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Nuclear mattersMore efficient nuclear fuel sought

Published 16 September 2009

DoE funds research to address the shortcomings of uranium dioxide — the fuel most commonly used to generate nuclear energy

Researchers headed by a California Davis University physics professor searching for more efficient fuels for nuclear reactors have received a grant of almost $1.2 million from the U.S. Department of Energy. The team will use the money to develop computer models that will allow it to theoretically manipulate the fuels and investigate their behavior.

Professor Sergey Savrasov will work with two colleagues at Rutgers University in New Jersey to address the shortcomings of uranium dioxide — the fuel most commonly used to generate nuclear energy. As uranium dioxide is an insulator, it heats unevenly during the reactor cycle. During the cycle, as temperatures approach the material’s melting point around 4,900oF, extreme heat differences within the bulk of the fuel cause it to crack and burn inefficiently.

To avoid this problem, scientists have been looking for fuels with good thermal conductivity. “You could use metallic fuels because they conduct heat very well,” said Savrasov. “But you also have to have a fuel with a high melting temperature because you don’t want the material to melt. So what we are looking for are those materials that have better thermal conductivities and higher melting temperatures.”

The team will work with computer models of the fuels as working with nuclear reactor fuels is extraordinarily expensive. Not only are they costly, but the explosive and radioactive materials require many protective and safety measures.

Savrasov has been collaborating on similar projects with his two colleagues at Rutgers, Kristjan Haule and Gabriel Kotliar, for nearly a decade.

Their current work will focus on oxide, nitride and carbide compounds of uranium and plutonium as well as their mixtures with certain elements that are created during fission, including neptunium, americium and curium. The trio will also study and model properties of various metallic alloys such as uranium-zirconium and plutonium-aluminum.

Building a robust theory that can predict the complex behavior of these materials has great potential for the computational design of advanced nuclear energy systems,” added Savrasov. 

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