Posiva has spent more than 40 years preparing for the permanent disposal of spent nuclear fuel.

Research on permanent disposal solutions has practically continued for the entire history of nuclear power in Finland as the very first nuclear power plant permits obligated nuclear power companies to take care of the permanent disposal of fuels.

The decision in principle to build ONKALO was issued in 2001. It was the first of its kind in the world for the permanent disposal of spent nuclear fuel. A research site was first excavated in Olkiluoto where the construction requirements of ONKALO were studied for nearly 12 years. The nuclear installation construction permit, required for the construction of disposal tunnels for nuclear waste, was issued in 2015. After this, YIT started expanding ONKALO to its current scale in 2016.

ONKALO consists of a spiral access tunnel, four vertical shafts (personnel shaft, capsule shaft and two ventilation shafts), tunnels and technical facilities. By this point, more than 10 kilometres of tunnels have been excavated in the bedrock. During the operations of ONKALO, about 40 kilometres of new disposal tunnels will be excavated. New disposal tunnels will be opened in phase with the closing of old tunnels.

ONKALO is planned to be used until about the 2120s.

ONKALO excavation completed – ensuring nuclear safety generates innovative methods

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Picture: Posiva.