Units 3 and 4 of Dukovany Nuclear Power Plant to Undergo Joint Maintenance of Shared Systems

Dukovany Nuclear Power Plant staff will initiate a planned extended outage for Unit 4 on the evening of August 1, while Unit 3 will remain in its outage state. Both units will be offline simultaneously in August, and the plant will use this window to conduct comprehensive inspections, maintenance, and modernization of the shared facilities of Units 3 and 4.

Bohdan Zronek, member of the Board of Directors of ČEZ Group and head of the nuclear energy division, stated that the simultaneous shutdown of Units 3 and 4 at Dukovany will place the plant under an intensive work schedule over the coming weeks. Experts from ČEZ and its suppliers will handle hundreds of tasks, and the effectiveness of the outage work depends on precise coordination across all stages.

According to the plan, this joint outage will last approximately one month. Unit 3 is expected to return to operation by the end of September after completing fuel replacement and other scheduled activities. Under the current schedule, a similar joint outage is not expected to occur again until 2032.

This round of modernization focuses on the shared cooling system and water treatment-related systems to ensure the safe and reliable operation of both units. The plant will also replace certain valves and compensators in the shared systems, marking the first time such component replacements have been carried out since the Dukovany plant went into operation.

Unit 3 of Dukovany Nuclear Power Plant was taken offline for maintenance in mid-July. During the outage, the plant will replace part of the nuclear fuel, conduct hundreds of equipment inspections and tests, implement 50 investment projects, and advance important modernization efforts to further enhance nuclear safety levels and ensure the plant's long-term stable operation.

Roman Havlín, Director of Dukovany Nuclear Power Plant, stated that this year's outage of Unit 3 has created conditions for extensive maintenance of the shared equipment of Units 3 and 4, with some components being replaced for the first time. These activities will improve equipment reliability and lay the foundation for the plant's safe operation over the coming decades.

In recent years, ČEZ's nuclear power plants have gradually extended their refueling cycles. Since 2024, Dukovany has extended its fuel replacement cycle to 16 months, meaning each unit operates for approximately 14 months before an outage, followed by another outage exceeding one month. Temelín Nuclear Power Plant also completed its refueling cycle adjustment this year, extending the cycle to 18 months.

Under the new model, Temelín units operate for approximately 16 months followed by an outage of about two months. Unit 2 of Temelín is already operating under this model, and Unit 1 will enter the final phase of the longer refueling cycle adjustment this autumn. These adjustments aim to increase total electricity generation, utilize nuclear fuel more efficiently, and reduce technical stress on equipment through stable operating parameters.