Onkalo
Onkalo is a repository facility operated by Posiva Oy in Finland. Its capacity is not publicly disclosed.
The first deep geological repository for spent nuclear fuel anywhere, 400 metres down in Olkiluoto granite, using copper canisters in bentonite clay. Construction is complete and the encapsulation plant has been tested with dummy fuel; it awaits an operating licence, with emplacement expected to begin in 2026. Sweden's Forsmark repository, using the same KBS-3 method, is the second to start construction.
Facility
| Stage | Back end |
|---|---|
| Operator | Posiva Oy |
| Country | Finland |
| Capacity | not disclosed |
| Figure applies to | — |
| Note on the figure | Licensed for roughly 6,500 tU of spent fuel over its operating life. |
| Status | construction |
| Commissioned | 2026 |
| Coordinates | 61.2350, 21.4800 |
Position in the chain
No disclosed capacity, so its share of world repository capacity cannot be stated.
Other repository facilities
| Facility | Capacity | Status |
|---|---|---|
| Yucca Mountain | 70,000tHM total | closed |
| Forsmark spent fuel repository (KBS-3) | not disclosed | construction |
| Cigéo | not disclosed | planned |
| Canadian deep geological repository | not disclosed | planned |
| Nördlich Lägern | not disclosed | planned |
| Waste Isolation Pilot Plant | not disclosed | operating |
Sources
- Posiva Oy · retrieved 2026-09-06