Europe's largest nuclear reactor begins regular operations after 18 years.

Finland's Olkiluoto 3 nuclear reactor, Europe's largest, has begun regular output after 18 years of construction and technical issues. The reactor is expected to meet around 14% of Finland's electricity demand, reducing the need for imports from Sweden and Norway. The new reactor is expected to produce for at least 60 years, boosting Finland's energy security in a region to which Russia has cut gas and power supplies.