Czech Temelín disconnects second unit for partial fuel replacement

The Temelín nuclear power plant today disconnected its second unit from the transmission grid, starting a planned outage that will last two months. During the outage, technicians will replace some of the fuel assemblies and inspect safety systems and turbines. Plant staff will also complete the transition to a longer fuel cycle. The outage began shortly after 21:00 today, plant spokesman Marek Sviták told ČTK.

Operating personnel disconnected the turbogenerator from the transmission grid as planned. "Over the weekend, the equipment will gradually cool down; for example, in the primary circuit we will reduce the water temperature by around 300 degrees. We will start opening the reactor once it has cooled down, during Monday. Opening the reactor will take approximately four days," Sviták said.

Plant workers are gradually extending the operating period between outages, and will now complete the process at the second unit. They will replace 66 of the total 163 fuel assemblies, 12 more than last year. This will allow the unit to operate for two months longer, or 16 months. The second unit will thus reach the final stage of the extended fuel cycle. Temelín's first unit will move to an eighteen-month interval at the end of this year.

During the outage, plant staff will inspect safety systems, one of the four main circulation pumps, a steam generator and a range of other equipment. In addition to inspections, technicians are planning 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. They will also continue modernising the plant's control system, which began in 2022. In total, ČEZ plans to carry out more than 18,000 tasks during the production outage.

ČEZ will invest CZK 3.8 billion in modernising the Temelín nuclear power plant this year. This is CZK 700 million more than last year.

Czechia has six nuclear units at two power plants, which together generated 32.066 terawatt-hours (TWh) of electricity last year. The Dukovany nuclear power plant has four units. Korean company KHNP won the contract to build two additional units at Dukovany.