UNT Research, Volume 18, 2009 Page: 46
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senior technology specialist with the U.S.
Department of Energy.
Hetherly explains that in a fast reac-
tor, as opposed to a more conventional
thermal reactor, the fission chain reaction
is sustained without slowing, or moderat-
ing, the neutrons.
"The absence of a moderator requires
fuels that are more dense, but it allows
higher energy production per atom of
fuel, resulting in a more efficient use of
resources," he says.
Although many conventional nuclear
reactors are built with stainless steels,
materials in fast reactors are exposed to
higher radiation levels. Radiation exposure
eventually causes the steel to bulge, reduc-
ing its structural integrity.
"Newer ways of processing stain-
less steel potentially solve the problem,"
Hetherly says, "but the steels haven't been
fully tested, and physical experiments are
very expensive. Accurate computer mod-
eling offers a relatively low-cost way to
reduce the number of experiments needed
to test them."
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Under the guidance of Srinivasan
Srivilliputhur, assistant professor of materi-
als science and engineering, and Duncan
Weathers, associate professor of physics,
Hetherly uses computer models and simu-
lations to examine how the new stainless
steels react to high doses of radiation.
"With the models, we are able to
track each atom's position in an artificial
sample," he says. "This allows us to see
where each atom goes when it is hit with
radiation and how well the sample retains
its shape. With scientists at Los Alamos
National Laboratory, we can speed up the
simulation to see how the material will
react over long periods of time."
A mathematical program Hetherly
is writing will be tested on the Center
for Advanced Scientific Computing and
Modeling computer cluster at UNT. He
also will run his calculations on super-
computer clusters at the Texas Advanced
Computing Center in Austin and Lawrence
Livermore National Laboratory in Liver-
"Using the supercomputers, I can
manipulate more atoms in the same amount
of time or the same amount of atoms in
less time," Hetherly says.
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As an increasing number of develop-
ing countries plan to use nuclear power as
a way of supplying energy, it has become
necessary to ensure that these plants have
less impact on the environment.
"More countries are building new
nuclear power plants and are experimenting
with ways to reprocess and use the waste
from older plants for fuel," Hetherly says.
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S. Department of Energy, Jeff
Hetherly will use computer models
JInd simulations to study the effects of
radiation on stainless stool
Spent fuel rods are the most radioac-
tive of all nuclear wastes, and that radioac-
tivity takes thousands of years to decay. By
identifying building materials that absorb
fewer radioactive atoms and predicting
the lifespan of materials used in new fast
nuclear reactors, Hetherly's research will
allow more efficient structures to be built.
If the materials do not have to be replaced
as often, fewer nuclear waste storage facili-
ties will be needed, resulting in tremendous
cost savings for the industry as well as
good news for the environment.
"With these new materials, it would
take much less time for the harmful radio-
active material to decay in underground
storage," Hetherly says.
Hetherly competed for the AFCI
fellowship against more than 100 top stu-
dents in science and engineering fields from
universities including the Massachusetts
Institute of Technology and the University
of California at Berkeley. In the summer,
he traveled with the other new AFCI
fellows to visit the DOE headquarters in
Washington, D.C., and Argonne National
Laboratory in Illinois.
"I encourage the AFCI fellows to
work with national labs and the DOE
headquarters and to network with each
other," says Cathy Dixon, coordinator of
the fellowship program and director of
the University Research Alliance at West
Texas A&M. "The students chosen for the
program are the cream of the crop, and
they will work together throughout their
Hetherly says he is looking forward to
working with the other fellows and learning
from contacts at the national labs.
"It's a wonderful opportunity." I
46 " SPRING 2009 UNT RESEARCH
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University of North Texas. UNT Research, Volume 18, 2009, periodical, 2009; Denton, Texas. (digital.library.unt.edu/ark:/67531/metadc115032/m1/46/: accessed March 28, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting University Relations, Communications & Marketing department for UNT.