Abstract:

The Swedish Nuclear Fuel and Waste Management Co (SKB) has conduct-ed site investigations for a final repository in Sweden during the period of 2002–2008. The site investigations have established site descriptive models for two candidate sites. These models are the result of an interaction of several geoscientific disciplines, in-cluding rock mechanics. Within the framework of the rock mechanics program, a very large number of la-boratory tests were carried out. Intact rock and fractures were investigated by laborato-ry methods such as uniaxial- and triaxial compressive tests, indirect- and direct tensile tests, direct shear tests and tilt tests. Besides these laboratory methods the site investi-gation program also included a number of measurements uncommon in ordinary site investigation programs. For instance were micro crack volume measurements per-formed and the crack initiation stress investigated. Furthermore, the influence of alter-ation on the strength of the rock was also investigated. The paper outlines some im-portant experiences gained within the laboratory program and presents a couple of results with the focus on the tests that are infrequent in ordinary site investigation pro-grams.

1 INTRODUCTION
1.1 Site investigation program

In order to identify a suitable location for a geological repository for spent nuclear fuel at approximately 500 m depth in saturated granitic rock, the Swedish Nuclear and Fuel Management Company (SKB) has carried out a series of site investigations between 2002 and 2008 in two different areas, Forsmark (SKB 2008) and Laxemar (SKB 2009). Data collected from these site investigations have been interpreted and analysed to achieve a full site description of the area based on models for geology, thermal proper-ties, rock mechanics, hydrogeology, hydrogeochemistry, bedrock transport properties and surface ecosystems. All together these models build up an integrated understand-ing of the investigated sites (SKB 2008, 2009).

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