The Leningrad NPP-2: the upload of the dummy assemblies into the reactor vessel has begun at the 2nd VVER-1200 power block

The first dummy assemblies were delivered into the containment area of the innovative 2nd VVER-1200 Leningrad NPP-2 power block’s reactor hall and uploaded into the reactor vessel on September 6, 2019. All in all, the team needs to upload 163 assemblies.

The activity was subdivided into several stages: at first, the assemblies were moved from the fresh fuel storage to the power block construction site using special vehicles, 27 units per each transfer basket. Following that, an equipment airlock crane and a transport trolley, they were moved into the containment area via a railway and temporarily placed onto the middle level of the reactor building. At the end, the dummy assemblies are uploaded into the reactor vessel using a refueling machine.

A dummy assembly is a piece of equipment which constructively fully imitates standard reactor fuel assemblies in terms of their size, weight and construction materials (except for nuclear fuel). Being a part of the simulation zone, they are designed to model the physical dimensions of the reactor core and to verify the hydraulic characteristics of the reactor facilities during the circulation cleaning and the reactor cold and hot trials.

This is the second time the ‘imitation zone’ is used at the Leningrad NPP. The first one was three years ago at the 1st VVER-1200 power block. The same set of dummy assemblies has proven to be valuable at two Novovoronezh NPP power blocks. Following each use, the dummy assemblies were chemically cleaned from surface contamination, with the JSC ‘Electrogorsk Research And Engineering Center On Nuclear Power Plants Safety’ being in charge of the visual and instrumental control and re-evaluation.

According to the Leningrad NPP-2 nuclear safety and reliability team, multiple application does not do any harm to the dummy assemblies, which means those can be re-used for pre-commissioning activities until a license is granted to upload nuclear fuel into the reactor.


Compared to the traditional VVER-1000 power blocks, the project for the 3+ generation Leningrad NPP power block has a number of advantages that considerably increase its economic parameters and safety standards. The capacity of the nuclear facility has been increased by 20%, from 1000 to 1200 megawatt; the designed life span of the core equipment has doubled and is now 60 years. In addition to that, this power block complies with the top international standards with regard to nuclear security. The Leningrad NPP-2 project serves as a reference for several international projects by the Rosatom State Corporation, such as the Belarusian NPP, the Paksh-2 NPP, the El Dabaa NPP, the Hanhikivi-1 NPP, etc.

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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