Useful Fools

Fox News Reports: The IAEA has declared a “radiological emergency” based on the theft of “strategic quantities” of radioactive Americium in Nigeria - a country with a significant Muslim population and a history of Islamicist violence.

Presumable the terms “strategic quantities” means that enough has been stolen to be useful for one or more radiological bomb(s).

Radiological bombs (”dirty bombs”) are of little military use, but can be used to terrorize civilians and render unusable significant areas of major cities, necessitating expensive cleanup and causing major economic disruption. They are unlikely to result in mass casualties because few people would receive significant radiation doses before evacuating.

A potentially more deadly use, that has not been discussed in the media, would include a stealthy non-explosive release of fine radioactive particles (such as spraying it from atop a downtown building). This might dangerously contaminate a large number of people before it was detected. The material might be chemically converted into a liquid for aerosolization, or finely milled metal could be released.

The Americium is in the form of a compacted mixture of (radioactive) americium-141 oxide and (non-radioactive, but toxic) beryllium metal. Americium-141, a man-made decay product of Plutonium has a half-life of 14 years. It releases weak gamma rays and some neutrons. However, it is a sufficientlylow level radiator that it is commonly used in household smoke detectors. It also releases alpha particles (high energy helium nuclei) to cause ionization in a smoke detector. The smoke detector absorbs the alpha-particles, preventing their escape into the environment.

The greatest health hazard of a release would probably be inhalation of small particles (~1uM), assuming the material was milled to this size, because the long term presence of alpha emitters can cause cancer (this is the same radiological hazard as exists with Plutonium). The Americium in the Americium/Beryllium is of the form Americium-oxide which is not absorbed into the body and thus is not a hazard if ingested. However, a terrorist could convert this to a different chemical formulation which would be dangerous in food.

[Historical note: In the cold war, the term “dirty bomb” was used to refer to a type of nuclear weapon which produced an intentionally large amount of radioactive fallout (such as a nuclear bomb with a large cobalt jacket). The usage of the term has changed recently to mean a radiological weapon - one which has no nuclear explosion but which is designed to disperse radioactive material.]