At 1:30 a.m. on December 2, gunmen forced two truck drivers who had taken a nap at a gas station on the outskirts of Mexico City to surrender their vehicle. The thieves took off with the truck’s heavy and hazardous cargo: a decommissioned teletherapy unit that was once used for cancer treatment and still contained a small capsule of highly radioactive material. It’s unclear whether the thieves fully understood what they were stealing. According to statements by the Mexican authorities, they probably didn’t.
The capsule’s contents—some 3,000 curies of cobalt-60—made it a “category 1” radiation source, the most dangerous of five categories defined by the International Atomic Energy Agency (IAEA) to rank radioactive materials according to the risk they pose to people working with them. Taken out of their shielding containers, category-1 sources can kill anyone who is exposed to them at close range for a few minutes to an hour.
Two days later, the police found the radioactive capsule abandoned in a corn field. Although someone had extracted the capsule from its shielding (and likely received an unhealthy radiation dose in the process), there were no immediate reports of serious injuries and no contamination found in the area nearby. Thus the consequences of this incident appeared to be less grave than in two earlier cases—in Brazil in 1987, and in Thailand in 2000—when unsuspecting scavengers who dismantled old radiotherapy machines exposed themselves and their families to very high doses of radiation. Four of the exposed people died in Brazil, and three in Thailand, and more were seriously injured. The cost of cleanup and recovery for their communities was substantial.
Still, there hasn’t been a category-1 source stolen in transit in the United States. Does this mean that US transports of high-activity sources are generally secure? Not really. A few recent cases in North America and Western Europe demonstrate why:
- In July 2011, in the parking lot of a Texas hotel, a thief broke into a truck and stole a radiography camera containing 33.7 curies of iridium-192. The truck drivers had forgotten to switch on the vehicle’s alarm system when they went to dinner. Even though the hotel’s security camera recorded the thief’s car as it left, the device was never found.
- In February 2013, thieves stole another radiography camera in a small town north of Manchester, England. A courier had left it in his van, which was parked in front of the residence where he stopped for a weekend. The device turned up a month later, at a nearby shopping mall, luckily undamaged.
- In Canada, the Nuclear Safety Commission lists 17 cases from the past eight years in which radioactive materials were stolen from vehicles, or in which the vehicle itself was stolen with a radiation source in the trunk. Five of these cases involved radiography cameras. All five were eventually recovered.
Radiography cameras are category-2 devices. These contain less radioactivity than category-1 sources, but are still classified by the IAEA as “very dangerous.” Category-2 sources can cause permanent injury to a person who handles them unsafely for periods of minutes to hours, and they can kill a person who stays nearby and unprotected for hours or days. For terrorists, they could certainly be of interest, too, because the amount of material is enough to cause substantial damage when used as a weapon.
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