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

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6.96<br />

Specific areas <strong>of</strong> concern, as discussed below, are:<br />

* Effects <strong>of</strong> waste on ice sheet environment<br />

* Effects <strong>of</strong> ice sheet on waste<br />

* Effects <strong>of</strong> waste on land environment.<br />

Effects <strong>of</strong> <strong>Waste</strong> on Ice Sheet Environment. If waste canisters were allowed to reach or<br />

approach the bottom <strong>of</strong> the ice, they could possibly generate sufficient heat to produce a<br />

water layer over a large portion <strong>of</strong> the bottom surface <strong>of</strong> the ice. Furthermore, melt pools<br />

around the canisters could conceivably coalesce and also unite with any subglacial water, in<br />

the disposal area, to form a large water mass within the ice or at the edge <strong>of</strong> the ice-bed-<br />

rock interface. Either event might trigger an increase in the velocity <strong>of</strong> the ice mass and<br />

perhaps produce surging. It has been postulated that major surges in the East Antarctica ice<br />

sheet could affect solar reflection and alter the sea level. The most extreme effect would<br />

be the start <strong>of</strong> glaciation in the Northern Hemisphere (Wilson 1964). The accelerated move-<br />

ment could also move emplaced material toward the edge <strong>of</strong> the ice sheet, possibly reducing<br />

the residence time. Basal ice sheet water could also conceivably form a pathway for transporting<br />

waste material from the disposal area to the edge <strong>of</strong> the ice sheet, and thus to the<br />

ocean.<br />

Hypothetical dose calculations have been made for radionuclides released from an ice<br />

sheet disposal site into the ocean <strong>of</strong>f the coast <strong>of</strong> Greenland (EPA 1979). On the basis <strong>of</strong><br />

assumptions that a failure occurs in the disposal system, the release <strong>of</strong> radionuclides into<br />

the Greenland current <strong>of</strong> 8 x 106 m 3 /sec would be 0.3 percent/yr <strong>of</strong> the total inventory<br />

available. Complete mixing could occur in the ocean. Human pathways are assumed to be<br />

mostly via fish consumption. The maximum dose was considered to be from an individual con-<br />

suming 100 kg/yr <strong>of</strong> fish caught in these contaminated waters and is estimated to be 0.2<br />

mrem/yr. Further discussion <strong>of</strong> radioactive releases to the ocean is included in Section<br />

6.1.4.5 on the subseabed concept.<br />

Effects <strong>of</strong> Ice Sheet on <strong>Waste</strong>. Movement <strong>of</strong> the ice sheet might cause shearing or crush-<br />

ing <strong>of</strong> canisters, allowing water to come in contact with the waste form so that leaching<br />

could occur. Such breakage would most likely occur when the canisters are moved along the<br />

ice-bedrock interface.<br />

If major climatic changes were to produce an increase in temperature in the polar re-<br />

gion, the ice sheet might erode to such an extent that it would allow the waste to be much<br />

closer to the edge <strong>of</strong> the ice. The temperature increase could also increase the velocity <strong>of</strong><br />

the ice movement toward the coast.<br />

Effects <strong>of</strong> <strong>Waste</strong> on Land Environment. As in the case <strong>of</strong> space and subseabed disposal,<br />

geologic repository facilities are assumed to be constructed for TRU and other wastes not<br />

disposed <strong>of</strong> through the procedures established for the majority <strong>of</strong> HLW. Long-term effects<br />

could result from these auxiliary activities. These impacts would be similar to those

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