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Nuclear Terrorism Siegfried S. Hecker Los Alamos National Laboratory INTRODUCTION As pointed out by several speakers, the level of violence and destruction in terrorist attacks has increased significantly during the past decade. Fortunately, few have involved weapons of mass destruction, and none have achieved mass casualties. The Aum Shinrikyo release of lethal nerve agent, satin, in the Tokyo subway on March 20, 1995, clearly broke new ground by crossing the threshold in attempting mass casualties with chemical weapons. However, of all weapons of mass destruction, nuclear weapons still represent the most frightening threat to humankind. Nuclear weapons possess an enormous destructive force. The immediacy and scale of destruction are unmatched. In addition to destruction, terrorism also aims to create fear among the public and governments. Here also, nuclear weap- ons are unmatched. The public's fear of nuclear weapons or, for that matter, of all radioactivity is intense. To some extent, this fear arises from a sense of unlimited vulnerability. That is, radioactivity is seen as unbounded in three di- mensions: distance it is viewed as having unlimited reach; quantity it is viewed as having deadly consequences in the smallest doses (the public is often told incorrectly, of course that one atom of plutonium will kill); and time if it does not kill you immediately, then it will cause cancer decades hence. Fred Iklei recently stated that "the morning after . . . a nuclear weapon has been used, the rules of warfare throughout the world will be profoundly trans- formed." He added, "Democracy cannot survive if a nuclear bomb can be deto- nated in Paris or Manhattan." Democracy would be even more vulnerable if nuclear weapons were exploded in democracies with shallower roots, such as 149

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150 HIGH-IMPACT TERRORISM those in Russia or India, for example. Hence, the consequences of a nuclear explosion almost anywhere on Earth would seriously impact the affairs of all nations. POTENTIAL FORMS OF NUCLEAR TERRORISM A nuclear weapon delivered by a missile, plane, boat, or van produces the gravest consequences of all forms of nuclear terrorism. Fortunately, the key ingredients for making a weapon, the fissile materials plutonium or highly en- riched uranium, are difficult to make and the facilities to make them have quite visible signatures. A second form of nuclear terrorism that is much less devastat- ing, but much more likely, is radiological terrorism, that is, the dispersal of radioactive materials. These so-called radiological dispersal devices (RDDs) can be made by packaging radioactive materials with chemical explosives and deto- nating such devices in high-value surroundings. A third form of nuclear terror- ism is sabotage of nuclear facilities. All of these forms of nuclear terrorism are old problems with concerns first being expressed a few years after World War II. However, the world has changed significantly since then. As already mentioned, there is a strong procliv- ity toward greater levels of violence. Yet, the public today has a much lower tolerance for risk. There is also considerably greater technological sophistication today and there is much more information available to the public, especially on the Internet. The greatest change, however, since the early days of nuclear weap- ons and nuclear power is that terrorists have easier access to nuclear and radioac- tive materials. Nuclear Weapons Although nuclear weapons are complicated technological devices, it is gen- erally agreed that a determined, well-trained subnational group could in time build a crude nuclear device with yields on the order of a few to tens of kilotons. The atomic bombs dropped on Hiroshima and Nagasaki were less than 20 kilo- tons. They devastated these cities and caused several hundred thousand deaths. The most difficult part of building such bombs is acquiring on the order of the tens of kilograms of highly enriched uranium or plutonium required to build them. The difficulties that a determined adversary such as Saddam Hussein ex- perienced despite the expenditure of billions of dollars is a good case in point. However, the dissolution of the Soviet Union with the consequent loss of order and central government control, especially in the early 1990s, raised the specter of theft or diversion of nuclear weapons or weapons-usable materials from the nuclear complex of the former Soviet Union. Although the "loose- nukes" concern received much play in the American media, it appears over- blown. There is no evidence that Russia has lost control of any weapons in its

