Cernavodă Unit 2 stays offline longer after transformer fault, while Unit 1 moves into planned maintenance

Romania’s only nuclear power plant is entering another stretch of downtime, underscoring how quickly equipment issues can translate into extended outages—and how tightly nuclear operators must manage safety-critical repairs alongside scheduled work. Nuclearelectrica said Unit 2 at the Cernavodă facility will stay offline longer than initially expected after an automatic reactor shutdown earlier this month.

Unit 2 disconnected from the grid after transformer-related fault

The company reported that Unit 2 was disconnected from the national grid on the evening of 4 May after a fault was detected in an insulator associated with one of the unit’s power transformers. Nuclearelectrica said the problem activated the plant’s automatic protection systems, leading to a safe and controlled shutdown.

Controlled outage and transformer replacement extend downtime

According to the operator, Unit 2 is now undergoing a controlled outage procedure so that repair and replacement work can be carried out in line with nuclear safety standards and technical regulations. The planned maintenance includes replacing the affected transformer with a backup system, a step expected to extend the period the unit remains unavailable.

Nuclearelectrica stressed that the malfunction did not pose any risk to nuclear safety and that all safety systems operated as designed during the incident.

Unit 1 to start planned maintenance on 10 May

Alongside the unscheduled work on Unit 2, Nuclearelectrica confirmed that Unit 1 at Cernavodă is scheduled to enter a planned maintenance outage starting 10 May. During this period, engineers will carry out inspections, technical testing, maintenance operations, and system upgrades intended to support continued safe and efficient operation.

The Cernavodă plant—home to two CANDU reactors—remains central to Romania’s electricity supply mix, providing a significant share of baseload power for the national grid.