“Dirty” nuclear or radiological weapons are bombs that use conventional explosives to disperse radioactive material with the intent of causing lethal or debilitating radiation sickness. They are designed to kill or injure through radiation only, as opposed to blast or shock.
Dirty radiological weapons may be produced by encasing highly radioactive material in lead, and surrounding the device with conventional high explosives. The resulting explosion would disperse the radiation over a potentially wide area, depending on atmospheric and weather conditions. The potential health problems resulting from intense radiation are well established by the nuclear disaster at Chernobyl in 1986 and a second event in Goiania, Brazil in 1987
At the Chernobyl site, an accident in a nuclear reactor resulted in a series of explosions that totally destroyed one reactor and widely dispersed radioactive material that contaminated large parts of northern Ukraine, Belarus, and Russia. For the purposes of this report, the volume of nuclear material dispersed into the atmosphere is unknown. Thirty-one persons were killed and 140 developed significant illness, but none of these were amongst the general population, that is, they were plant personnel and rescue workers. The accident occurred in a relatively sparsely populated area of northern Ukraine. Large numbers of persons were evacuated from a 30-kilometer radius of the plant, and large amounts of land were declared off limits to farming. In the 15 years since the accident, there has been a significant increase in thyroid cancers, mostly in children, but no increases in the numbers of other cancers. Psychological disorders were a more common side effect of the disaster.
In the Brazilian case, scrap scavengers broke into a radiological clinic and stole a capsule containing about an ounce of highly radioactive cesium 137. The thieves broke up the cesium and passed the pieces to friends and relatives. Of the 249 persons contaminated, four died, 14 persons were “overexposed,” and 110,000 persons were subjected to continuous monitoring. In addition, 85 houses, and truckloads of personal possessions had to be destroyed. Large amounts of contaminated earth were also removed.
In April 2001, Uzbek customs officers intercepted and seized a truck carrying 10 lead-lined boxes filled with highly irradiated (with strontium-90) scrap metal. The shipment was destined for Quetta, Pakistan, near the Afghan border. Its origin is unknown, except somewhere in the Former Soviet Union.
According to published reports, a crude radiological weapon could be constructed with only “a few” kilograms of plutonium or highly enriched uranium. A small amount of plutonium dispersed by conventional explosives could cause fatalities over hundreds of meters from the detonation site.Several countries have nuclear weapons, and more have nuclear power plants. Theft of nuclear weapons is a remote possibility. Spent nuclear fuel could possibly be utilized in such a weapon, although the radiological yields would be relatively small compared to enriched uranium or plutonium. The Iraqis reportedly exploded three radiological weapons in the mid-1980’s using spent fuel from a nuclear plant packed inside conventional weapons. However, the Iraqis reportedly dropped development of their program because of the “disappointing” results, apparently due to the ineffectual dispersal of the radioactive material.
An airborne attack on a nuclear plant would probably produce greater deleterious effects. Nuclear power plants, although they are designed to withstand earthquakes, are not designed to withstand a fuel-laden aircraft crash. Nuclear power plants in the US are located outside high-density population areas, but “favorable” meteorological conditions could heighten the amount of radiation dispersed by such an attack. However, coordinating an aircraft hijacking with “favorable” weather conditions would be highly problematical. Plutonium, according to open source reporting, could be delivered in aerosol form, possibly by aerial spraying from an aircraft or UAV (NFI). This form of delivery would be even more subject to the vagaries of meteorological conditions.
Although UBL and associated groups are theoretically capable of organizing a dirty bomb attack, heightened awareness of a terrorist nuclear threat and the protective measures that have been instituted to protect nuclear assets following 11 September, dispersal of terrorist personnel, coupled with transportation difficulties, would make the delivery of a dirty nuclear device far more difficult now than prior to September 11. However, even though the expected casualty rate achieved by such a radiological attack is questionable, and more conventional attacks and psychological terror produced by real or imagined biological or chemical agents may be more productive, the results of a radiological attack of some kind would be a severe psychological blow to civilian morale.
According to the International Atomic Energy Agency, there have been 370 reported instances of nuclear smuggling since 1993. Most of these incidents likely occurred in the years following the collapse of the Soviet Union in 1991, when there are numerous accounts of terrorists and gangsters stealing and selling nuclear materials. In 1995, Chechen guerillas were able to obtain 15 kgs of cesium, apparently from a cancer treatment facility in the former Soviet Union, burying it near the entrance of a tourist attraction in Moscow. Although the container emitted massive amounts of radiation, up to 200,000 times normal levels, no casualties were reported from the exposure. Generally though, most reporting on the theft of nuclear materials in the former Soviet Union involves former Soviet Union criminal elements obtaining small amounts of spent nuclear fuel for criminal activities, including a gang-related murder. But many of the reported caught smugglers were ignorant of both the usage and consequences of stealing nuclear materials. More recent open source, unconfirmed reporting has raised the possibility that Chechen Muslims or the Russian Mafia obtained or sought nuclear materials for delivery to UBL groups in exchange for $30 million and two tons of narcotics.
Radioactive waste or material would have to be encased in lead or concrete and steel or the transport personnel themselves would be subject to lethal doses of radiation. Legitimate nuclear waste is transported in specially designed casks that could be blown open by shape charges, such as from an anti-tank weapon. Such an attack, however, would depend on terrorists’ foreknowledge of shipping means and times.
Obtaining, storing, and transporting nuclear materials are possibly the most difficult aspects of delivering an improvised radiological weapon. Nuclear materials in the US are well protected, forcing terrorists to obtain the radioactive materials abroad. International transportation and storage of these materials, not to mention placement and detonation, would require substantial resources in personnel, logistical support, and funding. The World Trade Center and Pentagon attacks reportedly required about $500,000 and years of planning and coordination, and produced about 4000 fatalities. The result of an aircraft crashing into a skyscraper or building crowded with workers is relatively easy to gauge. A radiological weapon, based on past results, is less dependable as a casualty-producing weapon, and carries with it the problems of transporting the material (probably across international borders), and obtaining enough and the right kind of explosives to detonate it. The Iraqi example shows the difficulties of producing an effective radiological weapon even with adequate resources.
At left is a map of the radiation contamination zone resulting from the Chernobyl disaster. As the winds blew north, radiation was swept into Belarus, Russia, Scandinavia, and beyond. Habitants are still excluded from the 30-km zone immediately surrounding the site, and farming is officially prohibited in parts of the radiation-affected fallout area 15 years after the disaster.
The purpose of terror weapons is not only to inflict casualties, but also to destroy morale, injure economic conditions, and create panic and fear amongst the citizenry. These goals might be accomplished by the detonation of some type of dirty nuclear device, however ineffective it would be as a producer of mass casualties. Abandonment of valuable real assets because of radiation contamination, and the resulting adverse economic and psychological effects on the population would probably be the most severe consequences of a dirty bomb attack