According to a Yahoo report from the Associated Press:

Finland’s much-delayed and costly new nuclear reactor, Europe's most powerful by production capacity, has completed a test phase lasting more than a year and started regular output, boosting the Nordic country’s electricity self-sufficiency significantly.

The Olkiluoto 3 reactor, which has 1,600-megawatt capacity, was connected into the Finnish national power grid in March 2022 and kicked off regular production on Sunday. Operator Teollisuuden Voima, or TVO, tweeted that “Olkiluoto 3 is now ready" after a delay of 14 years from the original plan.

It will help Finland to achieve its carbon neutrality targets and increase energy security at a time when European countries have cut oil, gas and other power supplies from Russia, Finland’s neighbor.

The Olkiluoto 3 is Western Europe’s first new reactor in more than 15 years. It is the first new-generation EPR, or European Pressurized Reactor, plant to have gone online in Europe. It was developed in a joint venture between France’s Areva and Germany’s Siemens.

https://finance.yahoo.com/news/europes-most-powerful-nuclear-reactor-125942008.html