Three drilling holes made during summer
This past summer saw the making of three drilling holes at Olkiluoto. OL-KR51 reached 650 metres, OL-KR52 427 metres and OL-KR53 300 metres below the ground.
Drilling holes OL-KR51 and OL-KR52 were made in an area, at the eastern part of the Olkiluoto island, which previously had not been used for drilling holes to help improve the overall geological profile of the area. The drilling holes were also used to locate fracture zones of the bedrock, which serve as flow routes for groundwater.
OL-KR53 helped locate a fracture zone at the Rumminperä area. The fracture zone was suspected to be found there based on previous geophysical studies conducted, as well as due to the small hollow visible to the eye between Ilavainen and Olkiluoto. This fracture zone is considered to be the eastern border for the rock volume intended for the final disposal of spent nuclear fuel.