At a container terminal at the heart of Rotterdam's vast harbor, the routine looks smooth. Trucks hauling 40-foot seagoing containers toward their cargo ships first roll slowly between two 20-foot-high white pillars, housing detectors that profile any gamma or neutron radiation on computer screens in a nearby command post.
Manning those screens, Wiersema's agents are now expert readers of the distinctive "signatures" of vegetables, ceramics and other items with slightly radioactive minerals. If anything's suspicious, they order the container to an enclosure where powerful X-rays probe for material that is extremely dense, like radioisotopes.
None has turned up, and that's fine, Wiersema said. "This isn't cocaine or cigarettes," his agents' usual smuggling haul. "There aren't a million bombs. But it's important for prevention. They know we're here."
The greatest deterrent to would-be bombers remains the radiation itself. How would novices extract, handle, transport such material?
"Very quickly," Tannenbaum said dryly. "You'd wear lead underwear and a lead apron. You'd use tongs to keep yourself separated from it." Some experts even theorize, improbably, that relay teams of "suicide technicians" would be needed.
An official U.S. planning scenario envisions a worst case: a bomb laden with powerfully radioactive cesium chloride powder, whose blast kills relatively few people, but whose long-term contamination keeps many blocks of a city uninhabitable for years.
A dirty bomb, if not a mass killer, would be "an economic weapon and a fear weapon," said Carolyn MacKenzie, an IAEA radiation source specialist. "Spreading radioactive materials around can shut down an area for a very, very long time."
But is a highly lethal load of radioactivity necessary? Some suggest a dirty bomber could achieve his goal, terrorizing a population, with a small amount of low-level radioactivity, posing little threat - as long as Geiger counters go off in New York, Washington or whichever city.
The IAEA urges governments to plan carefully to keep the public well informed in such an emergency. Then, said MacKenzie, "it is up to the press not to inspire fear."
NEXT: Part IV - Nuclear terrorism.
On the Net:
Proceedings of the 2003 IAEA conference "Security of Radioactive Sources":