Why Dirty (Nuclear) Bombs Don’t Work
Nuclear Weapons Are Not Useful (Most of the Time)
Paul M Cole, MSFS, PhD
March 2, 2018
Radioisotope Dispersion Device (RDD)
With regard to Radioisotope Dispersion Devices (RDD’s), aka a “dirty bomb,” there is no consensus on the definition of this type of weaponized radioisotope. The following are two competing definitions:
- A radiological dispersal device (RDD) would be designed to disperse radioactive material over a large area.
- A dirty bomb is designed to spread radioactive material and contaminate a small area.
RDD’s are neither weapons of mass destruction, nor are they nuclear explosive devices. Despite this fact, RDD’s were mistakenly defined as a “weapon of mass destruction” by the U.S. Congress in the National Defense Authorization Act (NDAA) for fiscal year 1997.
NDAA FY1997 not only gave RDD’s unwarranted credibility, the mis-categorization of RDD as a weapon of mass destruction weakened the government’s ability to address RDD’s with appropriate policies and plans.
There are many reasons why an RDD should not be classified as a weapon of mass destruction.
Most relevant is the fact that an RDD, which does not produce a nuclear explosion, is an amalgam of conventional explosives (e.g., TNT) and radioactive material that together cannot create a nuclear explosion. The majority of fatalities or injuries that could be potentially caused by an RDD would result from the conventional explosion itself.
There are significant indications that RDD’s are clumsy, ineffective devices that pose a greater threat to those attempting to assemble one. Radioisotopes pose a great danger to human beings. An individual attempting to assemble an RDD who mishandled a Cobalt-60 rod, which would cause a lethal dose of radiation within a minute, would probably die within a couple of weeks.
Several nations have investigated the utility of RDD’s. “According to a UN report, Iraq tested a one-ton radiological bomb in 1987 but gave up on the idea because the radiation levels it generated were insufficient.”
Israel undertook a four-year dirty bomb project with radioisotopes to determine the effectiveness of a dirty bomb attack and how to defend against one. The conclusion was that such an attack would be ineffective and that RDD’s do not pose a substantial danger beyond the conventional blast and the psychological effect.
While large numbers of people in a densely populated area in the close proximity to the detonation of an RDD might become exposed to radiation and require decontamination, few if any will be contaminated to a level that would necessitate medical treatment.
In 1995 Chechen rebels, who buried dynamite attached to a small amount Cesium137 in Moscow’s Ismailovsky park, instructed a TV station where to find it. The Chechens apparently concluded that the RDD’s value as a weapon of intimidation was greater than any political utility that could be derived from the detonation of the device. There is no evidence, however, that the discovery of the RDD altered Russia’s policy or conduct in favour of the Chechens. In fact, the revelation that the Chechens were contemplating the use of an RDD may have had the opposite effect by hardening the Russian attitude against the Chechens responsible for planting the RDD.
Detailed scientific studies of RDD’s of various designs using a range of radioisotopes conducted over many years concluded that RDD’s are ineffective radioisotope dispersion devices. The U.S. Sandia National Laboratory “conducted experiments on the aerosolization of radiological dispersal devices […] for more than twenty years. […] Over 500 explosive experiments were undertaken with more than 20 [radioactive] materials and 85 device geometries to determine the aerosol physics that are representative of what might occur from the detonation of an actual device.” One important conclusion from this series of experiments was that it is extremely difficult to disperse radioisotopes in an aerosol form of sufficient intensity to cause mass casualties.
Although the public may associated plutonium and enriched uranium with the word radioactive, these TENORM are not effective RDD materials for several fundamental reasons. TENORM radioisotopes, which are primarily alpha emitters, are costly, cannot be obtained in large amounts, are well-tracked and secured, and are more useful to terrorists in the production of an actual nuclear weapon than being wasted in an RDD. Attachment of plutonium to the skin or hair poses no hazard since the alpha rays cannot penetrate human skin. Spent nuclear fuel is also a useless material for dirty bombs, primarily due to the fact that is is a very heavy, dense ceramic, thus nearly impossible to disperse in aerosol form.
