Smart Detectors Against Dirty Nukes

March 12, 2002 -- It's a nightmare scenario that could take place in the not-too-distant future, say some experts. Terrorists craft and explode a "dirty bomb" — an explosive weapon laced with nuclear or radioactive material such as cesium or cobalt.

Security experts recently testified before Congress that such bombs won't kill as many people as an outright explosion from a true nuclear weapon. But they said a dirty bomb could spread invisible and deadly radiation for miles and contaminate areas for years — making such devices an ideal weapon of terror.

In order to ward off such potential disasters, the U.S. government is taking several steps, including the use of new, "smart" radiation detectors.

According to experts, traditional radiation detectors — Geiger counters — don't tell users enough about material that's giving off waves of radiation.

"As you get closer, the Geiger counter clicks faster," says Ralph James, associate lab director for the Energy, Environment and National Security Group at Brookhaven National Labs in Upton, N.Y.

But that happens if the material is plutonium 239 — a material in nuclear weapons — or americium 241 — a material used in smoke detectors in every house. "That [clicking] is simply not enough information when detecting a radiological weapon," says James.

Seeking Radioactive Signatures

The new sensors, called gamma ray detectors, use exotic chemicals such as germanium and cadmium zinc telluride. More sensitive to certain types of radiation, these chemical sensors help give searchers a more accurate idea of the kind of nuclear threat they are facing.

Every radioactive element gives off a certain unique pattern or "signature" of energy, says James.

"They're just like different frequencies on a radio dial," he says. "In smart detectors, we have the ability to discern isotopes in weapons — like uranium or plutonium — from a wide range of naturally occurring isotopes."

In other words, the smart detectors will give security and law enforcement personnel a better way to screen out potentially false alarms — such as a shipping container that really contains only minute amounts of cesium for medical experiments.

Elite Tools for Now

Experts note that smart detector technology has been deployed with emergency groups such as the Nuclear Emergency Search Teams, groups that respond to the threat of nuclear weapons and materials. And after recent intelligence reports suggested that the al Qaeda terrorist network may have or will soon have dirty bombs, the U.S. Army's elite Delta Force counterterrorism group may also have acquired such detection capabilities.

But some experts note that it's unlike the technology will reach to where it may be most useful: among firefighters, emergency rescue and medical technicians, and police officers — the "first responders" who react to disasters such as terrorist attacks.

For one, the detectors are too expensive to put among every firehouse or police precinct in the nation. At about $20,000 to $30,000 per detector, experts say all but the largest of city fire departments and emergency organizations would be unable to afford such high-tech gear.

Using the Tools at Hand

But even without the new detectors, experts such as William Brobst Jr., an adjunct instructor at the Center for Terrorism Preparedness in the University of Findlay, Ohio, say that most first responders are prepared to handle any crisis involving radioactive material.

Brobst, who is also a captain of a special hazardous materials, or hazmat, unit for the Columbus Fire Department, says fire departments in most major cities do have radiation detectors — mostly Geiger counters or similar devices. "Under federal requirements for hazmats, we are expected to test for radioactive chemicals at any scene we're called out to," he says.

And while the new technology would be a help to rescuers arriving on the scene of a suspected dirty bombing, he's also confident in the protective clothing and gear that most first responders already carry. "The 1950s- and '60s-style detectors are still good," says Brobst.

At least, it's good enough to warn rescuers that they face a threat of radiation and thus need to limit their time in the dangerous area.

"We'll save victims and then we'll be wise enough to back out and turn it over to hazmat [teams]," says Brobst. "Radiation isn't a big killer. No one comes down with radiation sickness in 10 or 15 minutes."