Posiva's ONKALO site is facing a busy year end – excavation, underground studies and tests for new equipment
The preliminary works for initiating final disposal are being refined at Olkiluoto and ONKALO underground rock characterisation facility all the time. During this year, among other things, two new demonstration tunnels will be excavated, more information on bedrock suitable for final disposal will be gathered and new installation equipment planned for final disposal will be tested at the ONKALO site.
Research manager Kimmo Kemppainen from Posiva, what kind of excavation work will be carried out at ONKALO during this year?"At the moment, a part of the connection tunnel has been excavated at ONKALO to connect ONKALO with the future final repository. Later, two pilot holes will be drilled in the area of the approximately 70-metre-long tunnel. The plans will be updated during the year.
Two new demonstration tunnels will be needed for R&D work at ONKALO. Excavation work for them will be started during late summer. One tunnel will be 23 metres long and the other 26 metres. The tunnels will be excavated for the Dopas POPLU experiment."
How is the research work progressing at ONKALO at the moment?"We are collecting more research data and refining the existing information for rock suitability classification (RSC). The data is being collected by boring three new pilot holes at ONKALO. The three new pilot holes were completed during spring in the eastern side of the demonstration tunnels. In hole measurements were carried out during the spring.
At ONKALO, we are also investigating the rock behaviour under loading conditions. In the test, a repository hole is heated and changes in the surrounding bedrock are monitored. The test arrangement are dismantled and the surface of the hole are studied visually to establish the extent of damages.
A long-term test of the bentonite buffer is also still underway with constant measurement and monitoring being performed.
What are the main stages of development work this year?
Tests for the disposal canister transfer and installation vehicle are scheduled at the end of this year at Olkiluoto."
What other work important for the disposal project will be performed at Olkiluoto?"More test disposal holes will be bored in Demonstration Tunnel 2. They are scheduled for the late autumn.
We are also planning to overcore a bentonite-filled copper tube which was installed in one drillhole in 2005. This will provide us with information on the changes that take place in bentonite and concrete at a depth of 400 metres.
In addition, important research work will be carried out in a project for testing the construction and functioning of the end plug for the disposal tunnel. During the late summer and early autumn, we will be preparing a slot for the plug at ONKALO. After that the tunnel behind the plug will be filled and instrumented, a concrete mould for the plug created and the plug itself cast. The work is part of the Dopas project funded jointly by the European Commission and nuclear waste companies.