One of the key events of the year happened at Unit 2 of Leningrad Phase II which is under construction. Erection of the inner containment of the reactor has been completed. The last tier was concreted up to 67 meters in height. Now, the builders will be able to start constructing the highest section of the dome up to 68.5 meters. 

The inner containment is the NPP localizing safety system. It is a pre-stressed reinforced concrete construction consisting of the cylindrical part and semi-spherical dome. To build the inner containment, 11,000 cubic meters of concrete and 3,000 tons of rebars were needed. Thickness of reinforced cast-in-place concrete of the inner containment was 1,200 mm that corresponds to the design requirements. 

“The erection of the inner containment is a complicated and lengthy process where serious material, engineering and labor resources were involved,” Pavel Ivanov, Leading Engineer of Construction Control (Technical Supervision) Department, Leningrad Phase II CD, noted. “In parallel with concreting, we build the pre-stressed system of the reactor containment. It was extremely important for us to complete the inner containment in due time so that to complete these works as well. Now we start the next large stage, i.e. the tension of vertical and horizontal wires of the reactor dome PSCS,” he added 

For the reference: 

The construction project of VVER-1200 of Leningrad NPP provides for the double containment over the reactor building: the inner and outer containments. In accident, the first is to prevent a release of radioactive substances in the environment and the second one is to serve as physical protection from natural and man-induced external impacts including earthquakes and tornadoes.