2014:07 Technical Note, Review of the geological mapping and geophysical measurement techniques for the determination of critical properties around deposition holes -Main Review Phase

This Technical Note reports the findings of a detailed evaluation of the geological and geophysical methods proposed by SKB with respect to their ability, resolution, performance, reliability and robustness to measure the geomechanical parameters critical for determining deposition hole acceptability during repository operation. Addressed are specific questions focusing on the detection of discriminating fractures intersecting deposition hole positions that may impact long-term safety by enabling either shear movements in excess of those the canisters are designed to withstand, or high water inflows that may lead to piping and erosion of the buffer material. Also addressed are: i) the feasibility of measuring the excavation damage zone (EDZ) around the deposition tunnels and deposition holes to ensure that transmissivities do not exceed the values required for long-term safety, and ii) the detection of less common (subordinate) rock types with lower thermal conductivity properties that may impact long-term safety by enabling temperatures in the buffer to exceed design threshold values.