2009:22 Alternative modelling of brittle structures in a sub-area of the SKB candidate area at Forsmark, eastern Sweden

A reasonable understanding of the character of the bedrock hosting a deep geological repository, i.e. the natural barrier, is an important component in the safety assessment of the deep geological repository for spent nuclear fuel. The structures in the rock, together with the regional stress field, affect the mechanical stability of the bedrock and the ground water transport within the bedrock. The rock types, the alteration of the bedrock and the character of the infilling material in fractures affect the groundwater chemistry. Together, these factors have influence on the environment within which transport of substances may occur, both in the near- and the far-field of the geological repository.

The Swedish Nuclear Fuel and Waste Management Co (SKB) has, in accordance to their initial and complete site investigation programmes, concluded the surface-based site investigations at two sites, the Forsmark and Laxemar candidate areas, located in the eas-tern and southeastern part of Sweden, respectively. Based on the site investigations SKB has presented geological models for the candidate areas.

The Swedish Radiation Safety Authority (SSM) will use the present study in their technical review of SKB’s site investigation programme for potential repository sites.