But it has also remained controversial in many countries due to its high cost and long build times, as well as concerns over the safety of nuclear reactors and the unresolved issue of what to do with nuclear waste."Onkalo" is a Finnish word for a cave or a hollow. It's a fitting name for a huge grave made in Finland over the last 20 years. Onkalo, which lies 450m (1,500ft) deep inside the bedrock of Olkiluoto island in the southwest of the country, is the world's first permanent storage site for spent nuclear.
Onkalo has cost €1bn (£860m/$1.07bn) to build and is expected to begin operations in about two years. Its arrival has been hailed as a game changer by many, including the International Atomic Energy Agency (IAEA). "Everybody knew of the idea of a geological repository for high-level radioactive nuclear waste, but Finland did it," commented Rafael Mariano Grossi, IAEA director general, on a visit to the site in 2020.
The Onkalo repository is based on the KBS-3 concept developed by the Swedish Nuclear Fuel and Waste Management Company, in cooperation with Posiva. The idea is to create three barriers around nuclear waste: first, put it in copper canisters, then wrap the canisters in bentonite — a water-absorbing clay — and finally, bury them in tunnels deep in the bedrock.
"We've all benefited from nuclear energy for over 60 years," says Lewis Blackburn, a lecturer in nuclear materials at the University of Sheffield in the UK. "It's our generation of scientists' and engineers' responsibility to undertake the challenge to dispose of the waste, instead of leaving it to future generations.
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