Aboveground Site Investigations

Site investigations related to final disposal of spent nuclear fuel have been carried out in Olkiluoto ever since the 1980s. These investigations have been principally conducted at the surface, but after the construction of the ONKALO research facility, new studies have also been started underground.

The original purpose of the site investigations was to produce information to underpin the selection of the final disposal site.  After Olkiluoto was chosen as the final disposal site, the site investigations have been continued, now with the aim of ensuring Olkiluoto’s suitability for final disposal. Furthermore, information provided by the site investigations supports the planning and designing of the repository and the assessment of the long-term safety of the final disposal, as well as assists in the construction of ONKALO.

One of the major site investigation methods is to drill deep drillholes and to use them in various groundwater investigations. Other important methods are, among others, excavating investigation trenches and conducting variablegeophysical examinations. The surface environment, including the flora and fauna, is also actively studied.