Management of Commercially Generated Radioactive Waste - U.S. ...

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operation. During this period all wastes are emplaced retrievably to allow their timely
removal should events during construction warrant this action. The retrievable period also
provides an opportunity to evaluate the repository interface with emplaced wastes. Instru-
mentation will be installed to monitor temperature profiles in the waste and rock and to
measure room and pillar stress and deformation. Results of these studies may verify
repository design or indicate the need to modify waste emplacement procedures.
5.3.1.2 Facility Description
The conceptual repository consists of 1) surface facilities for waste receiving and
handling and for mining and general operations support and 2) subsurface facilities for
waste handling and emplacement and for mined rock removal. Surface facilities, shown in
Figure 5.3.1, are similar for all repositories regardless of geology. These facilities and
the mined rock storage pile constitute the visible evidence of the repository and occupy an
area of about 180 ha at the salt and shale repositories and 280 ha at the granite and basalt
repositories. The additional 100 ha at the granite and basalt repositories are required for
larger amounts of rock that are mined from these formations to accommodate the additional
waste disposal capacity resulting from higher thermal limits. Figure 5.3.2 provides an
artist's concept of a geologic repository.
All surface structures in which radioactive wastes are handled are operated at less
than atmospheric pressure. Ventilation flows are controlled by pressure differential from
areas of low contamination potential to areas of successively higher contamination poten-
tial. Exhaust air is processed through a roughing filter and two high-efficiency particu-
late air (HEPA) filter banks in series prior to discharge via the 110 m mine ventilation
stack.
Additional details of surface facilities at the repository are found in DOE/ET-0028.
The conceptual repositories for the once-through fuel cycle require three shafts in
salt and shale and four shafts in granite and basalt to support waste handling and mining
operations. These are the canistered waste (CW) shaft, the men and materials (M&M) shaft,
and ventilation exhaust (VE) shaft in all the media and the mine production (MP) shaft in
granite and basalt to support the larger mining effort.
The canistered waste shaft provides a means for transporting the canisters of spent
fuel from the canistered waste building to the subsurface emplacement areas. The men and
materials shaft is provided to handle mine and storage personnel, equipment, ventilation air
and mined rock during excavation and backfilling. The ventilation exhaust shaft is divided
into two compartments to provide separate exhaust for mining and for placement operations.
The shaft discharges into the ventilation exhaust building.
The mine production shaft contains skip hoist equipment for removal of mined rock to
the surface and supplies additional ventilation air to the mine.
The repository underground layout is a conventional room and pillar arrangement that
serves the need for repository ventilation, opening stability, thermal effects, and effi-
cient use of excavated space. Of the 800 ha underground area, actual spent fuel emplacement