Finland will soon become the first country in the world to seek to bury nuclear waste in a deep underground grave, where it could be stored for the next 100,000 years.
The Finnish authorities’ plan is to encapsulate the spent nuclear fuel in airtight containers and store it 400 metres below ground in a forest in the south-west of the country, according to Interesting Engineering. Finland plans to carry out this operation in 2025 or 2026. The construction of the underground storage facility is nearing completion and is being regularly analyzed to detect any gaps, ensuring maximum safety.
Onkalo, which means “cave” or “hollow” in Finnish, is the name of the new facility that will store nuclear waste for centuries to come. The facility is located near three nuclear reactors on Olkiluoto Island, about 240 kilometers (150 miles) from the capital Helsinki.
Every operating nuclear reactor produces radioactive waste, which can be divided into three categories. The first category is low-level waste such as paper, rags, tools, and clothing, which are radioactive for a short period of time. The next category is intermediate-level waste such as plastics, chemicals, and reactor parts, which are radioactive for a slightly longer period of time. The third category is high-level waste, which is spent fuel from nuclear power plants.
The small amount of radioactive material remaining in the fuel has an extremely long shelf life and must be isolated from the environment. For this reason, final containers are designed to be airtight and impermeable long enough for the radioactivity of the spent fuel to gradually decline to a level that is not harmful to the environment.
Nuclear fuel waste is a product stored at Onkalo because its radioactivity can be dangerous to humans and all living things for centuries. Posiva, the company in charge of building Onkalo, said the facility includes a spiral entrance tunnel, four vertical tunnels (a personal tunnel, a container transfer tunnel and two ventilation tunnels), other tunnels and technical rooms.
The company received a permit from the Finnish government to build the facility in 2015. According to the company, more than half a million cubic meters of solid rock had been removed from the site by 2020. Prior to that, the company had conducted numerous tests and surveys to determine whether the site was suitable for a nuclear waste storage facility.
Posiva’s 2023 annual report says that commissioning will take place in 2024. Final system installation at the facility is nearing completion. A safety assessment and notification from the Finnish Nuclear and Radiation Safety Authority (STUK) on the outcome of Onkalo’s application for an operating license are expected in 2024.