Along with salt, a liter of seawater also contains sulfates, magnesium, potassium, bromide, fluoride, gold, and uranium. There isn’t much of the latter – something like 3 micrograms per liter (0.00000045 ounces per gallon), but when you consider how big the ocean is, that works out to 500 times more uranium in the sea than could be mined on land – that’s 4 billion tons, or enough to run a thousand 1-gigawatt fission reactors for 100,000 years.
The tricky bit is how to get the uranium out of the water. One approach developed by the Japan Atomic Energy Institute used polymer mats that would draw the uranium atoms out of solution. But this was very expensive, and a cheaper process that involved doping polymers with amidoxime and then irradiating them was developed at Oak Ridge National Laboratory.
While this showed more promise, PNNL and Idaho-based LCW took it a step further by taking ordinary acrylic yarn and converting it into a uranium adsorbent. The exact details of the process haven’t been released, but PNNL says that the yellowcake sample shows that not only does the technique work, but that the acrylic can be cleaned and reused.
In addition, the technique can even use waste fibers for a greater cost savings and that analysis shows that seawater extraction could be competitive with land mining at present prices.
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