2014:59 Technical Note, Relation between earthquake magnitude, fracture length and fracture shear displacement in the KBS-3 repository at Forsmark – Main Review Phase

This study addresses one of several scenarios that could impair the physical integrity of the repository of spent nuclear fuel at the Forsmark site. Two sources of threat are:

i) events due to thermal loading on the rock mass by the heat from canisters with spent nuclear fuel, and
ii) seismic events, i.e. earthquakes, at the nearby deformation zones and zones intersecting the repository area.

The effect relevant to the repository safety is the shear displacement on rock fractures induced either by the effect of thermal loading, or by an earthquake at a nearby deformation zone, or by the combination of the two. In SKB’s safety assessment SR-Site, a shear displacement of 50 mm of a target fracture that crosses a canister position in the repository area is regarded as the upper limit of canister failure.