Electricity production at unit 2 of Finland’s Olkiluoto NPP (OL2) has been suspended due to increased moisture detected in the generator of the turbine plant, power company Teollisuuden Voima Oyj (TVO) have reported. The duration of the production interruption is not yet known. The issue has no impact on nuclear safety.
The rotor of OL2’s generator malfunctioned last autumn, and the unit has been operated at reduced power of 735 MWe for several months to prevent further damage and due to a shortage of spare parts. The power output of OL2 was in the process of being restored to full capacity after the arrival of a replacement rotor at Olkiluoto. The annual outage of Olkiluoto 2, expected to last about three weeks, is scheduled to begin on 25 May.
OL2 is a 890 MWe boiling water reactor that began commercial operation in 1982. The unit had been operated at a reduced net output to minimise risks associated with damage to the generator rotor. The damage was discovered in early September 2024, leading to a shutdown of electricity production and disconnection from the national grid. The faulty water-cooled rotor was replaced with a spare rotor, and electricity production resumed on 6 October 2024. To ensure operational reliability, production has continued at a reduced level for several months, as the rotor installed in October was the last spare rotor in TVO’s inventory.
Electricity production at Olkiluoto 1 and Olkiluoto 3 has continued normally during OL2’s reduced output period. Olkiluoto 3 is currently undergoing annual outage, which is scheduled to be completed on 2 May. Olkiluoto 1’s annual outage is scheduled for 11–22 May.
