Teollisuuden Voima Oyj (TVO), the operator of Finland’s Olkiluoto Nuclear Power Plant, has halted electricity production at Olkiluoto 2 (OL2) due to elevated moisture levels detected in the turbine plant’s generator. The duration of this suspension remains uncertain, but TVO has confirmed that the issue does not affect nuclear safety.

Aerial view of work being carried out on the OL2 generator

Last autumn, the generator rotor at OL2 experienced a malfunction, prompting TVO to reduce the unit’s output to 735 MWe for several months to avoid further damage and due to limited spare parts. A replacement rotor recently arrived at the Olkiluoto facility, and efforts were underway to restore OL2 to its full capacity of 890 MWe. However, the current moisture issue has interrupted these plans. The annual maintenance outage for OL2, expected to last approximately three weeks, is set to begin on 25 May.

OL2, a boiling water reactor operational since 1982, faced challenges in September 2024 when damage to its water-cooled rotor was identified. This led to a temporary shutdown and disconnection from Finland’s national grid. On 6 October 2024, electricity production resumed after installing a spare rotor, though output remained reduced to ensure reliability, as the replacement was TVO’s last available spare.

Operations at Olkiluoto 1 and Olkiluoto 3 have continued without disruption during OL2’s reduced output period. Olkiluoto 3 is currently undergoing its annual maintenance, scheduled to conclude on 2 May. Olkiluoto 1’s annual outage is planned for 11–22 May. TVO continues to prioritize operational stability and safety across all units at the Olkiluoto facility.