SRK Consulting (UK) Limited (SRK) has reviewed the Engineering Geology and Rock Engineering aspects of the operation and closure of a KBS-3 repository at the Forsmark site in Sweden. The review assignment is part of a Swedish Radiation Safety Authority (SSM) Initial Review Phase. The review was carried out by David Saiang (PhD) on behalf of SRK. Therefore some of the views expressed in the review report may not totally represent those of the company (SRK).
In general SRK is satisfied with the efforts of SKB in dealing with the engineering geology and rock engineering aspects of the repository. There are some aspects, such as, the response of the rock due to the excavation, which cannot be fully understood until the actual excavation is carried out. SKB has accepted this limitation and has clearly indicated plans to verify and validate these aspects to give greater confidence to overall safety of the repository.
With respect to the engineering geology of the Forsmark site, SKB has developed a Site Descriptive Model (SDM), which is the basis for all engineering design in rocks, including a repository. The SDM developed by SKB is cross-disciplinary, in that, it received inputs from geology, hydrogeology, rock mechanics and other branches involved in geosphere science. Although, there is some uncertainty in some aspects, such as the initial ground stress conditions, it has never been easy to determine the ground stresses given the complexity of the rock mass and the limitations of the many stress measurement techniques available today. Nevertheless, SKB has attempted to address the impacts of this uncertainty on the excavations.