Trial run at Finnish encapsulation plant completed

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. From the encapsulation plant, the canisters will be transferred into the underground tunnels of the repository, located at a depth of 400-450 metres, and further into deposition holes lined with a bentonite buffer.

Posiva has now completed the Trial Run of Final Disposal (TRFD) at the encapsulation plant. The fifth and final canister used in the trial run - which began in August last year - has been encapsulated, subjected to a construction inspection, and transferred successfully to the underground storage at a depth of 430 metres. In the so-called retrieval test, one canister was retrieved back to the encapsulation plant according to plans.

"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. We have an extremely high mindset to execute TRFD to a high standard and safely."

The Trial Run of Final Disposal next continues underground once individual tests have been acceptably completed on all the underground production equipment. During the Trial Run, the operation of the complete final disposal facility is tested. Instead of actual used nuclear fuel, the trial run is conducted using non-radioactive test elements. Areas identified at the encapsulation plant as needing improvement included adjustments of some equipment.

The government granted Posiva a construction licence for the project in November 2015 and construction work on the repository started in December 2016. 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 nuclear power plants. The operation will last for about 100 years before the repository is closed.