Finnish radioactive waste management company Posiva has completed the Trial Run of Final Disposal (TRFD) at the used fuel encapsulation plant in Olkiluoto. The fifth canister, which was the last of the TRFD canisters, was encapsulated, subjected to a construction inspection, and successfully transferred to the underground storage at a depth of 430 metres.
The encapsulation plant is part of Posiva’s final disposal facility complex. Once the final disposal operation starts, used nuclear fuel will be transported from interim storage to the encapsulation plant where it will be packed into final disposal canisters made of copper and spheroidal graphite cast iron. The canisters will then be transferred into the underground tunnels of the repository, located at a depth of 400-450 metres, and subsequently into deposition holes lined with a bentonite buffer.
“This was a significant milestone of the test production stage,” said Posiva Production Director Karri Osara. “We are now in a good position and feeling positive to move forward and go underground to continue the Trial Run at the final disposal repository.” Posiva is determined to execute TRFD to a high-standard and safely, he noted.
The part of TRFD carried out at the encapsulation plant comprised the encapsulation of a total of five test canisters and their transfer to the underground repository facility. In the so-called retrieval test, one canister was retrieved back to the encapsulation plant according to plan. The TRFD began in August 2024.
During the Trial Run, the operation of the complete final disposal facility is tested. Instead of used nuclear fuel, the Trial Run is conducted using non-radioactive test elements. The whole encapsulation process is carried out under remote control in facilities with high-standard radiation shielding. Areas identified during the TRFD at the encapsulation plant as needing improvement included adjustment of some equipment. At the same time, the focus was on strengthening competences and ensuring the continuous development of all personnel involved.
Posiva President & CEO Ilkka Poikolainen said the TRFD in its entirety is an important stage in verifying Posiva’s readiness for the production stage in both organisational and technical terms. “After the success experienced at the encapsulation plant, we can move forward to executing TRFD on the underground production equipment and further toward the production stage, he noted. The underground TRFD will go ahead once individual tests have been completed on all the underground production equipment.
Posiva, jointly owned by Finnish nuclear utilities Fortum and TVO, applied for a construction licence for a repository to the Ministry of Employment and the Economy in 2013 and the government granted the licence in November 2015. The site for a repository at Eurajoki, near the Olkiluoto NPP, was selected in 2000 and parliament approved the decision-in-principle on the repository project in 2021.
Once it receives the operating licence, Posiva can start the final disposal of the used fuel generated from the operation of TVO’s Olkiluoto and Fortum’s Loviisa NPPs. The facility will operate for about 100 years before it is closed.
