Onkalo spent nuclear fuel repository

Onkalo is a deep geological repository for spent nuclear fuel located in Finland, specifically near the town of Eurajoki, close to the Olkiluoto Nuclear Power Plant. The project is notable for being the world's first permanent disposal site for high-level radioactive waste. The term "Onkalo" means "hiding place" in Finnish, reflecting its purpose of safely isolating nuclear waste from the environment for thousands of years.