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TERRORISTS’ USE OF “DIRTY BOMBS” – ASSESSING THE THREAT

 By the Los Angeles Terrorism Early Warning Group – Analysis Section

 A “dirty bomb,” also known as a radiological weapon, is a conventional explosive (such as dynamite) which has been packaged with radioactive material which scatters when the bomb goes off. A dirty bomb kills or injures through the initial blast of the conventional explosive and by airborne radiation and contamination – thus, the term “dirty.” Such bombs could be small devices or as big as a shipping container or a large truck bomb. A second type of radiological dispersal device might involve a powerful radioactive source hidden in a public place, such as a trash receptacle in a busy train or subway station, where people passing close to the source might get a significant dose of radiation.

An Honest Evaluation 

The purpose of this article is to provide a realistic assessment of the threat posed to the citizens of the United States by terrorists’ employment of a Radiological Dispersal Device – from here on referred to as a RDD or dirty bomb. The article will answer basic questions about RDDs and dirty bombs, the hazards associated with these devices, and provide an intelligence assessment of the threat posed by these devices in the hands of terrorists.

In terrorist situations, RDDs can be used for psychological impact to create panic, to cause evacuation of key areas, and to overburden disaster response organizations.

Although the use of RDDs by terrorists implies the capability to create panic, deny key areas, and cause long-term contamination, the limits of such weapons must be recognized, but the possibility of their use (or their actual use) will cost time and will represent a psychological weapon to opponents.

In order to mitigate the psychological impact the use of a RDD will have on responders and the public, public safety agencies must develop response protocols based upon facts and be able to quickly get factual information to everyone who might be impacted. A number of federal agencies have responsibilities for dealing with possible detonations of dirty bombs. Interested parties should check out their Web sites. In addition, their offices of public affairs stand ready to promptly answer press questions on the subject or to provide access to experts in and out of government. Their Web sites and phone numbers follow:

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Elements to Investigate

There are three key items to be determined in any investigation related to the possible use of RDDs: the radioactive material, the dispersal system, and the means of delivery.

A RDD normally consists of two components: a radioactive material with shielding and a dispersal system. Both components would be joined together and housed in a package which could be delivered by missile, bomb, or nonconventional means (such as a truck bomb). The most likely delivery means by a terrorist will be nonconventional. Prior to its employment, it is likely a radiological dispersal device would be stored in an unassembled form.

It doesn’t take much expertise to develop a RDD, at least not much more than it takes to make a conventional bomb. No special assembly is required; the regular explosive would simply disperse the radioactive material packed into the bomb. The hard part is acquiring the radioactive material – not building the bomb. The Washington Post reported in March 2002 that the Bush administration’s consensus view was that Osama bin Laden’s al Qaeda terrorist network probably had such often stolen radioactive contaminants as strontium 90 and cesium 137 which could be used to make a dirty bomb.

Smuggled Material

International Atomic Energy Agency records show a dramatic rise in the level of smuggling of radiological materials (defined as radioactive sources which could be used in dirty bombs but not nuclear bombs). In 1996, there were just eight of these incidents, but, last year, there were 51. Most cases are believed to have occurred in Russia and elsewhere in Europe. Smugglers target the radioactive materials used in factories, hospitals and research laboratories which are not guarded as securely as those used by the nuclear industry. Since 1993, there have been 300 confirmed cases of illicit trafficking in radiological materials; 215 of them in the past five years. And the IAEA warns that the real level of smuggling may well be significantly larger, citing reports of another 344 instances over the past 11 years which have not been confirmed by any of the countries which monitor illicit trafficking.

Indeed, the relative ease of constructing such weapons makes them a particularly worrisome threat. Even so, expertise matters. Not all dirty bombs are equally dangerous: the cruder the weapon, the less damage caused. We don’t know if terrorists could handle and detonate high-grade radioactive material without fatally injuring themselves first.

