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Summary:
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Posiva Oy prepares for disposal of spent nuclear fuel into bedrock focusing in Olkiluoto, Eurajoki. This is in accordance of the Decision-in-Principle of the State Council in 2000, and ratification by the Parliament in 2001. The ONKALO underground characterization premises have been constructed since 2004.
Posiva Oy is aiming for submitting the construction licence application in 2012. To support the compilation of the safety case and repository and ONKALO design and construction, an integrated Olkiluoto site Description including geological, rock mechanics, hydrogeological and hydrogeochemical models will be depicted.
Mise-à-la-masse (MAM) surveys have been carried out in the Olkiluoto area since 1995 to follow electric conductors from drillhole to drillhole, from drillhole to the ground surface and also between the ONKALO access tunnel and drillholes or the ground surface.
The data and some visualisation of the data have been presented as part of reporting of the 1995 and 2008 surveys. The work presented in this paper includes modelling of all the measured data and combining single conductors modelled from different surveys to conductive zones. The results from this work will be used in updating the geological and hydrogeological models of the Olkiluoto site area.
Several electrically conductive zones were modelled from the examined data, many of them coincide with the known brittle deformation zones but also indications of many so far unknown zones were detected.
During the modelling Comsol Multiphysics® software for calculating theoretical potential field anomalies of different models was tested. The test calculations showed that this software is useful in confirming the modelling results, especially in complicated cases.
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