Seawater Could Provide an 'Endless' Source of Uranium for Nuclear Plants

You might be surprised to find out that very small amounts of uranium are found in seawater. A liter of seawater contains about a grain of salt's worth of the material. In a new article in the journal Nature Energy, a team of researchers from Stanford detailed their novel technique for extracting it, which could lead to a practical approach to pull uranium from seawater instead of mining it (and then refining it) to power a nuclear power plant.

"The oceans are so vast that if we can extract these trace amounts cost effectively, the supply would be endless," Yi Cui, a Stanford materials scientist and co-author of the new research, said in a statement. (In a 2016 study, researchers from the Oak Ridge National Laboratory estimated the oceans hold up to 4 billion tons of uranium which they estimated could account for the world's energy needs for 10,000 years.)

The find holds promise both for nations that don't have access to uranium mines and for delivering power that doesn't contribute to climate change.

"We need nuclear power as a bridge toward a post-fossil-fuel future," said Professor Steven Chu, a Nobel Prize-winning physicist and co-author of the article in the journal Nature Energy. "Seawater extraction gives countries that don't have land-based uranium the security that comes from knowing they'll have the raw material to meet their energy needs."

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The idea isn't new and has been studied in Asia and by Department of Energy scientists in the US. But the Stanford team has made strides in a more efficient capture method.

When uranium dissolves in seawater, it combines with oxygen to form uranyl ions, which can be collected by dipping plastic fibers coated with a compound called amidoxime, which makes the uranyl stick to the plastic.

The Stanford researchers created a hybrid amidoxime-carbon fiber, and then sent pulses of electricity down the fiber, which improved the amount of the uranyl collected, the speed in which their collected, and the ability to reuse the fibers.

Tests using the electrified fiber were conducted using seawater at Half Moon Bay, in Nothern California.

"We have a lot of work to do still but these are big steps toward practicality," Cui said.

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