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

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6.1.5.1 Concept Summary<br />

6.82<br />

6.1.5 Ice Sheet Disposal<br />

It is estimated that, without significant climatic changes, the continental ice sheets<br />

could provide adequate isolation <strong>of</strong> high-level radioactive waste from the earth's biosphere.<br />

However, the long-term containment capabilities <strong>of</strong> ice sheets are uncertain. Areas <strong>of</strong> uncer-<br />

tainty have been reviewed by glaciologists (Philberth 1958, Zeller et al. 1973, and Philberth<br />

1975). These reviewers cited the advantages <strong>of</strong> disposal in a cold, remote, internationally<br />

held area and in a medium that should isolate the wastes from man for many thousands <strong>of</strong> years<br />

to permit decay <strong>of</strong> the radioactive components. But they concluded that, before ice sheets<br />

can be considered for waste disposal applications, further investigation is needed on:<br />

* Evolutionary processes in ice sheets<br />

* Impact <strong>of</strong> future climatic changes on the stability and size <strong>of</strong> ice sheets.<br />

Most <strong>of</strong> the analysis in these studies specifically addresses the emplacement <strong>of</strong> waste in<br />

either Antarctica or the Greenland ice cap. Neither site is currently available for waste<br />

disposal for U.S. programs: Antarctica because <strong>of</strong> international treaties and Greenland be-<br />

cause it is Danish territory.<br />

Proposals for ice sheet disposal suggest three emplacement concepts:<br />

* Meltdown - emplaced in a shallow hole, the waste canister would melt its own way to the<br />

bottom <strong>of</strong> the ice sheet<br />

* Anchored emplacement - similar to meltdown, but an anchored cable would allow retrieval<br />

<strong>of</strong> the canister<br />

* Surface storage - storage facility would be supported above the ice sheet surface with<br />

eventual slow melting into the sheet.<br />

Ice sheet disposal, regardless <strong>of</strong> the emplacement concept, would have the advantages <strong>of</strong><br />

remoteness, low temperatures, and isolating effects <strong>of</strong> the ice. On the other hand, transpor-<br />

tation and operational costs would be high, ice dynamics are uncertain, and adverse global<br />

climatic effects are a possibility.<br />

6.1.5.2 System and Facility Description<br />

Systems Options<br />

The reference concept for the initial ice sheet disposal <strong>of</strong> nuclear waste has been deve-<br />

loped from a number <strong>of</strong> options available at each step from the reactor to disposal in the ice<br />

sheet. It includes the three basic emplacement options and was selected through judgment <strong>of</strong><br />

a "most likely" approach based on available information and is not supported by a detailed<br />

system engineering analysis.<br />

Various options to be considered for ice sheet disposal are summarized in Figure 6.1.14.<br />

The bases for selection <strong>of</strong> the options chosen for the reference design (those blocked <strong>of</strong>f)<br />

are detailed in a variety <strong>of</strong> source material cited in Appendix M.

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