Nuclear facility projects Nuclear facility projects

Nuclear facility projects

Nuclear facility projects

Olkiluoto 3


The Nuclear Power Plant Unit Olkiluoto 3 located in Olkiluoto, Eurajoki, is owned by Teollisuuden Voima Oyj (TVO). The plant is an EPR type (European pressurised water reactor) pressurised water plant with net electric power of approximately 1,600 MW. The plant provider consortium is made up of AREVA GmbH, AREVA NP SAS and Siemens AG.

Nuclear power plant types (in Finnish)

Olkiluoto 3 is undergoing pre-loading commissioning test phase and is in the fuel loading preparation phase. According to the plant provider’s updated schedule, the loading of the nuclear fuel in the reactor will begin in March 2021 and commercial operation in February 2022.

A picture of Olkiluoto 3 Nuclear Power Plant

The operation of the nuclear power plant begins when the nuclear fuel loading has been started. After the fuel loading, pre-critical tests will be carried out.

In pre-critical tests, the operations and features of the plant which cannot be tested before the fuel is loaded but do not require the criticality of the reactor will be examined. After this, the reactor is made critical for the first time, followed by low power tests.

Low power tests ensure that the reactor core behaves as anticipated and that the plant and its systems are functioning as planned also when the reactor is working in power operation. After the low power tests, the power of the plant will be increased gradually.

Power tests ensure that the plant functions in different power levels as planned and, if possible, the plant behaviour in case of operating problems is also tested. The regular electricity generation and commercial operation of the plant will start after the nuclear commissioning phase.

The Radiation and Nuclear Safety Authority supervises

The nuclear safety supervision tasks of the Radiation and Nuclear Safety Authority (STUK) and participation in the licensing are described in detail on STUK’s supervision of nuclear safety website. The licensing model has four phases (decision in principle, construction license, operating license and decommissioning). Licenses granted by STUK are also required before loading the nuclear fuel into the reactor, the first criticality and low power tests as well as during the power test on certain power levels.

The licensing model has four phases: decision in principle, construction license, operating license and decommissioning.

​​​​In the licensing phases and continuous supervision, STUK’s task in the supervision of nuclear safety is to ensure that the requirements for the use of nuclear energy are adequate and that nuclear energy is used according to these requirements. STUK describes its regulatory oversight activities in its triannual reports.

Phases of the OL3 project

Teollisuuden Voima Oyj initiated investigations concerning the construction of a new plant at the Olkiluoto nuclear power plant area in Eurajoki at the end of the 1990s, and filed an application for a Government decision-in-principle with the Government in November 2000. In February 2001, STUK provided a preliminary safety assessment for the Government decision-in-principle, in which the preliminary plans and designs related to the plant were assessed and the major safety concerns were raised. The Government issued a favourable decision-in-principle in 2002, which was subsequently ratified by Parliament.

At the beginning of 2004, TVO filed an application for a construction license with the Finnish Government, which was granted in February 2005. The construction of the third nuclear power plant unit in Olkiluoto at the western end of the Olkiluoto island, next to the OL1 and OL2 units, was commenced in June of the same year.

In the spring 2016, TVO filed an application for an operating license with the Finnish Government, which was granted in March 2019. The operation of the nuclear power plant begins when the nuclear fuel loading has been started. The launch of the loading requires a separate loading authorisation from STUK. The loading launches the nuclear commissioning phase of the plant during which the operations of the plant will be tested as a whole for the parts that could not be tested before the fuel loading and criticality. After the nuclear commissioning, the commercial operation of the plant begins.