Research and Development
Posiva investigates the bedrock on the final disposal site and develops technical release barriers for the final disposal of spent fuel. The purpose of the R&D efforts is to ensure compliance with the requirements set forth for the long-term safety of final disposal.
Site Characterisation Above Ground
Site characterisation investigations related to the final disposal of spent nuclear fuel have been carried out in Olkiluoto since 1980s. The investigations have focused on above-ground conditions, but along with the construction of research facility ONKALO the investigations have proceeded underground. Above-ground site investigations include drilling of drillholes for research purposes, excavating investigation trenches as well as groundwater and environmental studies.
ONKALO
The excavation of the underground rock characterisation facility ONKALO is part of the site investigations carried out in Olkiluoto. ONKALO will reach down to the final disposal depth (ca. -400 m) and is being excavated by a drilling-blasting method. Shafts are built using the raise-drilling method.
The investigations carried out in ONKALO focus on the bedrock and groundwater
conditions prevailing on the final disposal site and how construction work
affects them. They also serve the purposes of construction and design
activities at the construction stage as well as the general design of the final
disposal facility.
Modelling
The investigations carried out in Olkiluoto both above ground and in ONKALO and the results of the investigations are utilised in modelling. Models can be used to assess the performance of final disposal and the effects it has on the rock environment in terms of long-term safety.