Finland has completed construction of an underground repository for spent nuclear fuel, located 430 meters beneath the island of Olkiluoto in the western part of the country. This is the world’s first fully operational repository of its kind, designed for the permanent disposal of nuclear waste
The facility was built in extremely old granite rock dating back approximately 1.9 billion years, which provides high geological stability and reliable isolation of radioactive materials. The granite formation demonstrates exceptional strength and has undergone virtually no tectonic changes over billions of years.
After the repository is filled, it will be completely sealed: tunnels will be plugged, and the entire site will be backfilled and covered so that the facility remains invisible to future generations. The concept assumes that the repository will not require active maintenance and will safely isolate the waste from the biosphere for tens of thousands of years.
The construction of the underground repository at Olkiluoto marks the completion of a multi-year project that began in the 2000s and resulted from cooperation between the energy company Posiva, Finnish regulators, and scientific institutions. The project sets a precedent for other countries seeking a reliable solution to the problem of long-term nuclear waste disposal.