Kalinin and Beloyarsk outages due to non-nuclear faults, says Rosenergoatom 

Kalinin units 1, 2 and 4 were disconnected from the grid yesterday after a transformer switch short circuited. Units 1 and 2 were shut down, while unit 4 was offline at reduced thermal power output, Rosenergoatom said. Kalinin unit 3 was unaffected and continued operating as usual, it added.

The plant is just over 200 miles north-west of Moscow, in the Tver region of Russia.

"The radiation level at the station and surrounding territory remains without change and is in line with normal background levels," Rosenergoatom said.

Unit 4 was reconnected to the grid the same day, while the other two units are offline until the cause of the fault has been identified, it added.

Company spokesman Andrey Timonov said in the same statement that the fault had nothing to do with reactor equipment and was not nuclear-related.

"A transformer stands near every power plant, regardless of how electricity is generated. The task of the transformer is to change the characteristics of the electrical current generated at a plant so that it can be transferred to the grid. There is a device on the transformer that switches on or off in different modes. This morning, there was a short circuit in one of the switches. As a result, the entire transformer was disconnected, which in turn caused the disconnection of power lines from the plant. The power units had nowhere to generate electricity, and so they stopped and disconnected from the network according to the design algorithm."

The Kalinin nuclear power plant consists of four power units with water-cooled power reactors (VVER-1000) with an installed capacity of 1000 MW each.

On July 12, unit 4 at the Beloyarsk nuclear power plant was shut down after an automatic safety mechanism was triggered. The BN-800 fast reactor was restarted on 16 July and is now producing electricity “in accordance with the dispatch schedule”, Rosenergoatom said. It had been restarted "after establishing and eliminating the causes of the electrical generator disconnection", it said.

Unit 3 - a BN-600 fast reactor - was unaffected and continued to operate as normal, Rosenergoatom said.

The BN-600 has been in operation at the same site, in Zarechny, Sverdlovsk District, since 1980. The BN-800 was commissioned in 2015. They are licensed to operate until 2025 and 2056, respectively.