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

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identify at this time, such as siting and engineering scope requirements necessary to pro-
vide a fully functional facility. Also included in the estimates are the possible variances
of the assumed rock densities used in the development of mining costs. The contingency
factors are such that, within the stated accuracy range, there is an approximately equal
likelihood of the indicated cost overrun or underrun. The construction cost estimation
methodology is explained in more detail in DOE/ET-0028, Vol. 1, Section 3.8.
Construction costs for repositories in different media are based on a fixed repository
area of 800 ha (2000 acres). However, since waste emplacement density is a function of the
thermal characteristics of each type of media, actual waste quantities emplaced differ for
each 800 ha repository. Table 5.6.1 shows equivalent waste quantities emplaced, the resul-
tant mining requirements and the construction costs. Operating costs and unit costs are
also given in this table to facilitate comparisons of cost relationships. These costs are
discussed in subsequent sections.
Since mining costs account for 30% to 50% of total construction costs, the total con-
struction costs vary significantly between geologic media. However, emplacement capacity
increases for media with higher mining costs (see Section 5.3) and the relative unit cost
differences between geologic media are smaller than the relative construction cost differ-
ences. For example, construction costs for an 800-ha repository in basalt are about three
times those of an 800-ha repository in salt for the once-through cycle, but the cost per
TABLE 5.6.1. Cost Estimates for 800-hectare Geologic Repositories
Mined Construc-) Total Unit
Geologic Quantiy Equivalent MTHM tion Cost(a) Operating Cost(b) Cost(c)
Waste Type Media 106 MT of Waste Emplaced Millions of $ Millions of $ $/kg HM(e)
Spent Fuel Salt 30 51,000 1,000 590 52
Granite 77 121,600 2,600 2,350 78
Shale 35 64,500 1,300 810 57
Basalt 90 121,600 3,100 2,390 87
HLW(d) TRU(d)
Reprocessing
Cycle Wastes Salt 35 62,000 100,000 1,200 1,210 47
Granite 53 69,000 108,000 2,000 1,940 77
Shale 30 30,500 56,000 1,300 830 73
Basalt 59 56,000 92,000 2,300 1,740 93
(a) Includes mining, backfilling and shaft sealing costs. Backfilling and shaft sealing costs are
approximately 10% of total construction costs. Uncertainties in construction cost estimates
are about +20%.
(b) UncertaintTes in operating cost estimates are about +25%.
(c) Includes decommissioning costs. Uncertainties in unTt cost estimates are about +50%.
(d) The metric ton of heavy metal (MTHM) equivalent of high-level waste stored at the initial
repository is less than the MTHM equivalent of TRU wastes since the high-level waste must be
cooled 5 years before it can be sent to the repository and deliveries to the repository lag
behind TRU waste deliveries.
(e) Costs may be expressed in $/GW-yr by multiplying by 38,000 KgHM/GW-yr.