Nuclear reactors power everything from electricity grids to naval ships, but keeping them safe over decades of use is one of the toughest engineering challenges.
At the heart of the problem are the materials themselves.
Metals inside reactors must withstand intense radiation, high heat, and corrosive environments.
Over time, they can crack, corrode, or fail in ways that are often invisible until it’s too late.
Now, researchers at MIT have developed a new way to actually watch these failures happen in real time, at the scale of individual crystals inside the metal.
This technique, which uses extremely powerful X-rays, could help scientists design materials that last longer, making reactors safer and more efficient.
Seeing failure as it happens
Traditionally, scientists could only study damaged reactor materials after the fact.
A sample would be removed, analyzed, and imaged—giving a snapshot of what went wrong, but not showing how the damage developed. Ericmoore Jossou, a professor of nuclear science and engineering at MIT and the senior author of the study, says his team wanted to see the whole process unfold.
“We are interested in watching the process as it happens,” he explains. “If we can follow the material from beginning to end, we can understand when and how it fails. That knowledge is invaluable for designing stronger materials.”
To mimic the extreme conditions inside a nuclear reactor, the team turned to synchrotrons—facilities that generate some of the world’s most powerful X-ray beams. These beams can probe the structure of a material in three dimensions and at the nanoscale, all while the material is under stress.
For their experiments, the team focused on nickel, a key ingredient in alloys commonly used in advanced nuclear reactors. But preparing the samples proved more difficult than expected.
The researchers used a process called solid-state dewetting, in which a thin film of nickel is placed on a silicon wafer and then heated until it transforms into crystals. Unfortunately, when nickel touched the silicon directly, the two reacted and formed a new chemical compound, spoiling the experiment.
After repeated trial and error, the team discovered that adding a thin layer of silicon dioxide between the nickel and silicon wafer solved the problem. This buffer layer stopped unwanted chemical reactions and allowed the nickel crystals to form properly.
There was still another challenge. When the crystals grew, they were under heavy strain, meaning the atoms were slightly displaced from their usual positions. Normally, this much strain would prevent imaging algorithms from reconstructing the crystals’ 3D structure.
But then the team noticed something surprising: if they kept the X-ray beam on the sample for a few extra minutes, the strain gradually relaxed. With the buffer layer in place, the nickel crystals stabilized just enough to allow detailed imaging.
“No one had been able to do that before,” says Jossou. “Now we can actually watch processes like corrosion and cracking unfold in three dimensions, under conditions similar to a nuclear reactor. That’s a huge step forward.”
Beyond nuclear power
The discovery didn’t just open a new window into nuclear reactor materials. It also revealed a potential tool for a completely different field: microelectronics.
Engineers in microelectronics often manipulate strain in materials to change their electrical or optical properties. With MIT’s new technique, X-rays could be used to precisely control strain during manufacturing, potentially offering new ways to design faster, more efficient devices.
“While this wasn’t our main goal, it’s like getting two discoveries for the price of one,” Jossou says.
The MIT team now plans to extend this work to more complex materials, including steel and other alloys used in both nuclear and aerospace applications. They also want to test how changing the thickness of the silicon dioxide buffer layer might affect their ability to control strain.
Experts outside the study are taking notice. Edwin Fohtung, a professor at Rensselaer Polytechnic Institute, called the work “significant,” saying it not only improves our understanding of how nanoscale materials respond to radiation but also highlights how the supporting surface—the substrate—can determine whether particles release or retain strain when exposed to X-rays.
Ultimately, Jossou believes the technique could help extend the lifespan of nuclear reactors by enabling the development of tougher, more reliable materials. Longer-lasting materials would mean reactors could run safely for more years before requiring costly replacements.
“If we can improve materials for a nuclear reactor, it means we can extend the life of that reactor,” he says. “It also means the materials will take longer to fail, so we can get more use out of the reactor than we do now.”
By showing how metals corrode and crack in real time, MIT’s team has given the nuclear industry—and perhaps even the electronics world—a powerful new tool.
And as the world seeks cleaner energy and more resilient technologies, being able to watch materials fail might turn out to be one of the best ways to make them stronger.
