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

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6.165<br />

6.2 COMPARISON OF ALTERNATIVE WASTE DISPOSAL CONCEPTS<br />

This section provides an assessment <strong>of</strong> the nine waste management concepts discussed in<br />

Chapter 5 and Section 6.1 <strong>of</strong> this Statement.<br />

For the reader's convenience, a brief review <strong>of</strong> each <strong>of</strong> the alternative concepts is<br />

first presented in Section 6.2.1. Next, ten assessment factors and a set <strong>of</strong> related stan-<br />

dards <strong>of</strong> judgement are introduced. The first stage <strong>of</strong> the analysis follows, in which the<br />

concepts are screened using the standards <strong>of</strong> judgement introduced in the previous section.<br />

Concepts which remain after the screening are then compared on the basis <strong>of</strong> the assessment<br />

factors and most promising concepts identified.<br />

6.2.1 Summary Description <strong>of</strong> Alternative <strong>Waste</strong> Disposal Concepts<br />

This section presents brief descriptions <strong>of</strong> the nine waste management concepts con-<br />

sidered in this comparison. Characteristics <strong>of</strong> each concept are described in more detail<br />

in Chapters 4 and 5 and Section 6.1. Technical approaches not summarized here have been<br />

advanced for certain concepts that if implemented might result in a waste management system<br />

differing from that described here. In addition, the developmental process might result in<br />

a system different than described here, especially for concepts currently in a very prelimi-<br />

nary stage <strong>of</strong> development.<br />

6.2.1.1 Mined Repository<br />

In the mined repository concept, disposal <strong>of</strong> waste would be achieved by manned emplace-<br />

ment in mined chambers in stable geologic formations. Engineered containment would be pro-<br />

vided by the waste form, canisters, overpacks, and sleeves. Use <strong>of</strong> a tailored backfill<br />

would provide an additional engineered barrier. Isolation and natural barriers would be<br />

provided by the host rock and surrounding geologic environment, which would be selected to<br />

provide stability, minimal hydrologic transport potential and low resource attractiveness.<br />

A waste packaging facility would be located at the repository site where spent fuel<br />

assemblies would be individually sealed into canisters. The canisters would be incorporated<br />

into the multibarrier package and then would be placed in individual boreholes in the floor<br />

and walls <strong>of</strong> mined chambers 500 to 1,000 m deep in suitable host-rock formations. Backfill<br />

would be placed around each package following emplacement. As each chamber is ready, it<br />

would be backfilled with rock and sealed. When the repository is filled the access tunnels<br />

and shafts would be filled with appropriate materials and sealed.<br />

All waste types referenced in Table 6.2.1 could be emplaced in the mined repository.<br />

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

fied to a stable waste form, packaged in canisters that are part <strong>of</strong> a multibarrier package,<br />

and emplaced in the mined repository. Transuranic waste(a) would also be packaged and<br />

emplaced in the mined repository.<br />

(a) Hulls, hardware, remotely handled and contact-handled TRU waste. See Table 6.2.1.

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