A tunnel for the disposal of radioactive waste and spent nuclear fuel has been dug at the Onkalo spent nuclear fuel storage facility (Olkiluoto, Finland). This was stated by the radioactive waste management company Posiva Oy.
The tunnel will be used for “joint functional tests”, which involves the disposal of a limited amount of waste in real conditions. Testing is a mandatory element of commissioning.
The length of the tunnel, which will be dug in the coming months, will be about 80 meters. During the joint tests, four more deposition holes will be drilled in the tunnel. The central test tunnel has already been dug.
“In February, we will reach 48 metres, after which the excavation will be interrupted, the base of the tunnel will be levelled out and the required compaction work will be done,” said Kimmo Letola, construction manager at Posiva.
After the inspection of the tunnel, excavation work will continue, and by April-May the tunnel is expected to reach 80 meters in length. This is a trial depth — the final tunnel according to the project should be 350 meters in length and 450 in depth.
Combined functional tests will be conducted in 2023, but without spent nuclear fuel in canisters, as the purpose of the inspection will be to ensure that the final disposal technology works according to plan. The tests will be monitored by government officials, who will use their results to decide on the issue of a license to operate the storage facility.
“Once the tunnel for the joint functional test is complete, excavation of the first five final disposal tunnels will begin,” said Juha Riihimäki, contractor at the site”. Actual final disposal activities will begin in one of the tunnels around 2025.”
The site for Posiva’s repository was selected in 2000. The Finnish parliament approved the decision-in-principle on the repository project the following year.