To address the threat of smuggled nuclear materials being brought into
the U.S., a Lawrence Livermore National Lab research program is developing
a scanner which would examine cargo shipping containers, which now carry
up to 90% of the world's trade.
Six million such containers enter the U.S. each year, the bulk arriving
through 10 ports, the top three being Los Angeles, Long Beach, and New
York-New Jersey. A parcel of radioactive material, intended as part
of a terrorist bomb, would presumably be shielded inside the cargo container,
precluding passive detection.
The Livermore scanner would work in the following way: the container,
on a moving conveyor, would slide past and be exposed to a neutron beam.
The neutrons would irradiate all the contents of the container, but
would especially activate such dangerous materials such as uranium-235
and plutonium-239. These radioactive species, perturbed by the neutrons,
would fission, resulting in the emission of characteristic gamma rays
detectable in arrays located downstream of the neutron beam.
Speaking at this week's meeting of the American Physical Society (APS)
in Denver, Thomas Gosnell (email@example.com) said that the goal of
the Livermore research is the development of a scanner capable of locating
5 kg of highly enriched uranium or 1 kg of plutonium with a false-positive
or false-negative rate of 1% or less. He expects a prototype "nuclear
car wash" device would be working within a year and be deployed on a
trial basis in a port, such as Oakland, California, a year after that.