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

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8.4<br />

Decontamination Factor (DF): The ratio <strong>of</strong> the original contamination level to the contamination<br />

level after decontamination.<br />

Deep Continental Geologic Formations: Geologic media beneath the continents and isolated<br />

from the land surface by several hundred to thousands <strong>of</strong> meters <strong>of</strong> overlying rock<br />

material.<br />

Depositional Environment (sedimentary environment): A geographically restricted environment<br />

where sediment accumulates under similar physical, chemical, and biological conditions.<br />

Devitrification: The process by which glassy substances lose their vitreous nature and<br />

become crystalline.<br />

Diaprisim: The piercing <strong>of</strong> overlying rocks by an upward-moving mobile core or material,<br />

such as a salt body or an igneous intrusion.<br />

Discharge: In ground-water hydrology, water that issues naturally or is withdrawn from an<br />

aquifer.<br />

Disposal (radioactive waste): The planned release <strong>of</strong> radioactive waste in a manner which is<br />

considered permanent so that recovery is not provided for.<br />

Dome: A dome-shaped landform or rock mass; a large igneous intrusion whose surface is convex<br />

upward with sides sloping away at low but gradually increasing angles; an uplift or<br />

an anticlinal structure, either circular or elliptical in outline, in which the rock dips<br />

gently away in all directions, for example, a salt dome.<br />

Dissolution: In this context it refers to the dissolving <strong>of</strong> spent fuel by nitric acid as a<br />

process step in fuel reprocessing.<br />

Dose: Herein generally means the more rigorous term "dose-equivalent." The latter,<br />

expressed in units <strong>of</strong> rem, implies a consistent basis for estimates <strong>of</strong> consequential<br />

health risk, regardless <strong>of</strong> rate, quantity, source, or quality <strong>of</strong> the radiation exposure.<br />

DOT: U.S. Department <strong>of</strong> Transportation.<br />

Dry Storage: Storage <strong>of</strong> waste packages without liquid cooling.<br />

EIA: Energy Information Administration.<br />

EPA: U.S. Environmental Protection Agency.<br />

Epeirogeny: The broad movements <strong>of</strong> uplift and subsidence which affect whole or large portions<br />

<strong>of</strong> continents or ocean basins.<br />

Fault: A fracture or fracture zone along which there has been displacement <strong>of</strong> the sides<br />

relative to one another parallel to the fracture.<br />

Fault Block: A crustal unit either completely or partly bounded by faults.<br />

Fault System: A system <strong>of</strong> parallel or nearly parallel faults that are related to a particular<br />

deformational episode.<br />

Feldspar: Any <strong>of</strong> a group <strong>of</strong> common rock-forming minerals that are silicates <strong>of</strong> alumina and<br />

some other base, such as potash, soda, or lime.<br />

Fission (nuclear): The splitting <strong>of</strong> a nucleus into two or (rarely) more fragments; usually<br />

limited to heavier nuclei such as isotopes <strong>of</strong> uranium, plutonium, and thorium.<br />

Fission Product: Any radioactive or stable nuclide produced by fission, including both primary<br />

fission fragments and their radioactive decay products.<br />

Fissionable Material: Actinides capable <strong>of</strong> undergoing fission by interaction with neutrons<br />

<strong>of</strong> all energies.

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