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[edit] Dirty bomb

The term dirty bomb is used as a more popular name for what is known as a radiological dispersal device (RDD), which is a radiological weapon combining radioactive material with conventional explosives. Although the dirty bomb disperses radioactive material over a large area as a result of the explosion, it is not to be confused with a nuclear weapon (i.e., it does not involve either fusion or fission) [1]. A dirty bomb detonation is unlikely to cause many casualties other than those caused by the explosion itself; it is unlikely that the emitted radiation will deliver doses large enough to cause death unless the victim is in the immediate vicinity of the explosion. The dirty bomb is therefore not usually considered a weapon of mass destruction (WMD). The purpose of using a RDD is rather believed to be: 1) cause mass panic through fear of radioactive materials, the explosion, and the risk of a terror attack, to frighten the public, but also to 2) cause massive economical harm through lost working hours during and because of the following extensive decontamination of the affected areas. The dirty bomb is therefore generally considered a weapon of mass disruption [2]. The first known dirty bomb was created and tested in Iraq in 1987 to determine whether it was a viable military weapon, but the program was abandoned because the levels of radiation produced were too low to produce acute effects [3].


[edit] Dirty bombs and terrorism

Since the 9/11 attacks the fear of terrorist groups using dirty bombs has increased significantly, which has been frequently reported in the media [4]. The meaning of the term terrorism used here, can be described by the U.S. Department of Defence's definition, which is "the calculated use of unlawful violence or threat of unlawful violence to inculcate fear; intended to coerce or to intimidate governments or societies in the pursuit of goals that are generally political, religious, or ideological objectives" [5]. Although there exists an increased fear of terrorists deploying dirty bombs, there has only ever been two cases of such, and neither was detonated. The first ever attempt of radiological terror was carried out in November 1995 by a group of Chechen separatists, who buried a caesium-137 source wrapped in explosives at the Izmaylovsky Park in Moscow. A Chechen rebel leader alerted the media, the bomb was never activated, and the incident amounted to a mere publicity stunt [6].

The caesium filled package uncovered in Moscow’s Izmaylovsky Park.
The caesium filled package uncovered in Moscow’s Izmaylovsky Park.

In December 1998 the second attempt was announced by the Chechen Security Service, who discovered a container filled with radioactive materials attached to an explosive mine. The bomb was hidden near a railway line in the suburban area Argun, 10 miles east of the Chechen capital of Grozny. The same Chechen separatist group as above was suspected to be involved in the incident [7]. It should be noted that despite the enhanced fear of a dirty bombing attack, it is very hard to asses whether the actual risk of such an event has increased significantly [8]. The following discussions on implications/effects and probability of an attack, as well as indications of terror groups planning such, will be based mainly on statistics, qualified guessing and a few comparable scenarios.

[edit] Effect of a dirty bomb explosion

When dealing with the implications of a dirty bomb attack, there are two main areas to be addressed: (i) the civilian impact, not only dealing with immediate casualties and long term health issues, but also the psychological effect and then (ii) the economical impact.

With no prior event of a dirty bomb detonation, it is difficult to predict the precise impact. Some insight into the progress of contamination spread can be gained from the tragic radiological accident occurring in Goiânia, Brazil, between September 1987 and March 1988: Two metal scavengers broke into an abandoned radiotherapy clinic and removed a teletherapy source capsule containing powdered caesium-137 with an activity of 50 TBq. They brought it home to one of the men to take it apart and sell it as scrap metal. Later that day both men were showing acute signs of radiation illness with vomiting and one of the men had a swollen hand and diarrhea. A few days later one of the men punctured the 1 mm thick window of the capsule, allowing the powder to leak out and when realizing the powder glowed blue in the dark, brought it back home to his family and friends to show it off. After 2 weeks of spread by contact contamination causing an increasing number of adverse health effects, the correct diagnosis of acute radiation sickness was made at a hospital and proper precautions could be put into procedure. By this time a total of 249 people were contaminated, 151 exhibited both external and internal contamination of which 20 people were seriously ill and 5 people died [9].

