Olkiluoto is the biggest nuclear power plant in Finland. Source: TVO.
Olkiluoto 3 will be the first 1.6GW-class European Pressurised Reactor (EPR) to come online in Europe. Source: TVO.
Olkiluoto 1 and Olkiluoto 2 have been connected to the grid since 1978 and 1980, respectively. Source: TVO.

Olkiluoto is one of the two nuclear power plants operational in Finland. Owned and operated by Teollisuuden Voima Oyj (TVO), the plant comprises two 890MW boiling water reactor (BWR) units commissioned in 1978 and 1980, respectively.

TVO is a Finnish nuclear power company owned by Pohjolan Voima (58.5%), Fortum Power and Heat (25.8%), Oy Mankala (8.2%), EPV Energia (6.6%), and Kemira (0.9%).

Construction of a third reactor unit at the Olkiluoto nuclear power plant (NPP) has been completed and its first criticality took place in December 2021. Scheduled to start commercial operations in the first half of 2022, Olkiluoto 3 (OL3) will be Finland’s first new nuclear reactor to come online in four decades.

With a net power output of 1.6GW, OL3 will be the biggest nuclear reactor in Europe and the first European Pressurised Reactor (EPR) to be commissioned in the continent.

Location and site details

The Olkiluoto nuclear power station is located on the Olkiluoto Island in Eurajoki, on the west coast of Finland.

The Onkalo nuclear waste disposal facility, the world’s first permanent geological repository for spent nuclear fuel, is being constructed on a site close to the Olkiluoto NPP.

Scheduled to enter service in 2025, the underground facility will store nuclear waste produced by TVO’s Olkiluoto NPP and Fortum’s Loviisa NPP in Finland. Posiva, a joint venture of TVO (60%) and Fortum (40%), is responsible to construct and operate the Onkalo nuclear waste repository in Olkiluoto.

Power production at Olkiluoto NPP

The Olkiluoto nuclear power facility produced 14.4 terra-watt hours (TWh) of electricity accounting for approximately one-sixth of the total electricity consumption in Finland in 2021.

The power station is expected to produce approximately 30% of the country’s electricity following the commissioning of Olkiluoto 3.

Olkiluoto 3 reactor development details

Construction of the OL3 EPR started in August 2005, whereas the reactor pressure vessel was installed in June 2010 followed by the installation of steam generators inside the reactor building in February 2011.

The Finnish Radiation and Nuclear Safety Authority (STUK) granted an operating licence for OL3 in March 2019 and permitted to load fuel into the reactor in March 2021.

Fuel loading was completed in April 2021 and TVO received permission to start up the reactor and conduct power tests in December 2021.

The OL3 EPR reactor is expected to start producing electricity at a 25% power level following its grid connection in Q1 2022. It is expected to start commercial operations in June 2022.

Olkiluoto 3 plant make-up

The Olkiluoto 3 (OL3) plant unit is located next to the existing Olkiluoto 1 (OL1) and Olkiluoto 2 (OL2) units, at the western end of the Olkiluoto island.

It comprises a reactor building housing a 1,600MW EPR supplied by Framatome, along with a turbine building and auxiliary buildings.

The reactor building comprises a reinforced concrete and double-shell containment measuring 63m high with 57m outer diameter. The containment building houses the reactor core within a pressure vessel, as well as the reactor coolant system that includes four steam generators, pressurisers, and reactor coolant pumps.

The reactor core comprises 241 fuel assemblies. The OL3 EPR is designed to generate 4,300MW of thermal power operating at a reactor pressure of 155bar.

The OL3 turbine building houses a 1,500 revolutions per minute (rpm) steam turbine, generator, exciter, and condensers, among other systems. The steam turbine has one high-pressure (HP) section and three low-pressure (LP) sections and is designed to provide 1,600MW of net electrical power operating at a main steam temperature of 290°C.

OL3 will consume 32 tonnes (t) of uranium dioxide (UO2) fuel a year and use seawater at a flow rate of 57m3/s for cooling. It is estimated to produce up to 13TWh of electricity a year.

Details of Olkiluoto 1 and Olkiluoto 2 units

OL1 and OL2 are two identical plant units, each of which is equipped with a BWR of Swedish (Asea-Atom) design and a 3,000rpm steam turbine having one HP and four LP sections.

