Radiological Dispersal Devices

Assessing the Transnational Threat
by James L. Ford, Strategic Forum of the National Defense University Institute for National Strategic Studies

The Defense Science Board Summer Study report recognizes a "new and Ominous trend - a transnational threat with a proclivity towards much greater levels of violence." The report states that the transnational groups have both access to, as well as the motivation to use, weapons of mass destruction (WMD). Military and civil defense planners are increasingly concerned about the possible state and non-state use of radiological dispersal devices (RDD) against U.S. forces and population centers abroad and at home.

Practically any state or non-state actor can build and detonate RDD's as technological barriers have fallen and radiological materials have become more plentiful. However, weapons design experts contend that the physical threat from these RDD's may be overstated.

The psychological and political effects of RDD use are not well understood and are potentially more significant that the lethality effects of such use. While RDD's may not be well suited as military weapons in the classic sense, the use of RDD's could be powerfully coercive and could trigger enormous political reactions within host countries or among allies in a coalition. These reactions could produce major strategic consequences for the military campaign.

With protective and decontamination equipment and training, U.S. forces should be able to withstand the physical effects of most RDDs. At home, US civil defense planners - including first responders being trained under the Nunn-Luger-Dominici initiative, must also be prepared to deal with the RDD threat.

"As the new millennium approaches, the United States faces a heightened prospect that regional aggressors, third-rate armies, terrorist cells, and even religious cults will wield disproportionate power by using - even threatening to use - nuclear, biological or chemical weapons against our troops in the field and our people at home."

- Statement of Secretary of Defense William S. Cohen in the Preface to the Defense Science Board's 1997 Summer Task Force Final Report, Oct. 1997

Radiological Dispersal Devices Defined

The Department of Defense (DOD) defines an RDD as, "any device, including weapon or equipment, other than a nuclear explosive device, specifically designed to employ radioactive material by disseminating it to cause destruction, damage, or injury by means of the radiation produced by the decay of such material." Almost any radioactive material can be used to construct an RDD, including fission products, spent fuel from nuclear reactors, and relatively low-level materials, such as medical, industrial and research waste. Weapons grade materials ( i.e., highly enriched uranium or plutonium) are not needed although they could be used. An RDD is designed to scatter radioactive debris over a wide area, thereby contaminating it and possibly causing casualties through radiation sickness, as well as denying its use to military forces or others for some period of time. According to a recent DOD report, the RDD threat is threefold: the blast, and fragmentation effects from the conventional explosive, the radiation exposure from the radioactive material used, and the fear and panic that its use would spread among the target group or population.

Background

The possibility of employing radioactive materials as a weapon was first considered during World War II. In 1941, the national Academy of Sciences proposed radiological warfare as a military application of atomic energy. In its report, the Academy's first option was the "production of violently radioactive materials...l carried by airplanes to be scattered as bombs over enemy territory." After British physicists demonstrated the technical feasibility of nuclear explosive weapons, attention quickly turned to their development throughout the remainder of the war. In 1946, the US conducted the Operation Crossroads nuclear tests at Bikini Atoll in the Marshall Islands. The widespread contamination of ships used in these tests gave dramatic evidence of the potential of so-called radiological warfare. In 1947, the DOD began creating panels of experts to study the offensive and defensive aspects of what it termed "Rad War". This led to an active test program, including releases of radiation into the atmosphere in the 1940's and 1950's. The results of these early experiments showed that while RDD's were not effective as battlefield weapons, such weapons could have a significant psychological effect. Yet, for the nest four decades, there was little documented interest in developing radiological weapons.

Recent concerns with an RDD threat center on both state and non-state actors. According to Western press reports in January 1991, Iraq claimed to have "secret or unusual" weapons that could kill tens of thousands of its foes. US intelligence concluded that it was possible for Iraq to build a functioning RDD. An unclassified CIA report stated that Iraq could have obtained radioactive material from research reactors and that it could disperse this material using a conventional explosive. The report concluded that an Iraqi RDD would not be a "militarily significant" weapon because it could not cause widespread radiation sickness even if used against unprepared and unprotected civilians in a city. However, the report also concluded that any Iraqi use of an RDD would have substantial psychological impact.

