'Green Rust' can protect groundwater from nuclear waste, researchers report.
A naturally occurring substance called "green rust" can help protect groundwater against radioactive contamination from stored reactor waste, Danish researchers have discovered.
The researchers, led by geochemist Bo C. Christiansen of the University of Copenhagen, studied how green rust contained neptunium, a waste product from uranium reactors that can prove dangerous to human health if it seeps into groundwater--even millions of years after it is discarded at a repository.
"Neptunium is a relatively exotic problem," said Christiansen, whose team included chemists, physicists and geologists at the university's Nano-Geoscience Research Group. "Not a lot of people need to safeguard a radioactive waste depot. But green rust appears to be effective against nearly any kind of pollution."
Green rust--a type of anionic clay that includes iron that has not entirely rusted--has an electron deficit that makes it react easily with pollutants. The researchers found that green rust could immobilize neptunium at the Swedish Nuclear Fuel and Waste Management's research facility at Okskarshamn, on Sweden's east coast, and at the Karlsruhe Institute of Technology in Germany.
"Our study shows that even the safest encapsulation of radioactive waste could be made safer if radioactive waste canisters are buried in a place where green rust will form," said Christiansen, who noted that for years, green rust was studied primarily because scientists wanted to know how to prevent the formation of the rust in reinforced concrete. "Green rust is no quick-fix to clean up after pollution that suddenly presents itself. But our experiments have shown the surprising result that nature can help to clean itself. Even when the pollution is with a substance as serious as neptunium."
The scientists noted that green rust could be used to encase radioactive-debris-holding canisters to ensure the radioactivity is contained.
The team's findings are published in the March issue of the journal Geochimica et Cosmochimica Acta.
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|Publication:||Nuclear Waste News|
|Date:||Apr 5, 2011|
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