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

6.1.1.2 System and Facility Description
System Options
6.9
The reference concept for the initial VDH disposal of nuclear waste has been developed
from a number of options available at each step from the reactor to disposal in the very deep
hole.
Various options to be considered for VDH disposal are summarized in Figure 6.1.1. The
bases for selection of options for the reference concept (those blocked off) are reviewed in
detail in various documents listed in Appendix M.
Because options for the waste disposal steps from the reactor up to, but not including,
the geologic medium are similar for mined geologic repositories and VDH disposal, the options
selected for the reference design are similar for the two concepts. From that point on, the
options selected for the reference design are based on current program documentation for VDH
disopsal.
Waste-Type Compatibility
Very deep hole disposal would be limited to unreprocessed spent fuel rods and the HLW
from uranium-plutonium recycle cases. Because of cost constraints, VDH disposal of contact
handled and remotely handled TRU wastes is not considered likely. Handling the large volume
of these wastes would substantially increase drilling activities, costs, and the extent of
adverse environmental impacts for VDH disposal. Thus, the low- and intermediate-level TRU
wastes would require some other form of terrestrial disposal. It is assumed for the refer-
ence case that these wastes would be placed in mined geologic repositories.
Waste-System Description
The reference concept design was selected through judgment of a "most likely" approach
based on available information and data. The fuel cycle and process flow for the reference
concept are shown in Figure 6.1.2. In the reference concept, a VDH repository is designed
for disposal of 10,200 canisters per year of spent fuel or for 2,380 canisters per year of
solidified HLW. With a 40-year repository operation period, emplacement of spent fuel would
require 68 holes per year with 150 canisters placed in each. Multiple holes would be drilled
while others are being filled. HLW would require emplacement of 375 canisters per hole in
six to seven holes per year (Bechtel 1979a), also with simultaneous drilling and emplacement
operations.
Predisposal Treatment and Packaging. The predisposal treatment of waste for the VDH con-
cept would be identical in many respects to the predisposal treatment of waste for the mined
geologic repository concept. Chapter 4 of this document discusses the predisposal systems
for both spent fuel and HLW common to all of the disposal concept alternatives.
The specific waste form required for emplacement in the deep hole is not yet identified.
The waste form and canister would have to be structurally strong to resist downhole stresses
and crushing forces, and chemically resistant to the waste emplacement medium. A metallic
matrix or a granular waste form would be possible (Bechtel 1979a).