Glossary

Alpha rays: Comparatively large, slow particles emitted from the nucleus of an atom. They are easily stopped but can cause great damage if the chemicals emitting them are inhaled or ingested.

Background radiation: Radiation (at a typical rate of 60-100 mrem per year) coming from space or from the earth. It can be both natural and man-made.

Beta rays: Charged particles (electrons) emitted from the nucleus of an atom that are smaller and faster than alpha rays and can penetrate several layers of tissue up to a few millimeters, or a few meters of air.

Curie: A measure of the amount of radiation emitted per second by radioactive chemicals, named after Marie Curie, the discoverer of radium. It is the number of disintegrations taking place each second in 1 gram of radium, leading to the emission of some 37 billion gamma rays or other particles every second.

millicurie -- one one-thousandth of a curie.
microcurie -- one millionth of a curie.
picocurie -- one trillionth of a curie or one micro-microcurie.

Fuel cycle: The sequence of steps needed for the production and combustion of fuel to produce nuclear energy including mining, milling, conversion, enrichment, transportation, and waste storage.

Gamma rays: A very high energy form of radiation similar to X-rays emitted from the nucleus of an atom that can penetrate steel and concrete.

Kiloton: A measure of the power of an atomic bomb, equal to the detonation of 1000 tons of TNT. The first A-bombs had a size of 10-20 kilotons, now regarded as small, tactical weapons.

Megaton: A million tons of TNT in explosive force, or the energy of 1000 kilotons, some 100 times that released by the first atomic bombs.

Rad and millirad: A radiation measure that refers to the energy absorbed per gram of tissue which is equal to about 83% of the Roentgen value. A millirad or mrad is a thousandth of a rad.

Rem and millirem: A radiation measure that reflects the difference in biological damage of the radiation dose produced by different particles. The relation between rad and rem depends on the kind of particle emitting the radiation: for gamma rays, 1 rad = 1 rem; for beta, 1 rad = 10 rem; for alpha, 1 rad = 30 rem.

Roentgen: The original term used for measuring the amount of ionizing radiation incident on the body. It is equal to the quantity of radiation that will produce one electrostatic unit of electricity in one cubic centimeter of dry air at 0 degrees C.

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