The threat of nuclear terrorism has long been the stuff of Hollywood blockbusters. In these films, the terrorists acquire or steal a ready-made device, usually from a remote part of the former Soviet Union. They then arm the device and threaten to detonate it in a Western city. These films play fast and loose with the extremely complex safeguards which states incorporate into warheads to prevent such a possibility. If one goes missing and is then sourced by nuclear forensics after terrorist misuse the response is likely to be devastating. They also ignore data collected by the International Atomic Energy Agency, which shows a marked fall in cases of smuggled fissile material, as distinct from the increasing disappearance, and illicit circulation, of industrial or medical radioactive materials.
Security experts are less troubled by the standard Hollywood scenario than by the probability of a terrorist group building a dirty bomb — or a radiological dispersal device (RDD). These do not involve a nuclear reaction like the plutonium and uranium bombs which exploded above Hiroshima and Nagasaki. The difference between these and a dirty bomb is roughly the same as that between the power of a lightning bolt and a light-bulb. A Chernobyl-style event, which contaminated a huge area, requires something to go radically wrong at a major nuclear reactor; thankfully, British reactors are heavily guarded.
RDDs rely upon conventional high explosives dispersing a radioactive isotope, the most commonly commercially available being cobalt-60 and cesium-137. As with a conventional car or truck bomb, the initial explosion is likely to kill or maim more people than the dispersed radiological materials. This also depends on whether these materials are in milled or solid form, as well as on ambient physical and environmental factors. In other words, such weapons are instruments designed to cause immediate mass panic, followed by longer-term economic dislocation to business or tourism, because of what would be a protracted decontamination process. Clean-up costs alone could run into hundreds of millions.
For the possible effects we have to extrapolate from the few instances where people have been unwittingly contaminated by radioactive materials. In 1987, thieves in Goiânia in Brazil stole a radiological capsule from a defunct radiotherapy machine. Their friends and neighbours were tantalised by the blue glow it emitted, with some unwisely deciding to break the capsule and smear the contents on their bodies. A thousand people were contaminated and four of them died. In 2001, three Georgian woodcutters stole a nuclear-fuelled generator used to power a remote lighthouse with a view to employing it as a heat source on chilly nights. They all suffered fatal radiation sickness. Earlier this year, panic ensued after a scrap dealer in a slum near New Delhi decided to dismantle equipment containing cobalt-60. No one has died yet.
While security agencies should certainly countenance worst-case scenarios — which is as likely to involve river-borne gunmen debouching from the Thames by the London Eye as it is a dirty bomb — historical experience suggests this is a threat with which we can deal. Although al-Qaeda would like to get its hands on such weapons, in practice only Chechen Islamist separatists have easy access to sloppily guarded radioactive materials. In 1995, Chechen terrorists drew the attention of the Russian media to a small amount of cesium-137 they had buried in a Moscow park. Three years later, they planted a landmine sheathed in radioactive materials next to a railway line used to ferry Russian troops to the Caucasus. Neither device was detonated. In 1999, two Chechen terrorists attempted to steal radioactive materials from a plant in Grozny. They both collapsed (and one of them died) within a few minutes of carrying the container.
Even if such a device were successfully detonated, any casualties would result mainly from the explosion itself and the ensuing mass panic, rather than from the effects of radiation poisoning. People need to be educated about the realities of such an attack, with clear instructions about covering one’s face and closing any doors and windows. The government needs to account precisely for all disused or orphan radioactive materials and to inspect every conceivable target, with a view to understanding how contamination could be contained and neutralised. In addition to ensuring the availability of personnel to deal with the crisis, it needs to rehearse the means needed to reassure what will be a hysterical public reaction. As we are discovering with the financial crisis, sharing bad news with the people is one hallmark of a mature and resilient democracy.