A unit of the Leningrad Nuclear Power Plant switched off due to damage to the Silmash turbine

The fifth power unit of the Leningrad NPP-2 with a capacity of 1.2 GW was shut down twice this year due to the destruction of steam turbine blades produced by Power Machines, Rosatom said. After the first shutdown in the summer, the blades on the turbine were replaced, but the situation repeated itself on November 12. There were no problems with the same turbines at other nuclear power plants. The cause of the problems, according to analysts, could be both violations in the design and installation of the turbine, and errors during operation. Silmash suggests waiting for the results of the investigation. At the same time, the shutdown of a nuclear power plant unit leads to an increase in wholesale electricity prices.

Rosenergoatom (REA, part of Rosatom) named the reasons for the shutdown of the fifth power unit of the Leningrad NPP-2 (1.2 GW VVER-1200 reactors). This year, the unit was disconnected from the network twice due to the destruction of the low-pressure cylinder (LPC) blades of a high-speed steam turbine, said the general director of the concern, Alexander Shutikov, speaking at a meeting on the results of preparations for the heating season. The unit is equipped with a K-1200 turbine (1.2 GW) manufactured by Silmash. The power unit stopped for the first time on July 20, was taken out for repairs to replace the blades, and was connected to the network on September 23. But on November 12, the power unit stopped again due to damage to the blades on another LPC (the turbine has four LPCs).

“The most important thing is to understand the cause of the destruction of the blades. This is a new phenomenon. We are in a serious search for the reasons, together with the plant, why the blades of the last stages of the LPC are damaged. The blades are large – 1270 mm,” Mr. Shutikov said at the meeting. He noted that the concern hopes to launch the fifth power unit on December 22. One of Kommersant’s sources, familiar with the investigation into the incident, notes that the separation of the blade is only the immediate cause of the shutdown of the power unit. The root cause of the recurrence of the defect is determined, all options are considered, Kommersant’s interlocutor notes: design solutions, design, operation, as well as other factors.

An unplanned and prolonged shutdown of a nuclear power plant unit significantly increases prices on the wholesale electricity market, a Kommersant source in the industry says.

For example, he says, due to the latest shutdown, the 795 MW power unit of the Kirishi State District Power Plant had to be urgently launched. As a result, on November 13, the price on the day-ahead market in the North-West power system jumped by almost 10%, to 1.45 thousand rubles. for 1 MWh, and in general in the first price zone (the European part of the Russian Federation and the Urals) – by 9.5%, to 1.62 thousand rubles. If the nuclear power plant unit was turned on, the price in the North-West for the last two days would have been approximately 5% lower than the current one.

In total, four K-1200 high-speed turbines, manufactured in 2010–2013, operate in Russia. One such turbine is installed at two new power units of the Leningrad NPP-2, launched in 2018 and 2020. Two more machines are installed at the units of Novovoronezh NPP-2 (VVER-1200): the sixth unit has been operating since 2016, the seventh – since 2019. In addition, two K-1200 turbines, manufactured in 2015 and 2017, are installed at the power units of the Belarusian Nuclear Power Plant (2.4 GW, built by Rosatom), as follows from the data on the Silmash website.

The problem with the turbine occurred only at the fifth power unit of the Leningrad NPP-2; there were no identical problems at other facilities in Russia, the REA told Kommersant.

“We always take a comprehensive look at each case of failure in the operation of nuclear power plant equipment,” the concern explained. “We analyze the causes and proactively implement corrective measures.”

Silmash told Kommersant that serial K-1200 turbines have been successfully operating in Russia since 2016, and “the operating time of stages with such blades without incidents is more than 1 million hours.” No similar or other significant comments on the work were identified. The company also said that it is taking all steps to launch the power unit as soon as possible. Now Silmash specialists, together with NPP specialists, are inspecting equipment at the station to identify defects and collect information for investigation. Based on the results, conclusions will be drawn and compensatory measures will be determined, the company said.

The reasons for problems with a turbine can be different: errors in design and installation, errors in operation, etc., lists independent expert Yuri Melnikov. In his opinion, Silmash is the only supplier of turbines for large Rosatom nuclear power plants both in Russia and abroad. And for the sanctioned Power Machines, the state corporation Rosatom is the only buyer of such steam turbines (they are not suitable for thermal power plants). Therefore, Yuri Melnikov concludes, it is in the interests of both companies to jointly find and eliminate the cause of the destruction of the blades.

Polina Smertina