At unit 6 of Russia’s Leningrad NPP, specialists have installed an upgraded generator stator in the engine room and are setting the turbine shaft line. Final assembly of the generator involves connecting the cooling pipelines, as well as numerous sensors that control the temperature of the winding of the stator, vibration, etc. Hydraulic and high voltage tests will then take place before the generator is connected to the turbine.
Currently Leningrad NPP has four units in operation – units 3&4 with Soviet RBMK-1000 reactors, as well units 5&6 with new VVER-1200 units (also known as Leningrad-II 1&2). Units 5&6 replaced units 1&2 with RBMK-1000 reactors, which were decommissioned in 2018 and 2020. New VVER-1200 units (7&8) will replace units 3&4.
The work involved specialists with extensive experience in the movement of large-sized equipment. The team delivered the generator stator to the installation site ahead of schedule.
At the next stage, employees of the specialised repair organisation, Atomenergoremont, will deal with the generator. They have to set an air gap between the rotor and the stator, measure the magnetic axes of the rotor and stator, assemble the generator, perform a complex of hydraulic and electrical tests, connect the generator with the turbine and transfer the turbine unit to operation. The installation will be supervised by the manufacturer’s chief engineers.
“The modernisation of the stator was carried out to strengthen the frontal parts of the winding. By increasing the rigidity and reliability of the winding mount, we increased vibration resistance and the ability to withstand electrodynamic loads. This will allow the equipment to work reliably and efficiently as intended,” said Alexander Belyaev, Chief Engineer of the Leningrad-II.
During the outage of unit 6 which started on 8 February specialists will also carry out large-scale audits and maintenance of reactor and turbine equipment, security systems, diesel generator sets, lifting mechanisms, etc., if necessary, individual components and parts will be replaced.
They will also carry out work with nuclear fuel and check the sealed shell of the reactor building for integrity and density, as well as undertaking tests of the transport and packaging container intended for the export of used nuclear fuel. Scheduled repairs will be completed at the end of March.