Although several analyses have predicted that RDDs will neither sicken nor kill many people [10], the Goiânia incident to some extent predicts the contamination pattern if it is not immediately realized that the explosion spread radioactive material, but also how fatal even very small amounts of ingested radioactive powder can be [11]. This raises new worries of terrorists using powdered alpha emitting material, that if ingested can pose a serious health risk [12], as in the case of now deceased former K.G.B. spy Alexander Litvinenko, who either ate, drank or inhaled polonium-210. “Smoky bombs” based on alpha emitters might easily be just as dangerous as beta or gamma emitting dirty bombs [13]. However, for the majority of people involved in an RDD incident, the radiation health risks (i.e. increased probability of developing cancer later in life due to radiation exposure) are small and comparable to the health risk from smoking five packages of cigarettes or eating ice cream on a daily basis [14]. The fear of radiation is not always logical although the exposure might be minimal; many people find radiation exposure especially frightening because it is something they cannot see nor feel and it thereby becomes an unknown source of danger. Dealing with public fear may prove the greatest challenge in case of an RDD event [15]. Statements from the US government after 9/11 may have contributed unnecessarily to the public fear of a dirty bomb: when Attorney General John Ashcroft on June 10, 2002, announced the arrest of José Padilla, allegedly plotting to detonate such a weapon, he said:

[A] radioactive "dirty bomb" (…) spreads radioactive material that is highly toxic to humans and can cause mass death and injury.

– Attorney General John Ashcroft, [16]

This public fear of radiation also plays a big role in why the costs of an RDD impact on a major metropolitan area (such as lower Manhattan) might be equal to or even larger than that of the 9/11 attacks [17]. Assuming the radiation levels are not too high and the area does not need to be abandoned such as the town of Pripyat near the Chernobyl reactor [18], an expensive and time consuming cleanup procedure will begin. This will mainly consist of tearing down highly contaminated buildings, digging up contaminated soil and quickly applying sticky substances to remaining surfaces to adhere the radioactive particles before they penetrate into the building materials [19]. These procedures are the current state of the art for radioactive contamination cleanup, but some experts claim that a complete cleanup of external surfaces in an urban area to current decontamination limits may not be technically feasible [20]. Loss of working hours will be vast during the cleanup period, but even after the procedures have been accomplished and the radiation levels reduced to an acceptable level, there might be residual public fear of the site including possible unwillingness to conduct business as usual in the area. Tourist traffic is likely never to resume [21].

[edit] Constructing and obtaining material for a dirty bomb

In order for a terrorist organization to construct and detonate a dirty bomb, they must first acquire radioactive material either by stealing it or buying through legal or illegal channels. Possible RDD material could come from the millions of radioactive sources used worldwide in the industry, for medical purposes and in academic applications mainly for research [22]. Of these sources, only nine reactor produced isotopes stand out as being suitable for radiological terror: americium-241, californium-252, caesium-137, cobalt-60, iridium-192, plutonium-238, polonium-210, radium-226 and strontium-90 [23], and even from these it is possible that radium-226 and polonium-210 do not pose a significant threat [24]. Of these sources the U.S. Nuclear Regulatory Commission has estimated that within the U.S., approximately one source is lost every day of the year either because they are lost, abandoned or stolen. Within the European Union the annual estimate is 70 [25]. There exists thousands of such "orphan" sources scattered throughout the world, but of those reported lost, no more than an estimated 20 percent can be classified as a potential high security concern if used in a RDD [26]. Especially Russia is believed to house thousands of orphan sources, which were lost following the collapse of the Soviet Union. A large but unknown number of these sources probably belong to the high security risk category; noteworthy are the very strong Russian beta emitting strontium-90 sources used as thermoelectric power generators for beacons in lighthouses in remote areas [27]. In December 2001, three Georgian woodcutters stumble over such a power generator and drag it back to their camp site to use it as a heat source. Within hours they suffer from acute radiation sickness and seek hospital treatment. The International Atomic Energy Agency (IAEA) later stated that it contained an amount of strontium equivalent to the amount of radiation released immediately after the Chernobyl accident [28].

The Georgia radioactive device and its containment bucket with handles.
The Georgia radioactive device and its containment bucket with handles.

