Glossary

Daughter Product
The term used to describe a decay product of a radioactive substance.
See; Half Life, Radioactivity.
Decay
The decrease in activity of any radioactive material with the passage of time due to spontaneous emission from the atomic nuclei of either alpha or beta particles, sometimes accompanied by gamma radiation.
See; Half Life, Radioactivity.
Decontamination
The reduction or removal of contaminating radioactive material from a structure, area, object, or person. Decontamination may be accomplished by (1) treating the surface so as to remove or decrease the contamination; (2) letting the material stand so that the radioactivity is decreased as a result of natural decay; and (3) covering the contamination so as to attenuate the radiation emitted. Radioactive material removed in process (1) must be disposed of by burial on land or at sea, or in other suitable ways.
See; Contamination.
Delayed Fallout
See; Fallout.
Deterrence
Dissuasion of a potential adversary from initiating an attack or conflict by the threat of retaliation.
Deuterium
An isotope of hydrogen of mass 2 units; it is sometimes referred to as heavy hydrogen. It can be used in thermonuclear fusion reactions for the release of energy. Deuterium is extracted from water which always contains 1 atom of deuterium to about 6,500 atoms of ordinary hydrogen.
See; Fusion, Isotope, Thermonuclear.
Diffusion
A technique for uranium enrichment in which the lighter Uranium 235 isotopes in UF6 gas move through a porous barrier more rapidly than the heavier Uranium 238 isotopes.
See; Isotope.
Dirty Bomb
A dirty bomb is a conventional explosive such as dynamite, filled with deadly radioactive particles which scatter when the bomb goes off. Known as a radiological weapon, a dirty bomb's initial conventional explosion kills or injures people, and then spreads radiation -- hence the term "dirty. Such bombs could be miniature devices or be as big as a truck.
Disassembly
Process of taking apart a nuclear warhead and removing the subassemblies, components and individual parts.
Dose
A (total or accumulated) quantity of radiation. The absorbed dose in rads represents the amount of energy absorbed from radiation per gram of specified absorbed material.
See; Radiation.
Dual-use equipment
Components that can be used for nuclear and non-nuclear purposes.
E = mc2
Albert Einstein's equation E = mc2 is the most famous in the history of science. It states that energy and mass are equivalent, a concept that enabled scientists to understand the energy source of the sun and other stars and led to the development of nuclear energy. Specifically, the equation states that a mass m can theoretically be transformed into an amount of energy, E, equal to m multiplied by the square of the speed of light (3 X 10 to the 10th power cm/sec). Einstein deduced this concept from his theory of special relativity. The equation first appeared in a paper he published in 1907.
See; Binding Energy.
Electromagnetic Pulse
A sharp pulse of radio-frequency (long wavelength) radiation produced when an explosion occurs in an asymmetrical environment, especially at or near the earth's surface or at high altitudes. The intense electric and magnetic fields can damage unprotected electrical and electronic equipment over a large area. It is now thought that a single high-altitude blast over the U. S. could seriously disrupt the nation's communications system, and perhaps shut down the entire power grid. At present, however, there is no known way of providing complete protection against the effect.
See; Electron.
Electromagnetic Radiation
A traveling wave motion resulting from oscillating magnetic and electric fields. Familiar electromagnetic radiations range from X rays, through the ultraviolet, visible, and infrared regions, to radar and radio waves. All electromagnetic radiations travel, in a vacuum, with the velocity of light.
Electromagnetic Separation
The separation of uranium isotopes by electromagnetic means (to produce uranium 235 for an atomic bomb).
See; Site X.
Electron
A particle of very small mass, carrying a unit negative charge. Electrons, surrounding the nucleus, are present in all atoms; their number is equal to the number of positive charges (or protons) in the particular nucleus.
See; Beta Particle.
Electron Volt (eV)
The energy imparted to an electron when it is moved through a potential difference of 1 volt. It is equivalent to 1.6 x 10-12 ergs.
See; Electron.
Element
One of the distinct, basic varieties of matter occurring in nature which, individually or in combination, compose substances of all kinds. Approximately ninety different elements are known to exist in nature and several others, including plutonium, have been obtained as a result of nuclear reactions.
Eniwetok Atoll
On November 1, 1952 a 10.4 megaton thermonuclear explosion code-named "Mike", at Eniwetok Atoll, demonstrated the release of energy from nuclear fusion. The island of Elugelab in the Eniwetok Atoll on which the test was conducted, was completely vaporized. It left a crater deeper than the height of the Empire State Building and large enough to house several Pentagons.
See; Hydrogen Bomb.
Enriched uranium
Uranium with an increased concentration of the isotope U-235. Natural uranium contains 0.7 percent U-235, whereas nuclear weapons typically require uranium enriched to 90 percent or more U-235. Nuclear power plant fuel typically uses uranium enriched to 3 to 5 percent U-235, material that is not sufficiently enriched to be used for nuclear weapons.
Enrichment
The process of increasing the concentration of one isotope of a given element.
Equivalent Megatons (EMT)
In evaluating the destructive power of a weapons system it is usual to use the concept of equivalent megatons (EMT). Equivalent megatonnage is defined as the actual megatonnage raised to the two-thirds power.
See; Yield.

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