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Printer FriendlyReprinted with permission from Popular
Science, February 1999.
© Copyright, Times Mirror Magazines, Inc.
Detecting Nuclear Blasts
POLICING THE Comprehensive Nuclear Test Ban Treaty is critical to preventing the spread of nuclear weapons. But detecting small explosions is tricky.
Now scientists at the Department of Energy's Pacific Northwest National Laboratory in Richland, Washington, have developed two devices that drastically improve the chances for success. Both devices will be stationed strategically around the globe in 80 different locations.
The Automated Radioxenon Sampler/Analyzer (ARSA) and the Radionuclide Aerosol Sampler/Analyzer (RASA) work in different ways. David Robertson, manager of the two projects, explains: "ARSA" is designed to detect underground explosions by sensing any noble gases-principally xenon-that might escape because they are inert and don't react with soil. The xenon radioisotopes are relatively shorted-lived, and they really are a smoking gun."
RASA, on the other hand, is designed to look for particulate radionuclides in the atmosphere; these fission products are indicators of an aboveground explosion.
ARSA is 10 to 100 times as sensitive as other detection systems, and RASA is more than 100 times as sensitive as the best previous technology. "We achieved these increases by upping the sample size," say Robertson. "Both of these systems are designed for large-volume sampling. RASA can sample the atmosphere at a flow rate of 20 million liters a day, and ARSA can sample 120,000 liters a day."
Both detectors are designed to operate remotely and automatically, and to require maintenance only once a year or so.-Arthur Fisher
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