After years of delays, the French-German-designed European pressurized nuclear reactor ( EPR ) began operating Sunday in Finland to cover 15 percent of the country's energy needs, according to the operator TVO group.

After two decades of construction, the Olkiluoto-3 reactor, one of the most powerful reactors in Europe, became operational at the end of December 2021 and reached its full production capacity of 1,600 megawatts for the first time on September 30.

Since it was brought online in March 2022, its operation has been delayed several times during the testing period. From Saturday to Sunday, the reactor, built by the French Areva group, entered service.

"The test was completed and regular power generation began today," the group said in a statement.

She added that with the production of the existing reactors 1 and 2 accounted for, "about 30 percent of Finland's electricity is now produced in Olkiluoto" in the country's southwest.

Construction of this new reactor began in 2005.

The aim of this model of the French development reactors was to re-launch nuclear energy in Europe after the Chernobyl catastrophe in 1986 and was presented as having greater power and better safety.

However, its development posed a technical dilemma, and not only in Finland.

In northwestern France, the construction of the Flamanville reactor in the north of the country was also delayed after it began in 2007. In contrast, two reactors were put into service in China.