Posiva concludes successful test of above-ground encapsulation process
Finland has made progress toward the permanent disposal of spent nuclear fuel, completing the first trial run at Posiva’s Onkalo final repository encapsulation plant, a statement said on Tuesday.
Posiva said five spent nuclear fuel canisters had been encapsulated during the trial. Those were subjected to inspections and transferred successfully to the underground storage at a depth of 430 metres.
According to Posiva’s production director Karri Osara, staff is now ready to begin the trial run phase for the repository facilities located underground.
A full-system trial run at Onkalo began on 30 August 2024 to test all equipment and related systems working together for the first time.
The first stage of the trial in September involved transferring an empty test cask for spent fuel from nuclear operator Teollisuuden Voima’s (TVO) interim storage to Posiva’s encapsulation plant.
In the final disposal facility, spent fuel assemblies will be encapsulated and placed in the bedrock at a depth of about 400 metres. The facility comprises two sections: the above-ground encapsulation plant for the encapsulation of the spent fuel in canisters, and the final repository deep in the bedrock, with tunnels in which the spent fuel will be placed.
Posiva said it has been using non-radioactive test elements instead of actual spent nuclear fuel during the trials.
According to the company, the trial run of final disposal is a final demonstration of the functionality of the final disposal process as a whole and of the readiness of the personnel for commercial operation.
Posiva has been working for several decades at the Onkalo site to develop a concept for final disposal and demonstrate long-term safety. In May 2021, excavation began of final disposal tunnels while Posiva has also built the above-ground encapsulation plant for used fuel at the Onkalo site.
Onkalo will become the first operational deep geological disposal facility in the world with full startup scheduled for the mid-2020s.
