Scientists discover how the structure of plutonium nanocluster
contaminants increases risk of spreading
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ARGONNE, Ill. (April 22, 2008) — For almost half a century, scientists have
struggled with plutonium contamination spreading further in groundwater than
expected, increasing the risk of sickness in humans and animals.
Funding for this research was provided by the U.S. Department
of Energy, Office
of Science, Office of Basic
Energy Sciences. The mission of the Basic Energy Sciences (BES)
program – a multipurpose,
scientific research effort – is to foster and support fundamental research
to expand the scientific foundations for new and improved energy technologies
and for understanding and mitigating the environmental impacts of energy
use. The portfolio supports work in the natural sciences, emphasizing
fundamental research in materials sciences, chemistry, geosciences, and
aspects of biosciences. |
It was known nanometer-sized clusters of plutonium oxide were the culprit,
but no one had been able to study its structure or find a way to separate it
from the groundwater.
Scientists at the U.S. Department of Energy's Argonne National Laboratory,
in collaboration with researchers from the University
of Notre Dame, were able
to use high-energy X-rays from the Advanced
Photon Source (APS) at Argonne
to finally discover and study the structure of plutonium nanoclusters.
" When plutonium forms into the clusters, its chemistry is completely
different, and no one has really been able to assess what it is, how to model
it or how to separate it," said Argonne senior chemist Lynda Soderholm. "People
have known about and tried to understand the nanoclusters, but it was the modern
analytical techniques and the APS that allowed us understand what it is."
The nanoclusters are made up of exactly 38 plutonium atoms and have almost
no charge. Unlike stray plutonium ions, which carry a positive charge, they
are not attracted to the electrons in plant life, minerals, etc. which stopped
the ions' progression in the ground water.
Models have been based on the free-plutonium model, creating discrepancies
between what is expected and reality. Soderholm said that with knowledge of
the structure, scientists can now create better models to account for not only
free-roaming plutonium ions, but also the nanoclusters.
The clusters also are a problem for plutonium remediation. The free ions are
relatively easy to separate out from groundwater, but the clusters are difficult
to remove.
"As we learn more, we will be able to model the nanoclusters and figure
out how to break them apart," Soderholm said. "Once they are formed,
they are very hard to get rid of."
Soderholm said other experiments have shown some clusters with different numbers
of plutonium atoms, and she plans to examine their unique electric and magnetic
properties – together with her collaborators S. Skanthakumar, Richard Wilson
and Peter Burns of Argonne's Chemical Sciences and Engineering Division.
Funding for the research was provided by the U.S. Department
of Energy, Office of
Science, Office of Basic
Energy Sciences.
The mission of the Basic Energy Sciences (BES) program – a multipurpose, scientific
research effort – is to foster and support fundamental research to expand the
scientific foundations for new and improved energy technologies and for understanding
and mitigating the environmental impacts of energy use. The portfolio supports
work in the natural sciences, emphasizing fundamental research in materials
sciences, chemistry, geosciences, and aspects of biosciences.
Argonne National Laboratory brings the world's brightest scientists and engineers
together to find exciting and creative new 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 managed by UChicago
Argonne, LLC for the U.S.
Department of Energy's Office
of Science.
For more information, please contact Brock Cooper (630/252-5565
or bcooper@anl.gov) at Argonne.
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