Fortunately, “dirty bombs” have another inherently self-regulating feature. The greater the dispersal achieved and the more people affected, the lesser the dose of radiation. For example, a 25 gram CsCl137 source (about 2,200 Ci) is lethal after about one hour of exposure at one meter. However, the source is not lethal if spread over the one-billion square feet of surface area in 10 by 10 city blocks, which would the area of a large downtown metropolis covered by a good-sized car bomb.
It appears that RDD’s are ineffective unless created on a massive scale. The explosion of the Chernobyl nuclear power plant was the largest RDD event in history. The power of the Chernobyl explosion was equivalent to “ten tons (10t) of TNT,” or one percent (0.01) of one kiloton, or ten tons of TNT.
Chernobyl released approximately 27 kilograms of Cs137, which was the equivalent of 200-400 times as much radiation as released by either the Hiroshima or Nagasaki bombs. The blast contaminated approximately 63,000 square miles (163,169 km2). A non-state actor does not have the resources to create a RDD event of this magnitude.
There is also evidence that there is little interest among non-state actors to acquire the TENORM required to construct an RDD.
Past experience suggests there has not been a pattern of collecting such sources for the purpose of assembling an RDD. It is important to note that the radioactivity of the combined total of all unrecovered sources over the past 8 years (when corrected for radioactive decay) would not reach the threshold for one high-risk radioactive source.
The task, therefore, is not to abolish the probability of a RDD, which is impossible; rather, the task is to minimize the putative political utility that could be derived by a non-state actor.
The TENORM required to construct an RDD must come from a reactor or a storage facility. The most critical measure, therefore, is to prevent the illegal introduction of unregulated radioactive material into the hands of those capable of assembling a functioning device.
In the event that prevention fails, the emphasis shifts to mitigation. The key to mitigating the effects of an RDD explosion is an effective public relations and clean-up strategy.
There is little political utility to be derived by a non-state actor (e.g., a terrorist organization) from the detonation of an RDD.
In contrast to the limited political utility that could be derived from an RDD a great deal of political utility that may be derived by a national government from proper preparation and publicity that will diminish the psychological impact and physical effects of an RDD explosion.
Improvised Nuclear Device (IND)
An Improvised Nuclear Device (IND) is defined as:
- An illicit nuclear weapon bought, stolen, or otherwise originating from a nuclear state, or a weapon fabricated by a terrorist group from illegally obtained fissile nuclear weapons material that produces a nuclear explosion.
- Built from the components of a stolen weapon or from scratch using nuclear material (plutonium or highly enriched uranium).
- Produces same physical and medical effects as nuclear weapon explosion.
- Results in catastrophic loss of life, destruction of infrastructure, and contamination of a very large area.
- If nuclear yield is NOT achieved, the result would likely resemble a Radiological Dispersal Device (RDD) in which fissile weapons material was dispensed locally.
- If nuclear yield is achieved, results would resemble a nuclear explosion.
- Like nuclear explosions, IND explosions may be modeled using a fallout map.
The problems associated with deriving political utility from an IND are almost symmetrical with the problems associated with an RDD.
The technical problems associated with creating an IED are symmetrical with the construction of an RED. An IED would require 25 to 50 kilograms of HEU or Pu238. However, weapons-grade fuel is not required to build an IND. Uranium enriched to approximately 20 percent would suffice.
Non-state actors lack the capacity to produce the TENORM required for an IND, thus the only option is to acquire the material from sources controlled by national governments, through theft or some other type of illegal activity. Obtaining TENORM sufficient for an IND, however, appears to be a difficult task.
“There have been some twenty known cases of theft of plutonium and highly enriched uranium since 1990 and many more of other radioactive materials.” There have been two decades of illicit trade in radioactive material, yet not one example of an IND.
The task, therefore, is to prevent the transfer of large quantities of TENORM, including that contained in an existing NED. The regulatory regime required to achieve this objective would be a combination of treating TENORM as a hazardous material with nuclear non-proliferation measures.
Nuclear Explosive Device (NED)
The term “Nuclear Explosive Device” (NED) is defined as “any device, whether assembled or disassembled, that is designed to produce an instantaneous release of an amount of nuclear energy from special nuclear material that is greater than the amount of energy that would be released from the detonation of one pound of trinitrotoluene (TNT).”
