Second Czech Temelín unit connected to grid after planned two-month outage

Following a planned two-month outage, operators have connected the second unit of the Temelín Nuclear Power Plant to the grid. It began supplying electricity after part of its fuel assemblies were replaced. It will operate for 16 months, six months longer than three years ago. Energy workers also transferred control of part of the technology to a new system from Westinghouse and inspected the safety systems, turbine and generator. Plant spokesperson Marek Sviták informed journalists of this today.

As recently as three years ago, the standard operating period for both Temelín units between outages was approximately ten months. Operators are now extending it to 16 months, followed by a two-month outage. “At the second unit, we have reached the target state. The transition was not abrupt but gradual, in three steps since 2023, with each step extending operation between outages by two months,” said plant director Petr Měšťan.

Longer fuel cycles are intended to improve operational safety and efficiency and create conditions for the long-term operation of nuclear units in Czechia. “Extending fuel campaigns is a global trend. Dukovany has moved to a longer fuel cycle, and we are completing the same process at Temelín this year. Less frequent outages mean less strain on equipment, while also creating the conditions for increasing annual generation,” added Bohdan Zronek, a member of the ČEZ board of directors and head of its nuclear energy division.

Operators now face the final phase of tests to verify the even distribution of reactor power. Technicians will also monitor the turbine, where hundredths of a millimetre matter during operation. During the two-month outage, workers completed more than 20,000 tasks. They also inspected the safety systems, turbine and generator. Approximately one-third of the equipment was transferred to control by the new system. More than a thousand people, including contractors, were involved in the work.

ČEZ Group’s nuclear power plants have gradually moved to extended fuel campaigns in recent years. At Dukovany, a 16-month fuel campaign has been the standard since 2024, with units operating for 14 months between outages followed by an outage lasting more than one month. Temelín will also complete its transition to a longer, specifically 18-month, fuel campaign this year. In its case, this means 16 months of operation and an outage of approximately two months. The first unit will reach the target state of the longer fuel campaign in the autumn of this year.

Since the start of the year, the Temelín plant has generated 3.8 terawatt-hours of electricity. ČEZ will invest CZK 3.8 billion in the modernisation of the Temelín Nuclear Power Plant this year. This is CZK 700 million more than last year.