Encapsulation and final disposal phase
After interim storage of several decades, the spent fuel assemblies will be transferred from the interim storage pools to the encapsulation plant in an impact-resistant cask for the transfer.
The cask will protect the environment from radiation and prevent damage to the fuel assemblies. Fuel stored in the Loviisa interim storage facility can be transported to Olkiluoto either by road or by sea. As regards the transport operations, the principle is that the transport cask may not lose its radiation shielding properties even in the worst-case accident. The safety of each transport operation is secured through separate permit and safety procedures, supervised by the Finnish Radiation and Nuclear Safety Authority (STUK).
The final disposal facility for spent nuclear fuel will be constructed within the solid Olkiluoto bedrock with no major fractures at a depth of 400–450 meters. Potential effects of earthquakes and future ice ages have been taken into account in the design of the final disposal concept.