Olkiluoto is a pine-covered island jutting out into the Baltic Sea, just off the western coast of Finland. Beneath the surface, there’s 2-billion-year-old bedrock made mostly of gneiss, hard as steel. It’s here that engineers are digging a facility known as Onkalo, Finnish for “cavity” or “pit.” They’re constructing a tomb, a quarter of a mile underground, to store spent uranium rods from nuclear power plants for the next 100,000 years. And depending on who you ask, future generations might be warned away from sites like it by glowing cats….
