Some scientists have said that new radiation detecting devices might be of little use in preventing terrorists from detonating a nuclear weapon or “dirty bomb,” the New York Times reported today (see GSN, March 6).

The key to finding a nuclear device is information — without it, “needle in a haystack” does not describe the challenge, said Steven Fetter, a physicist and professor of public policy at the University of Maryland.

“If you tell me there’s a warhead in New York, it’s just hopeless,” Fetter said.  “You just hope you never get to the point where you have to track down one of these in a city.”

Under ideal conditions, it is possible to detect a nuclear weapon from more than 200 feet away, but a weapon under terrorist control might be more difficult to find, said Frank von Hippel, a physicist and science policy professor at Princeton University.

A joint U.S.-Russian study in 1989 “showed that U.S. and Soviet warheads were quite detectable,” von Hippel said.  “That might not necessarily be true for a terrorist warhead.”

Terrorists could attempt to shield a nuclear device with lead to block emissions that detectors would otherwise pick up, the Times reported.  Some of the most dangerous nuclear materials, such as uranium and plutonium necessary for a bomb, emit very little radiation.  Natural radiation could also mask a faint signal coming off of a nuclear device, according to the Times.

The best way to prevent nuclear terrorism is to make sure terrorists do not have access to nuclear materials, according to some experts.

“The moral of the story is you lock up nuclear materials as well as you can lock them up,” Fetter said.  “Once you let them get out, the problem is a thousand times harder.”

New Sensors

Since Sept. 11, the U.S. National Nuclear Security Administration’s annual budget for the development of radiation sensors has doubled to $20 million, according to the Times.  In addition, federal laboratories are spending up to $18 million on the effort, an NNSA spokeswoman said (James Glanz, New York Times, March 18).

Lawrence Berkeley National Laboratory engineers have developed the Cryo-3, a small, 10-pound detector that uses a high-purity germanium crystal to find a radiation source.  Photon, X and gamma rays interact with the germanium to create a corresponding charge.  The charge is then processed to determine the type and quantity of radioactive isotope present.

The germanium crystal is cooled by the same kind of mechanical cooling device currently used to cool low-noise cell phone antennae.  The Cryo-3 can operate for six hours on two camcorder batteries that can be switched while the detector is running, allowing for almost unlimited operational time.

“Whatever you can detect with a germanium crystal, you can detect with the portable system,” said Lorenzo Fabris of Berkeley Laboratory’s Engineering Division. “Ideally, we would be able to place one at any customs port” (U.S. State Department release, March 17).

Researchers at the U.S. Energy Department’s Brookhaven National Laboratory are working on another type of radiation detector, one that would use semiconductor chips that could detect radioactive isotopes through their individual radiation “fingerprints,” according to United Press International.

“You’re after something that’s low-power, battery operated, very compact in size, long-term operation unattended, no maintenance, all those things are going to be required …,” said Ralph James, associated director for energy, environment and national security at Brookhaven.  “This (chip) technology really fits the bill.”

One major factor is the ability of a radiation detector to be able to differentiate between naturally occurring radiation and that given off by a terrorist nuclear device, James said.

“What we need is something that can discern special nuclear materials that might be part of something with nuclear yield,” he said.  “These are cases of plutonium-239, uranium-235, the ones people know about.  (We have to spot these) materials from a wide range of naturally occurring isotopes.”

The new semiconductor chip technology can do just that, James said.

“Just as you can tune your radio to find the frequency of your favorite station, you can identify each isotope by tuning into the unique energies associated with the emissions,” he said.  “We can spectrally ‘window’ and determine if (a source) is plutonium-239, a great concern for nuclear weapons, or something like americium-241, which is in practically every smoke detector in the United States” (Scott Burnell, United Press International, March 17).

Who Will Track Down Nuclear Devices?

Any new radiation detectors would be sure to find their way into the hands of the Nuclear Emergency Search Team (NEST), part of the Energy Department’s Nevada Operations Office, which is in charge of responding to a nuclear terrorism threat (see GSN, March 4).

NEST can send about 600 personnel to the site of nuclear terrorism threat, though deployments have so far involved fewer than 45 people, according to the Bulletin of the Atomic Scientists.  NEST personnel come from the Nevada operations office, Energy Department laboratories and three private contractors.  There are 17 different types of NEST personnel representing a wide range of abilities, including four types of physicists, chemists, mathematicians and communications specialists.

If there is a nuclear terrorist threat, the first step the team takes is to determine its validity.  NEST maintains a database on nuclear weapons design information, taken from sources ranging from scientific journals to spy novels, in order to check the technical accuracy of a threat.  Psychologists examine the wording and structure of any accompanying communication to determine the mindset of the terrorist and where in the world he or she might have originated.

If it is necessary to respond to a threat, NEST has more than 150 tons of equipment at hand, according to the Bulletin.  The team has its own air fleet consisting of four helicopters with radiological search systems and three airplanes equipped for remote sensing missions.  NEST can also deploy vans equipped to detect radioactive emissions and has its own graphics agency to disguise the vans and blend in with commercial traffic.

NEST already has in its arsenal handheld nuclear detectors that can be hidden in objects the size of suitcases or briefcases.  These detectors can silently alert a NEST member to the presence of a nuclear device through a signal transmitted to the member’s earphone, the Bulletin reported.

NEST also has diagnostic and disablement equipment if a nuclear device is discovered.  If it is necessary to disable a nuclear or “dirty” bomb, team members might surround it with explosives and then detonate them or use a 30-millimeter cannon to break the bomb up into tiny pieces.  NEST can also build a nylon tent 35 feet high and 50 feet in diameter around a nuclear device, and then pump up to 30,000 cubic feat of foam to limit the spread of radiation (Jeffrey Richelson, Bulletin of the Atomic Scientists, March/April 2002).

About Newswire  |  Contact National Journal  |  Re-Use Guidelines

HOME  |  CONTACT US  |  GET INVOLVED  |  SITE MAP

Back to top