Tome Architecture and management of a geological repository - Andra
Tome Architecture and management of a geological repository - Andra
Tome Architecture and management of a geological repository - Andra
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6 – C waste <strong>repository</strong> zone6.6 Disposal process as part <strong>of</strong> the reversibility rationale6.6.1 Installation <strong>of</strong> the disposal cellsIn the same way as for the B waste <strong>repository</strong> tunnels, the detailed exploratory work <strong>of</strong> a C wastemodule host block is carried out in stages (Figure 6.6.1), as excavation work progresses..This program aims at defining:- the position <strong>of</strong> the h<strong>and</strong>ling drifts on the basis <strong>of</strong> horizontal boreholes drilled from a driftaccessing to the block <strong>and</strong> <strong>of</strong> geophysical measurements between boreholes;- the layout <strong>of</strong> disposal boreholes using <strong>geological</strong> surveys at the h<strong>and</strong>ling drift walls, short verticalboreholes <strong>and</strong> geophysical <strong>and</strong> hydro-<strong>geological</strong> measurements;- cell qualifications on the basis <strong>of</strong> <strong>geological</strong> surveys <strong>of</strong> the wall <strong>and</strong> additional measurementscarried out in the disposal boreholes.At each exploration stage, the information gathered is compared to the criteria as defined throughunderground laboratory studies <strong>and</strong> safety analyses.Through these comparisons, module architecture is gradually adjusted to the characteristics <strong>of</strong> thegranite in the block <strong>and</strong> disposal cell qualification rate by module can be managed.6.6.2 Construction <strong>of</strong> the connecting <strong>and</strong> h<strong>and</strong>ling driftsAs for B waste module connecting drifts, full section excavation by drilling <strong>and</strong> blasting is taken as thereference method. Likewise the use <strong>of</strong> low-damage techniques such as "smooth blasting", is envisagedin the vicinity <strong>of</strong> the future module seal sites.Two excavating techniques can be envisaged for the h<strong>and</strong>ling drifts:- drilling <strong>and</strong> smooth blasting;- a combination <strong>of</strong> mechanical excavating techniques using a tunnel boring machine (TBM) in theh<strong>and</strong>ling drifts <strong>and</strong> smooth blasting for the interconnecting drifts.At this stage excavating with explosives has been taken as the reference method because it <strong>of</strong>fersgreater flexibility with today’s proven techniques. This method is the same as the one adopted by SKBfor their spent fuel disposal borehole design: KBS-3V. This choice is based on results <strong>of</strong> the APSEexperiment, which has demonstrated that it is possible to limit the development <strong>of</strong> a damaged zone toabout thirty centimetres through blasting pattern adjustments.Dossier 2005 granite - ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL REPOSITORY182/228
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