Tests of the tightness of the inner containment of the reactor have been completed at unit 1 of the Leningrad-II nuclear power plant (also known as Leningrad 5), Aleksandr Belyaev, the plant’s chief engineer of said on 31 December. 

“The test results have confirmed that, after the first two years of commercial operation of the unit since October 2018, the shell of the reactor building is still strong and airtight,” he noted. “It is able to continue to withstand significant mechanical, thermal and other design loads. There are no defects, cracks or deformations.” The testing involved first evacuation and then overpressure.

The inner containment is a localising safety system  made of pre-stressed reinforced concrete with a thickness of 1000 to 1200mm and clad with 6mm carbon steel. Its task is to prevent the release of radioactive substances outside the reactor building in all operating modes of the nuclear power plant, including emergency situations. 

The check of the sealed enclosure was carried out during the scheduled   maintenance outage which began in October and will continue until early 2021.

The existing Leningrad nuclear power plant in Sosnovy Bor with four RBMK-1000 units is being replaced by Leningrad-II with four VVER-1200 units. Leningrad 1 was shut down for decommissioning on in December 2018 after Leningrad-II-1 was connected to the grid in March 2018. Leningrad-II 2 is replacing Leningrad 2, which was closed down in November after being in operation for 45 years. Formal commissioning for Leningrad II-2 is planned for 2021.