Repository in ONKALO

The construction work of ONKALO®, located in Olkiluoto, Eurajoki, started in June 2004.

In the initial phase, ONKALO was primarily an underground research facility, where studies were carried out to confirm the suitability of Olkiluoto bedrock for final disposal. In over 15 years, ONKALO® has established its position in Finland and internationally and, today, the concept has expanded to cover the entire disposal facility of Posiva. ONKALO® extends to a depth of about 455 m.

In 2015, Posiva received the disposal facility construction licence from the Finnish Government. The repository in ONKALO® will be constructed to a depth of 400–430 m.

ONKALO® consists of a spiral-shaped access tunnel, four vertical shafts (personnel shaft, canister shaft and two ventilation shafts), tunnels and technical rooms. By 2020, approximately 10 km of different kinds of tunnels have been excavated in bedrock in Olkiluoto. During final disposal operations, some 40 km of new tunnels will be excavated in bedrock.