Tag: Uranium

A new form of uranium identified at the ESRF

A new form of uranium identified at the ESRF

Heavy elements or actinides, such as uranium and plutonium, have complex electron configurations, i.e. a variety of oxidation states that lead to unusual and diverse bonding behaviours. Studying these bonds and exotic oxidation states can shed light on the chemistry of heavy elements, which is crucial for nuclear energy and managing radioactive waste. In terms of applications, actinide bonding research could improve nuclear fuel design, improve radioactive waste management and could lead to new materials with unique properties.

Now researchers from Helmholtz-Zentrum-Dresden-Rossendorf and the Rossendorf Beamline at the ESRF (BM20) have identified a specific form of uranium, the U(III) oxidation state, and investigated how tightly uranium holds on to its electrons when it bonds with other elements such as fluorine and chlorine.

For the last 15 years, the team had been studying uranium, which is less radioactive and more abundant than other actinides, and searching for its low valent form. “We tried to find it several times, with samples from different groups, but they always resembled U(IV)”, explains Kristina Kvashnina, head of the Rossendorf Beamline at the ESRF and corresponding author of the publication.

One of the main challenges of low-valent uranium compounds is that they are less stable than other uranium-containing materials and require carefully controlled conditions during the transport and experiment. Kvashnina and her group joined forces with Florian Kraus, a professor at the Philipps-Universität Marburg (Germany), who advised them on how to prevent oxidation of the samples during transportation and the experiment itself.

To keep samples stable, the scientists sealed them under anoxic conditions to prevent the uranium systems from reacting with oxygen in the air, transported under LN2 (liquid nitrogen) conditions and carried out measurements under cryogenic conditions.

Read more on ESRF website

Promising material provides a simple, effective method capable of extracting uranium from seawater

Promising material provides a simple, effective method capable of extracting uranium from seawater

  • Uranium can be extracted from seawater simply and effectively using a new material
  • Adding neodymium to layered double hydroxides (LDHs) improved their ability to capture uranium selectively
  • Multiple techniques at ANSTO clarified the octahedral coordination environment, oxidation state and adsorption mechanism

An Australian-led international research team, including a core group of ANSTO scientists, has found that doping a promising material provides a simple, effective method capable of extracting uranium from seawater.

The research, published in Energy Advances and featured on the cover, could help in designing new materials that are highly selective for uranium, efficient, and cost-effective.

Read more on the ANSTO website

Ancient fluid in quartz provides key to finding new uranium deposits

Ancient fluid in quartz provides key to finding new uranium deposits

Saskatchewan’s Athabasca Basin is home to some of the world’s largest and richest uranium deposits, but it can still be tricky to find them.

Researchers at the University of Regina are studying how the deposits formed more than 1.5 billion years ago to help figure out the best places to look.

“We’re trying to understand the geological factors that control the formation of these deposits so that we know what features we should be looking for to find more uranium resources,” said Dr. Guoxiang Chi, a geologist at the University of Regina.

Chi, his Ph.D. student, Morteza Rabiei, and colleagues used the Canadian Light Source (CLS) at the University of Saskatchewan to analyze samples of quartz from areas known to contain uranium and nearby barren regions, the quartz having formed at the same time as the Athabascan uranium ore. They sliced the quartz into thin sections and studied the tiny droplets of primordial fluid trapped inside. It was from this fluid, circulating through geological fault lines billions of years ago, that today’s uranium ore formed. “By getting information about this paleo-fluid and seeing how it is distributed we can infer where the original uranium came from and what factors control its deposition,” said Chi. Understanding the conditions under which uranium ore is likely to form can help mining companies know where to look.

The results, however, were more complex than expected, he said. Fluid from ore-bearing areas had high levels of uranium, as expected, but so did the fluid from areas with no uranium ore. On the one hand, that is good news as it means that the uranium-rich fluid is more pervasive than first thought, but it also complicates the search for new deposits.

“We were hoping to see a major difference, but found uranium-rich fluid in both places,” he said. “So, if we want to use it as a guide to locate ore, we’ll have to understand the other factors that control deposition.” Chi said those other factors likely involve reducing agents that allow precipitation of the oxidized uranium in the fluid. “Without a reducing agent, you can’t have ore.”

Read more on CLS website

Protecting Saskatchewan lakes from contamination

Protecting Saskatchewan lakes from contamination

Using the Canadian Light Source synchrotron, a University of Saskatchewan-led research team has developed a method for monitoring uranium contaminants in mine tailings using samples from McClean Lake, SK.

While mining companies work to extract as much uranium as possible from processed ore, small amounts remain in the solid and liquid residue—called tailings—left over from the milling process.

To protect the downstream environment from potential impacts of the solid waste, the Canadian Nuclear Safety Commission requires companies to monitor the chemistry of uranium and other potentially harmful elements in their tailings facilities.

Numerous researchers have studied the chemistry of nickel, arsenic, selenium and molybdenum in Orano Canada’s tailings management facility at McClean Lake, but to date little was known about residual uranium. One of the challenges has been the extremely low concentrations of the element left after processing at Orano’s ore mill, which began operating in 1997.

Read more on the Canadian Light Source website

Image: Arthur Situm conducting research at SXRMB beamline. Photo by David Stobbe for USask.