The Russian-designed VVER-TOI nuclear power reactor design - developed from the VVER-1200 - has been formally certified as compliant by the European Utility Requirements (EUR) organisation.

A cutaway of a plant based on the VVER-TOI design (Image: Rosatom)

Atomenergoproekt, a subsidiary of Russian state nuclear corporation Rosatom, announced the VVER-TOI (typical optimised, with enhanced information) design in 2010, developed using technical results from the VVER-1200 project. This design has an upgraded pressure vessel, increased power to 3300 MWt and 1255-1300 MWe gross (nominally 1300 MWe), improved core design to increase cooling reliability, further development of passive safety with 72-hour grace period requiring no operator intervention after shutdown, lower construction and operating costs, and 40-month construction time. It will use a low-speed turbine-generator.

Rosatom describes the VVER-TOI as the "logical development" of its so-called Generation 3+ units and an "evolutionary step" in improving the reactor vessel design of high-capacity plants. This design provides for an increase in the dimensions of the shell of the core of the reactor vessel, the use of improved welding materials, and the optimisation of the design of steam generators, the corporation says. The design also "ensures high economic performance with the maximum safety level of the unit", it adds.

European experts have carried out a detailed review of the VVER-TOI design documentation and information provided in the documents on the reference project, the Kursk II nuclear power plant in western Russia. The analysis included the study of answers to 4332 fundamental safety questions of EUR requirements, which cover the entire complex of the nuclear power plant.

As a result, the European experts concluded that the VVER-TOI project complies with European requirements for nuclear power plant safety and efficiency.

"I can justifiably state that the VVER-TOI project has passed the most thorough and deep examination, and it fully complies with the requirements of EUR," said EUR Honorary President Guillaume Jacquard as he presented a certificate during a ceremony in St Petersburg yesterday.

The EUR requirements cover a broad range of conditions for a nuclear power plant to operate efficiently and safely. They include such areas as plant layout, systems, materials, components, probabilistic safety assessment methodology and availability assessment. Although still requiring regulatory design approval in each country, EUR compliance indicates that the reactor design meets a list of requirements set by the utilities for the next generation of light water reactors (LWRs).

The EUR effort was launched in December 1991 by several European utilities to produce a common set of utility requirements endorsed by major European utilities for the next generation of LWR nuclear power plants. It was modelled on the US Electric Power Research Institute's Utility Requirements Document for advanced LWRs. EUR currently has about 15 members, including EDF of France, Iberdrola of Spain, Rosenergoatom of Russia and TVO of Finland.

The first Russian reactor design that received a certificate of compliance with the requirements of EUR was the AES-92 advanced semi-passive VVER-1000 design in April 2007.

Alexander Lokshin, first deputy director general for Operational Management at Rosatom, said: "We created the VVER-TOI, where we applied new technological solutions that increase the level of safety and reliability of nuclear power plant operation. The EUR certificate received today is a confirmation of the compliance of these decisions with international requirements."

Rosatom said that receiving EUR certification for the VVER-TOI design will "contribute to the promotion of Russian nuclear technologies in foreign markets".

First concrete for Kursk II unit 1 was poured in April 2018, with that for unit 2 poured in April this year. The Kursk II units will replace four RBMK units currently operating at the site and commissioning of the units will be synchronised with the closure of Kursk 1 and 2.