Public Perceptions of the Threat

Since the Gulf War, RDD's have received growing attention. In particular, a number of experts on international terrorism now believe that the threat from radiological weapons is real and growing. Increasingly, observers discount the long-standing assumption that only states have the resources and expertise to develop or acquire such weapons. According to one report, Iranian agents are known to have tried to buy nonfissile but radioactive nuclear material originating in the former Soviet Union. Moreover, subnational and terrorist groups appear to be more likely to use them. Th Aum Shinrykio Sarin gas attack in Tokyo provides chilling evidence of terrorist willingness to kill large numbers of people. Indeed, the Aum Shinrykio and subnational groups such as the Chechens are known to have pursued development of RDD's. In November 1995, Chechen rebels placed a 30 lb. container of radioactive cesium in a Moscow park - perhaps the recent manifestation of an adversary's willingness to use an RDD to achieve its goals.

Today, popular but sometimes inaccurate characterizations of the RDD threat focus on the danger of radiation effects from detonation, the relative ease and ready availability of radiological materials needed to construct such a device, and the readiness of potential adversaries to do so. A recent article in Foreign Policy notes that, "Some have pointed our that if a simple radiological device had been used in conjunction with the World Trade Center explosive, large areas of lower Manhattan would still be uninhabitable." This article underscores the relative ease with which the technical know-how, materials and equipment to make RDD's can be acquired. An article in American Legion points out the danger from RDD terrorism might in fact be greater "because of the relative ease with which terrorists could obtain radioactive materials, such as X-ray machines, irradiated materials from a hospital, radioactive matter from medical laboratories or construction sites, and even linens from a cancer treatment facility". Many such claims are often overstated and could be misleading.

How the Experts See It

Notwithstanding popular perceptions, the physical effects of an RDD are dependent on several factors, both the type and amount of radioactive material used in any device are especially critical. Current DOD studies underscore the vast difference in lethality produced by different types of radioactive materials. For instance, compare the effects of two different RDD's detonated at the Washington Monument with 100 pounds of high explosives. One device, a man-pack RDD, contains 5,000 curies of Cobalt-60 (Co-60); the second carrying 50 kilograms of bundled, not ground, one-year-old spent fuel rods.

An RDD constructed of Co-60 would produce a maximum dosage at the point of detonation of 12 rem (Roentgen Man Equivalent), resulting in no radiation related deaths. In marked contrast, the RDD from spent reactor fuel would result in a maximum dosage at the point of detonation of 3,064 rem (six times the lethal dose). The detonation could produce a circle of potential lethal dosage extending about a kilometer to the Washington waterfront, and, a significant amount of radioactive material would remain at the detonation site. Clearly these two RDD's would produce very different physical effects, the second far more lethal than the first.

National Laboratory scientist generally hold that construction and use of a physically effective RDD is more difficult and use of a physically effective RDD is more difficult that popularly assumed. State and subnational groups would have to overcome significant technical difficulties to construct and effectively deliver an RDD on target. while it is possible for a state or even subnational group to assemble enough highly radioactive materials to produce mass casualties or to achieve wide area denial. Even if a significant amount of the right material can be acquired, the handling of gamma-emitting radioactive substances becomes very difficult due in part to the heat generated by large quantities of such material and the extreme exposure hazard from the intensity of the radiation. These substances require heavy shielding to protect handlers from the overexposure and death. For example, the WWII Radioactive Subcommittee estimated that a bomb carrying 10,000 curies (Enough to contaminate 250,000 sq. ft. of open fields, approximately 5.7 acres) would require 310 lbs. of lead shielding to protect those handling the device. In addition, the radioactive material would have to be grounded to a dust of 5 micron-size particles and then mixed with an inactive solid material to enhance and increase the inhalation hazard. Lastly, the effects would be highly dependent on local weather conditions and terrain. These early experiments showed that cities, or build-up area, would require "something approaching 100 times greater concentration" because structures would absorb a large fraction of the radiation. As a result of these early studies, the US government concluded that RDD's were not military useful weapon.

The Threat: Perceptions Versus Reality

The perception that practically any state or non-state actor can build and detonate RDD's may well be coming true. However, the perception that all RDD's will have major physical effects is flawed. Experts contend that public commentators have overstated the ease of constructing and deploying an RDD that could cause mass casualties and deny an area's use for a lengthy period of time. Acquiring a sufficient amount of material, constructing the device without overexposure to radiation in the process, effectively delivering the device on target, and achieving the necessary lethality are tasks beyond the capabilities on most non-state actors. US research and experimentation over the last 50 years indicate that lethal RDD's are not easy to build.

On the other hand, it is true that almost any use of an RDD could have a tremendous psychological - and therefore political - impact. Thus even crude RDD's might meet some state or terrorist groups' objective, particularly if that objective were to create panic, to disrupt (or slow down) military operations, or to bring public pressure on political leaders to change a course of action.

This has been reprinted with permission of the author and ND Press publications.

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