Temelín prepares for a planned outage of Unit 2. During this shutdown, it will complete the transition to longer operation between shutdowns.

Technicians plan to disconnect the Unit 2 generator from the transmission grid on Friday evening, when the reactor is operating at about one‑third power. According to plant management, this will be a standard outage involving important inspections and investment activities. Energy workers will also transfer the unit to the final phase of a longer fuel cycle. “We will replace 66 of the 163 fuel assemblies, which is twelve more than last year. Thanks to this, the unit will operate for two additional months. A total of sixteen months. Unit 2 will thus enter the final phase of its extended fuel cycle,” said Petr Měšťan, Director of the Temelín Nuclear Power Plant.

 

Turbine inspections, investment projects, fuel transfer to storage, and control system modernization

During the outage, technicians will inspect safety systems, one of the four main circulation pumps, the steam generator, and a number of other components. “We expect a lot of work around the turbine. We will inspect all four rotors and install a new monitoring system,” added Petr Měšťan.

In addition to inspections, technicians plan 80 investment projects focused on modernization and further strengthening of plant safety. They will transfer three containers holding 57 spent fuel assemblies to storage. The modernization of the plant’s control system — a project ČEZ has been working on since 2022 — will also move into its next phase.

Approximately one thousand people, including contractors, will take part in the outage. The outage of Temelín’s Unit 1 is planned to begin in mid‑October.

 

The Temelín outage follows the outage at Dukovany

The planned outage of Temelín Unit 2 follows the upcoming restart of the first generating unit at Dukovany. “This year, due to the transition to longer fuel cycles, we will have two outages instead of just one as last year. Even with extended cycles, we plan outages so that we use the fuel optimally while avoiding overlap. This is beneficial for coordinating work, ensuring capacity for both our teams and contractors, and for the transmission system,” said Bohdan Zronek, a member of the ČEZ Board of Directors and Director of the Nuclear Energy Division.

Technicians plan to reconnect Dukovany Unit 2 at the beginning of the second half of February.

Extended fuel cycles are fundamentally changing the operation of both Czech nuclear power plants. Dukovany is already operating on a sixteen‑month cycle, while Temelín is transitioning to an eighteen‑month refueling interval. Longer cycles mean fewer outages and more efficient use of equipment. However, they also change annual production patterns, as Temelín will now alternate between one and two planned outages each year. This will affect the annual output of Czech nuclear plants. As a result, ČEZ expects lower nuclear generation this year compared to last year. By the end of the decade, annual production should stabilize above 32 TWh of zero‑emission electricity.

 

Since the beginning of the year, the Temelín power plant has produced 2.2 terawatt hours of electricity. Together with Dukovany, these are the sources that produce the most clean electricity and thus contribute significantly to ČEZ Group's emission-free production. Annually, approximately 20 million tons of CO₂ are not released into the atmosphere thanks to nuclear power plants.