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So much for safety risks; a new "flytrap" molecule has been discovered that literally gobbles up nuclear waste ions.  (Source: Mercouri Kanatzidis / courtesy Argonne National Laboratory)
Molecule could be used to cleanup Chernobyl and make future plants even safer.

Mercouri Kanatzidis, a scientist at the U.S. Department of Energy's (DOE) Argonne National Laboratory, and Nan Ding, a chemist at Northwestern University, have discovered a little molecule that may make a big difference in the nuclear power debate by making nuclear plants safer.

The molecule features a bizarre mechanism in which it behaves like a Venus flytrap, closing selectively on radioactive ions.  That's a big deal as few molecules in the past have shown the potential to effectively and permanently isolate radioactive particles.

The researchers were exploring ways to trap radioactive cesium ions, a dangerous component of nuclear waste water.  Cesium radioactive isotopes typically have a long half life meaning that if they are accidentally released they decay slowly and pose a serious health risk.  One cesium isotope, Cesium-137, which has a half life of 30 years, has played a critical role in maintaining dangerous levels of radioactivity in the Chernobyl disaster zone.  Residents of the region have experienced higher cancer rates and incidences of other problems.

That's why it's so exciting to find a molecule that could potentially isolate those stray particles and allow them to be filtered out of local water supplies -- finding the metaphorical needle in a haystack.

Describes Professor Kanatzidis, "The name of the game in cleaning up nuclear waste is to concentrate the dangerous isotopes as efficiently as possible.  That's where this new material does its job."

The new material is a rigid frame composed of negatively charged metal sulfides.  Its interior has a pore that attracts positively charged ions.  Non-radioactive sodium ions are freely attracted inside the pore, and then interchanged with other sodium ions.  However, when radioactive cesium ions enter the pore, they get stuck.

The researchers discovered the reason behind this.  Sodium, like most positively charged ions, attracts a shell of water that helps to isolate it within the pore.  Cesium, a large ion, only weakly interacts with water, so it's relatively unprotected.  Sulfur atoms in the ring framework around the pore bind to the cesium, changing the shape of the pore, much like a Venus flytrap shutting on its prey.

Professor Kanatzidis elaborates, "Imagine the framework like a Venus flytrap.  When the plant jaws are open, you can drop a pebble in and the plant won't close—it knows it isn't food. When a fly enters, however, the plant's jaws snap shut."

He adds, "As far as we know, this Venus-flytrap process is unique.  It also works over a large range of acidities—an essential property for cleanup at different sites around the world, where pH can range considerably."

The research was published in the prestigious journal 
Nature Chemistry and could lead to discoveries of similar flytrap molecules that could be used to capture other radioactive ions.

Argonne National Laboratory is funded by the U.S. Department of Energy, but is privately managed by UChicago Argonne, LLC.  President Barack Obama has recently become a major advocate of the U.S. adopting nuclear power, pushing for more research grants and guaranteed loan funding for new plant construction.

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RE: Screw that waste of time that is uranium
By eachus on 3/4/2010 9:43:27 PM , Rating: 2
The idea that Thorium is some how "waste free" is a joke.

I think he is referring to molten salt reactors. In an MSR molten salt circulates through a graphite core where the nuclear reaction occurs. These convert Th-233 to U-234, which then fissions, so you really aren't doing away with Uranium. However, the really nice feature of MSRs is that you can add waste fuel from boiling water and pressurized water reactors and burn up the transuranics along with the U-235 and U-238. So MSRs are potentially a way to reduce nuclear waste. (Yes, the salt would be nasty stuff if you had to dispose of it when a power plant was decommissioned, but the value of the salt as fuel for a new plant would be in the millions of dollars. (New fuel would require adding U235 from enrichment plants, or Plutonium-239 from breeder reactors or disassembled nuclear weapons.)

The problem with early MSRs were the electromechanical pumps to circulate the salt. I've seen more modern designs using thermal (gravity) circulation and heat pipes to transfer the heat to the working fluid (water) for the power generating turbines. How safe are MSRs? The Air Force actually flew one in a bomber prior to perfecting in-flight refueling. The idea was to use regular jet engines during take-off, and have the molten salt providing the heat source in one or more sustainer engines for cruise. It turned out that mixing nuclear reactors and nuclear weapons in the same airplane (not to mention humans) was not the greatest idea--and in-flight refueling turned out to be a lot easier than expected.

By porkpie on 3/6/2010 11:11:42 AM , Rating: 2
" It turned out that mixing nuclear reactors and nuclear weapons in the same airplane (not to mention humans) was not the greatest idea"

That wasn't the issue. There were 3 factors behind the program cancellation. One was simply that, by the time the program was nearing fruition, improved missile technology made an ultra-long range, long-loiter bomber less valuable to the military. The second was growing anti-nuclear movement in the nation. The third was that a nuclear-powered bomber would have been seen as a major escalation, at a time when the US was attempting to thaw relations with the Soviets (detente was only a few years away).

In regards to thorium waste, any of the GenIV reactors dramatically reduce waste over our current models...the IFR is particularly suited to this role (though I think other designs ultimately have more promise).

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