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

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327<br />

ALTERNATIVE DISPOSAL CONCEPTS<br />

into account at any given site. However, conceptual and mathematical modeling will be<br />

required to analyze the impact <strong>of</strong> permeability on the consequences <strong>of</strong> operation. This type<br />

<strong>of</strong> analysis is important in defining the values <strong>of</strong> parameters that are satisfactory.<br />

Draft p. 3.3.33<br />

Issue<br />

Response<br />

Some discussion <strong>of</strong> retrievability from deep holes should be provided. (208-NRC)<br />

This issue is one that would require careful consideration before any waste could be<br />

emplaced using the very deep hole concept. A thorough analysis <strong>of</strong> failure modes and possi-<br />

ble corrective actions, including retrieval or recovery <strong>of</strong> the waste, would be necessary.<br />

Methods employing overcovering or other means for retrieval would be analyzed. Although<br />

overcovering or other methods might be feasible for use, as currently envisioned, waste<br />

emplaced in a hole would not be retrievable.<br />

Draft p. 3.3.33<br />

Issue<br />

It is stated that, "It will be necessary to locate sites in strong, unfractured rock <strong>of</strong><br />

low water content." This will exclude such media as shale and salt because <strong>of</strong> strength, and<br />

most other media because <strong>of</strong> fracturing. Why hasn't this same site selection criterion been<br />

applied to conventional geologic disposal? (208-NRC)<br />

Response<br />

In defining the very deep hole concept for the Statement it was necessary to make<br />

assumptions regarding the criteria for siting <strong>of</strong> a concept repository. The requirement for<br />

strong unfractured rock <strong>of</strong> low permeability was one such assumption. On the basis <strong>of</strong> cur-<br />

rent information about the characteristics <strong>of</strong> deep geologic systems, other assumptions might<br />

be equally valid. For example, emplacement <strong>of</strong> waste in very deep holes that terminate in<br />

salt, shale, or other media may be feasible. Research would be required however, to resolve<br />

geologic requirements for this concept. For the mined repository, however, many <strong>of</strong> the site<br />

selection criteria have been established on the basis <strong>of</strong> the large body <strong>of</strong> information<br />

available.

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