UW-Madison: Radiation Studies Key to Nuclear Reactor Life, Recycling Spent Fuel

CONTACT: Todd Allen, (608) 265-4083; allen@engr.wisc.edu

MADISON – Two University of Wisconsin-Madison projects to study advanced materials
and fuels for current and future nuclear reactors received roughly $1 million this
month under the Department of Energy Nuclear Energy Research Initiative (NERI).

The NERI program supports research and development under three Department of Energy
nuclear initiatives: Generation IV nuclear energy systems, advanced fuel cycles and
nuclear hydrogen.

In one three-year project, UW-Madison nuclear engineers will study the resistance to
radiation damage of oxide, carbide and nitride nuclear fuel “matrix” materials-the
vessels that contain nuclear fuel. A second project will exploit recent advances in
computational power and technique to develop computer models of how a reactor’s
structural materials behave as a result of long-term radiation exposure.

The projects were among 24 selected across the country; UW-Madison was among five
universities to receive funding for multiple projects.

Matrix materials are a key element of future fast-spectrum reactors, which are
capable of safely and efficiently recycling spent nuclear fuel. The nuclear fission
process produces high-energy radioactive neutrons, called “fast” because of their
great energy. Current thermal reactors use a moderator to reduce the neutrons’
velocity, making them capable of sustaining the nuclear fission reaction using
simpler fuel.

But to recycle and minimize the waste impact of the spent fuel, you need to keep
those neutrons fast, says Todd Allen, an assistant professor of engineering physics.
He and James Blanchard, a professor of engineering physics, are researching how
proposed matrix materials hold up under a barrage of radiation.

“It’s all in the context of devising new fuel forms that will allow you to
efficiently recycle reactor fuel in a way that minimizes the net waste output from
the entire fuel cycle,” says Allen. “And the reason for looking at recycle is to
limit the number of underground repositories you have to build.”

Another project involves applying complex materials modeling to nuclear reactors. In
it, Allen and Dane Morgan, an assistant professor of materials science and
engineering, will incorporate the properties of iron, chromium and nickel into more
complete computer models of radiation damage in steel, a common reactor structural
material.

Previously, a lack of computing power limited such models to single pure materials
like copper or iron. “People have learned a lot about radiation damage,” says Allen.
“But you never build anything out of just copper or just iron.”

The effort may lead to structural materials that are better able to withstand
long-term exposure to radiation-in some cases, nearly 60 years, says Allen.