Nuclear bombs are normally described in relation to yield, such as a ten kiloton device or a 20 megaton device. Yield is not applicable to RDDs. Radioactivity measurements are a more important measurement of the strength of a RDD.

Sources

Several radioisotopes have short half-lives, necessitating a short time span between production and use. According to a U.N. report, Iraq tested a one ton radiological bomb in 1987, but gave up on the idea because the radiation levels it generated were not deadly enough. The Iraqi RDD used zirconium oxide (half-life of 64 days) and the period between irradiation and use could not exceed one week. Plutonium and spent nuclear fuel have much longer half-lives (on the order of several thousand years) and the amount of time between material production for a RDD and use in a RDD could be much longer. There are a number of sources for radioactive material around the world. The U.S. Nuclear Regulatory Commission, together with 32 states which regulate radioactive material, has over 21,000 organizations licensed to use such materials. For example:

• Hospitals use small quantities of radioactive material, such as cesium-137, in nuclear medicine;

• Universities use similar materials to conduct scientific research;

• Food irradiation plants use radiation from cobalt-60 to kill harmful bacteria on food;

• Natural radioactive uranium isotopes are mined for use in nuclear energy. Terrorists could conceivably acquire uranium from various mines in Africa;

• There are a number of abandoned “nuclear batteries” scattered around the former Soviet Union. These portable thermoelectric generators contain a sizable amount of strontium-90, a highly potent radioactive isotope;

• People could also collect spent radioactive fuel from Russian reactors which have been abandoned in old nuclear submarines, among other places; and

• They could also put something together using various low-level radioactive materials available to anybody, such as the radioactive material in smoke alarms.

The exact assembly sequence of a RDD is not known. It is likely that persons with at least a rudimentary knowledge of science and technology would assemble the RDD.

Available Information

Much has been written about the availability of the instructions to make various bombs on the Internet and in the open press. However, these instructions may not always be applicable to a RDD. Because of the radioactivity of the materials involved, some shielding is required in these low technology bombs to protect the individuals developing the bomb. If no shielding is used (and shielding is not specified in the Internet or open press instructions), the perpetrator could be incapacitated before the weapon could ever be used. Descriptions of bombs using radium are available in the open literature; however, these descriptions also do not discuss the radiological hazards which could be faced by someone developing a radium bomb.

The most likely dirty bomb would contain a small, or medium, amount of explosives (ten to 50 pounds [4.5-23 kg] of TNT, for example) with a small amount of low-level radioactive material (say a sample of cesium-137 or cobalt-60 from a university lab).

Aftermath

This sort of bomb wouldn’t be terribly destructive. Most likely, any immediate deaths (and all property damage) would be from the explosive itself rather than the radiation. The explosive would act as a propellant force for the radioactive material. A radioactive dust cloud would extend well beyond the explosion site, possibly covering several square miles. Bombs containing radioactive waste from nuclear power plants or portable nuclear generators would inflict more damage, but terrorists would be less likely to use them because they are harder to handle. The bombers could die from exposure just building and transporting the bomb.

Nonconventional delivery methods include those methods used in improvised delivery methods for bombs, such as pipe bombs, a shipping container, or car/truck bombs. A truck bomb would be more likely to be used by a terrorist group because it is more amenable to creating and delivering a bomb with the shielding requirements of a RDD. Past experience with terrorist devices indicates a RDD would probably have a timer for delayed detonation and could also have an antitamper device.

Experts report that, if people got rid of contaminated clothes, showered and evacuated the area within a day or so of a small or medium blast, they would probably be fine. The bomb would boost radiation levels above the normal, “safe” level, but not by a lot. In the short term, the human body could handle this increased exposure fairly easily. People very close to the blast could conceivably suffer radiation sickness and might require hospital care.

Long-Term Exposure

The main concern would be prolonged exposure. Many radioactive isotopes bind with other materials, including concrete and metal, extremely well. This would make it nearly impossible to completely remove the material without demolishing all contaminated structures. Cleanup crews could wash away a lot of the radioactive material, but a small amount would probably remain at the location for many years, even decades. Anybody living there would be exposed regularly to this radiation which could conceivably cause cancer.

