Part 1 of 2 Parts
MIT researchers have developed a technique that permits real-time, 3D monitoring of corrosion, cracking, and other material failure processes inside a nuclear reactor environment.
This development could allow engineers and scientists to design safer nuclear reactors that also deliver higher performance for applications like electricity generation and naval vessel propulsion.
During their experiments, the MIT researchers utilized extremely powerful X-rays to replicate the behavior of neutrons interacting with a material inside a nuclear reactor.
They discovered that adding a buffer layer of silicon dioxide between the material and its substrate, and keeping the material under the X-ray beam for a longer period of time, improved the stability of the sample. This permits real-time monitoring of material failure processes.
By reconstructing 3D image data on the structure of a material as it fails, researchers will be able to design more resilient materials that can better withstand the stress caused by irradiation inside a nuclear reactor.
Ericmoore Jossou has shared appointments in the Department of Nuclear Science and Engineering (NSE), where he is the John Clark Hardwick Professor, and the Department of Electrical Engineering and Computer Science (EECS), and the MIT Schwarzman College of Computing. He said, “If we can improve materials for a nuclear reactor, it means we can extend the life of that reactor. It also means the materials will take longer to fail, so we can get more use out of a nuclear reactor than we do now. The technique we’ve demonstrated here allows researchers to push the boundary in understanding how materials fail in real-time.”
Jossou is a senior author of a study on this technique. He is joined on the paper by lead author David Simonne, an NSE postdoc; Riley Hultquist, a graduate student in NSE; Jiangtao Zhao, of the European Synchrotron; and Andrea Resta, of Synchrotron SOLEIL. The research has been published in the journal Scripta Materiala.
Simonne added, “Only with this technique can we measure strain with a nanoscale resolution during corrosion processes. Our goal is to bring such novel ideas to the nuclear science community while using synchrotrons both as an X-ray probe and radiation source.
Studying real-time failure of materials used in advanced nuclear reactors has been a long-time goal of Jossou’s research group.
Currently, researchers can only learn about such material failures after the fact, by removing the material from its environment and imaging it with a high-resolution instrument.
Simonne continued, “We are interested in watching the process as it happens. If we can do that, we can follow the material from beginning to end and see when and how it fails. That helps us understand a material much better.”
They simulate the process by firing a tightly focused X-ray beam at a sample to mimic the environment inside a nuclear reactor. The researchers must employ a special type of high-intensity X-ray, which is only available in a handful of experimental facilities worldwide.
For their experiments they studied nickel, an element incorporated into alloys that are commonly used in advanced nuclear reactors. But prior to the start of the experiment, they had to prepare a sample.
To do this, the researchers utilized a process called solid state dewetting. This process involves putting a thin film of a material onto a substrate and heating it to an extremely high temperature in a furnace until it transforms into single crystals.
Jossou said, “We thought making the samples was going to be a walk in the park, but it wasn’t.”
MIT Nuclear Research Laboratory
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