Autonomous radiation monitoring of small vessels

by K P Ziock, A Cheriyadat, L Fabris, J Goddard, D Hornback, T Karnowski, R Kerekes, J Newby

5-mCi 137Cs source passing in front of the gamma-ray imager

Individual images of a 5-mCi 137Cs source passing in front of the gamma-ray imager (left). These are shifted horizontally so that the peaks fall on top of each other and then summed to generate the overall result from the vessel (bottom right). The video image of the targeted vessel is shown with its bounding box shown in white to identify it (top right). Below the composite gamma-ray image is an arrow indicating the length of the vessel. The thin line near the bottom of the image represents the line for zero counts. The pixel at the peak of the image has a statistical significance of 48 sigma.


Small private vessels are one avenue by which nuclear materials may be smuggled across international borders. While one can contemplate using the terrestrial approach of radiation portal monitors on the navigable waterways that lead to many ports, these systems are ill-suited to the problem. They require vehicles to pass at slow speeds between two closely-spaced radiation sensors, relying on the uniformity of vehicle sizes to space the detectors, and on proximity to link an individual vehicle to its radiation signature. In contrast to roadways where lanes segregate vehicles, and motion is well controlled by inspection booths; channels, inlets, and rivers present chaotic traffic patterns populated by vessels of all sizes. We have developed a unique solution to this problem based on our portal-less portal monitor instrument that is designed to handle free-flowing traffic on roadways with up to five-traffic lanes. The instrument uses a combination of visible-light and gamma-ray imaging to acquire and link radiation images to individual vehicles. It was recently tested in a maritime setting. In this paper we present the instrument, how it functions, and the results of the recent tests.

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Publication Citation

Nucl. Inst. Meth. in Phys. Res. 2011 pp 10-15