Olkiluoto Nuclear Power Plant

The Olkiluoto Nuclear Power Plant (, ) is one of Finland's two nuclear power plants, the other being the two-unit Loviisa Nuclear Power Plant. The plant is owned and operated by Teollisuuden Voima (TVO), and is located on Olkiluoto Island, on the shore of the Gulf of Bothnia, in the municipality of Eurajoki in western Finland, about from the town of Rauma and about from the city of Pori.

The Olkiluoto plant consists of two boiling water reactors (BWRs), each with a capacity of 890 MW, and one EPR type reactor (unit 3) with a capacity of 1,600 MW. This makes unit 3 currently the most powerful nuclear power plant unit in Europe and the third most powerful globally. began on 1 May 2023. 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.

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. 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. The environmental impact assessment program, published in January 2024, investigates options to extend the lifetime by 10 or 20 years at the current power or uprating to 970 MW (in 2028 at the earliest) in addition to the 10 or 20-year extension.

Unit 3

thumb|right|[[Rafael Grossi visit to Olkiluoto NPP on 26 November 2020]]

thumb|Olkiluoto 3 in 2009

Unit 3 is a EPR, a type of third generation pressurized water reactor. It has a nameplate capacity of 1600 MW. Japan Steel Works and Mitsubishi Heavy Industries manufactured the unit's 526-ton reactor pressure vessel.

History

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.

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 SCRAM occurred on 14 January 2022, delaying connection to the national grid to February 2022. Electricity production of Olkiluoto's third nuclear power plant unit started on 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.

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 and unit 3 was shut down for an investigation, delaying the end of commissioning testing. On 28 October, it was announced that cracks a few centimetres long had been found in all four of the feedwater pump impellers. The feedwater pumps are larger than in other nuclear reactors. In January 2023, it was announced that new more robust impellers will be installed in all four feedwater pumps, and test operation at full power should restart in February.

The plant started regular electricity production on 16 April 2023 after test production and commercial operation on 1 May 2023. Unusual for nuclear reactors in Scandinavia, OL3 reduced production in May 2023 due to negative market prices during the spring thaw when hydropower was unable to absorb surplus.

Construction delays

The first licence application for the third unit was made in December 2000 In August 2020, TVO announced that regular electricity generation was 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,

Many nuclear power plants were constructed in Europe in the 1970s and 1980s. After that there was a long break in the construction, and experienced experts retired.
Areva did not have experience in construction of nuclear power plants. In all the earlier projects in which Areva supplied the reactor, Électricité de France was responsible for the construction management. Many experienced subcontractors had left the business, and Areva had to find new subcontractors and to coach them in nuclear manufacturing.
The original schedule, four years from construction start to grid connection, was too ambitious for a first-of-a-kind plant that is larger than any earlier reactor.
The project started very slowly because Areva was not adequately prepared. When the construction permit was given in 2005, parts of the detailed design were not yet available. Areva did not recognize how much additional work was needed to complete it. The construction started to proceed in a controlled manner two years later.
Areva was not used to STUK's regulatory approach with an early focus on the quality of structures and components. Manufacturing information and a quality control plan must be approved by both the licensee and STUK before manufacturing of the most important components is allowed to start. Inspections with hold points are made during the manufacturing.
The large size of the reactor and the application of new technologies brought major challenges. Some manufacturing technologies had not been used before. For instance, new welding techniques were used in the reactor pressure vessel. Many large components, such as pressurizer forgings and some reactor internal parts, had to be re-manufactured once or twice to achieve the specified quality.
TVO's key persons did not have experience from management of a large construction project.

Construction of the turbine succeeded better under the responsibility of Siemens. Installations of the main turbine equipment were completed about one year behind the original schedule. Taishan 1 in China became the first EPR to start power generation on 29 June 2018, and the second one (Taishan 2) came online in 2019.

Cost

The main contractor, Areva, was expected to build the unit for a fixed price of €3 billion, with any construction costs above that price falling on Areva. In July 2012, those overruns were estimated at more than €2 billion, The agreement would settle all legal actions between the two companies. With the settlement, TVO disclosed its total investment to be around €5.5 billion. Areva had accumulated losses of €5.5 billion. The total cost of the project, therefore, is estimated to be €11 billion.

