Finland is the first country in the world to undertake the burial of nuclear fuel waste in a geological tomb, to securely store radioactive materials for the next 100,000 years.
The ambitious plan, set to begin as early as 2025, involves the construction of an underground disposal facility that is already well underway. The facility, named Onkalo—meaning “cavity” in Finnish—is located near the island of Olkiluoto, close to three nuclear reactors, and about 150 miles (240 kilometers) from the Finnish capital, Helsinki.
Onkalo is designed to safely contain high-level radioactive waste, specifically spent nuclear fuel, which remains hazardous to humans and the environment for thousands of years. The plan is to place the nuclear waste in robust, watertight canisters that will be buried approximately 1,312 feet (400 meters) below the earth’s surface. The facility is being meticulously constructed and continuously monitored to ensure it meets the highest safety standards.
Nuclear waste management is a critical aspect of operating nuclear reactors, which produce three types of radioactive waste. Low-level waste, such as contaminated paper, tools, and clothing, is only radioactive for a short time. Intermediate-level waste, including resins and reactor components, remains radioactive for a longer period. However, the most dangerous is high-level waste—spent fuel from nuclear power plants—which contains radioactive materials with extremely long lifespans, necessitating their isolation from the environment.
To address this, the final disposal canisters at Onkalo are designed to remain sealed and impervious long enough for the radioactivity to decay to safe levels. Posiva, the company overseeing Onkalo’s construction, describes the facility as a complex structure consisting of a “spiral-shaped access tunnel, four vertical shafts (personnel shaft, canister shaft, and two ventilation shafts), tunnels, and technical rooms.” The Finnish government granted Posiva the license to build this disposal facility in 2015, following extensive testing and surveys to ensure the site’s suitability.
By 2020, over half a million solid cubic meters of rock had been excavated to create space for the facility. The construction has been guided by rigorous safety assessments and environmental studies. Posiva’s 2023 annual report indicates that a trial run for the final disposal process, including simulations using unirradiated fuel elements, is scheduled for 2024.
Final system installations in the encapsulation plant are nearing completion, with safety assessments and the Finnish Radiation and Nuclear Safety Authority’s (STUK) review of the operating license expected in the same year.
