Tuesday, September 29, 2009

GSU scientists investigate a type of soil’s ability to absorb byproduct of nuclear reactions

Georgia State University researchers, in conjunction with the U.S. Department of Energy and the Georgia Tech Research Institute, are investigating whether a type of soil might absorb a radioactive isotope, perhaps leading to better ways of remediating a byproduct of nuclear reactions.

W. Crawford Elliott, chair of the Department of Geosciences, is the lead investigator on a project to evaluate the absorption of cesium-137 by a soil commonly found in the Piedmont regions of the South at the Savannah River Site in South Carolina, near Augusta, Ga. The research has been funded with a $149,477 grant from the Department of Energy Office of Biological and Environmental Research.

Cesium-137 is a byproduct nuclear fission with uranium-235. The fission releases energy that can be used in nuclear reactors to produce power.

The Savannah River Site, located in Aiken and Barnwell counties in South Carolina was the home of production for elements of nuclear weapons during the Cold War, but much of the work performed there now involves mitigation of the legacies of nuclear reactions.

Cesium-137, which has a half-life of about 30 years, emits both beta particles and gamma radiation. It has been found in the environment as a result of nuclear waste and accidental releases.

One hypothesis is that a common soil mineral in Piedmont regions, called hydroxy interstratified vermiculite, might absorb the cesium, and researchers will first test the soil using natural, non-radioactive cesium-133.

“We think that there’s a special place in the hydroxy interstratified vermiculite lattice that favors the uptake of cesium, and if that's the case, we’re first going to study these soils to see how much natural cesium is being taken up,” Elliott said.

The next step is to take cesium-137 and pour it through the soil to see what kind of exchange happens.

“We have a good hypothesis that these soils sequester natural cesium on their own, as much and maybe more so than other micas or other kinds of minerals,” Elliott said.

The work might lead scientists to a better understanding of how to mitigate the radioactive element.

“The project would certainly give us some of the best knowledge about the role of soils in the process and how they could naturally attenuate the cesium," he said.

A side project will investigate a byproduct of kaolin processing — a clear, shiny mica that is sorted out from kaolin and sold to paint companies and others. The mica might be able to absorb and mitigate cesium-137.

“You might be able to make into a permeable barrier, or even make it into a material similar to what’s used at a grocery store to clean up a spill,” Elliott said.

Elliott is working on the project with Seth Rose and Eirik Krogstad, associate professors of geosciences at Georgia State; Marion Wampler, adjunct associate professor in geosciences; Bernd Kahn and Robert Rosson of the Georgia Tech Research Institute; and Daniel Kaplan of the U.S. Department of Energy.

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