Construction of OL1 started in February 1974 with commercial operations starting in October 1979. Construction of OL2 started in November 1975 and its commercial operations began in July 1982.

The initial net power of both the units was 660MW, which was increased in multiple stages to reach the current capacity of 890MW between 2018 and 2019.

The Finnish government approved the extension of operating licences for OL1 and OL2 until 2038, in September 2018.

Fuel supply

The three units of the Olkiluoto NPP are estimated to require 70t of nuclear fuel a year. The fuel deliveries for OL1 and OL2 have been secured through long-term contracts with Westinghouse Electric Sweden (WSE) and GNF ENUSA Nuclear Fuel (GENUSA).

Framatome is the fuel supplier for OL3. TVEL, the fuel division of Russia’s State Atomic Energy Corporation (Rosatom), has also agreed to test its TVSK-14 fuel design at OL3 from the third cycle onwards.

Power evacuation

The electricity generated by the Olkiluoto NPP is fed into the national grid via Fingrid’s Olkiluoto 400kV substation.

Battery energy storage at Olkiluoto

TVO contracted Hitachi ABB Power Grids to provide a 90MW battery energy storage system at Olkiluoto in June 2021.

Scheduled for commissioning in 2022, it will be one of the biggest battery energy storage facilities in Europe. It is intended to act as a fast-start back-up power source and minimise the effect of power fluctuations on the grid.

Contractors involved in the Olkiluoto NPP

Framatome supplied the nuclear island along with the digital control system and the first fuel core for the OL3 ERP unit, while Siemens was responsible for the engineering, procurement, and construction (EPC) of the turbine island.

Siemens also supplied the turbine generator set along with other auxiliary equipment for the OL3 turbine building.

Heitkamp was subcontracted to construct the turbine building and the pump house of OL3, whereas KSB provided pumps and pressure valves for the project. Roctest supplied its Telemac/Smartec monitoring system for the OL3 plant unit.

TVO selected General Electric (GE) to continue providing maintenance services on the steam turbines and generators of OL1 and OL2 in March 2020.

OL3 project background

The Finnish government approved the construction of a fifth nuclear power reactor in the country in May 2002. TVO contracted the Franco-German consortium comprising Framatome and Siemens to deliver the OL3 EPR plant unit on a turnkey basis in December 2003.

TVO was the first customer for the EPR technology. With commissioning originally scheduled for 2009, OL3 was expected to be the world’s first EPR to enter commercial operations.

However, the project ran 14 years behind its original schedule due to construction delays, cost overruns and several legal disputes between TVO and the consortium partners.

While the installation of main equipment at the turbine island was completed in 2008, works at the nuclear island suffered significant delays due to poor construction management, inadequate design and engineering prior to the start of construction, and the failure to obtain timely regulatory approval for the reactor’s instrumentation and control (I&C) architecture.

The OL3 project lacked the architect-engineering and construction management expertise provided by EDF for other EPR projects around the world.

OL3 cost overruns

The cost of the OL3 EPR project was initially estimated at Є3.2bn ($4bn), which increased almost threefold to Є9bn ($11bn).

The legal disputes related to the costs and losses caused by the delay in project completion were resolved through an International Chamber of Commerce (ICC) arbitration, which ruled that a Є450m ($555m) financial compensation be paid to TVO by the contractors. The parties signed the settlement agreement in March 2018.

EPR reactor development details

Framatome and Siemens created a joint venture called Nuclear Power International (NPI) to develop the 1,600MW-class third-generation pressurised water reactor (PWR) design EPR in 1989. NPI was later renamed as Areva NP.

Areva (now Framatome) became the sole owner of the company after it bought Siemens’ 34% stake in Areva NP for Є1.62bn ($2.3bn) in April 2011.

The world’s first EPR units came online at the Taishan NPP in China. The Taishan 1 EPR unit entered commercial operation in 2018 followed by Taishan 2 in September 2019. Construction on the two units had started in November 2009 and April 2010, respectively.

The other EPRs currently under construction in Europe include Flamanville 3 in France and two units at Hinkley Point C in the UK. Construction of Flamanville 3 started December 2007 with commissioning expected in 2024. The two EPR units at Hinkley Point C have been under construction since December 2018 and December 2019 with commissioning expected in 2026 and 2027, respectively.