Radiation Dispersal Devices (RDDs) and Radiological Sources
Gregory J. Van Tuyle
Los Alamos National Laboratory
Radiation dispersal device (RDD) is the technical name for the so-called dirty bombs that are believed to be potential weapons of terror. These are aptly called weapons of mass disruption, since the anticipated problems with fear and contamination could be highly disruptive, while the anticipated loss-of-life would be modest in comparison to weapons of mass destruction. Many types of radioactive materials have been postulated for dispersion, but one area of particular concern is radiological sources used widely in industrial, medical, and research applications. The radioactive materials and the quantities used in the larger applications vary widely, and their potential impacts if dispersed by terrorists range for insignificant to massively disruptive. While the potential impacts are highly scenario dependent, it is obvious that the dispersal of large radiological sources could have the greatest impact. Radioisotopes commonly used in large sources include cobalt-60, cesium-137, strontium-90, americium-241, and plutonium-238. The chemical form varies according to source application, with some used as metals, some as oxides, some in salt form, and some other variations. The chemical form can contribute to concerns about dispersion, and the experience with Cesium-Chloride has been particularly bad, including an accidental dispersion of a teletherapy source in Goiania Brazil. Because of these bad experiences with accidental dispersion of cesium chloride, there has been interest in reducing or eliminating its use. Alternate chemical forms are under consideration, and if they provide better performance and economic viability, the availability of an undesirable radiological source material could be greatly reduced.