Finland / Olkiluoto-3 Back Online After Longer Than Scheduled First Outage

TVO says annual service took twice as long as planned.

The Olkiluoto-3 nuclear power plant in Finland returned to electricity production on 16 May after a first annual service outage that lasted twice as long as originally planned.

Teollisuuden Voima Oyj (TVO), owner and operator of the 1,575-MW EPR unit, said the plant was synchronised to the national grid and was “technically ready for a power increase”.

The outage was scheduled to take 37 days, but lasted for 74 days and 9 hours. TVO said delays were due to the shutdown process and preparations for refuelling taking longer than expected, and because of technical problems identified during maintenance activities.

TVO also detected indications of a risk of foreign material in the fuel elements during the outage, which meant inspections of the elements were took significantly longer than expected.

“It was anticipated that the service outage after the first operating cycle would be very laborious,” TVO said in a statement. “As OL3 is the largest nuclear power plant unit in Europe, the amount of equipment and components is extremely high. All in all, about 7,500 work phases were carried out during the OL3 outage.”

In addition to refuelling, the most important activities carried out during the annual outage included preventive maintenance on the protection system, washing of steam generators, generator maintenance, pressure equipment inspections, leak-tightness tests on containment isolation valves and servicing of pressuriser safety relief valves.

The plant also underwent a significant number of different periodic tests and maintenance activities during the outage.

Olkiluoto-3, the first EPR plant in Europe, began commercial operation in May 2023. TVO said Olkiluoto-3 is by far the most efficient electricity production plant in Finland and produces about 14% of the country’s electricity.

Finland has five commercial nuclear reactors – two at Loviisa, owned and operated by Fortum, and three at Olkiluoto.

The Generation III EPR was designed in France, where an EPR is nearing operation at Flamanville-3, a project that has seen delays and cost overruns.

Two other EPR units in China have begun commercial operation. Taishan-1 in China was the first EPR unit to begin commercial operation, in December 2018. A second EPR at Taishan began commercial operation in September 2019.

In the UK there are two EPRs under construction at Hinkley Point C, where there have also been delays and significant cost overruns.