Vehicle and Cargo Scanning for Contraband

There is a need to inspect vehicles and their contents for Special Nuclear Material (SNM) and general contraband. The most widely used technology for scanning vehicles, ranging from vans and trucks to railcars, is gamma-ray and X-ray radiography. New technologies are required for higher penetration to reduce insufficient penetration alarms, for improved image quality and material discrimination to increase detection at high throughput and to enable scanning fast-moving trains. In most cases, the scanning footprint, which includes the radiation exclusion zone, must be small due to the limited space available at the inspection sites. Some of these conflicting requirements have been addressed by employing adaptive intensity and/or energy modulation of the X-ray source. Any alarms produced by these primary systems need to be cleared or confirmed to eliminate labor-intensive manual inspection. Various technologies have been proposed and used for secondary inspection, mainly based on the detection of fission signatures. Such systems would preferentially require minimal infrastructure and cost would be kept reasonably commensurate with the performance improvements to allow for wide deployment. The Domestic Nuclear Detection Office (DNDO) has performed tests of some of these systems to determine the envelope of the various technologies. Selected results with primary systems, and examples of potential system improvements are presented.