‘Renewable uranium’: trace uranium in seawater harvested in Australian study

An Australian study has discovered a method for harvesting trace uranium from seawater, providing a path to renewable nuclear fuel with a lessened environmental impact.

Ranger uranium mine in the heart of Kakadu has now ceased operations and a five-year environmental clean up has begun. Picture: Che Chorley

An Australian study has discovered a method for harvesting trace uranium from seawater, providing a path to renewable nuclear fuel with a lessened environmental impact.

A study led by Jessica Veliscek-Carolan with the Australian ­Nuclear Science and Technology Organisation and the University of NSW has engineered a hydroxide powder that when placed in seawater, will adsorb the water’s small amounts of uranium.

“We worked on making these layered double hydroxide materials which are made by a simple precipitation method. They’re really easy to make,” Dr Veliscek-Carolan said.

“It’s kind of like a sandwich where you’ve got these layers of that magnesium-aluminium hydroxide which is positively charged, and then there’s layers of negatively charged anions ­between those sandwich layers.”

She prefaced that more research would be needed to make it commercially viable, since it was deployed as a powder for maximum surface area. But a solid object composed from the hydroxide could be left for long periods to collect uranium.

“If you had a material that was renewable you could use (the uranium harvesters) multiple times. You could strip the ­uranium off and then redeploy the material and use it again to extract more uranium out of the sea­water,” Dr Veliscek-Carolan said.

The technology could also exploit one of the few forms of renewable nuclear fuel, as uranium in seawater replenishes after harvesting at the rate of its consumption, absorbing trace minerals from the earth until its composition is returned to the initial level. There is about 3.3 tonnes of uranium in each cubic kilometre of seawater.

Dr Jessica Veliscek-Carolan led the study which could give the nuclear industry access to renewable uranium.

“Uranium in the ground is a non-renewable resource. So at some point the scales will tip, and it might become actually viable to be looking at those sorts of non-conventional technologies,” Dr Veliscek-Carolan said.

“Mining from the earth, you have to extract the uranium from an ore and you end up with waste. That’s all the ore that’s left over. Whereas with this technology, particularly if you’ve made something that’s really selective for the uranium, then it’s not pulling anything else out of the ocean,” she said.

Brandon Munro, Bannerman Energy chief executive and World Nuclear Association General Advisory Council member, said the large uranium stockpiles of many nations will not be sufficient in many cases as governments look to build and supply power stations for decades to come.

“Seawater extraction at scale is likely to be decades away from technical and commercial reality,” he said. “However, recent progress is important, given the plethora of geological, social and environmental constraints on new sources of mined uranium in most countries.

“Demand for nuclear power will continue to grow over the next several decades, meaning the industry will want to increase its utilisation of recycled spent fuel and (push) seawater extraction to complement mined uranium.”

Bannerman Energy CEO Brandon Munro argued that widespread seawater uranium infrastructure was still decades away, but could be integral to the future of the sector

Australia has abouta third of the world’s uranium ore, with mines at Olympic Dam, Honeymoon and Beverley Four Mile in South Australia and Ranger in the Northern Territory.