What You Need To Know About Dirty Bombs
The attack has been in the planning stages for nearly two years. Surveillance of potential targets determined a downtown area near you as a prime location. Two years of gathering necessary materials have yielded a 3,000 pound improvised explosive device containing the high explosive PETN and a mixture of ammonium nitrate and fuel oil. Also contained in the device is a significant amount cesium 137, a highly radioactive substance which will be dispersed throughout the downtown area by the explosion. At 11:15 a.m., just about a minute ago, an enormous explosion destroyed the downtown area, collapsing a building, heavily damaging many other structures and killing or maiming dozens on the sidewalks or in cars. You heard the nearby boom and felt the floor shake under your feet. Moments later your radio crackles to life. What are you going to do? Such is the case presented in National Planning Scenario #11 from the U.S. Department of Homeland Security (DHS).
It is no secret terrorists have desired to attack targets using radiological dispersal devices (RDD), otherwise known as dirty bombs. In 2006, police in London foiled an attempt by Dhiren Barot, an al-Qa’eda sympathizer, to detonate a dirty bomb in the heart of London as a precursor to future attacks in Britain and the United States. Police uncovered files by Barot where he hoped an RDD would “produce general panic, health consequences including immediate fatalities and long-term increases in cancer incidence, long-term denial of property use, disruption of services and property and facility decontamination needs.”
Barot’s wishes reflect the desires of many would-be terrorists whose method of attack is an RDD. But how effective would such a device be? In order to know, it is important to learn a little about them. Let’s start with some basics about these devices. In simple terms, an RDD is an explosive device containing radioactive material meant to be spread over the target area by the blast. According to the Counter-Terrorism Operations Support Center for Radiological Nuclear Testing (CTOSCRNT) in Nevada, the most immediate and serious consequences would occur as a result of the blast. As with any other bomb the size of the one in our opening scenario, the blast zone (see my companion piece, Blast Zone Awareness on Medium.com) would contain heavy damage and numerous casualties. Different from other blast zones would be the presence of radioactive material.
What is radioactivity? According to the U.S. Nuclear Regulatory Commission (NRC), radioactivity results from the spontaneous emission of energy from unstable atoms. The amount and kind of radiation depends upon the radioactive material involved.
There are four kinds of radiation; alpha, beta, gamma and neutron. Alpha can only travel a few inches and is not topically dangerous as it cannot pass through the skin. The greatest hazard with alpha radiation is inhalation. Once inside the body, it can damage cells and make you very sick. Beta radiation on the other hand is a bit stronger, and can travel up to thirty feet from its source. It is a topical and inhalation hazard that can be blocked by glass, metal foil safety glasses and heavy clothing. Gamma radiation is more dangerous as it can travel hundreds of feet from its source, and is a full-body hazard, able to be absorbed directly into a person. Lead, steel and concrete are effective barriers to gamma. Finally, neutron radiation, similar to gamma, can travel hundreds of feet. It too is a full-body hazard. Blocking it would be accomplished by material with high hydrogen content, such as thick shields of plastic, water, concrete or dirt.
The NRC recommends a combination of time, distance and shielding, to protect against radiation hazards. Reducing the time one is exposed and creating as much distance from the source as possible will help reduce one’s exposure to radiation hazards. Shielding oneself with physical barriers or protective clothing serves as a recommended adjunct to time and distance factors.
Getting back to our opening scenario, ongoing fires and the need to treat the wounded would bring dozens if not hundreds of first responders to the scene. They would be oblivious to the presence of radioactivity unless someone thought to take radiation readings in the area. Once it is discovered radiation is present, it presents a complication many first responders are unprepared for. The psychological impact on first responders, victims and the community can be devastating. Since the radioactivity could be spread over many city blocks, or even miles from the explosion. The cleanup costs to remove the contamination, and the length of time it would take, would have a staggering effect on the local and regional economy. This is precisely what terrorists like Barot are looking for.
Barot failed to account for one thing. According to CTOSCRNT, it is unlikely an RDD would leave lethal amounts of radiation in its wake. Since much of the radiation would be carried on the dust at the scene, first responders should, at a minimum, wear respiratory protection and protect the skin and eyes from the dust. They should also spend as little time in the area as possible, and then leave the area after undergoing decontamination procedures, if available. This procedure would be in keeping with Time, Distance and Shielding. While not a perfect solution, it is a start, and would help to protect against alpha and beta radiation, the two most likely radiation types found in RDDs.
The NRC advises the health hazards from radiation are proportional to the exposure. They also state, “Just because a person is near a radioactive source for a short time, or gets a small amount of radioactive dust on himself or herself, it does not mean he or she will get cancer.” Again, the greatest risk from an RDD is the explosion itself more so than the dispersed radiation.
While an RDD would likely cause great panic and denial of access to contaminated areas, the lethality outside of the initial blast would be minimal, contrary to Barot’s wishes. I am not advocating anyone unnecessarily expose themselves to the aftermath of an RDD incident. But as first responders, we are faced with the unenviable choices of avoiding the area, knowing people are injured and dying, or entering the area knowing we will be exposed to radiation.
If one decides to enter into the hazard area, they can take minimal steps described above to help protect themselves. While not perfect solutions to stopping all radiation from entering the body, they will help to limit one’s exposure and subsequent contamination.
The best precaution against an RDD event is education. Arming oneself with knowledge about the hazards of radiation would greatly enhance one’s ability to safely respond to such events. The CTOSCRNT is a tremendous resource for first responders seeking to learn about radiological and nuclear hazards. They are part of the U.S. DHS’ Domestic Preparedness Consortium, and can be found at www.ndpc.us. Further information is available via the U.S. DHS’ website at www.dhs.gov or the Nuclear Regulatory Commission at www.nrc.gov.
Robert Leverone is a contributor to the Homeland Security (HS) Vortex, which is a platform where insiders from the policy, law enforcement, fire service and emergency management fields converge to discuss issues related to Homeland Security.
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