CEZ Shuts Down Temelin Reactor After Control Fault
CEZ halted Temelin Unit 2 after a non-nuclear control system fault, with operations expected to resume within 24 hours.
CEZ, the operator of the Temelín nuclear power plant, reported an unexpected shutdown of Reactor Unit 2 on Wednesday. The unit was disconnected from the grid following a detected malfunction in the control system governing the non-nuclear components of the facility. This event interrupts the plant's output, which is critical for CEZ’s portfolio as it manages a significant portion of the Czech Republic's nuclear generation capacity.
The fault was isolated to an electronic card within a control cabinet. CEZ technicians inspected the system and replaced the defective component. The company stated that further checks were ongoing to ensure stability before restarting the unit, with full operations expected to resume by Thursday. This brief outage represents a temporary revenue loss for CEZ but avoids potential long-term damages by acting swiftly on the control system anomaly.
Unit 1 continues full capacity
Reactor Unit 1 at the Temelín site remained unaffected by the incident and continued operating at full capacity. This dual-unit configuration allows CEZ to maintain a substantial share of its nuclear output despite the localized failure in Unit 2. The plant consists of two pressurized water reactors of the WWER 1000/320 type, located in southern Czechia, where the mix of Russian reactor technology and US control systems has historically drawn scrutiny from nuclear opponents.
Recent overhaul extends operational window
Reactor Unit 2 had only recently returned to service in April after a nearly two-month annual maintenance overhaul. During this period, CEZ replaced certain fuel elements to optimize performance. The plant extended the interval before the next scheduled overhaul to 16 months, an increase of six months over previous standards. This strategy aims to maximize the utilization rate of the unit and improve the return on investment for the existing infrastructure before new capacity comes online.
Strategic expansion targets nuclear growth
The Czech Republic’s energy strategy relies heavily on expanding nuclear capacity, aiming to raise its share in the energy mix from one-third to over half by 2040. To meet this target, the state plans to construct two new reactor units at the Dukovany site. The reliability of existing assets like Temelín is therefore vital for CEZ, as any prolonged outages could complicate the transition period and increase operational costs for the utility sector.
