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

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kilogram of disposal in a basalt repository is only 67% higher. These unit cost relation-
ships may change somewhat for repositories of optimized size at specific sites.
Construction costs for repositories in granite and basalt are much higher than for
repositories in salt and shale, mainly because of mining cost differences. These differ-
ences arise because of different mined quantities, as noted previously, and because of
hinher unit mining costs reflecting the greater difficulty in hard-rock mining.
5.6.2 Operating Costs
Operating costs include the costs of direct labor, monitoring and safety, materials,
utilities, maintenance, administrative and other overhead, hole drilling and/or trenching
and retrievability sleeve placement. The materials category includes all overpacks,
sleeves, and plugs used in the repository. Waste packaging or encapsulation costs were con-
sidered to be a predisposal cost and can be found in Section 4.9. Costs of the waste canis-
ters are included in the encapsulation costs in the case of spent fuel or in the waste
treatment and packaging costs in the case of reprocessing cycle wastes.
Labor, utilities, and maintenance requirements are based on estimates given in
Y/OWI/TM-36, Vol. 10, 19, 14 and 16. Materials requirements, wage rates, and utility costs
are based on annual receipts and price data described in DOE/ET-0028, Vol. 1, Section 3.8.2.
Unit hole drilling, trenching, and sleeve placement costs were derived by the architect/
engineer making the construction cost estimates and are detailed in DOE/ET-0028, Vol. 4,
Sections 7.4.10.2 and 7.5.10.2. The allowances for maintenance, overhead, and miscellane-
ous costs have been derived by factoring either capital or direct labor costs. After
inclusion of a 25% contingency factor the operating cost estimates have an estimated uncer-
tainty of approximately +25%.
Total operating costs for the waste repositories are shown in the sixth column of
Table 5.6.1. These figures represent the cumulative operating costs during the repository
waste receiving periods. Cumulative operating cost differences between repositories are
principally due to differences in amount of waste emplaced. The granite and basalt reposi-
tories generally have significantly higher cumulative operating costs than do repositories
in salt and shale because of their greater capacity and longer operating lifetimes. Another
significant factor in operating cost differences in spent fuel repositories is the higher
cost of hole drilling in granite and basalt for canister placement.
5.6.3 Decommissioning Costs
Decommissioning costs are defined here to include decommissioning of the surface faci-
lities and sealing of the repository shafts. Based on decommissioning cost estimates for
other fuel cycle facilities, the decommissioning cost of the repository surface facilities
is estimated at 10% of the construction cost of these facilities. Shaft sealing costs are
estimated to be approximately $25,000,000 per repository. The total decommissioning costs,
excluding room backfilling, are shown in Table 5.6.2 for spent fuel and reprocessing-waste
repositories.