Between 2013 and 2017 OL1 and OL2 produced between 13,385 GWh and 14,740 GWh per year at capacity factors between 87.2% and 96%. OL3 is expected to produce an additional 12,000–13,000 GWh annually. Even taking into account all OL3 construction delays the long-term target for operational production cost (not including investments and subsidies) for all three plants is 33 €/MWh. Production cost for the OL3 reactor alone is estimated at 49 €/MWh, as OL1-2 had a production cost of app. 18 €/MWh during 2016-2020, prior to OL3 entering service.

Criticism

In 2009, Stephen Thomas wrote: "Olkiluoto has become an example of all that can go wrong in economic terms with new reactors," and Areva and the TVO "are in bitter dispute over who will bear the cost overruns and there is a real risk now that the utility will default."

| January 2009

| reactor pressure vessel and vessel head arrive on site

| May 2009

| main control room lifting in Safeguard Building 2

| Summer 2009

| polar crane installation, dome installation

| Autumn 2009

| steam generators arrive on site

| September 2009

| EPR dome installed

| June 2010

| installation of the reactor pressure vessel in the reactor building

| June 2011

| Anne Lauvergeon leaves her position as CEO of Areva

|June 2018

| The completion is delayed to September 2019 due to delays in the hot functional testing.

|November 2018

|The completion is delayed to January 2020 due to commissioning tests taking longer than expected.

|March 2019

|The Finnish Government granted an operating license to the reactor.

|April 2019

|TVO indicated that the January 2020 deadline for production is expected to be pushed back by two months due to delays.

|July 2019

|Areva delays another 4 months to startup in July 2020.

|December 2019

|Areva announces new schedule: connection to power grid in November 2020, commercial production in March 2021.

|August 2020

|Areva announces new schedule: fuel loading in March 2021, connection to power grid in October 2021, commercial production in February 2022.

|April 2021

|Finished loading of all 241 fuel assemblies to the reactor.

|August 2021

|Turbine refurbishment takes longer than expected, causing another delay of at least three months. Reactor start expected in January 2022, production of electricity in February 2022 and commercial production in June 2022.

|December 2021

|TVO applied for and was granted permission for startup, with production of electricity revised to start late January 2022.

|March 2022

|Electricity production started on 12 March 2022.

Incidents

On 7 March 2025, during a maintenance outage from 1 March 2025 until early May. 100 cubic metres of radioactive coolant water leaked from the reactor into containment space rooms because a hatch in the reactor refueling pool had not been properly closed due to human error. TVO said "a significant operating event occurred during the maintenance work when radioactive coolant leaked ... the significance of the event to radiation safety was low".

Unit 4

thumb|Final disposal capsule for waste nuclear fuel as shown at the Olkiluoto Nuclear Power Plant Visitor Centre

On 14 February 2008, TVO submitted an environmental impact assessment of unit four to the Ministry of Employment and Economy. The event caused a full-scale emergency response at the power plant and at the Radiation and Nuclear Safety Authority. There was no radioactive release to the environment, and the workers were not exposed to radiation. The event was categorized as 0 on the INES scale, which means that it was an exceptional event with no safety significance.

On 3 June 2024 at 11:41, electricity production of unit 3 was briefly interrupted due to a turbine malfunction. An immediate investigation found the cause to be a failure in the differential pressure measurement of the generator's sealing oil and hydrogen coolant. The unit returned to normal production on the following night. The incident had no impact on nuclear safety.

Notes and references

External links

Radiation and Nuclear Safety Authority in Finland
European Pressurised Reactor at Olkiluoto 3, Finland – Brief Interim Review of the Porosity and Durability Properties of the In Situ Cast Concrete at the Olkiluoto EPR Construction, Reactor at Olkiluoto 3, Finland – Review of the Finnish Radiation Nuclear Safety Authority (STUK) Assessment, R3123-A2, July 2005
Reactor at Olkiluoto 3, Finland – Review of the Finnish Radiation Nuclear Safety Authority (STUK) Assessment, R3123-A2, July 2005
Status of Nuclear Power in Finland.