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NUCLEAR TERRORISM 151 nuclear arsenal. Unfortunately, we do not have similar confidence about the potential loss of weapons-usable nuclear materials. In fact, several high-visibili- ty cases in the middle l990s demonstrated that weapons-usable plutonium or highly enriched uranium were trafficked illicitly from Russia and other states of the former Soviet Union. These incidents provided a "wake-up" call for Russia. Since that time, Russia has greatly enhanced the security of its weapons-usable materials with much of the effort being financed by the U.S. government. Although, the quickest way to deliver a nuclear weapon is by missiles, that remains an unlikely probability for a decade or more. Crude nuclear devices would be most easily transported to the desired site by boat, plane, or van. Although nuclear devices have a distinct radioactive signature that can be detect- ed by sophisticated sensors, this signature is attenuated significantly by distance and by shielding. Moreover, the number of entry points into the United States or other states that have a significant U.S. presence is overwhelming. Hence, today we must assume that if a group possesses a nuclear device, there is a very high probability that such a device could be delivered to a place where it could cause unacceptable damage. Hence, our government must remain ever vigilant to pre- vent nuclear weapons or weapons-usable materials from falling into the wrong hands. Radiological Terrorism The human consequences of radiological devices detonated in high-value places are orders of magnitude less than those of a nuclear detonation. The immediate effects are principally those of the chemical explosive used to deto- nate the RDD. Dispersing the radioactive materials limits their immediate lethal- ity. Furthermore, the lethality depends strongly on the nature of the radioactive material. Plutonium and highly enriched uranium, which are most feared by the public, are unlikely to result in a large number, if any, of immediate deaths because they do not emit highly penetrating radiation. Even the long-term cancer potential of their dispersal may not be terribly great. However, radioactive materials with intensely penetrating radiation may cause significant casualties. Such materials result from the burning of uranium in nuclear reactors (that is, their spent fuel or nuclear waste from reprocessing of spent fuel) or from medical or industrial radiation sources used to generate in- tense radiation. Fortunately, the more lethal a terrorist's choice of radioactive material, the less likely it is for a terrorist to be able to fashion it into an RDD without first killing the terrorist. Moreover, it would be easier to detect such a device unless it is heavily shielded. Hence, it is generally agreed that the greatest consequences of an RDD are public fear and the potentially enormous cleanup costs along with the conse- quent economic losses. Unfortunately, there is essentially no barrier to terrorists' acquiring a wide range of radioactive materials. By far the most vulnerable are

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152 HIGH-IMPACT TERRORISM medical and industrial radiation sources. There are currently more than 135,000 licensees of medical and industrial radiation sources in the United States, with more than 1.8 million sources in used Even in the United States, which has rather stringent regulations for the use and disposition of radioisotopes, approxi- mately 200 sources are reported lost, stolen, or abandoned annually. Around the world, more than 110 states have no minimum infrastructure to properly control radiation sources.3 In Russia, there were 500 reported incidents involving un- lawful movements of materials with elevated levels of ionizing radiation in the year 2000 alone. The International Atomic Energy Agency (IAEA) has reported that since 1993 there have been 175 cases of trafficking in nuclear material and 201 cases of trafficking in other radiation sources. Fortunately, only 18 of these cases have actually involved small amounts of highly enriched uranium or pluto- nium. It is somewhat reassuring that historically there have been surprisingly few incidents of the theft or smuggling of radioactive materials for malevolent purposes. However, the increased proclivity toward greater violence in terrorist acts gives one much reason for concern. Nuclear Sabotage Blowing up a nuclear facility constitutes another form of potential nuclear terrorism. The much more than 1000 nuclear facilities around the world consti- tute a target-rich environment. Although nuclear power reactors are typically well guarded and some are designed to withstand a significant external insult, the radioactive source terms at such facilities have the potential to cause massive casualties. These power reactors, like other critical facilities such as dams and chemical plants, pose potentially serious hazards for nearby populations. The potential damages resulting from terrorist attacks on nuclear power plants de- pend on inherent design features and on local protective measures, which in turn vary widely from country to country. The IAEA reports that there are 438 nucle- ar power reactors in operation worldwide (with 103 of these in the United States). Since the Oklahoma City bombing, the U.S. Nuclear Regulatory Commission has overseen a significant safety enhancement of U.S. nuclear power reactors against the truck bomb threat. The situation for storage sites housing spent fuel or high-level waste result- ing from reprocessing is similar to that for nuclear reactors. The radiation source terms are potentially enormous. In addition, there are 651 research reactors (only 284 are currently in operation) and 250 fuel cycle plants around the world, in- cluding uranium mills and plants that convert, enrich, and store nuclear materi- als. These nuclear facilities represent a much smaller source term, but are also typically much less secure. Although sabotage of some power reactors may cause Chernobyl-like dam- ages, most sabotage attempts would most likely result in the dispersal of some radioactive materials without mass casualties, but with enormous public fear and

