ČEZ completes uprate of all units at Czech Dukovany plant

At the Dukovany Nuclear Power Plant, ČEZ has completed the uprate of all four reactor units from 500 megawatts (MW) to 512 MW. The fourth and final Dukovany unit reached its new output for the first time on Sunday. Since last year, the plant’s total available electrical output has increased by 48 MW. As a result, Dukovany’s electricity generation this year will rise by up to 350,000 megawatt-hours (MWh), plant spokesperson Jiří Bezděk told the Czech News Agency (ČTK) today.

Last April, energy workers increased the output of Dukovany unit 3, followed by unit 2 in August and unit 1 in November. Unit 4 first reached the increased output on Sunday, 30 March, at 17:20. Energy workers will still carry out a series of verification checks and tests on the unit. “As with the first three units, increasing their output to the current 512 megawatts required a huge amount of work and inspections. The condition is always that we must not reduce the level of safety,” said plant director Roman Havlín.

The planned outage of Dukovany unit 4 ended on 6 March. It was disconnected from the grid again on 13 March for the repair and inspection of two valves in the non-nuclear part of the facility, and resumed supplying electricity to the grid on 24 March.

The project to improve the efficiency of the Dukovany plant began in earnest in 2020. Through minor modifications, energy workers raised the temperature of the primary circuit water at the reactor outlet from 298.4 to 300.4 degrees Celsius, an increase of about two degrees. Under optimal conditions, the turbines can therefore deliver 12 MW more electrical output, ČEZ said today. The project also included a switch to a longer, 16-month fuel cycle in 2023.

Czechia has six nuclear units at two power plants. Last year, Dukovany supplied 14.7 terawatt-hours (TWh) of electricity to the transmission grid, while Temelín generated 15 TWh.

“At Dukovany and Temelín, we are pursuing two main long-term goals: safe and reliable operation beyond the 60-year mark, and gradually achieving average annual generation of up to 32 TWh. Modernising equipment and making use of design reserves are helping us meet these goals,” said Bohdan Zronek, a ČEZ board member and director of its nuclear energy division.

This year marks 40 years since the first Dukovany unit began operation; it entered trial operation on 3 May 1985. All four Dukovany units have been in operation since July 1987. When they started up, their electrical output was 440 MW. Subsequent equipment upgrades enabled energy workers to increase the output of each Dukovany unit to 500 MW.

Last year, the government decided to build two more reactors at Dukovany. They are to be built by South Korean company KHNP, with which ČEZ is negotiating a final contract. The government expects the final contracts to be signed within the next few weeks, Prime Minister Petr Fiala (ODS) told reporters on Monday. The first of the new reactors is expected to be completed in 2036.