Temelín in Czechia to shut down second unit as it completes transition to longer fuel cycle

The Temelín nuclear power plant will carry out a planned shutdown of its second unit on Friday evening. During the two-month outage, technicians will replace part of the fuel assemblies and inspect the safety systems and turbines. The utility will also complete its transition to a longer fuel cycle, extending operation between outages. The plant will use the production break for further modernisation of its control system. In total, ČEZ has planned more than 18,000 tasks, plant spokesman Marek Sviták said in a press release today.

Plant staff are gradually extending operating periods between outages, and the process will now be completed at the second unit. “We will replace 66 of the total 163 fuel assemblies, which is 12 more than last year. This will allow the unit to operate for two months longer, or 16 months. The second unit will thus enter the final stage of the extended fuel cycle,” said Temelín Nuclear Power Plant director Petr Měšťan. Temelín’s first unit will switch to an 18-month interval between fuel replacements—16 months of operation and a two-month outage—at the end of this year.

During the outage, technicians will inspect safety systems, one of the four main circulation pumps, the steam generator and a range of other equipment. “A great deal of work awaits us around the turbine. We will inspect all four rotors and install a new monitoring system,” Měšťan added. In addition to the inspections, technicians have planned 80 investment projects focused on modernisation and further strengthening the plant’s safety. Three containers holding 57 used fuel assemblies will be moved to storage. Modernisation of the plant’s control system, which began in 2022, will also continue.

The planned outage of Temelín’s second unit follows the end of the outage at Dukovany’s first unit. “This year, in connection with the transition to longer fuel cycles, we have two outages ahead of us, compared with only one last year. Even with the extended cycle, we plan them in a way that optimises fuel use while avoiding overlaps. This is advantageous for coordinating work and ensuring the capacity of our suppliers, as well as from the perspective of the transmission system,” said Bohdan Zronek, a ČEZ board member and director of the nuclear energy division.

According to plant management, longer cycles mean fewer outages and more efficient use of equipment. At the same time, however, they change the distribution of generation between individual years, as Temelín will now alternate between years with one and two planned outages. ČEZ therefore expects lower generation at its nuclear power plants this year compared with last year. By the end of the decade, it should achieve long-term average annual production of more than 32 terawatt-hours of zero-emission electricity, the plant spokesman said.

ČEZ will invest 3.8 billion koruna in modernising the Temelín Nuclear Power Plant this year. This is 700 million koruna more than last year. Since the start of the year, the Temelín plant has generated 2.2 terawatt-hours of electricity.