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23.04.2007 12:00

ONKALO EXTENDS NOW OVER TWO KILOMETRES - Research data confirm earlier perception of bedrock in Olkiluoto

The construction of the underground characterisation facility ONKALO, built for investigations related to final disposal of spent nuclear fuel, has now progressed to a length of ca. 2010 metres, and to a depth of almost 200 metres. Investigations and excavation operations proceed on schedule, and according to plans the final disposal depth at -420 m level will be reached in 2009. The application for the construction licence of the repository is scheduled to be submitted to the Finnish Government in 2012.

"Posiva's project schedule has been drawn up so as to ensure availability of required investigation results in the preparation of the application for the construction licence in the early 2010s", says Posiva's President Eero Patrakka. Final disposal of spent nuclear fuel is to start in 2020, and will continue till the end of the century.

"The information so far gathered from the excavated two-kilometre distance of ONKALO has been well in consistency with the earlier perception of bedrock in Olkiluoto, based on drillings and investigations carried out from above ground", concludes Antti Mustonen who is the Research Coordinator for Posiva. Drillings to the repository depth can be started in ONKALO next year, whereby the focus of investigations will shift to the determination of bedrock properties and conditions at final disposal depth.

Apart from ONKALO, also above ground characterisation studies continue in Olkiluoto. Four new deep boreholes will be drilled within the research area this spring and summer to gather more information about bedrock on the northeast and east sides of ONKALO. The total number of deep boreholes implemented so far in Olkiluoto is 43.

By the end of the year, the excavation of exhaust shaft and personnel shaft in ONKALO will proceed to a depth of 178 metres. A year ago Posiva adopted a new implementation model for the ONKALO construction project, with Posiva assuming total responsibility for the site. "The selected implementation solution has proven successful, and work has progressed as planned", says Project Director Pertti Huovinen.

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