The question is: Would this make a significant health difference? There are two schools of thought on this issue. Many experts have asserted that the health risks would be negligible if the government spent a few weeks or months on cleanup. The radiation level would be only marginally higher than normal, acceptable levels and it would not significantly increase the risk of developing cancer. People in the immediate vicinity would likely die from the force of the conventional explosion itself. Some survivors of the blast might die of radiation poisoning in the weeks afterward. Those farther away from the explosion might suffer radiation sickness in the days and weeks afterward, but recover. Over time, risks of cancer in the affected area would rise, but perhaps only slightly, experts say. According to the atomic experts Richard Garwin and Georges Charpak, the explosion of a dirty bomb containing one kilogram of plutonium in the center of Munich, Germany, could ultimately lead to 120 cancer cases attributable to the blast.

The other school of thought asserts that such an attack could make a city uninhabitable for years or decades. The Federation of American Scientists (FAS) recently prepared a report detailing three representative scenarios of a dirty bomb attack. In all three scenarios, the FAS assert that the risk of cancer in some contaminated areas would be so high that the government would desert or demolish the area. These predictions are based on the Environmental Protection Agency’s current guidelines for safe radiation levels.

There’s no precedent for a dirty bomb attack, but we can learn from other incidents of radioactive contamination. Nagasaki and Hiroshima were both exposed to a much larger amount of radioactive material, from an actual nuclear blast and, today, they’re both considered completely safe for habitation. On the other hand, there are still areas around Chernobyl that are considered unsafe because of high radioactivity.

Bottom Line

No matter their opinion on the long-term health risks, most experts agree that a dirty bomb would be more of a disruptive weapon than a destructive weapon. The news of radioactive contamination would probably cause widespread panic and the rush to evacuate the targeted city could actually cause more damage than the bomb itself. The local economy could also take a dive. Even if the government did assure the public that the area was inhabitable, real estate values and tourism could plummet. This is the precise reason dirty bombs are such an attractive weapon to terrorists.

Based upon all of the current information available, we assess that it is highly likely that a terrorist group/organization will try to use a dirty bomb as a method of attack. It will most likely be employed by a nonstate sponsored group (i.e., al Qaeda) or by surrogates (individual members of HAMAS or GIA – under the umbrella of Islamic extremist groups) that would allow state sponsorship to be nonattributable. Organizations responsible for public safety would be well served to assess their own risk and develop appropriate response protocols and standardized response folders (playbooks) for this threat. The authors are available to assist legitimate public safety entities in this endeavor. Written requests for assistance can be addressed to LA-TEW – Analysis Section, 1275 N. Eastern Ave., Los Angeles, CA 90063.n

The LA-TEW analysis section includes: Sgt. Mark Tharp (LAPD), Detective Larry Richards (LASD), Officer Tim Schey (LAPD), Deputy James Royal (LASD), Deputy Dennis Stangeland (LASD), and Deputy Jeannie Lavallette (LASD).

Department of Energy: www.energy.gov/; phone (202)586-4940

Department of Health and Human Services: www.hhs.gov/; phone (202)690-6343

Department of Homeland Security: www.dhs.gov/; phone (202)282-8010

Department of Justice: www.usdoj.gov/; phone (202)514-2007

Environmental Protection Agency: www.epa.gov/; phone (202)564-9828

Federal Bureau of Investigation: www.fbi.gov/; phone (202)324-3691

Federal Emergency Management Agency: www.fema.gov/; phone (202)646-4600

National Nuclear Security Administration: www.nnsa.doe.gov/; phone (202)586-7371

Nuclear Regulatory Commission: www.nrc.gov/; phone (301)415-8200

Transportation Security Administration: www.tsa.gov/public/; phone (571)227-2829