Onkalo Nuclear Fuel Repository: Finland Plans to Bury Spent Radioactive Waste in Underground Cave-Like Facility

In a daring step toward sustainable nuclear waste management, Finland is set to become the first country to bury spent nuclear fuel beneath the Earth for long-term storage.

(Photo: Wikimedia Commons/ Kallerna)

Challenges in Nuclear Waste Management

Nuclear energy currently provides 10% of global electricity. It is considered by many as a vital player in the fight against climate change due to its low carbon footprint. However, it has also remained controversial in many countries because of its high cost and long build times. Most importantly, nuclear energy comes with safety concerns involving reactors and the issue of nuclear waste disposal.

Huge amounts of spent fuel and radioactive waste are being accumulated from nuclear plants. Since nuclear waste remains radioactive for thousands of years, it can pose safety and environmental hazards.

Radioactive waste must be kept away from humans and isolated from the environment for a long time. This challenge has made radioactive waste management one of the biggest problems with nuclear energy.

The International Atomic Energy Agency (IAEA) estimates that as of 2016, around 260,000 tonnes of spent nuclear fuel was in interim storage worldwide. Approximately 70% of the spent fuel in the world is in storage ponds, while some are contained in concrete-and-steel facilities called dry casks.

Nuclear Waste Repository

In Finland, nuclear waste was disposed of on-site at the Olkiluoto nuclear power plant in Eurajoki. In a couple of years, radioactive waste will be buried 1,493 feet (455 meters) deep in an underground cave-like facility in Onkalo.

"Onkalo" is a Finnish word which means "cave" or "hollow", implying something big and deep. It is a fitting name for a huge underground facility located deep inside the bedrock of Olkiluoto Island in southwest Finland.

Finland's Onkalo project is a huge milestone in the effort to curb nuclear waste. It will be the first permanent storage site in the world for spent nuclear fuel. It cost $1.07 billion to build and is expected to start operating in 2025.

According to the Finnish Radiation and Nuclear Safety Authority, the characteristics of the Onkalo bedrock are favorable for ensuring the safety of spent nuclear fuel final disposal. Like the rest of the country, Onkalo is stable geologically, with a low risk of earthquakes. As geologist Antti Joutsen describes, the rock in Onkalo is migmatite-gneiss, a mixture of two different rock types in one rock. This material is almost two billion years old and is very hard.

This property is crucial since the rock is one of the three safety barriers in the waste disposal concept. It must also be stable enough to construct deposition tunnels and holes deep below the ground.

Finland decided to construct a facility at Onkalo when its two nuclear producers agreed to dispose of their spent nuclear fuel in a single location two decades ago. The Finnish government approved plans to build the facility in December 2000. A final license for waste disposal at the site is expected to be issued in 2024.