14 May 2014

Advancements in uranium-driven energy

SASKATOON – Clean electricity generated from uranium is estimated to reduce carbon dioxide emissions by 2.5 billion tonnes a year. Now, scientists working at the Canadian Light Source are working to make uranium use even cleaner.

Uranium today provides almost a fifth of the world’s electricity, and it is an incredibly  useful element . Saskatchewan is at the hub of the world’s uranium production, and hosts the largest mine in the world at McArthur River. 

Ensuring that mining sites and their surroundings remain clean and healthy is an important focus for Saskatchewan mining companies and researchers alike.

Luckily, natural wetlands at many mining sites may help sequester uranium tailings. Researchers are interested in understanding and enhancing this process in order to make nuclear power generation even cleaner and safer for the environment. 

“The wetlands have the ability naturally to immobilize uranium contaminant through binding to natural organic matters and when we understand how this functions we can also start to think about other technologies,” says Dr. Dien Li of the Savannah River National Laboratory based in South Carolina. 

Li is devoted to a diverse range of research surrounding mines and  contaminated site remediation, which includes the study of groundwater, sediments and the wetlands, nano particle transport in the subsurface, and developing new materials to effectively remove contaminants. 

“Natural attenuation may be among the most cost-effective technologies for treatment of U contaminated sites,” Li says, and studying uranium in these wetlands can help best manage wetlands sequestration.

Recently, he and a team of researchers from Savannah River National Laboratory, Savannah River Ecology Laboratory, Princeton University, Guelph University, the University of Saskatchewan, the University of Chicago and the US Environmental Protection Agency completed a careful study of the biogeochemical behavior of uranium in wetland soils.

Using the HXMA beam line at the Canadian Light Source , the team performed X-ray absorption near-edge structure spectroscopy analysis, which allowed them to identify the uranium’s oxidation state, or number of electrons lost. 

Electron configuration is key to element bonding, so helps researchers predict whether uranium would bond to organic matter in soil, ultimately locking it in place and reducing contamination.

“Uranium(VI) is normally the more bioavailable state, and causes problems for the environment. Uranium (IV) is not mobile, and is not easily bioavailable,” explains Dr. Li. Using HXMA, Li’s team found that uranium mostly existed in the bioavailable U(VI) state in the SRS wetland sediments; however, it might be bonding to organic carbon atoms in the wetlands, making it immobile. 

The impact of wetlands sequestration on U(VI) is good news for the future of uranium site treatment, says Li.

“Understanding the chemical speciation is important to assessing the risk of each contaminated site and to developing new treatment technologies.”

Next, the team plans to confirm their analysis of uranium bonding on a molecular level for an even deeper understanding of uranium treatment. 

This work was supported by Department of Energy, Environmental Management and Office of Sciences, the Savannah River Ecology Laboratory, along with work at the Advanced Photon Source, which is supported by the U.S. Department of Energy.

CLS Scientist Ning Chen conducts experiments on the HXMA beamline. By using powerful X-rays, researchers can determine contaminants around uranium mining sites.
This photo and many others are available for use under a Creative Commons licence in the CLS Flickr Gallery
Story by Victoria Martinez
Cite: Li, Dien, et al. "Retention and chemical speciation of uranium in an oxidized wetland sediment from the Savannah River Site." Journal of environmental radioactivity (2013). 
DOI: http://dx.doi.org/10.1016/j.jenvrad.2013.10.01

About the CLS:

The Canadian Light Source is Canada’s national centre for synchrotron research and a global centre of excellence in synchrotron science and its applications. Located on the University of Saskatchewan campus in Saskatoon, the CLS has hosted 1,700 researchers from academic institutions, government, and industry from 10 provinces and territories; delivered over 26,000 experimental shifts; received over 6,600 user visits; and provided a scientific service critical in over 1,000 scientific publications, since beginning operations in 2005.

CLS operations are funded by Canada Foundation for Innovation, Natural Sciences and Engineering Research Council, Western Economic Diversification Canada, National Research Council of Canada, Canadian Institutes of Health Research, the Government of Saskatchewan and the University of Saskatchewan.

Synchrotrons work by accelerating electrons in a tube to nearly the speed of light using powerful magnets and radio frequency waves. By manipulating the electrons, scientists can select different forms of very bright light using a spectrum of X-ray, infrared, and ultraviolet light to conduct experiments.

Synchrotrons are used to probe the structure of matter and analyze a host of physical, chemical, geological and biological processes. Information obtained by scientists can be used to help design new drugs, examine the structure of surfaces in order to develop more effective motor oils, build more powerful computer chips, develop new materials for safer medical implants, and help clean up mining wastes, to name a few applications.

For more information visit the CLS website 
For photos to accompany this story and more images from the CLS visit our Flickr gallery

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