Sandia tests new approach to radiation detection

Scanning freight containers for radiological materials is a cotnentious topic. Security experts and many legislatros want a 100 percent inspection policy of U.S.-bound containers, but the technology is not quite here yet to do so effectively and expeditiuosly. Perhaps this is going to change as a result of work done at Sandia National Laboratories. Mobile radiation detectors assembled at Sandia/California are being tested on ships in transit from Oakland to Honolulu to determine whether they can reliably detect nuclear material on those ships without many false alarms. “You’ve got days on the ocean, and you only get minutes in the port,” Sandia physicist George Lasche said. “The alternative is to inspect all these containers before they leave foreign ports.”

A major challenge in identifying radiological threats on land is sorting them out from background radiation. “It’s like trying to hear someone through a crowded restaurant,” Lasche said. At sea, there is significantly less background noise. “It’s more like trying to hear a whisper in a library,” he said. This creates its own challenges, however. Without background radiation to compete with, even the amount of natural uranium in aluminum can be detected. “We’ve gotten rid of the aluminum in our containers, so now I expect we’ll see all the uranium in beer cans traveling from Oakland to Hawaii,” Lasche said in a news release. “Any instrument in a real deployment must be able to discriminate innocent uranium from threatening uranium.”

Contra Costa Times’s Betsy Mason writes that Lasche’s team is working on such issues during the test runs. Team members are also learning to deal with other potential false alarms such as fertilizer. A total of eight test runs were originally scheduled, but DHS has added several more to test additional detection equipment. The containers house an array of detectors, including high-purity germanium gamma-ray detectors, bonnerspheres neutron spectrometers, fission meter multiplicity detectors and muon-neutron correlation detectors. Matson Shipping Lines agreed to work with Sandia to test the detectors in a real shipping environment. “It sounds very simple, but ships are very, very big things with lots of stuff on them,” Lasche said. “One of the big goals is to very rarely have such a false alarm that we have to stop a ship at sea and board it.”