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

5.40
sealed in an appropriately sized overpack canister. RH-TRU waste in 55-gal drums is shipped
to the repository by truck, arriving in shielded Type B overpacks (see Section 4.5.3.2 for
Type B overpack definition). The overpacks are lifted by crane from the truck bed to
shielded transfer cells for remote removal of the drums. The drums are placed three each
into steel drum-pack canisters which are sealed with a welded lid. The drum-pack is trans-
ported to the canistered waste shaft and lowered into the repository.
CH-TRU waste arrives at the repository on pallets of twelve 55-gallon drums stacked two
by three by two drums high or in steel boxes measuring 1.2 x 1.8 x 1.8 m (4 x 6 x 6 ft),
roughly equivalent in size to the pallet of drums. The CH-TRU is shipped by truck in spec-
ial cargo carriers (see Section 4.5) loaded with three pallets or boxes of waste. The pal-
lets and boxes are unloaded from the cargo carrier using shielded forklifts, inspected for
damage and repaired if necessary, transported to the CH-TRU waste shaft and lowered into the
repository.
Wastes are received at subsurface transfer stations that form integral structures with
the shafts. Shielded transporters remotely remove the containers from the transfer sta-
tions for delivery to an emplacement area.
At the conceptual repositories in salt and shale formations, HLW canisters are lowered
into vertical holes in the emplacement rooms in accordance with the same minimum hole spac-
ing (1.8 m) described for spent fuel canisters in the once-through fuel cycle repositories
and with an allowable thermal density calculated specifically for the HLW's characteristics.
In these formations, RH-TRU waste is also emplaced in drilled holes; however the minimum
hole spacing is increased to 2.3 m as a result of the larger-hole diameters necessary for
the 0.76-m-diameter canisters.
The conceptual repositories in granite and basalt formations emplace HLW in vertical
holes as described for the salt and shale repositories. However, RH-TRU canisters are
lowered into trenches running the length of the rooms. The canisters are held upright in a
single row by storage racks that allow a minimum spacing of 1 m center-to-center.
Shielded forklifts stack the CH-TRU waste pallets and boxes two high along the walls
of CH-TRU waste emplacement rooms.
Table 5.3.7 lists the contents based on the example treatment processes described in
Section 4.3 of conceptual repositories located in salt, granite, shale, and basalt forma-
tions at the end of operations. Because of the differences in thermal criteria the capaci-
ties of different rock media vary. For the conceptual repositories illustrated here, the
relative quantities of high-level waste and TRU wastes are different on an MTHM-equivalent
basis. This is because the five-year cooling hold up for the HLW resulted in a dispropor-
tionately larger quantity of TRU waste being emplaced. Subsequent repositories would fill
up with more nearly equivalent amounts of HLW and TRU wastes. The capacities when equiva-
lent quantities of HLW and TRU wastes are emplaced are also shown.