1. 8. 2025

Unit 1 of Temelín produces electricity again. It will be in operation for fourteen months, four months longer than before.

Yesterday evening, the Temelín Unit 1 began to supply electricity to the grid again. Operators connected it to the transmission system after replacing the partial refuelling. It will be in operation for fourteen months, four months longer than before. The energy engineers also converted the control of part of the technology into a new Westinghouse system, checked safety systems, the turbine or the generator. Together with the Dukovany power plant, six nuclear units are currently in operation.

Like last year, the Temelín Units 2 and 1 also officially switched to a longer fuel cycle. In practice, the unit will be in operation for fourteen months between refuelling outages, four months longer than in the original cycle. This will allow for a higher proportion of fresh fuel. The energy industry has also taken an essential step in the unit control system. Since 2022, the unit control system has been undergoing a significant and demanding modernisation.

"Through the new system, we are already managing part of the technology, such as the pumping stations of technical and fire water. Other parts of the power plant will also pass on to it in further outages. The modification will be finished on both units in 2029,"

said Jan Kruml, Director of the Temelín Nuclear Power Plant.

The longer fuel cycle and the modernisation of the control system are key projects according to CEZ's top management.

"The modernisation of the control system will ensure units' safe operation for the next decades. Longer fuel cycles, and therefore less downtime, mean lower equipment load and, at the same time, we create the prerequisites for increasing the year's production of both nuclear power plants by almost two terawatt-hours of electricity,”

said Bohdan Zronek, member of the CEZ Board of Directors and Director of the Nuclear Energy Division.

The increase in production by 2 TWh represents approximately 3.5% of last year’s total electricity consumption in the Czech Republic.

In total, within two months, the energy industry managed more than 18 thousand work tasks and inspections. Technicians checked the safety systems, the turbine or the generator. Together with suppliers, more than a thousand people have also been involved in the work. In the coming weeks, the suppliers will move to Dukovany, where they will start a further outage of the local Unit 2 at the end of August.

The Temelín Unit 1 began supplying electricity to the transmission system at 50% of the rated reactor power. Its full power should be achieved within a few days. During the start-up, there are still a few tests waiting for the energy technicians. For example, at 80% of the rated reactor power, they will verify the even distribution of reactor power.

 

Since the beginning of the year, the Temelín power plant has produced 9.4 terawatt hours of electricity. Together with Dukovany, these are sources that generate the most clean electricity and thus contribute significantly to ČEZ Group's emission-free production. Annually, approximately 200 million tons of CO2 have not been released into the atmosphere thanks to nuclear power plants.