Preliminary modelling of the 2010 MAM survey data

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 underground characterisation facility design and construction, a series of Olkiluoto Site Descriptive Model including six parts: the surface system geology, rock mechanics, hydrogeology and hydrogeochemistry and migration, have been compiled. To support the next update of the Olkiluoto Site Description and especially, the geological and hydrogeological sub-models, the preliminary modelling of the recent mise-a-la-masse (MAM) surveys has been carried out. This report discusses the mise-a-la-masse (MAM) surveys carried out in the Olkiluoto area in 2010 and aims to find out the continuation of some electrically conductive zones intersected by drillholes OL-KR49 ...OL-KR53 in the eastern part of the Olkiluoto island. Several electrically conductive zones were modelled from the examined data, many of them coincide with the brittle deformation zones presented in the geological model, but also indications of some so far unknown zones were detected. The complexity and the extent of the group of zones including the hydraulically conductive zones HZ19A, HZ19B and HZ19C (Vaittinen et al. 2009) emerged from the data during this work. Modelling of this group in detail needs more information from both geological and hydrogeological investigations. (orig.)