The elevator display reads ¡°433,¡± the number of meters below ground. The doors slide open, revealing the entrance to what is expected to be the world¡¯s first permanent repository for radioactive spent nuclear fuel.

Blasted into 1.9 billion-year-old stable bedrock in Eurajoki, southwest Finland, the geological repository for spent nuclear waste ¡ª dubbed Onkalo which means ¡°cave¡± in Finnish ¡ª is nearly ready to start operations.

Countries have been wrestling with what to do with dangerous nuclear by-products since the first plants were built in the 1950s. Currently, most of it is in temporary storage.