Architecture and management of a geological repository - Andra

The condition of the drift liner shall be inspected as backfill removal progresses and, if applicable,reinforced with rockbolts or arches according to proven techniques used in the civil engineering ormining field.Seal deconstruction operations are expected to last approximately one week. The rate at which backfillwill be removed from the site is estimated at 60 to 200 m per month and per drift, depending on theneed to provide reinforcement to the drift liner.Access to all the cell of a module requires the removal of approximately 60,000 m 3 of backfill. Thetime required for this operation is approximately the same as that needed for digging the initial drifts.The cell reconditioning and package retrieval processes to be implemented for retrieval operations arethose described in the previous paragraphs.10.4.3 Package retrieval capability: ConclusionAs long as the repository closing process is not commenced, there is total package retrieval capability(like under storage conditions) over multi-century periods (typically 200 to 300 years) during whichcell mechanical stability is ensured. If this stage were to be extended beyond that time, specificinterventions should be scheduled (package retrieval, possible cell maintenance and improvementwork, etc.).After repository closure has commenced, package retrieval operations are possible if preparatory workfor restoring access to the cell is conducted prior to retrieval. Naturally, the preparation conditions foraccess to the cells depend on the level of closure reached. As the closing process progresses,preparatory work becomes more extensive (relatively proportionately to the string of drifts to becleared), but does not pose unsurmontable technical problems. The ability to carry out the packageretrieval operation per se is solely contingent upon sustained geometric and mechanical integrity of thecell sleeve. The capability to withdraw the packages from the cell is little or not influenced whenmoving from one stage of the closing process to the next. In fact, as long as the cell sleeve is stable,i.e. as long as the functional clearances between the packages and the sleeves are maintained, packageretrieval may be performed by using procedures identical or similar to those used for installation.Thus, technically speaking, the ability to retrieve the packages is feasible throughout the operationallife of the cells, i.e. at least two to three centuries. If this possibility is to be extended while the closingprocess has commenced, one should go backward to the access to the cells to schedule specificinterventions such as those discussed above.DOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM433/495