The December 2, 2013 theft of a truck near Mexico City that was carrying “a dangerous radioactive source” quickly became worldwide news. The cargo turned out to be a teletherapy device that had been used for cancer treatment and contained the material cobalt 60. It was stolen near the disposal site to which it was being transported after a nearly 1,800-mile journey from the northern border town of Tijuana. Initial press reports focused on the danger the source would pose if it were removed from its shielding, and raised the issue of whether the theft was the first step in a “dirty bomb” plot that might target the United States.
Mexico immediately informed the International Atomic Energy Agency (IAEA). Fortunately, authorities located the device quickly and not far from where it was stolen, but unfortunately the source capsule had been removed from its shielding. No contamination resulted because the capsule (typically a small welded stainless steel container that holds a wire containing cobalt ) was not itself opened. An official of the Mexican National Commission for Nuclear Safety and Safeguards reported that there was “nothing to indicate the theft of the cobalt was intentional or in any way intended for an act of terrorism.”
However, a follow-up report from the IAEA indicated that the strength of the cobalt 60 was 3,000 curies (a unit of radiation), making it an IAEA Category 1 source—the most dangerous of the organization's five classes of radioactivity. A simple online calculator helps give an idea of the danger level the source posed if it was at the reported strength at the time of the theft. At a distance of 30.5 centimeters (1 foot) from an unshielded source with an activity level of 3,000 curies, the dose to a bystander would be about 37,000 Rem per hour (a measure of radiation exposure). This means that anyone within a foot of the source when it was out of its shield was being exposed to about 10 Rem per second, a level that would typically kill half of a population exposed to it for 30 seconds. Since some reports suggest that the source capsule was found 1 kilometer (0.6 miles) from the teletherapy unit, the person or persons who removed the source probably received fatal doses. Thus this was a serious incident with potentially fatal consequences for some of the thieves involved.
What can we learn? The number of fatalities will not be nearly as high as it would have been if the source capsule had been left in a public place. Cobalt 60, like other high-risk radiological sources, is more lethal when it is kept intact as a high-strength source than it would be if spread using a radiological dispersal device such as a so-called “dirty bomb.” Nonetheless, had the Mexican source been used in a dispersal device, the economic consequences could have been extremely significant. Fortunately, none of the worst-case scenarios has come to pass, but the world may be less fortunate in the future, so officials should draw a number of lessons from what happened in Mexico.
First, it is important to determine the prevalence of radioactive source thefts. The IAEA’s Incident and Trafficking Database (ITDB) indicates that approximately 120 participating states reported about 30 total incidents of theft per year from 2008 to 2012. This figure should be seen as a baseline number, since reports are voluntary and countries may not disclose all thefts. The director general of the Mexican National Commission for Nuclear Safety and Safeguards said that on average, a half-dozen thefts of radioactive sources occur in Mexico each year, which would add up to 20 to 25 percent of such incidents worldwide. It's more likely that the ITDB is not receiving reports of all thefts.
However, thefts that involve Category 1 sources are rare. As the ITDB shows, in 2012 stolen sources ranged from Category 2 to Category 5. Examples of sources in these less-dangerous classes include radiography imagery systems for pipeline inspection and well logging, both typically Category 2, and moisture-density gauges used in construction work, which are typically Category 4. These are mobile devices. In contrast, Category 1 sources are usually larger and, since they require heavy shielding, remain in fixed locations for most of their useful lives, only being transported from the manufacturer to the point of use and then again for disposal or recycling.
Other questions arise: Did the authorities or law enforcement personnel do anything wrong in the Mexican incident? Why wasn’t there security? Could it happen again? Mexican officials have criticized the trucking company for apparent deviations from the law. One indicated that the truck should have had a GPS device and better security, and that the driver showed he “lacked common sense” by stopping to sleep. However, while this apparent crime of opportunity might have been prevented by a GPS or more common sense, it's unlikely that any of the measures with which the trucking operation supposedly failed to comply could have stopped a well-planned hijacking.
In the United States, the Nuclear Regulatory Commission provides guidance for the transportation of Category 1 and 2 radioactive materials. But would the Commission's provisions have prevented the Mexico City incident? Probably not.
US standards on transportation of radioactive materials focus on enhancing communications and establishing a constant surveillance umbrella. They emphasize the importance of lead time, notifications, adherence to the planned route, and liaisons with law enforcement along the way. Compliance with US regulations would arguably give authorities a better head start in responding to a crime of opportunity, but they also do not provide security assurance against a planned, armed hijacking.
Toward global nuclear security. Questions about the Mexican theft are being asked on a national level at this point, but broader international issues should also be considered. While the United Nations has issued international recommendations for shipping radioactive materials (which fall under the category of hazardous goods), and there is an IAEA code of conduct on the safety and security of sealed sources in Categories 1 through 3, there are no international instruments that set enforceable standards for the security of radioactive materials or their transportation within a state. The IAEA provides non-binding guidance, but states have no obligation to follow the recommendations.
Establishing global standards would be an important step toward enhancing the global nuclear security regime, but that is unlikely to happen quickly given the difficulty of negotiating and implementing binding international instruments. Yet governments could take some shorter-term steps.
For instance, some (generally wealthy) countries use accelerators instead of radioactive sources for medical treatments. Like hospital X-ray machines, accelerators produce radiation when they are on, but do not contain anything radioactive and therefore pose little risk of misuse. The international community should seek to increase such substitutions.
Countries could also individually implement better disposal rules. While the Mexican case involved a legitimate (if poorly executed) shipment to a disposal site, around the world many accidents involve radiological sources that have escaped regulatory control, often ending up dangerously mixed with scrap metal. One useful new rule would be to require buyers of radioactive material to set aside money for disposal at the time of purchase.
Finally, the Mexican incident illustrates the value of exchanging information internationally when strong radioactive sources are lost or stolen. Currently countries often provide such information to the IAEA and other governments, but don’t share it publicly. Since reporting to the ITDB is voluntary, it may be time for the international community to consider a new agreement parallel to the Convention on Early Notification of a Nuclear Accident, which does not cover incidents involving radioactive sources.
One could argue that losing control of a source the size of the one in the Mexican incident would, in fact, be covered under Article 1 of the convention, which calls on states to notify others when “a release of radioactive material occurs or is likely to occur and ... has resulted or may result in an international transboundary release that could be of radiological safety significance for another state.”
However, while such an argument might be convenient, no nation currently accepts the idea that the Convention on Early Notification would apply to an incident like the one in Mexico. There is simply no international requirement that countries report like Mexico did. Rather than waiting until a hazardous radioactive source escapes control in a serious way, the international community should codify the good global citizenship Mexico has shown, either by creating a new instrument or amending the current Convention on Early Notification. The third Nuclear Security Summit, which will bring world leaders to the Netherlands in March 2014, would be an excellent forum for initial discussions.
Neither individual governments nor the international community should wait for the radioactive-source equivalent of a Chernobyl to start taking these measures. This time the results weren't catastrophic, but we might not be so lucky again.