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NUCLEAR TERRORISM 153 economic losses. In addition to these consequences, any successful act of nuclear terrorism would also most likely set back any expansion of nuclear power or other peaceful uses of the atom for decades. HOW TO DEAL WITH THE THREAT OF NUCLEAR TERRORISM? Much has been written over the years about the nature of the threat. During the past four years, the U.S. Defense Science Board has twice focused on the nuclear terrorism threat during its summer studies. The principal recommenda- tion from these studies is to develop a comprehensive architecture to counter all aspects of nuclear terrorism. Such an architecture should include the following: Information and intelligence Security Detection Disablement Mitigation Attribution Some aspects of nuclear terrorism, such as the dispersal of radiation sources, have low consequences but virtually no barriers. Others, such as a nuclear deto- nation have unacceptable consequences but significant barriers. Hence, informa- tion and intelligence about potential terrorist activities is paramount to provide as much early warning as possible. Keeping radioactive materials secure that is, protected, controlled, and accounted for is very important, especially for weapons-usable plutonium and highly enriched uranium. Security of radiation sources is most problematical. A major worldwide effort is necessary to have every country with such sources develop a proper regulatory framework and system of control. The threat of nuclear sabotage calls for extending tight securi- ty requirements to all nuclear facilities. Unlike biological and chemical agents, nuclear materials and radioisotopes have a distinct radioactive signature that can be detected at a distance. Unfortu- nately, this signature is attenuated by distance and by shielding, which makes it more difficult to detect some of these materials in a sea of cosmic background radiation. For example, plutonium's 7 x 107 gammas per second per kilogram are attenuated by a factor of 1 million by 1 km in air and a factor of 1000 by 1 inch of lead shielding. Detecting radiation at a distance continues to be one of the most important technological challenges in nuclear terrorism. Disabling a nuclear device is extremely difficult but possible if one can gain access and render the device safe. The U.S. nuclear weapons laboratories have over the years developed several potential approaches. Any knowledge of the type of device or its country of origin would prove very helpful in attempting to render the device safe. If a device is actually detonated, then treating the casual-

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154 HIGH-IMPACT TERRORISM ties promptly and effectively becomes crucial. Likewise, rapid and effective cleanup of contaminated areas will help to limit the economic damages. Again, the United States has significant training experience with the Department of Energy's Accident Response Group (ARG) and its Nuclear Emergency Search Teams (NEST). Likewise, there is a substantial body of expertise for decontam- ination and cleanup based on experience with decommissioning nuclear facilities and cleaning up nuclear dispersal accidents. Lastly, a comprehensive architec- ture must include attribution. Forensics must be developed to determine the iden- tity of the perpetrators, both for the purpose of retaliation and to guard against a potential repeat attack. One additional critical dimension of an integrated architecture to respond to terrorism is education of the public along with the role of mass media. This is especially important for nuclear terrorism because of the public's lack of under- standing of radiation and the great fear that accompanies this lack of understand- ing. For example, the likelihood of radiological terrorism in the near future is quite high the necessary materials are readily available. However, it is impor- tant for the public to understand that the threat to human life is very limited from most such devices. The economic consequences from contamination, disruption, and cleanup, however, can be severe. Radiological sabotage represents a consid- erably greater threat to human life in the vicinity of nuclear facilities. However, there are immediate actions, including well-established medical treatments, that can reduce the threat to human life. Even a nuclear explosion with its enormous destructive power has a limited range of lethality. Mass media can play an im- portant role in helping to educate the public on the real nature of the various nuclear threats. I believe that any integrated architecture would also benefit substantially from U.S.-Russian cooperation on a wide front of activities designed to deal with nuclear terrorism. The first cooperative agreement between the United States and Russia to combat terrorism in general dates back to September 1993, with a memorandum of understanding between the U.S. Department of Defense and the Russian Federation Ministry of Defense. Although not much activity has oc- curred under this agreement, recent statements made by President Bush and Russian Minister Ivanov underscore the importance of this problem. Specifically, I believe that cooperation between the Russian Academy of Sciences and the U.S. National Academies would be very beneficial. I believe that since this problem has so many dimensions, it should be viewed from as many different points of view as possible, including those of scientists and engi- neers. There are many areas in which specialists can help with the science and technology dimensions of nuclear terrorism. The U.S. National Academies have a long record of involvement in the counterterrorism arena. Working jointly with the Russian Academy of Sciences would prove very beneficial to both countries. Also, often the informal dialogue resulting from the discussion of specialists

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NUCLEAR TERRORISM 155 under the umbrella of the Russian and U.S. Academies can help to catalyze necessary government actions. NOTES Ikle, F.C. 1996. The second coming of the nuclear age. Foreign Affairs 75 (January-Febru- ary):ll9. 2. Lubenau, J.O. 1999. A century's challenges: historical overview of radiation sources in the USA. IAEA Bulletin 41(3):2. 3. Gonzalez, A.J. 1999. Strengthening the safety of radiation sources and the security of radio- active materials: timely action. IAEA Bulletin 41(3):2.