Unit 3 of Finland's Olkiluoto nuclear power plant was connected to the national grid on 12 March and has started supplying electricity, operator Teollisuuden Voima Oyj (TVO) announced. The 1600 MWe EPR is scheduled to enter regular electricity production in July.

Olkiluoto 3 (Image: TVO)

Olkiluoto 3 (OL3) attained first criticality on 21 December, after which its power output has been gradually increased to approximately 27%. At 12.01pm on 12 March, the unit was connected to the grid at a power output of 103 MWe.

"The moment was long-awaited," TVO said. "OL3 significantly improves Finland's electricity self-sufficiency and helps in achieving carbon neutrality goals. A new nuclear power plant was previously commissioned in Finland over four decades ago."

A test production phase, lasting about four months, will now follow during which OL3's power output will be gradually increased to 100%.

"This output is considerable," said TVO. "Approximately 3-4 terawatt hours during the test production phase, which corresponds with approximately 10% of Finland's electricity demand. The power output varies considerably during test production."

Once regular electricity production has started, OL3 will produce about 14% of Finland's total electricity consumption.

"The start of electricity production has been carefully prepared for, and this is a great demonstration of our expertise," said Marjo Mustonen, senior vice president of electricity production. "OL3 is a significant addition to clean electricity production in Finland, the share of which will rise to over 90%. At the same time, the need for the import of electricity will decrease to below half."

The Areva-Siemens consortium constructed the OL3 plant under a fixed-price turnkey contract. They have joint liability for the contractual obligations until the end of the guarantee period of the unit. Construction of Olkiluoto 3 began in 2005, with completion of the reactor originally scheduled for 2009, but the project has had various delays and setbacks.

The Finnish government granted an operating licence for OL3 in March 2019. Finland's nuclear regulator, STUK, granted a fuel loading permit in March 2021. Fuel loading was completed on 1 April, at which point an October start-up was envisaged. However, this was postponed to allow for extra turbine overhaul and inspection works by the plant supplier.

The grid connection of OL3 was welcomed by World Nuclear Association Director General Sama Bilbao y León, who said: "Olkiluoto 3's start-up will further reduce Finland's use of fossil fuels and need for electricity imports, increasing its energy security and reducing its greenhouse gas emissions.

"When Olkiluoto 3 reaches full output, around 90% of Finland's electricity generation will come from clean, low-carbon electricity sources, with nuclear generation supplying around half of that. We congratulate the staff of TVO, the Finnish regulator STUK and all the companies involved for this great achievement."

The first EPR units came online at Taishan in China, where unit 1 became the first EPR to enter commercial operation in 2018 followed by Taishan 2 in September 2019. In Europe, EPRs are currently under construction in France and the UK: Flamanville 3, currently expected to start up in 2023 with commercial operation in 2024; and two units at Hinkley Point C, currently slated for commercial operation in 2026 (unit 1) and 2027 (unit 2).

Researched and written by World Nuclear News