Nuclear power plants in Czechia will refuel less often, boosting output

Nuclear power plants in Czechia will refuel less often. The interval between outages will be extended from the current 12 months to 18 months at Temelín and 16 months at Dukovany. Among other things, ČEZ expects this to increase total electricity generation by almost two terawatt-hours (TWh) a year by 2030. The transition to extended fuel cycles will be gradual and should be fully implemented from 2025. Bohdan Zronek, a member of the ČEZ board and director of its nuclear energy division, told the Czech News Agency today.

Electricity consumption in the Czech Republic was 60.4 TWh in 2022, so the planned increase in generation represents up to three percent of Czech consumption. „This is, of course, conditional on very careful verification of all safety parameters and the preservation of all safety margins,“ Zronek said. He said extending the intervals did not require any special investment in equipment and was primarily a change in operating procedures.

The transition to a longer cycle between refuelling has now begun at Temelín, where ČEZ has started loading what is known as a transition fuel batch. Instead of the previous 42 fuel assemblies, staff will now load 48 fresh fuel assemblies into the reactor. Including the assemblies that are not being replaced, they will place a total of 163 in the plant’s shut-down second reactor. The second unit will therefore operate for approximately one month longer.

„The fuel enrichment will be the same, but the fuel assemblies will contain more absorber, which reduces the reactivity of the fresh fuel assemblies. Combined with the higher number of fresh assemblies, this will allow the unit to operate for longer,“ said Jan Kruml, director of the Temelín power plant.

„It is similar to putting seven coal briquettes in a stove instead of five and slightly closing the air supply: they last longer too. In our case, however, there are no emissions,“ he added.

According to ČEZ, extending the intervals should not change the length of outages; the company says that replacing a larger number of fuel assemblies will not affect their duration. „Outages will continue to last approximately two months,“ said Marek Sviták, spokesperson for the Temelín power plant. He noted that in addition to refuelling itself, outages include inspections of safety systems, turbines and other parts of the plant.

According to ČEZ, 18-month fuel cycles are already standard at most nuclear power plants abroad. The company began work on adopting them in the Czech Republic in 2018, when preparations for the permitting process began. The Dukovany plant will also transition to a longer cycle, although it will be two months shorter than at Temelín. Zronek said this was due to technical differences between the plants.

Dukovany and Temelín nuclear power plants generated a record amount of electricity last year. They supplied a total of 31.02 TWh of electricity to the transmission grid, almost 300,000 megawatt-hours (MWh) more year on year. ČEZ will invest approximately six billion crowns in Dukovany and Temelín this year, including in connection with plans to operate the plants for 60 years. It wants to operate the Dukovany nuclear power plant in line with its investment and inspection plans at least until 2047, and Temelín for a further 13 years.