All of the empirical evidence points to a similar conclusion, viz., that with a only two exceptions the utility of nuclear weapons as a tool of coercive force or diplomacy has been on the decline since the 1950’s.
- The first exception was the condition of mutually assured destruction that defined the U.S. – Soviet security relationship during the Cold War.
- The second exception is the only case where the target of a threat to use nuclear weapons has admitted that the threat altered the target’s behaviour, viz., the PRC during the Sino-Soviet border dispute in the late 1960’s.
Since the end of the Cold War, nuclear weapons have lost much, if not all, of their value as a nation-state’s ability to manifest force or coercive diplomacy. A 2012 study conducted by a group of former U.S. national-security officials and political leaders chaired by former Vice Chairman of the Joint Chiefs of Staff, General James Cartwright, concluded emphatically:
No sensible argument has been put forward for using nuclear weapons to solve any of the major 21st century problems we face [including] threats posed by rogue states, failed states, proliferation, regional conflicts, terrorism, cyber warfare, organized crime, drug trafficking, conflict–driven mass migration of refugees, epidemics, or climate change. […] In fact, nuclear weapons have on balance arguably become more a part of the problem than any solution. (Emphasis added)
In light of this finding, it is not surprising that the number of nuclear weapons has diminished significantly since the end of the Cold War. Warheads with high yields, including those in the megaton range, have been progressively phased out of U.S. and Russian inventories in favour of smaller weapons.
The fact of the matter is that utility of nuclear weapons as a means to influence or coerce other nations is negligible.
Extraordinary claims required extraordinary proof.
That which is asserted without evidence may be refuted without evidence.
The onus is on those who assert the political utility of radioactive explosive devices (RED) to produce verifiable evidence that demonstrates that nations alter their policies or conduct to accommodate the interests of nations that possess nuclear weapons.
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 “Fact Sheet on Dirty Bombs,” U.S. Nuclear Regulatory Commission, December 12, 2014 http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/fs-dirty-bombs.html
 “Dirty Bomb,” Homeland Security News, (Undated) http://www.nationalterroralert.com/dirtybomb/
 SEC. 1403. DEFINITIONS. In this title: (1) The term ‘‘weapon of mass destruction’’ means any weapon or device that is intended, or has the capability, to cause death or serious bodily injury to a significant number of people through the release, dissemination, or impact of— (A) toxic or poisonous chemicals or their precursors; (B) a disease organism; or (C) radiation or radioactivity.
 Recall, for example, that of the approximately 129,000 casualties caused by the atomic bombing of Hiroshima, the majority (perhaps as high as 75%) of casualties were the result of the blast, not radiation exposure. “Hiroshima, Nagasaki, and Subsequent Weapons Testing,” World Nuclear Association, December 2014. http://www.world-nuclear.org/info/Safety-and-Security/Radiation-and-Health/Hiroshima,-Nagasaki,-and-Subsequent-Weapons-Testing/
 A single “rod” or “pencil” of Co60 typically contains 10,000 Ci of radioactivity. One micro Curie (0.000001, or 1μCi) of Cobalt-60 costs approximately US$81.95.
 “Dirty Bombs,” Council on Foreign Relations, October 19, 2006 http://www.cfr.org/weapons-of-mass-destruction/dirty-bombs/p9548
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 The size or weight of a container or shipment does not indicate how much radioactivity is in it. For example, uranium-238 has 0.00015 curies of radioactivity per pound (0.15 millicuries), while cobalt-60 has nearly 518,000 curies per pound.
 “Emergency Response Guidance for the First 48 Hours After the Outdoor Detonation of an Explosive Radiological Dispersal Device,” Stephen V Musolino and Frederick T Harper, Healthy Physics Society, 2006, p 377 http://www.pearceglobalpartners.com/uploads/051106_dirtybomb.pdf
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 22 USCS §6305 (4) Title 22. Foreign Relations and Intercourse; Chapter 72. Nuclear Proliferation Prevention; Sanctions for Nuclear Proliferation
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