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At the Counterterrorism Blog, in a post entitled, Iran caught red handed in smuggling nuclear material, Olivier Guitta remarks on an intriguing news story alleging that Bulgaria had detained, at the Romanian border checkpoint at the Russebridge over the Danube, a truck containing materials that could be used to build a dirty bomb. Agence France-Presse first reported it. There's also a Sofia News Agency version, and a longer Daily Mail (UK) version. Each has a detail or two that the others don't, but this excerpt from the Dail Mail will give you the general idea:

Border guards seized a British lorry on its way to make a delivery to the Iranian military - after discovering it was packed with radioactive material that could be used to build a dirty bomb.

The lorry set off from Kent on its way to Tehran but was stopped by officials at a checkpoint on Bulgaria's northernborder with Romania after a scanner indicated radiation levels 200 times above normal.

The lorry was impounded and the Bulgarian Nuclear Regulatory Agency (NPA) was called out.

On board they found ten lead-lined boxes addressed to the Iranian Ministry of Defence. Inside each box was a soil-testing device, containing highly dangerous quantities of radioactive caesium 137 and americium-beryllium.

The soil testers had been sent to Iran by a British firm with the apparent export approval of the Department of Trade and Industry.

Last night, the head of the Bulgarian NRA, Nikolai Todorov, said he was shocked that devices containing so much nuclear material could be sold so easily.

He said: "The devices are highly radioactive - if you had another 90 of them you would be able to make an effective dirty bomb."

And a spokesman for the Bulgarian customs office, said: "The documentation listed the shipment as destined for the Ministry of Transport in Tehran, although the final delivery address was the Iranian Ministry of Defence.

"According to the documentation they are hand-held soil-testing devices which were sent from a firm in the United Kingdom."

The shipping company involved is Orient Transport Services of Sevenoaks, Kent, apparently located in one of the most affluent towns in Southeast England. According to their website, they ship to Iraq, Iran, Turkey, Syria, Jordan, Bulgaria, Romania, Yugoslavia, Serbia, Croatia, Slovenia, Hungary, Slovakia, Czech Republic, Poland, Belarus, Russia.

If in fact the radioactive soil-testing devices traveled all the way from Kent, they were a little less than half way on their 3,000 mile journey to Tehran when they were impounded by the Bulgarians, and would have already passed through Belgium, Germany, Austria, Hungary, and Romania before being stopped after crossing into Bulgaria.

The news articles imply that the radioactive materials were apprehended in the same truck they left Kent in. But an examination of the Orient Transport Services site has maps of countries where they deliver suggesting regular delivery routes, and the Map Key mentions an "Istanbul control centre" suggesting a transportation network rather than just individual trucks that make really long drives. Also, the truck stopped in Bulgaria had Turkish plates; the location where it was stopped is a little over 150 miles from the Turkish border. So it seems to me unlikely that the truck itself came all the way from Kent. News reports have not yet identified the UK company alleged to have sent the equipment.

So how much mischief could have been caused with the kind of stuff that was in the truck? Some. Apparently, these devices in their native state pose little danger of radiation exposure and breaking them down for parts is a lot of trouble for not very much radioactive material. Nonetheless, there is a perceived problem with the theft of portable radioactive gages, and some consideration has been given to what could be done with them. Here is a discussion of safety issues involving similar equipment left lying around in California: Radioactive material not life threatening: Soil density gauge stolen, then recovered in Chualar.

A scientific instrument the size of an ice chest that contains low-grade radioactive material touched off a nuclear alert Sunday when it was found abandoned outside a neighborhood grocery store in Chualar.

The device, a soil density gauge, had been stolen from a vehicle belonging to Salinas-based Kleinfelder Inc. on Saturday, the Monterey County Sheriff's Office said. The machine is used to measure soil density and helps contractors determine whether soil will support various structures.

. . . The machine was returned to Kleinfelder personnel, who assured the public safety workers that although the device does contain radioactive material there was no threat to anyone who came in contact with it.

In general it seems that while someone could use the contents of that truck as ingredients of something that might be called a "dirty bomb," it would be a rather disappointing one, not up to the standards of the popular imagination.

So what's going on here? Are Iranians with overactive imaginations ordering soil testing equipment in hopes of blowing stuff up and making a radioactive mess? Are Bulgarian customs officials with overactive imaginations detaining perfectly legal shipments of soil testing equipment which otherwise would have been shipped to someone at the Iranian Ministry of Defense who urgently needed some soil tested? Was the equipment really going to end up in Iran? If so, why was it traveling by ground when it was still about 1,500 miles from its destination? Or was it going to one of the other places OTS ships? Whatever the answers to these questions are, what this situation isn't is an open and shut case of the Iranian military ordering up fissionable materials from a source in the UK, which is what it appeared to be at first blush. It seems to me that someone somewhere in this supply chain is being conned. I'm just not sure who.