Borehole drilling is underway at Finland’s deep geological repository as Finnish nuclear waste management company Posiva Oy said last week it has begun drilling the first underground deposition hole.
Posiva said in its Aug. 27 company update that the operation started the afternoon of Aug. 26, when the drill head of the Deposition Hole Boring Machine cut into the approximately 1.9 billion-years-old bedrock in Olkiluoto. The drilling at the Finland site is 400 meters (or a quarter mile) deep. The deposition holes are the locations where spent fuel canisters will be placed.
Finland is the country furthest along in the process of building out a permanent deep geologic repository for spent nuclear fuel. Posiva began digging tunnels for the Onkalo repository in 2021, after the Finnish regulator issued Posiva its construction license in November 2015.
“We have already practiced with a couple of holes and preparations for the drilling of the actual deposition holes have been ongoing for quite some time,” Posiva Construction Manager of Operations Kimmo Lehtola said. “This day has been much anticipated by our team. It is great to have the opportunity to drill for the first time a hole which will actually become part of the final disposal process.”
Posiva said it expects to find out within days whether its first deposition hole that it drilled will be approved.
The company said the hole that is being constructed now is being drilled vertically into the floor of a previously mined final disposal tunnel. The finished hole is 8.4 meters deep, with a diameter of 1.75 meters, Posiva said.
The drilling of an eight-meter hole at the Onkalo repository takes about 10 hours of drilling time, Lehtola said. While in the preliminary efforts of the first couple deposition holes, Lehtola said once it gets into a routine with its drilling operation, it hopes to produce nearly two finished holes in one week.