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

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8.1<br />

CHAPTER 8<br />

GLOSSARY OF KEY TERMS AND ACRONYMS<br />

Abiotic: characterized by the absence <strong>of</strong> life.<br />

Abyssal Hill: relatively small topographic feature <strong>of</strong> the deep ocean floor ranging to<br />

600 to 900 m high and a few kilometers wide.<br />

Actinides: <strong>Radioactive</strong> elements with atomic number larger than 88.<br />

Activation: The process <strong>of</strong> making a material radioactive by bombardment with neutrons, protons,<br />

or other nuclear particles.<br />

Activity: A measure <strong>of</strong> the rate at which radioactive material is emitting radiation;<br />

usually given in terms <strong>of</strong> the number <strong>of</strong> nuclear disintegrations occurring in a given<br />

quantity <strong>of</strong> material over a unit <strong>of</strong> time. The special unit <strong>of</strong> activity is the curie (Ci).<br />

AFR: Away-from-reactor (spent fuel storage concept).<br />

Aging: Usually refers to time to permit decay <strong>of</strong> short-lived radionuclides.<br />

ALAP: As low as practicable, now generally replaced with ALARA (as low as reasonably<br />

achievable).<br />

ALARA: As low as reasonably achievable. ALARA refers to limiting release and exposure and<br />

is used by the NRC (10 CFR 50.34) in the context <strong>of</strong> ". . . as low as reasonably achievable<br />

taking into account the state <strong>of</strong> technology, and the economics <strong>of</strong> improvements in relation<br />

to benefits to the public health and safety and other societal and socioeconomic<br />

considerations. . ."<br />

Allowance Item: A number, arrived at by judgement, that represents material or equipment<br />

cost that cannot be developed otherwise because <strong>of</strong> the absence <strong>of</strong> design detail.<br />

Alluvial Fan: A sloping, fan-shaped mass <strong>of</strong> loose rock material deposited by a stream at<br />

the place where it emerges from an upland onto a broad valley or a plain.<br />

Alluvium: All detrital material deposited permanently or in transit by streams.<br />

Alpha Particle: A positively charged particle emitted by certain radioactive material. It<br />

is made up <strong>of</strong> two neutrons and two protons; hence it is identical with the nucleus <strong>of</strong> a<br />

helium atom.<br />

Amphibole: A group <strong>of</strong> dark, rock-forming, ferromagnesian silicate minerals which are<br />

closely related in crystal form and composition and which have abundant and wide distribution<br />

in igneous and metamorphic rocks.<br />

Andesitic: A volcanic rock composed primarily <strong>of</strong> the plagioclase feldspar andesine and one<br />

or more mafic constituents.<br />

Anion: An ion that is negatively charged.<br />

Anticline: A fold, the core <strong>of</strong> which contains stratigraphically older rocks, which in simplest<br />

form is elongate and convex upward with the two limbs dipping away from each other.<br />

APS: Atmospheric protection system.<br />

Aquifer: A water-bearing layer <strong>of</strong> permeable rock or soil that will yield water in usable<br />

quantities to wells.

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