The Leningrad NPP-2: the reactor check assembly has begun at the VVER-1200 2nd power block under constructio

The reactor check assembly has been started at the innovative VVER-1200 2nd power block under construction at the Leningrad NPP-2.

To conduct this critical operation, all structural units of the reactor facility have been delivered to the containment area of the reactor building: the in-vessel core barrel, the baffle, the reactor head and the protective tube unit. Besides, the ‘clean’ assembly zone has been established for large-sized equipment, and the latter will be gradually installed into the reactor’s vessel.

At first, the in-vessel core barrel weighing 75 tons will be installed using a polar crane. The main designation of this barrel is to facilitate the designed placement of all the equipment inside the vessel and to organize heat carrier flow in the reactor during the operation.

‘The assembly team is facing a challenging task – they need to join two large-sized elements of the reactor with pinpoint accuracy’, Vitaliy Demchenko, the deputy head of the centralized maintenance workshop at the Leningrad NPP-2, said. ‘Following all control measurements, they will install the baffle, the protective tube unit and, finally, the reactor head’.

According to the schedule, all reactor check assembly operations will take around two weeks. Afterwards, the equipment will be removed from the reactor vessel and placed at its storage.

‘The check assembly is just the first operation around the in-vessel equipment, and the reason we do this is to verify its quality and compliance with the technical standards’, Alexey Mochalov, the deputy head of the reactor workshop at the Leningrad NPP-2, explained. ‘It will be disassembled again before the liquid release over the open reactor, and the reactor will be re-installed with dummy assemblies for the hydraulic tests. This dummy procedure is required to imitate the reactor core physical dimensions. The reactor will be fully assembled in September 2019 for another key operation – the cold and hold functional tests’.

The Leningrad NPP is the country’s first plant with RBMK-1000 reactors (uranium-graphite circuit-type reactor running on thermal neutrons). The decision that marked its construction was taken in September 1966 by a resolution of the Central Committee of the Communist Party of the USSR and the Council of Ministers No. 800-252. According to that document, the Leningrad NPP was supposed to become a core in a network of nuclear power plants with RBMK-1000 reactors that were supposed to produce a substantial share of electric power. The construction of the Leningrad NPP was going well, and by 1973 the first power block was fully erected. On December 23, 1973, following stable 72-hours’ operation at the capacity of 150 megawatt, the State Commission signed the acceptance certificate stating that the first power block of the Leningrad nuclear power plant is commissioned for pilot production. 

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