Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Discovery sheds light on nuclear reactor fuel behavior during a severe event

21.11.2014

A new discovery about the atomic structure of uranium dioxide will help scientists select the best computational model to simulate severe nuclear reactor accidents.

Using the Advanced Photon Source (APS), a Department of Energy (DOE) Office of Science User Facility, researchers from DOE’s Argonne National Laboratory and Brookhaven National Laboratory, along with Materials Development, Inc., Stony Brook University, and Carnegie Institution of Washington, found that the atomic structure of uranium dioxide (UO2) changes significantly when it melts.


An Argonne-led research team found that when uranium dioxide melts, the number of oxygen atoms around uranium changes from eight-fold to a mixture of six- and sevenfold, which alters how it interacts with other materials. The discovery about will help scientists select the best computational model to use when simulating severe nuclear reactor accidents.

UO2 is the primary fuel component in the majority of existing nuclear reactors, but little is known about the molten state because of its extremely high melting point. Until now, the extremely high temperature and chemical reactivity of the melt have hindered studies of molten UO2. This lack of fundamental information has made it difficult to evaluate issues associated with the interaction of molten UO2 with a reactor's zirconium cladding and steel containment vessel.

The research team found that when uranium dioxide melts, the number of oxygen atoms around uranium changes from eight-fold to a mixture of six- and seven-fold, which changes the way it interacts with other materials. Many existing models, however, do not account for this change in structure or the rapid oxygen dynamics that occur at high temperatures.

"Determining the behavior of UO2 under extreme conditions is essential to enhancing our understanding of reactor safety during severe accidents," said Mark Williamson of Argonne’s Chemical Sciences and Engineering Division.

"Very few places in the world have the capability to safely measure the structure of molten UO2 at 3,000 degrees Celsius without introducing contamination from the container that holds the melt," added Chris Benmore of Argonne’s X-ray Science Division.

Researchers studied the UO2 in the hot crystalline and molten states. In this experiment, researchers relied on the APS's high-energy synchrotron X-ray beam to study a bead of UO2 that was aerodynamically levitated on a stream of argon and heated with a laser beam.

X-ray experiments were performed at sector 11-ID-C at the APS.

The work was funded by the DOE Office of Science (Office of Basic Energy Sciences), the DOE Small Business Innovation Research program and the Argonne Laboratory Directed Research and Development program.

The paper, "Molten uranium dioxide structure and dynamics," is published in Science magazine. To view the paper, visit the Science website.

“Our group plans to continue to use innovative synchrotron techniques to study molten materials like this,” said John Parise, who holds a joint appointment with Brookhaven National Laboratory and Stony Brook University. “The next steps include putting molten materials under different atmospheres, and that requires modifications to the existing set-up used at APS.”

Parise said this group of researchers, which includes colleagues from Materials Development, Inc., who built the apparatus used to study UO2, is discussing designs for next-generation levitation devices that could be installed at the X-Ray Powder Diffraction beamline at Brookhaven’s National Synchrotron Light Source II, for example.

“There’s a lot more work to be done," Parise said. "It’s important to understand how many other materials behave in a molten state. Theory is a good way to do that, but theorists need data on how atoms interact with each other in the molten state, under conditions that are as realistic as possible.”

The authors are Lawrie B. Skinner, of Argonne, Stony Brook University and Materials Development, Inc.; Chris J. Benmore, Mark A. Williamson, Andrew Hebden, Thomas Wiencek and Leonard Leibowitz, all of Argonne; Johann K.R. Weber and Oliver L.G. Alderman, of Argonne and Materials Development; Anthony Tamalonis of Materials Development; Malcolm Guthrie, of the Carnegie Institution of Washington; and John B. Parise, of Stony Brook University.

Rick Spence and Douglas Robinson, both of Argonne's X-ray Science Division, provided technical support and useful discussion.

Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation's first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America's scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

Tona Kunz | EurekAlert!
Further information:
http://www.anl.gov/articles/discovery-sheds-light-nuclear-reactor-fuel-behavior-during-severe-event

More articles from Physics and Astronomy:

nachricht Pulses of electrons manipulate nanomagnets and store information
21.07.2017 | American Institute of Physics

nachricht Vortex photons from electrons in circular motion
21.07.2017 | National Institutes of Natural Sciences

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA looks to solar eclipse to help understand Earth's energy system

21.07.2017 | Earth Sciences

Stanford researchers develop a new type of soft, growing robot

21.07.2017 | Power and Electrical Engineering

Vortex photons from electrons in circular motion

21.07.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>