Allison Harward is a senior studying chemical engineering at the University of Utah. She has co-authored four papers and given several conference presentations. Her research focuses on using molten salt for sustainable nuclear energy.
One important use of molten salt is in the process of nuclear recycling. It is used as the fluid in an electrorefiner that separates uranium from spent fuel rods. This makes it possible to reuse the uranium as fuel for nuclear reactors.
The problem with this process is that the molten salt’s composition changes over time from processing spent fuel. Ultimately, the salt has a high melting point and must be disposed of. This salt is hygroscopic, meaning it tends to absorb water from the air to the point of forming a liquid salt solution, which is very corrosive and can readily corrode its container and leak into the environment. Given the radioactivity of the salt, this would be highly detrimental to the environment.
Harward has worked on a team of researchers that include her advisor, Professor Michael Simpson, and scientists from Idaho National Laboratory. She has taken an innovative approach to stabilizing the element, by utilizing a microporous material known as Zeolite 4A. Zeolite 4A has a crystalline structure that works to make it act as a sponge for salts such as those used for uranium electrorefining. Various chemical exchanges occur between the molten salt and Zeolite 4A, making the molten salt less hygroscopic.
Ultimately, this salt still needs to be disposed of. “This intermediate waste form is a safer version of the molten salt, and it has less risk of corrosion. It isn’t a final waste form, as it requires further processing, but it is a better alternative,” she said.
Although she is in her final semester, she plans to continue her work after graduation.
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