Researchers Tout New Approach to Detecting Smuggled Nuclear Materials

The International Atomic Energy Agency has said most illegal trafficking of nuclear materials is in small quantities.

“You don’t have people with big spheres of this stuff in their suitcase walking through an airport,” said Andy Gilbert, a researcher at the Department of Energy’s Pacific Northwest National Laboratory.

Smugglers attempt to carry small amounts in their suitcases or baggage and shield it with steel, lead and other metals to evade detection.

The lab, in a joint project with the University of Texas at Austin, has applied the relatively new field of spectral X-rays to the problem, he said in an interview.

Regular X-rays only measure the amount of energy. As they pass through an object, some are absorbed and some pass through. Materials such as metals are darker, which is why they are easy to spot on images. 

Spectral X-ray technology can “bin” the energy, or categorize it, which gives those looking at the image a better idea of what the object comprises, he said.

Different materials interact with X-rays differently. The composition of an object causes a spectral shift when the energy is moving through it.

With spectral X-rays, “you get an extra piece of information,” Gilbert said, and operators can therefore make inferences on the identity of an object.

Spectral X-ray technology has been the subject of research for about a decade, he said. The medical community is also pursuing the technology in hopes that it can improve body scans and perhaps lower the energy dosage fired into a patient’s body.

The research team has developed an algorithm than can improve the detection of uranium and plutonium that is being concealed in small, layered objects. 

The smaller the amount being smuggled the more difficult it is to detect, Gilbert noted. “A thin layer of nuclear material looks a lot like a thicker material of lower density.”

The detection method is designed with minimal user input in mind. A Customs and Border Protection officer should not have to be a trained X-ray technician. The system should automatically make its own calibrations.

All this research, published in April in the Journal of Applied Physics, has come from simulations. The team wants to move on to experiments with a real spectral X-ray machine, and then ultimately make them larger.

“We plan to apply the algorithm to high-energy X-ray systems that could be used for verification of arms-reduction treaties,” University of Texas researcher Mark Deinert, one of the authors on the paper, said in a statement.

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