After more than a decade of delays, the Finnish Radiation and Nuclear Safety Authority (Stuk) has finally given the Olkiluoto 3 nuclear reactor the green light to begin operations. It was originally scheduled to go online in 2009.

"The criticality and low power test permission granted today [...] means that the company can start the nuclear reaction in the Olkiluoto 3 reactor (OL3) for the first time," Stuk's press statement reads.

STUK added that the commissioning tests, including re-testing after modifications, have shown that the plant is operating as planned. According to estimates, the generator will begin providing energy to the grid in February. The unit is expected to be running at full capacity by June.

Project Manager Essi Vanhanen says that the commissioning process has been "a learning lesson for all the parties involved."

The Olkiluoto nuclear power plant has been operating since 1979 in Eurajoki, near Rauma on Finland's west coast. Its second unit, OL2, went online in 1982. Plans for a fourth reactor were abandoned in 2015.