Dirty bomb

The term dirty bomb is most often used to refer to a Radiological Dispersal Device (RDD), a radiological weapon which combines radioactive material with conventional explosives. Though an RDD is designed to disperse radioactive material over a large area, the conventional explosive would likely have more immediate lethal effect than the radioactive material. At levels created from most probable sources, not enough radiation would be present to cause severe illness or death. A test explosion and subsequent calculations done by the Department of Energy found that assuming nothing is done to clean up the affected area and everyone stays in the affected area for 1 year, the radiation exposure would be "fairly high".

Earlier uses of the term

The term has also been used historically to refer to certain types of nuclear weapons. Due to the inefficiency of early nuclear weapons (such as "Fat Man" and "Little Boy"), 2% or less of the nuclear material would be consumed during the explosion. Thus, they tended to disperse large amounts of unused fissile material in the form of nuclear fallout. During the 1950s, there was considerable debate over whether "clean" bombs could be produced, and these were often contrasted with "dirty" bombs. "Clean" bombs were often a stated goal, and scientists and administrators said that high-efficiency nuclear weapon design could create explosions which generated almost all of their energy in the form of nuclear fusion, which does not create harmful fission products. But the Castle Bravo accident of in 1954, in which a thermonuclear weapon produced a large amount of fallout which was dispersed among many human populations, suggested that this was not what was actually being used in modern thermonuclear weapons, which derive around half of their yield from a final fission stage. While some proposed producing "clean" weapons, other theorists note that one could make a nuclear weapon intentionally "dirty" by "salting" it with a material (most commonly a type of cobalt) which would generate large amounts of long-lasting fallout when irradiated by the weapon core. In the post-Cold War age, this usage of the term has largely fallen out of use.

Related Topics:
Nuclear weapons - Fat Man - Little Boy - Fissile material - Nuclear fallout - Nuclear weapon design - Nuclear fusion - Fission products - Castle Bravo - 1954 - Cobalt

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