Olkiluoto

The Olkiluoto Nuclear Power Plant ( fi, Olkiluodon ydinvoimalaitos, sv, Olkiluoto kärnkraftverk) is one of Finland's two nuclear power plants, the other being the two-unit VVER Loviisa Nuclear Power Plant. The plant is owned and operated by Teollisuuden Voima Oyj (TVO), a subsidiary of Pohjolan Voima, and is located on Olkiluoto Island, on the shore of the Gulf of Bothnia, in the municipality of Eurajoki in western Finland, about 20 kilometres from the town of Rauma and about 50 kilometres from the city of Pori.

The Olkiluoto plant consists of two boiling water reactors (BWRs), each producing 890  MW of electricity, together comprising 22% of the country's electricity generation for 2020. A third reactor, Unit 3, reached first criticality in late 2021, and at a nameplate capacity of 1,600 MW net electric output, will by itself satisfy 14% of the country's electricity demand.

Unit 3 is an EPR reactor and has been under construction since 2005. The start of commercial operation was originally planned for May 2009 but was postponed repeatedly. The reactor eventually started up on 21 December 2021, and electricity production started on 12 March 2022. In May 2022, foreign material was found in the turbine steam reheater, and the plant was shut down for about three months of repair work. On 30 September 2022, the reactor reached its maximum output power for the first time. In October damage was detected in all of the feed water pumps and unit 3 was shut down for an investigation. Regular production is expected to begin at the end of January 2023 at the earliest.

Units 1 and 2

Units 1 and 2 consists of two BWRs, each producing 890 MW of electricity. The main contractor was ASEA-Atom, now a part of Westinghouse Electric Sweden AB. Turbine generators were supplied by Stal-Laval. The units' architecture was designed by ASEA-Atom. The reactor pressure vessels were constructed by Uddcomb Sweden AB, and reactor internal parts, mechanical components by Finnatom. The electrical equipment was supplied by Strömberg. Unit 1 was constructed by Atomirakennus and unit 2 by Jukola and Työyhtymä. Unit 1 achieved its initial criticality in July 1978 and it started commercial operations in October 1979. Unit 2 achieved its initial criticality in October 1979 and it started commercial operations in July 1982.

The original power of the reactors was 660 MW. They were uprated to 710 MW in 1983–1984, to 840 MW in 1995–1998, and further to 860 MW in 2005–2006. Major upgrades were carried out to the units in 2010 and 2011, including replacement of turbines and generators, isolation valves, electrical switchgear and seawater pumps. The upgrades increased the net electrical output by 20 MW to 880 MW each.

In 2017, unit 2 was upgraded and modernized, increasing the output further to 890 MW from the beginning of 2018. A similar upgrade to unit 1 was performed in 2018. The extended maintenance was also made to prepare for a license renewal application. The license extension was granted in September 2018 and allows the reactors to operate until 2038.

A decision-in-principle for a fourth reactor to be built at the site was granted by the Finnish parliament in July 2010, but, in June 2015, TVO decided that it would not apply for a construction license for Olkiluoto 4.

Unit 3

In February 2005, the Finnish government gave its permission to TVO to construct a new nuclear reactor, making Finland the first Western European country in 15 years to order one. The construction of the unit began in 2005. The start of commercial operation was planned for 2010, but has been pushed back several times.

Olkiluoto 3 is the first EPR, which is a type of third generation PWR, to have gone into construction. It will have a nameplate capacity of 1600 MW. Japan Steel Works and Mitsubishi Heavy Industries manufactured the unit's 526-ton reactor pressure vessel.

At the start of construction, the main contractor was Areva NP (now Framatome, after the sell-off mentioned below), a joint venture of Areva and Siemens. However, in 2009, Siemens sold its one-third share of Areva NP to Areva, which is now the main contractor. Siemens remained on the project as the subcontractor with the main responsibility for constructing the turbine hall. Areva sold its majority stake in Framatome (previously Areva NP), its nuclear reactor and fuel business, to Électricité de France.

According to TVO, the construction phase of the project would create a total of about 30,000 person-years of employment directly and indirectly; that the highest number of on-site employees has been almost 4,400; and that the operation phase would create 150 to 200 permanent jobs. A 90 MW battery storage is scheduled for 2022.

On 8 December 2021 the company submitted its application to Finland's Radiation and Nuclear Safety Authority asking permission to start up Unit 3 and to move forward with initial testing of the unit. This was granted on 16 December 2021. First criticality of the OL3 EPR plant unit was reached on 21 December 2021. An unplanned automatic trip occurred on 14 January 2022, delaying connection to the national grid to February 2022. The electricity production of Olkiluoto’s third nuclear power plant unit started on Saturday, 12 March 2022, at 12.01 p.m. In May 2022, foreign material detached from the steam guide plates was found in the turbine steam reheater, and the plant was shut down for about three months of repair work. The test production phase should complete in December 2022, when regular electricity production should start.

In September 2022, the Radiation and Nuclear Safety Authority (STUK) granted a licence for the Olkiluoto 3 reactor to increase its power output to more than 60 percent to a full 4,300 MW of thermal capacity. On 30 September 2022, the reactor achieved its design output power. In October 2022, damage was discovered in the feedwater pumps, likely delaying the end of commissioning testing. On 28 October, it was announced cracks a few centimetres long had been found in all four of the feedwater pump impellers. The cause of the cracks was yet to be determined, and it was unclear how the schedule would be affected. The feedwater pumps are larger than in other nuclear reactors.

Construction delays

The first license application for the third unit was made in December 2000 and the date of the unit's entry into service was estimated to be 2010. However, since the start of construction, several delays to the schedule have been announced. In July 2012 TVO announced that the unit would not go into service before 2015, five years after the original estimate. In a statement, the operator said it was "not pleased with the situation" although solutions to various problems were being found and work was "progressing", and that it was waiting for a new launch date from Areva and Siemens. At the end of 2013, TVO said that the Areva-Siemens consortium plans to reduce workers and subcontractors on the construction site and says that it expects the contractor to provide details about the expected impact on the project's schedule. In February 2014, TVO said that it could not give an estimate of the plant's startup date because it was still waiting for the Areva-Siemens consortium to provide it with an updated overall schedule for the project." Later the same month it was reported that Areva was shutting down construction due to the dispute over compensations and unfinished automation planning. According to Kauppalehti, the estimated opening was delayed until 2018–2020. In July 2019 TVO announced that regular electricity generation is expected to start in July 2020. The delay was caused by slower than expected modification works. In August 2020 TVO announced that regular electricity generation is delayed to February 2022 due to slow progress in system testing, technical problems found in the testing, and delivery time of spare parts to replace faulty components.

The delays have been due to various problems with planning, supervision, and workmanship, and have been the subject of an inquiry by STUK, the Finnish nuclear safety regulator. The first problems that surfaced were irregularities in the foundation concrete, and caused a delay of months. Later, it was found that subcontractors had provided heavy forgings that were not up to project standards and which had to be re-cast. An apparent problem constructing the reactor's unique double-containment structure also caused delays, as the welders had not been given proper instructions.

In 2009, Petteri Tiippana, the director of STUK's nuclear power plant division, told the BBC
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