Although there exists a worry that terrorist organizations might obtain radioactive material through a "black market" [29], and there has been a steady increase in illicit trafficking of radioactive sources from 1996 to 2004, these recorded trafficking incidents mainly refer to rediscovered orphan sources without any sign of criminal activity [30], and it has been argued that there is no real evidence for such a market [31]. In addition to the hurdles of obtaining usable radioactive material, there are several conflicting requirements regarding the properties of the material the terrorists need to take into consideration: First, the source should be "sufficiently" radioactive to create direct radiological damage at the explosion or at least to perform societal damage or disruption. Second, the source should be transportable with enough shielding to protect the carrier but not so much that it will be too heavy to manoeuvre. Third, the source should be sufficiently dispersible to effectively contaminate the area around the explosion [32].

An example of a worst case scenario is a terror organization possessing a source of very highly radioactive material, e.g. a strontium-90 thermal generator, with the ability to create an incident comparable to the Chernobyl accident. Although the detonation of a dirty bomb using such a source might seem terrifying, it would be hard to assemble the bomb and transport it without severe radiation damage and possible death of the perpetrators involved. Shielding the source effectively would make it almost impossible to transport and a lot less effective if detonated.

Because of the three above mentioned constraints in making an effective dirty bomb, RDDs might still be defined as "high-tech" weapons and this is probably why they have not been used up to now [33].

[edit] Possibility of terror groups using dirty bombs

The present assessment of the possibility of terrorists using a dirty bomb is based on cases involving one terrorist organization, namely Al-Qaeda. This is because the attempts by this group to acquire a dirty bomb are the most well-described in the literature, in part due to the attention this group received for the involvement in the 9/11 attacks. Other groups may also be working on acquiring a dirty bomb, but they are not considered here due to the lack of publicly available information.

On 8 May 2002, José Padilla (a.k.a. Abdulla al-Muhajir) was arrested on suspicion that he was an Al-Qaeda terrorist planning to detonate a dirty bomb in the U.S. This suspicion was raised by information obtained from an arrested top Al-Qaeda official in U.S. custody, Abu Zubaydah, who under interrogation revealed that the organization was close to constructing a dirty bomb. Although Padilla had not obtained any radioactive material at the time of arrest, law enforcement authorities uncovered evidence that he was on recognisance for usable radioactive material and possible locations for detonation [34]. It has later been doubted whether the alleged plotter, José Padilla, was preparing such an attack, and claimed that the arrest was highly politically motivated given the pre 9/11 security lapses by the CIA and FBI [35]. Although there was no hard evidence for Al-Qaeda possessing a dirty bomb, there is a broad agreement that Al-Qaeda poses a potential dirty bomb attack threat [36] because they need to overcome the image that the U.S. and its allies are winning the war against terror [37]. A further concern is the argument, that "if suicide bombers are prepared to die flying airplanes into building, it is also conceivable that they are prepared to forfeit their lives building dirty bombs" [38]. If this would be the case, both the cost and complexity of any protective systems needed to allow the perpetrator to survive long enough to both build the bomb and carry out the attack, would be significantly reduced [39].

[edit] Notes

  1. ^ Reshetin (2005)
  2. ^ Zimmerman and Loeb (2004); Ring (2004)
  3. ^ King (2004); Broad (2001)
  4. ^ Petroff (2007)
  5. ^ US Deparment of Defense Dictionary of Military and Associated Terms (April 2007)
  6. ^ King (2004); NOVA, Chronology of events
  7. ^ Edwards (2004); NOVA, Chronology of events
  8. ^ Frost (2005)
  9. ^ King (2004); Zimmerman and Loeb (2004); Sohier and Hardeman (2006)
  10. ^ Reshetin (2005); Dingle (2005)
  11. ^ Zimmerman and Loeb (2004)
  12. ^ Mullen et al. (2002); Reshetin (2005)
  13. ^ Zimmerman (2006)
  14. ^ Ring (2004)
  15. ^ Johnson (2003)
  16. ^ Zimmerman and Loeb (2004)
  17. ^ Zimmerman and Loeb (2004)
  18. ^ "The Lifeless Silence of Pripyat", Time Magazine, June 23, 1986 Online article from Time Magazine
  19. ^ Vantine and Crites (2002); Zimmerman and Loeb (2004); Weiss (2005)
  20. ^ Zimmerman and Loeb (2004)
  21. ^ Zimmerman and Loeb (2004)
  22. ^ Ferguson et al. (2003); Frost (2005)
  23. ^ Frost (2005)
  24. ^ Ferguson et al. (2003)
  25. ^ Ferguson et al. (2003); Zimmerman and Loeb (2004)
  26. ^ Ferguson et al. (2003)
  27. ^ Burgess (2003); Van Tuyle and Mullen (2003); Sohier and Hardeman (2006)
  28. ^ NOVA, Chronology of events
  29. ^ King (2004); Hoffman (2006)
  30. ^ Frost (2005)
  31. ^ Belyaninov (1994); Frost (2005)
  32. ^ Sohier and Hardeman (2006)
  33. ^ Sohier and Hardeman (2006)
  34. ^ Ferguson et al. (2003); Hosenball et al. (2002)
  35. ^ Burgess (2003); King (2004)
  36. ^ King (2004); Ferguson et al. (2003)
  37. ^ Petroff (2007)
  38. ^ Burgess (2003)
  39. ^ Zimmerman and Loeb (2004)

