Concreting of the foundation slab of the block pumping station for unit 2 was completed two weeks ahead of schedule, the plant said on 17 March. The block pumping station (BPS) is located between the turbine building and the tower evaporative cooling tower. It is designed to circulate water between the turbine condenser and the cooling tower to cool the steam used in the turbine, as well as to remove heat from the auxiliary equipment of the turbine building.
“The block pumping station is the deepest building of all those being constructed at the Kursk NPP-II site,” explained Aleksey Buldygin, head of the Kursk NPP-II Construction Department. “The foundation slab starts 13 metres below ground. The thickness of the slab is three metres, and in some places it reaches 8 metres, because of the water intake pipe located in it. In total, about 6,000 cubic metres of concrete mixture were laid in the foundation slab.”
The foundation slab serves as the base for the underground part of the building. The underground section comprises a water intake part, a turbine room for circulation pumps and rooms for auxiliary equipment. Completion of the slab paves the way for construction of the contour walls of the underground part of the unit 2 BPS building.
Meanwhile, four housings of the main circulation pump (MCP) have been installed in the unit 1 reactor building. The units are mounted at an elevation of 14.5 metres. “During the operation of the nuclear power plant, all four main circulation pumps will be in operation, explained Aleksey Volnov, Chief Engineer at Kursk-II. “The MCP for the VVER-TOI project is distinguished by an optimised design. Water will be used instead of oil to cool and lubricate the pump and motor bearings. This will increase the fire safety of the NPP, simplify the layout and the start-up procedure of the MCP.”
One MCP unit weighs more than 53 tons. It is capable of pumping about 22,000 cubic metres of water an hour. All the MCP housings have undergone the strength tests. During hydrotesting, which was carried out at the manufacturing plant, the body of each main circulation pumping unit was filled with specially purified water, heated to the required temperature and held at a pressure of 24.5 MPa for 10 minutes.
In addition, Severstal-metiz (part of the Severstal hardware group) in Cherepovets has produced and supplied the first batch of high-strength reinforcing ropes for Kursk-II. The steel production technology for the new product was developed and mastered by the specialists of the Severstal Russian Steel division. Reinforcing ropes (strands) with a diameter of 15.2 mm, compressed in a polyethylene sheath, are designed for work on prestressing the inner containment of the reactor building. To obtain the mechanical properties of the product that meet the requirements of the nuclear industry, the employees of the Severstal Russian Steel division had to develop the wire rod from the wire rope steel grade in a new size.
On 18 March, Kursk-II also reported that the enclosing dam of the cooling pond was ready for flooding. The dam at the cooling reservoir for the Kursk plant is almost 14 km long. It separates the reservoir from the Seim River. The state of the dam and other hydraulic structures was examined by members of the flood commission including representatives of the Verkhne-Don department of regulator Rostekhnadzor, the department of water resources and the committee of natural resources of the Kursk region, and the main department of EMERCOM in the Kursk region.
“The commission checked the hydraulic structures of the first and second stages of the Kursk NPP. It was both a visual inspection and checking the documents,” said Vadim Trunov, head of the department of state energy supervision and supervision of hydraulic structures, The commission concluded that the hydraulic structures of the Kursk NPP are fully prepared for flooding. In addition to the enclosing dam, more than 30 hydraulic structures operate at the plant including canals, pools, pumping stations, and water intake facilities.
Over the 45-year history of the Kursk NPP, there have been no precedents to cast doubt on the reliability of the plant's hydraulic structures.
“During the spring flood, the Kursk NPP reservoir also solves the problem of flood waters in the Seim River, by taking part of the melt water into the station reservoir,” explained Dmitry Kholostov, Deputy Chief Engineer for Operation of Kursk NPP General Plant Facilities. “Thus, the risk of flooding of the territories located downstream of the Seim is minimised.”
Kursk-II is a replacement station for the current Kursk nuclear plant. Commissioning of the first two units with the new design VVER-TOI reactors will be synchronised with the decommissioning of the RBMK reactors at Kursk 1&2 of the operating plant.