Dirty bombsWhat is a dirty bomb and how dangerous is it?
The worrying news that individuals affiliated with the so-called Islamic State have undertaken hostile surveillance at a Belgian nuclear research facility has created growing speculation about the group’s nuclear ambitions. There are no indications that a terrorist group has obtained any fissile material to date. An easier option for a terrorist group would be to build a dirty bomb or, technically, a radiological dispersal device. This is the reason for sensible concern, rather than hysterical speculation about Islamic State’s recent activities in Belgium and, especially, Iraq and Syria. After all, without an effective government, it is unclear who controls the many radioactive sources in the region.
The worrying news that individuals affiliated with the so-called Islamic State have undertaken hostile surveillance at a Belgian nuclear research facility has created growing speculation about the group’s nuclear ambitions.
Nuclear weapons and dirty bombs are frequently mentioned in the same breath. However, they are two distinct technologies. Understanding the differences between these weapons and the damage they can cause can ground speculation in reality — and help us work out the most likely route a terrorist organization such as Islamic State may take in the future.
There are two types of actual nuclear weapon — fission and thermonuclear devices. Fission bombs are fueled with fissile material such as uranium and plutonium. When detonated, the atoms in the weapon’s core split and release huge amounts of energy — producing a nuclear explosion. Thermonuclear weapons use a fission bomb to ignite special fuel, consisting of light hydrogen isotopes. These nuclei are forced together — undergoing nuclear fusion — releasing an even larger explosion.
There are no indications that a terrorist group has obtained any fissile material to date. If they could it would be possible for them to build a fission device, although this does pose a huge technical challenge. While highly engineered weapons need only a few kilograms of fissile material, a crude terrorist-built design would require far more. Thermonuclear weapons, on the other hand, are too complex for terrorist groups to develop.
An easier option for a terrorist group would be to build a dirty bomb or, technically, a radiological dispersal device. These do not rely on complex nuclear reactions. Instead, conventional explosives are used to disperse radioactive material, contaminating an area with elements such as radioactive isotopes of cobalt, caesium or americium.
Under the command of Shamil Basayev, a Chechen separatist leader, militants buried a dirty bomb in a Moscow park in 1995. Basayev threatened to turn Moscow into “an eternal desert” unless his demands were met. The weapon was not detonated. The episode was a terrorist publicity stunt — threatening to use unconventional weapons against Russian civilians. But it did show that a dedicated group could build and use a dirty bomb.
