Research reactor in Otaniemi

Finland's first nuclear reactor was commissioned in Otaniemi, Espoo, in 1962. The research reactor was decommissioned in 2015, and ten years later, the facility was released from STUK's regulatory oversight.

The FiR 1 nuclear reactor of the Technological Research Center VTT Oy was a small research reactor with a thermal output of 250 kilowatts. The water-cooled, pool-type reactor originally built for research and education and later also for isotope production and radiotherapy has been specifically developed for the university environment.

The FiR 1 reactor was permanently shut down in summer 2015. VTT was granted permission to decommission the reactor in June 2021. The actual dismantling of the research reactor began in June 2023, once STUK had ensured that VTT was ready to start the dismantling work and take care of the resulting dismantling waste.

The dismantling of the research reactor was carried out in stages in accordance with the dismantling plan. STUK supervised the safe implementation of the dismantling work and waste management through document reviews and site supervision. The actual dismantling work was completed in spring 2024, after which the dismantling site was cleaned up and measured throughout. VTT submitted an application to STUK for release from supervision of the research reactor buildings and plant area in February 2025. VTT supplemented the application on two occasions. STUK verified the results of the measurements carried out by VTT through spot checks.

In December 2025, STUK made an approval decision on the release from supervision, as a result of which the research reactor ceased to be a nuclear facility. The area and buildings can now be used for other purposes and are no longer subject to STUK's regulatory oversight. However, from the perspective of international nuclear safeguards, the facility still exists. Inspectors from the European Commission and the International Atomic Energy Agency (IAEA) will visit later in 2026 to confirm that operations have ceased from their perspective as well.