ČEZ to replace five transformers at the Temelín plant in Czechia as it prepares for decades more operation

The Temelín nuclear power plant is preparing to replace auxiliary transformers that supply electricity for the plant’s own needs. The new equipment is being manufactured and will replace the current transformers over the next two years. The investment, worth hundreds of millions of crowns, will improve the reliability of the power supply to plant systems and is another step towards the plant’s long-term operation, plant spokesperson Marek Sviták told journalists. Temelín’s operating life is expected to be extended to 80 years, until 2080 and 2082.

ČEZ will purchase five new transformers. Four will be in operation, with two at each of the two units. The fifth will serve as a standby reserve. Technicians will carry out the replacement during scheduled refuelling outages. Next year, they will replace the transformers at Unit 2, and the following year at Unit 1.

Electricity generated at the plant flows through the auxiliary transformers back into the site, where it supplies pumps and ventilation systems. “These are pieces of equipment that will reach the end of their service life in the coming years. Replacing them is therefore a natural and necessary step as part of our investment in Temelín’s long-term operation, for up to 80 years,” said Bohdan Zronek, a member of ČEZ’s board of directors and director of its nuclear energy division.

The new transformers will enable advanced diagnostics to continuously monitor their technical condition. “More precise diagnostics will help us plan servicing and preventive maintenance better, significantly extending the equipment’s service life and improving operational reliability. Another benefit will be more precise voltage regulation, which will ensure maximum stability of the plant’s internal power grid—a key factor in the stable operation of the equipment it supplies,” plant director Petr Měšťan added.

The work will take approximately five weeks at each unit. “Each transformer weighs dozens of tonnes, and handling it in the confined space next to the turbine hall requires meticulous preparation. We therefore have to coordinate the replacement in detail with the other work scheduled during the unit outage,” project manager Pavel Jankovský explained.

The modernisation is part of a long-term operating strategy for Czech nuclear power plants, which envisages extending their operating lives by 20 years, to up to 80 years. Longer operation will require further substantial investment in modernisation at the plants, amounting to five to six billion crowns a year at each one. Temelín has 238 investment projects worth 3.8 billion crowns planned for this year.