Dirty Bomb v. Nuclear Bomb


This is the first post in a series that reviews the basic science, trade-offs, and policy issues around nuclear threat detection.

Nuclear bombs, dirty bombs, radiological dispersion…there are a lot of threats out there, and they are not all equal.

When governments assess terror risks to their citizens in part based on the potential scale of damage. A pressure cooker bomb in Boston killed 3 people; a suicide bomb outside the Afghan Supreme Court had upwards of 30 victims; the Madrid train bomb killed 191 people; nearly 3,000 people died in the 9/11 attacks.  Each of these attacks represents an order of magnitude increase in victims, to say nothing of the relative scales of injuries, economic damage, and psychological impact.

In the same way that a homemade bomb and an airplane-as-a-missile inflict vastly different scopes of damage, so a dirty bomb and a nuclear bomb are incomparable when it comes to impact.

A “dirty bomb” (technically referred to as a “radiological dispersion device”) is a conventional explosive packed with radiological material. In layman’s terms: it is a regular bomb that will spray radiation around the neighborhood. A dirty bomb might use any number of radioactive materials that are employed by hospitals for cancer treatment, in research labs, and are available from a range of low-security facilities. The recent hijacking of a truck in Mexico carrying Cobalt-60 recycled from a hospital precipitated a massive international response, due to the material’s utility in a dirty bomb. However, despite the large-dose lethality of Cobalt-60 and similar materials, a dirty bomb exploded in an urban area would be unlikely to cause radiation sickness, do to the diffusion of the material. The weapon is more effective in causing psychological and economic damage (the cost of cleanup, disruption to tourism) than physical harm to victims.

A nuclear bomb is a different story.

Whereas a dirty bomb is a “normal” explosion that sprays radiation, a nuclear bomb harnesses energy from splitting atoms. This results in an extraordinarily large explosion, the equivalent to tens or thousands of tons of TNT. The nuclear blast sends out a shock wave that can damage buildings, a blinding flash of radiation that can cause burns miles away, and a mushroom cloud of debris that showers intensely radioactive material in a large radius.

Even a crude, low-yield device (called an “improvised nuclear device,” or IND), has the potential to level a city block. The economic, psychological, and especially the human damage, would be on scales not achieved by any other type of terrorist attack.

This is why Silverside Detectors singles out nuclear terrorism as the target of its mission, and nuclear bomb materials as the target of its detectors. Nuclear terrorism is a threat that must never become a reality.