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Scientists build trap for radioactive isotope produced by nuclear power plants

Tuesday, April 13, 2010; HE06

Scientist Mercouri Kanatzidis calls it a Venus' flytrap for nuclear waste.

He and colleague Nan Ding have developed a powdery material that traps cesium-137, a prevalent, stubborn radioactive contaminant.

Essentially, the material's framework acts as a "very tiny, tiny building with rooms," Kanatzidis said. The cesium enters the building, then bonds to the sulfide walls of the interior. At that point, the building begins "making all the doors and windows smaller so the cesium cannot get out."

In more-scientific terms, the flexible sulfide structure contains organic, positively charged ions that can change positions with cesium in a watery solution. That reaction prompts the structure of the framework to close only on the cesium ions, preventing them from escaping.

Kanatzidis, a professor at Northwestern University and a senior scientist at Argonne National Laboratory, and Ding, an assistant chemistry professor at Claflin University in Orangeburg, S.C., made the discovery in 2007. They published their work in the journal Nature Chemistry in January.

"Nuclear waste is a big issue," Ding said, "and we need new . . . mechanisms to get rid of it as soon as possible."

Cesium-137 is produced by nuclear weapons testing and nuclear power plants. Scientists believe that cesium-137 is among the most dangerous radioactive isotopes, largely because the soft, silvery-white metal has a half-life of 30 years, easily enters the body and can bring on cancer decades after exposure.

-- Chicago Tribune

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