Teams from the University of Illinois at Urbana-Champaign, the University of Michigan, Los Alamos National Laboratory, Heriot-Watt University (Edinburgh, UK) and the University of Edinburgh have developed a new algorithm capable of quickly and inexpensively detecting weapons-grade nuclear materials at national borders, distinguishing between illicit radiation signatures and benign signatures evident in cargo.

According to the team, the algorithm was trained to identify the signatures associated with weapons-grade nuclear materials and can even identify weak radiation signals — for instance from plutonium-enveloped materials that absorb radiation and in high radiation backgrounds such as those encountered from cosmic rays from space or radon from rocks — and “untangle” them from benign radiation sources stored within the same cargo.

Benign radiation sources, including naturally occurring radioactive material like fertilizer and ceramics, and patients recently exposed to radionuclides during the course of nuclear medicine treatment, may trigger alarms at border radiation portal monitors, which are designed to detect nuclear-bomb making materials. Likewise, those naturally occurring radioactive material sources may be used to cloak such nuclear-bomb making materials.

As such, the team believes that the algorithm in conjunction with data from the detectors used at radiation portal monitors, might improve radiation detection at the borders, reducing the number of false-positives that trigger the alarms.

The study, "Expectation-propagation for weak radionuclide identification at radiation portal monitors," is published in the journal Scientific Reports.