the support truss was carried out using a Liebherr LR 13000 heavy caterpillar crane. The support truss is one of the elements of the reactor shaft in the form of a welded metal structure, designed for reliable fastening of the reactor vessel in the concrete shaft. It performs the functions of protecting the reactor from weight and seismic loads. The diameter of the truss is more than 9 meters, and the weight is 88 tons. The installation took 1 work shift with a duration of 8 hours; currently, work is being carried out for its consolidation, concreting the cavities, and installation of measuring channels.


The thrust truss, used to secure the reactor vessel on the reactor vessel in the concrete shaft, is essentially a welded metal structure having a diameter of over 7 meters and a weight of 27 tons. The installation, which took several hours, was preceded by pre-assembly and welding of structural elements.


"Installation of the support truss and the thrust truss is one of the key events of 2021 during construction of the second unit of Akkuyu NPP. The successful completion of the installation allows continuing work on the construction of the reactor shaft. Installation of such large-sized structures is a complex type of installation, since the permissible deviation relative to the reactor shaft is only 2 mm. The specialists who were installing the trusses took into account the experience of similar work on the first unit; this enabled them to complete the work ahead of schedule, noted First Deputy Chief Executive Officer – Director of the NPP under Construction Sergei Butсkikh.


Earlier, in the reactor building of the second power unit, dry shielding of the reactor had been installed. This is a safety and biological protection element weighing 142 tons, which ensures reliable operation of the NPP in any emergency, including even earthquakes with an intensity of up to 9 points. It also ensures stable operation of ionization chambers – special measuring channels required to monitor changes in the reactor power.


The package of work to install the shaft components precedes theinstallation of the "heart" of the nuclear power unit — the reactor pressure vessel. Immediately before installation of the pressure vessel, the builders will have to mount a support ring, which will bear the main weight load of the vessel.


The reactor cavity equipment is used to secure the reactor during operation. At the same time, it serves as biological and thermal protection against the neutron flux of the reactor core.