Onkalo spent nuclear fuel repository

The facility, named "Onkalo" (meaning "small cave" or "cavity")[8] is being built in the granite bedrock at the Olkiluoto site, about five kilometers from the power plants.

The facility's constructions plans are divided into four phases:[citation needed] Once in operation, the disposal process will involve placing twelve fuel assemblies into a boron steel canister and enclosing it in a copper capsule.

[17] This was refuted when SKB undertook follow-up studies, which indicated that the alleged corrosion process does not exist, and that the initial experiments were not correctly executed and/or the wrong conclusions were drawn.

The fissile Plutonium-239 content could contribute to humanity's conversion to clean and reliable energy into the future, and burying it in permanent sealed storage would limit that potential.

[21] Danish director Michael Madsen has co-written and directed a feature-length documentary Into Eternity (2010) where the initial phase of the excavation is featured and experts interviewed.

[22][23] American anthropologist Vincent Ialenti has written a book Deep Time Reckoning (2020) that explores how Onkalo repository "safety case" experts envisioned distant future ecosystems and reflected on the limits of human knowledge.

American singer and songwriter Emperor X used a sketch of the facility as the album art for the related song "10,000-Year Earworm to Discourage Resettlement Near Nuclear Waste Repositories".

Schematic of the geologic repository research tunnel at the Onkalo site near Olkiluoto Nuclear Power Plant, Finland.
Pilot cave at final depth.