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In Finland, a groundbreaking project called Onkalo is set to redefine the concept of isolation. This underground complex, located near the Olkiluoto nuclear power plant, is designed to safely store nuclear waste for an impressive 100.000 years. Once sealed in 2025, no humans will be able to access the site, marking a milestone in sustainable nuclear energy management.
Onkalo, which translates to “cave” in Finnish, is more than just a curious name. It represents a bold and necessary response to one of humanity’s greatest challenges: the safe storage of nuclear waste. Developed by Posiva, a Finnish waste management organization, the site is an intricate network of tunnels and chambers dug 450 meters underground, designed to resist geological changes and the passing of time.
BBC journalist Erika Benke was one of the few people to visit the tunnel before it closed for good. “It takes 15 minutes by car to descend the 437 meters to the Onkalo service station,” Benke said, describing the 4,5-kilometer tunnel with its solid rock walls and minimal lighting. At points, the floor becomes wet and muddy, a reminder that the environment here is inhospitable even to humans.
In the heart of Onkalo
The spent nuclear fuel will be sealed in airtight containers and deposited in vertical holes. The operation involves robots designed to ensure precision and safety, away from human touch. These measures are essential to protect the radioactive material from future generations and from nature itself, which can be unpredictable over such long periods.
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A challenge beyond human time
Understanding a period of 100.000 years is an almost impossible task for any human. For comparison, this interval is equivalent to 4.000 generations. 100.000 years ago, the planet was a place dominated by woolly mammoths and the first humans were beginning to explore the world outside of Africa.
This time horizon makes Onkalo a monument to Finland's commitment to environmental responsibility. The international community has already applauded the boldness and technical sophistication of the project, which combines natural and artificial barriers to safely isolate nuclear waste.
Onkalo's legacy
From 2025 onwards, Onkalo will be sealed, leaving behind a silent mission: to protect humanity and the environment from dangerous nuclear waste until nature itself makes it safe. Beneath the serene landscape of southwestern Finland, Onkalo will continue its work, unseen, while human history continues its course.
In this underground tunnel where no human will be able to set foot again, science, ethics and technology meet to leave a legacy that transcends our time.
I would like more details, verification control methods, construction details, cost, etc.
Any project that contains radioactive materials and is considered to be of strategic security, that is, details like the ones you want to know are not disclosed.
Materials Used
Concrete: Used extensively to create barriers that isolate nuclear waste and prevent contamination1.
Copper and Iron: The canisters that store the waste are made of copper and iron, materials chosen for their durability and resistance to corrosion2.
Granite: Onkalo is built on granite bedrock, which provides an additional natural barrier against radiation release…