Disposal of spent fuel in Finland
Final disposal of spent fuel in Finland
Finland is running a long-term research and development programme aimed at the implementation of high-level nuclear waste disposal. The Finnish Government granted Posiva Oy permission to construct a final disposal facility on 12 November 2015. The final disposal must not cause any harmful radiation exposure to people or the environment.
The schedule for the preparation of spent nuclear fuel for final disposal was defined in a Government decision in 1983. In accordance with the objectives set in the decision, the site for final disposal should be selected by the end of 2000, the construction of the disposal facility should be started at the beginning of the 2010s and disposal should begin around 2020.
Teollisuuden Voima Oyj and Posiva Oy conducted research aimed at the selection of the disposal site at six locations in Finland in the 1990s, and in 1999, Posiva proposed Olkiluoto in the municipality of Eurajoki as the location of the final depository in their application for a decision-in-principle. In the application for a decision-in-principle, the intended final disposal concept (KBS-3) was also presented. The aim is to encapsulate the used nuclear fuel in copper canisters and dispose of them, surrounded by bentonite clay, in premises built into the bedrock at a depth of 400–450 metres.
In May 2001, the Finnish Parliament ratified a decision-in-principle to build a disposal facility for spent nuclear fuel at Olkiluoto in Eurajoki.
In October 2003, the Ministry of Economic Affairs and Employment decided to revise the original schedule so that the construction licence application would be ready by the end of 2012.
Posiva submitted an application for a construction licence concerning an encapsulation and final disposal facility for spent nuclear fuel to the Ministry of Economic Affairs and Employment at the end of 2012. STUK issued its statement on the application on 11 February 2015. Upon the recommendation of the Ministry of Economic Affairs and Employment, the Government granted the permission on 12 November 2015.
Encapsulation and final disposal facility
For the final disposal of spent nuclear fuel, an above-ground encapsulation facility and an underground disposal facility are needed. In the above-ground encapsulation facility, the spent nuclear fuel is received, dried and packed into final disposal canisters. Before, spent nuclear fuel has been stored in water basins located at the sites of nuclear facilities in interim storages for spent nuclear fuel for 30–50 years.
The final disposal facility means the entity, which includes facilities for the final disposal of waste packages (repository) and related underground and above-ground auxiliary facilities. The encapsulation facility (above-ground) and disposal facility (underground) are connected to each other with an elevator shaft and canister transfer shaft as well as a separate access tunnel. In the processing of nuclear waste, mainly equipment operated by remote control is used.
The final disposal facility consists of an access tunnel that reaches a depth of approximately 450 metres, technical facilities located at a depth of 437 metres and central and final disposal tunnels to be built in phases during the facility’s use. Since 2004, Posiva has been building an underground research facility, called Onkalo, the premises of which are designed to function as part of the final disposal facility.
The disposal system consists of a tightly sealed iron-copper canister, a bentonite buffer enclosing the canister, a tunnel backfilling material made of swellable clay, the seal structures of the tunnels and premises and the enclosing rock.