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Ionising radiation

Environmental Radioactivity - Medicine - Occupational Radiation Protection - Nuclear Hazards Defence

Ionisierende Strahlung

Misuse of radioactive material in connection with an unconventional explosive device ("dirty bomb")

  • "Dirty bombs" are devices which make use of conventional explosives to disperse radioactive material.
  • The potential radiological danger caused by a "dirty bomb" is generally over-estimated.

The "dirty bomb" scenario is of prime concern in recent international efforts to secure highly radioactive sources against terrorist abuse and use in weapons of mass destruction.

The International Atomic Energy Agency (IAEA) defines a "dirty bomb" as a device constructed from conventional explosives and radioactive material, the detonation of which would result in the dispersion of the radioactive material contained in the bomb into the environment.

In the USA the term "radiological dispersion device ( RDD)" is used. The German equivalent is "USBV-A". The use of a "dirty bomb" and comparable scenarios are considered possible misuses of radioactive materials.

The potential threat of a "dirty bomb"

The use of a "dirty bomb" and comparable scenarios are currently regarded as the most likely form of deliberate misuse of radioactive material. Other scenarios such as the use of a nuclear weapon, improvised or otherwise, have on the other hand been conventionally regarded as far less likely.

When constructing a "dirty bomb", potential operatives are most likely to use those radioactive materials found in technological or medical applications. The first move when initiating protection against the impact of such a weapon is naturally to ensure the physical protection of any radioactive materials on site, thereby ruling out any misuse. The BfS and the other nuclear licensing bodies monitor adherence to these requirements under the heading "Securing nuclear facilities" in accordance with a set of rules approved between federal and state ministries of the interior and of the environment.

Potential radiological danger of a "dirty bomb"

The potential radiological danger caused by a "dirty bomb" is generally over-estimated. This is naturally in direct reference to the radiological dangers; the BfS is not called upon to assess any other associated risks directly.

Even for a high-activity caesium-137 source, the dose rates for the public very close to the point of release (i.e. very close to the centre of the explosion) would be so low, that extra radiation protection measures (e.g. staying inside or evacuation) would not be necessary.

The situation is different if plutonium-239 is used in a "dirty bomb", as it has a much higher radiotoxicity compared to all other radionuclides considered. Scenarios are possible in which emergency management measures would be necessary up to a few kilometres away from the point of release, as effective dose rates of 100 mSv for members of the public could not be ruled out. An effective dose of 100 mSv is the decision value which is also used for the evacuation of the public during emergeny or disaster management of a nuclear accident resulting in a release of radioactive material. Plutonium-239, however, is neither used in industrial or medical applications; it is a product of nuclear facilities, and its misuse therefore depends on achieving access to extremely high-security sites.

To sum up, this means: Even in the immediate vicinity of the detonation site, "dirty bombs" using radioactive materials found in industrial and medical contexts would accordingly pose no radiological risk to the majority of civilians. The potential radiological threat of a "dirty bomb" is limited.

Psychological effects

Aside from the objective assessment of the radiological danger, associations with the known effects of radiation and its possible health effects, which are long-held among the population, can cause psychological effects, such as e.g.

  • uncertainty (authoritarianism, aggression),
  • feeling over-whelmed (distress),
  • anxiety and
  • excessive responses (hysteria, hyper-activity and over-communication).

The causes of the psychological consequences mentioned above are, in particular; the association with nuclear weapons, the devastating results of the nuclear weapons deployment in Hiroshima and Nagasaki, the latent threat during the cold war, and the feeling of helplessness regarding the detection - humans have no way to sense radiation - and the control of these dangers.

Communication measures

Based on the level of knowledge gained in general emergency preparedness and response, the BfS has commissioned additional investigations into methods of informing the public on the topic of terror threats. Currently, these questions are being investigated in the research project "Public communication and measures for nuclear emergency management not arising from technical nuclear facilities in connection with new forms of threat: Precautionary information and information management in the event of nuclear terrorism".

The initial results (see report below, pp. 72 to 74) show, that the public discussion on the risks of nuclear energy are also an important factor in this regard, as it influences the ability of those affected (state and citizen) to communicate. Along with the development of strategies for public relations after an event, precautionary information for the public before an event is of high importance.

German security authorities well-prepared

In operational terms, Germany’s security authorities, including the BfS, are well-prepared to defend the population against any attack using a "dirty bomb". Preventing the illegal purchase and the misuse of such sources is of prime importance. Compared with safeguards in other European countries, the measures already implemented within the relevant sectors in Germany are of a high standard.

The Federal Office for Radiation Protection has recently established yet another important preventative measure – a register of highly radioactive sources, the so-called HRQ register. This is used to record every radioactive source exceeding a certain (isotope-dependent) activity, making it possible to ascertain the whereabouts of said material at any time. This register may be accessed by the German security authorities.

Focal element: police work

Police work nevertheless remains the focal element in the fight against nuclear crime. This is the responsibility of the individual federal states. The local police force receive support in this area - known as "Defence Against Nuclear Hazards" - from the relevant state radiation protection office.

The federation offers additional backup in the form of the "Central Federal Support Group for Serious Cases of Nuclear Hazard Defence", or ZUB for short. Of course any serious indication of a terrorist attack being planned for a target in Germany involving the use of radioactive materials is regarded as a serious case.

At the ZUB the Federal Bureau of Investigation, the federal police force and the Federal Office for Radiation Protection co-operate together. In a state of perpetual readiness, the ZUB is able to spring into action at any time.

Conclusion

Estimates concerning the radiological aftermath of a "dirty bomb" scenario reveal that one would only expect to find alarmingly high dose values in those individuals in immediate proximity to the detonation site.

For the majority of the population, the subjective perception of the health risks produced by a "dirty bomb" attack would exceed the actual risk of radiation exposure and could therefore lead to comparably a high rate of secondary consequences.

Averting the threat of a "dirty bomb" attack requires action from the government:

  • operative measures to avert such threats,
  • operative measures to cope with such attacks,
  • the preventative dissemination of information to allow the population to properly assess the risks associated with such an event, and
  • comprehensive communications in the event of a crisis.
State of 2018.12.20

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