POWER PLANT DESIGN | VVER-TOI
VVER-TOI: the latest evolution
The first-of-a-kind VVER-TOI reactor, being built at Kursk II in Russia, uses the same engineering approaches as earlier VVERs, but has a few unique features
THE RUSSIAN-DESIGNED VVER-TOI IS based on the engineering solutions used for a nuclear power plant with VVER-1200 reactors. The VVER-TOI design provides for a longer self-
sustained emergency operation of a plant, as well as a smaller amount of solid radioactive waste and emissions. It combines active and passive safety systems. In addition, it ensures the transition of the reactor plant to a safe state in the event of various combinations of natural and man- made events causing a complete black-out: the power unit can survive a commercial aircraft crash, an earthquake and a tsunami happening simultaneously. The plant grace period requiring no operator intervention has been extended to 72 hours. Since the VVER-TOI design uses the same engineering
approaches as its predecessor, it requires no changes in the basic conceptual, structural and layout solutions for the power plant, though a new equipment layout is required. The steam generators are arranged in two rows, with two steam generators in a row. Earlier designs required a tangential arrangement around the nuclear reactor.
Steam generator design The equipment modification includes a new design of the steam generator without a steam header at its top. Steam comes out of one nozzle directly connected to the steam line (the classical design provided for 10 nozzles of earlier design, through which the steam enters a common steam header and then the steam line). The new steam generator is one metre longer at 15m, and its diameter exceeds 4m. The weight of a steam generator is 355t. The steam generator has coolant inlet and outlet headers in its middle part, where the ends (coils) of 11,000 heat exchange tubes are fixed. The tube diameter is 16mm, the wall thickness is 1.5mm, and the length is 11-17m. The VVER-TOI steam generator has an increased steam
generation capacity, which is 1652t/h, compared with the VVER-1200 PGV-type steam generator capacity of 1602t/h. The nominal thermal power of the new steam generator is 828MW, compared with 803MWt for the VVER-1200 PGV steam generator.
Top: Kursk II construction site pictured in Spring 2021 Photo: Rosenergoatom Above: VVER-TOI reactor pressure vessel for Kursk II Photo: Atomenergomash
46 | October 2021 |
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Reactor pressure vessel The reactor vessel design has also been changed. The bottom diameter has been increased by 100mm and is equal to the outer diameter of the core shell (the classical design provides for a structural connection between the bottom and the core shell). The bottom shell of the nozzle
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