Dukovany Unit 4 back at full output after two-month outage

Unit 4 at the Dukovany Nuclear Power Plant is back at full output following a planned outage. It had been shut down since 17 April and resumed supplying electricity to the grid last Friday. The combined output of Unit 4's two turbine-generator sets currently stands at 499 megawatts (MW), ČEZ spokesperson Jana Štefánková told ČTK today.

All four Dukovany units are in operation. Their operation remains stable even on hot days, the spokesperson said. Unit 3 is scheduled to be shut down in the second half of July.

"Bringing a nuclear unit from an outage back to full output normally takes several days. At different output levels, we always verify parameters and carry out the necessary tests and inspections," said plant director Roman Havlín.

There is currently no outage at the Temelín plant either. According to the energy company, the operation of the nuclear plants remains stable even on hot days. High temperatures do not affect safety; they can only very slightly reduce generation efficiency in the plant's non-nuclear section, by low single-digit percentages, Štefánková said. Warmer cooling water is less effective at cooling steam downstream of the turbine, slightly reducing output. The plant has long been prepared for these conditions through its cooling towers, and its operation remains reliable without any need for restrictions, ČEZ said.

Planned outages of the Dukovany units are associated with the replacement of part of the nuclear fuel, equipment upgrades and maintenance. During the Unit 4 outage, energy workers completed more than 21,000 work tasks and carried out 60 major technical activities. "It was an outage with an above-standard volume of inspections and investment work," Havlín said last Friday.

Temelín and Dukovany generated a combined 32.066 terawatt-hours (TWh) of electricity last year, of which Dukovany accounted for 14.68 TWh. So far this year, the Dukovany plant has supplied 7.3 TWh of electricity.

The four Dukovany units were commissioned between 1985 and 1987. Under ČEZ's current assumptions, they can operate for up to 80 years from commissioning, i.e. until 2065 to 2067. Two additional units at Dukovany will be built by South Korea's KHNP.