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

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6.169<br />

A reprocessing fuel cycle would produce liquid high-level waste that would be converted<br />

to an immobile solid for incorporation into a multibarrier package designed for emplacement<br />

in the sediments. TRU waste would probably require another suitable disposal concept<br />

(Table 6.2.1).<br />

6.2.1.6 Ice Sheet Disposal<br />

In the ice sheet disposal concept, disposal <strong>of</strong> high-level waste would be achieved by<br />

remote emplacement within a continental ice sheet. The plasticity <strong>of</strong> the ice would eventu-<br />

ally seal the waste from the environment and subfreezing temperatures would preclude hydro-<br />

logic transport except possibly at the conditions encountered at the ice-rock interface.<br />

Engineered multibarrier containment would be provided by the waste form and canisters and<br />

possibly overpacks. Isolation and a natural barrier would be provided by the ice mass. The<br />

geographic location <strong>of</strong> the repository and the inclement weather <strong>of</strong> continental ice sheets<br />

would contribute to the remoteness <strong>of</strong> the repository and decrease the possibility <strong>of</strong> human<br />

intrusion.<br />

Spent fuel assemblies would be packaged individually in canisters at a waste processing<br />

facility located in the continental U.S. Packaged fuel assemblies would be loaded into<br />

shipping casks and transported by rail to the embarkation port facility. At the port facil-<br />

ity waste packages would be transferred from rail casks to ocean-shipping casks which would<br />

be loaded aboard ocean-going vessels. These vessels would transport the waste to a receiv-<br />

ing port at the ice margin. Here the waste packages in shipping casks, would be transferred<br />

to tracked vehicles for transport to the repository, located some distance inland. At the<br />

repository site the waste packages would be removed from the transport casks, placed into<br />

pilot holes drilled 50 to 100 m into the ice and tethered to anchor plates with 200 to<br />

500 m cables or allowed to melt freely into the ice. Heat from radioactive decay would melt<br />

the ice and the package would sink into the ice sheet, reaching its final position in six<br />

to eighteen months. The pilot holes would be sealed by filling with water which would sub-<br />

sequently freeze. Refreezing <strong>of</strong> water above the package as it progressed downward would<br />

complete sealing <strong>of</strong> the emplacement holes.<br />

A reprocessing fuel cycle would produce liquid high-level waste that would be con-<br />

verted to an immobile solid compatible with the ice environment. This solidified waste<br />

would be packaged and emplaced in the ice sheet repository. TRU waste would probably be<br />

disposed using an alternative disposal concept (Table 6.2.1).<br />

6.2.1.7 Well Injection<br />

In the well injection disposal concept, disposal <strong>of</strong> high-level waste would be achieved<br />

by remote emplacement <strong>of</strong> liquid or slurried waste into stable geologic formations capped by<br />

an impermeable boundary layer. A degree <strong>of</strong> engineered containment would be supplied by the<br />

waste form if a grout were used but would not be present during the injection phase. Isola-<br />

tion and natural barriers would be provided by the host rock and the surrounding geologic<br />

and hydrologic environment which would be selected for its stability, minimum hydrologic<br />

transport potential, high sorption potential and low resource attractiveness.

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