[edit] Bibliography

  • Belyaninov, K. (1994), “Nuclear nonsense, black-market bombs, and fissile flim-flam”, Bulletin of the Atomic Scientists 50 (2): 44-50 .
  • Dingle, J. (2005), “DIRTY BOMBS: real threat?”, Security 42 (4): 48 .
  • Edwards, R. (2004), “Only a matter of time?”, New Scientist 182 (2450): 8-9 .
  • Ferguson, C.D., Kazi, T. and Perera J. (2003) Commercial Radioactive Sources: Surveying the Security Risks, Monterey Institute of International Studies, Center for Nonproliferation Studies, Occasional Paper #11, ISBN 1-885350-06-6, Webpage with PDF file of paper.
  • Frost, R. M. (2005), Nuclear Terrorism After 9/11, Routledge for The International Institute for Strategic Studies, ISBN 0-415-39992-0 .
  • Hoffman, B. (2006), Inside Terrorism, Columbia University Press, N.Y., ISBN 0-231-12698-0 .
  • Hosenball, M., Hirsch, M. and Moreau, R. (2002) "War on Terror: Nabbing a "Dirty Bomb" Suspect", Newsweek (Int. ed.), ID: X7835733: 28-33.
  • Johnson, Jr., R.H. (2003), “Facing the Terror of Nuclear Terrorism”, Occupational Health & Safety 72 (5): 44-50 .
  • King, G. (2004), Dirty Bomb: Weapon of Mass Disruption, Chamberlain Bros., Penguin Group, ISBN 1-59609-000-6 .
  • Mullen, E., Van Tuyle, G. and York, R. (2002) "Potential radiological dispersal device (RDD) threats and related technology", Transactions of the American Nuclear Society, 87: 309.
  • Petroff, D.M. (2003), “Responding to 'dirty bombs'”, Occupational Health and Safety 72 (9): 82-87 .
  • Reshetin, V.P. (2005), “Estimation of radioactivity levels associated with a 90Sr dirty bomb event”, Atmospheric Environment 39 (25): 4471-4477 .
  • Ring, J.P. (2004), “Radiation Risks and Dirty Bombs”, The Radiation Safety Journal, Health Physics 86 (suppl. 1): S42-S47 .
  • Sohier, A. and Hardeman, F. (2006) "Radiological Dispersion Devices: are we prepared?", Journal of Environmental Radioactivity, 85: 171-181.
  • Van Tuylen, G.J. and Mullen, E. (2003) "Large radiological source applications: RDD implications and proposed alternative technologies", Global 2003: Atoms for Prosperity: Updating Eisenhouwer's Global Vision for Nuclear Energy, LA-UR-03-6281: 622-631, ISBN 0894486772.
  • Vantine, H.C. and Crites, T.R. (2002) "Relevance of nuclear weapons cleanup experience to dirty bomb response", Transactions of the American Nuclear Society, 87: 322-323.
  • Weiss, P. (2005), “Ghost town busters”, Science news 168 (18): 282-284 .
  • Zimmerman, P.D. and Loeb, C. (2004) "Dirty Bombs: The Threat Revisited", Defense Horizons, 38: 1-11.
  • Zimmerman, P.D. (2006), “The Smoky Bomb Threat”, New York Times 156 (53798): 33 .