To detect the presence of concealed nuclear or chemical material/weapons in cargo shipping containers, US national labs and defense contractors are investigating an approach where the container is sent through a scanner that floods the container with high energy neutrons (~14MeV). The energetic neutrons are penetrate almost anything that gets in their way and they will excite shielded contraband material (Uranium, Plutonium, etc.) into emitting detectable high-energy gamma rays (several MeV). Unlike the spontaneous radioactivity, these induced gamma rays are not usually present in the background and can be identified readily by the scanner.
Several articles have appeared in the press about this, but here is a technical feasibility study by Lawrence-Livermore National Labs that answers just about any question you could possibly ask "Detection of special nuclear material in cargo containers using neutron interrogation" (August, 2003). The study draws two interesting conclusions:
- The radiation produced by the scanning is a potential concern, but it will drop to acceptable levels within minutes.
- The scans will take about a minute, and they envision only suspect containers will be diverted through the scan after first being screened by passive techniques and traditional inspections.
An article describing the personal story of the dedicated physicists behind this effort appeared in the Daily Californian, Innovative Detection Methods May Help Tighten U.S. Security. The effort began in 2001 immediately after 9/11, and it is in laboratory testing as of mid-2004. They optimistically expect to achieve widespread deployment at ports by 2007.
Please visit www.nsd-fusion.com
We are an upstart, re-started, start-up neutron generator manufacturer which dares to challenge the established old technology. See our application example page for ContainerProbe.
Posted by: John sved | August 16, 2006 at 01:23 AM