The company said that the latest development was Dukovany's third unit achieving a thermal output of 1475 MWt - equivalent to 511 MWe - a 2.3% increase achieved without any increase in fuel consumption or emissions.
The units at the Dukovany nuclear power plant started up between 1985 and 1987 and are VVER-440 reactors, originally rated at 440 MWe. The installed capacity of each of them was increased after a nine-year modernisation programme to 500 MWe in 2009. The units at the Temelin nuclear power plant were also upgraded from 981 MWe to 1086 MWe.
Preparation for the latest capacity increase started in full in 2020 as part of a programme which also included the switch from an 11-month to a 16-month fuel cycle. Preparations included modernisation of some technological and safety systems, with the temperature of the water at the outlet of the reactor increased from 298.4°C to 300.4°C.
ČEZ says it expects the annual production of Dukovany to increase in 2025 by about 300,000 MWh after all the units are modified.
Daniel Beneš, Chairman and CEO of ČEZ Group, said the modernisation of their nuclear power plants had increased capacity by as much as building "a large coal-fired power plant or a smaller nuclear unit". He added that "of course, the absolute priority is safety, we would never take such a step without confirming the safety parameters".
Bohdan Zronek, director of the nuclear energy division, said: "Seemingly small changes in parameters will bring us hundreds of thousands of megawatts of electricity per year. Preparation for increased performance required confirmation of safety analyses, but no large-scale investment was required. The entire project fulfills the task of safely operating all our nuclear units for at least 60 years."
Roman Havlín, director of the Dukovany power plant, said the aim was to increase the outputs of the first and second units later this year and complete the project next year.
Four VVER-440 units are currently in operation at the Dukovany site. Two VVER-1000 units are in operation at Temelín, which came into operation in 2000 and 2002. The Czech Republic uses nuclear power for 34% of its electricity. Its current new nuclear plans include up to four new units, as well as a possible roll-out of small modular reactors.
