Electricity production at Finland’s Olkiluoto 2 nuclear power plant came to a halt on Tuesday evening after a rise in moisture levels was detected in the generator.
The cause of the issue remains unclear, according to the nuclear power plant's operator, Teollisuuden Voima (TVO).
Last autumn, Olkiluoto 2's generator rotor failed. Since then, the unit has been operating at reduced capacity to prevent rotor failure and also due to a shortage of spare parts.
A replacement rotor was delivered to Olkiluoto last week, and efforts began to restore the reactor to full power.
It is not yet known whether the recent increase in generator moisture is linked to the power ramp-up, according to TVO communications manager Johanna Aho.
"It’s too early to draw conclusions. We’re investigating the matter calmly," Aho said.
In its statement, TVO said there is no estimate yet for when Olkiluoto 2 will return to operation.
Currently, only Olkiluoto 1 is supplying electricity, as the Olkiluoto 3 reactor is undergoing scheduled maintenance and is expected to return to service in May.
Olkiluoto 2 accounts for nearly 10 percent of Finland’s electricity production, while OL3 meets about 14 percent of the country’s electricity needs.
Warm weather helps avert price spike
This week has brought sunny and warm weather, especially to southern Finland — a welcome development that significantly reduces the risk of electricity supply issues, according to Pekka Salomaa, Director of the trade association Finnish Energy.
However, the simultaneous outages at Olkiluoto 2 and 3 raise concerns and could risk driving up electricity prices.
"We’re in a season when the electricity supply is generally more stable. But the likelihood of an extreme situation still increases," Salomaa said.
Despite the low-snow winter, Salomaa said hydropower is playing a key role, with increased availability in the Nordic grid during spring.