Architecture and management of a geological repository - Andra

7 – The shafts and the drifts7.2.2 Number and assignments of the shaftsAt the current stage in the studies, a set of four shafts is planned to control all the flows to betransferred :- a shaft exclusively reserved for package transfers ;- a shaft exclusively reserved for air exhaust, to ensure all the air exhausts and smoke removals ;- a personnel transfer shaft and a construction shaft to ensure all the other flows, including the freshair supply.• Discussion and comparison with the WIPPThe thus-defined set of four shafts offers great flexibility for adapting to the various scenariosdescribed in chapter 3, while limiting interferences between flows.This set can be compared to the WIPP (see chapter 6), which for a comparable depth (650 m instead of500 m), but less important flows (annual excavation volume of a few tens of thousands of cubicmetres, no concrete, less bulky packages), includes also four shafts :- A waste package shaft ;- A construction shaft for muck handling, equipment and personnel ;- A shaft reserved for air intake (+ auxiliary personnel) ;- A shaft reserved for air exhaust.7.2.3 Design principles of the access and connnecting driftsThese principles were defined in chapter 6 :- hierarchising the drifts into main connecting drifts common to several zones, secondaryconnecting drifts specific to each zone, and access drifts specific to each module ;- specialising the drifts by function (construction with railway or path for tyred vehicles, operation,air exhaust).In addition, remember that the design presented in the current stage allows minimising the drifts’diameter.7.3 Description of the shafts7.3.1 Package transfer shaftThis shaft is exclusively assigned to the transfer of packages in their protection transfer cask (and forthe transfer of empty transfer casks). There are two reasons for this exclusive assignment : i) thespecial character of the transfers (high load, specific prevention and protection arrangements againstthe risk of packages falling in a shaft), ii) the number of packages to be transferred, which may beclose to a shaft’s maximum capacity.The shaft’s usable diameter is 11.50 m. This diameter is completely determined by the equipment :that is, the equipment necessary to transfer the waste disposal packages between the surface and thebottom, as well as the auxiliary equipment (emergency cage for the maintenance and inspectionpersonnel).The shaft’s ground support is adapted to the various grounds encountered.- Near the surface, a 60 cm thick moulded wall may be necessary to cross the potentially aquiferousgrounds (Barrois limestones, whose thickness can attain twenty metres).- Above the Callovo-Oxfordian layer, the ground support consists of 3 m long rockbolts andshotcrete ; the concrete thickness varies from 20 to 30 cm according to the ground and the depth.DOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM292/495