As terrorists continue to expand their knowledge base, their capability to unleash weapons of mass destruction on the American public moves from the realm of fictional thrillers to all-too-real concerns for public safety. A WMD attack by a terrorist, foreign or domestic, is not an "if" but a "when." It's a certainty that somewhere in the future American law enforcement will have to cope with the aftermath of a chemical, biological, radiological, or even nuclear assault.
A lot of excellent information has been made available to police officers about WMDs and their effects. But much of what has been published about one class of WMD, the radiological dispersion device (RDD) more sensationally known as the "dirty bomb," is inaccurate and likely to instill panic in both officers and the public. Let's take a look at how dirty bombs are constructed, what happens when they function, their potential for mass destruction, and how you, as a law enforcement officer, may be required to respond to such an attack.
A "dirty bomb" is quite simply a combination of radioactive material and something to disperse it, most commonly an explosive. Such a crude radiological weapon would likely be deployed by terrorists in a dense population center with the goal of killing and injuring as many people as possible for several square miles.
Such a scenario evokes images from an apocalyptic science fiction movie, streets and buildings once inhabited, now deserted. Fortunately, this description is a little long off the tee.
To understand why dirty bombs are unlikely to be the nightmare vision that they are made out to be in the popular press, you have to know a little bit about radiation.
At its most fundamental, a radioactive atom is naturally unstable. Nature loves equilibrium, so the unstable atom tries to balance itself by allowing pieces to break off and fly away. These pieces can actually be thought of as energy, and this energy is referred to as "ionizing radiation" to distinguish it from other types of radiation such as heat or light.
A radioactive material is anything that contains these unstable atoms. We say radioactive material because, for ease of handling, controlling energy emissions, and reducing costs, radioactive elements are usually embedded into other, more stable elements.
Different radioactive materials have different properties, and some radioactive elements release more energy than others. This is a key issue with dirty weapons because for an RDD to be truly lethal, it must contain highly radioactive material. Dispersing low-energy radioactive materials accomplishes nothing more destructive than instilling widespread panic.
Low-energy radioactive materials seem scary to the uninformed, but they are actually quite common and relatively harmless, at least in the short run. Truthfully, we are almost always in contact with low-energy radioactive materials. For example, thanks to the development of insulated, energy-efficient homes, trapped radioactive radon gas, a byproduct of decaying natural radium, has become a health issue in many American communities.
And that's just one example of how much low-level radiation you encounter in a given day. Several industrial products in your home emit low levels of radiation and have done so for a century. Even the lowly banana emits radiation. And the Earth is constantly showered with radiation from space, or the sun, or a myriad of other sources.
Building a Bomb
To construct an effective dirty bomb is a daunting task. Notice I say "effective." Making a bomb that spreads radioactive material is child's play.
At its most crude form, an RDD consists of a radioactive product and a method of dissemination. Because RDDs are called dirty "bombs," many officers have the mistaken belief that all RDDs involve explosives like dynamite, plastic explosives, or even gunpowder. But anything that can disperse the product can serve as the dissemination element of an RDD. If the radioactive product is powdered, for instance, compressed gasses or a ventilation system could even be more effective than an explosive.
The tricky part of building a dirty bomb is not dispersing the radioactive material; it's acquiring and working with the material. As discussed, the radioactive payload of a dirty bomb must be very active or "hot," but material hot enough to provide a dangerous short-term dose when spread would be lethal to work with directly in producing the bomb. Of course, a well-heeled terrorist group could counter such difficulties by acquiring protective equipment, but that would certainly raise some alarms. Worse, a dedicated fanatic could sacrifice his life to make the bomb.
A more difficult obstacle to overcome is the nature of extremely active radioactive material. When placed in a confined space (like in a bomb), the interaction between radioactive atoms generates tremendous heat. Heat isn't a friend to the explosive core, and it also could potentially melt the radioactive product.
Finally, most highly radioactive products are clad in extremely hard metal alloys. Simply strapping them to a bomb would, in the opinion of most explosive ordnance experts, simply project the items, intact, a distance.
Even if a dirty bomb could be constructed and transported into a population center, the actual effects of its detonation might disappoint its builders.
Nuclear weapons expert Charles Ferguson, who serves as scientist-in-residence at the Monterey Institute's Center for Nonproliferation Studies, says that the lethality of a radiological attack has been overstated. "The most important point to get across to law enforcement officials is the fact that most radiological attacks will kill few, if any, people."
To illustrate Ferguson's argument, let's consider a theoretical bomb consisting of a five-pound explosive charge wrapped with an attached radioactive product in a flat open area. At the time of the blast, the greatest hazards to people would be from airblast (overpressure) and projection of debris just like they would experience from any conventional bomb. Remember, this is not a nuclear weapon and there is zero potential for a release of nuclear energy called a "yield."
Once the shrapnel stops flying, the greatest hazard to people near a dirty bomb detonation comes from inhaling the dust from the blast or having it in contact with their bare skin for a long period of time. Why bare skin? Simple, certain types of radiation can't even pass through your clothes.
ABGs of Radiation
There are three types of radiation-alpha, beta, and gamma-that will be of critical importance for all first responders to a radiological attack.
Alpha and beta radiation don't have the energy to penetrate a couple of pieces of paper; however, they can cause serious skin burns. The primary danger from material that emits alpha or beta radiation is from ingesting it or inhaling it. If ingested or inhaled and allowed to embed in the victim's body, over time even a dose of low-energy alpha particles could potentially cause long-term health effects.
Still, even in the worst case, the deadliest effects of alpha and beta radiation require long-term exposure. Not so with another type of radiation called "gamma." Sometimes called gamma "rays," gamma radiation is a characteristic of very hot radioactive material. It will penetrate walls of buildings, and even short-term exposure can be very dangerous.
Fortunately, gamma radiation is only emitted by hot radioactive material. And, as we've discussed, the most likely payload of an RDD will be low-level material. Consequently, it is thought by many, based upon years of data accumulated on personnel working with low-level radioactive materials, that the health effects of an RDD release will be more along the lines of increased risks for cancer-related problems years later, rather than radiation poisoning and immediate fatal effects.