New study could lead to safer and longer-lived satellites, submarines, and nuclear reactors

Rensselaer professor Suvranu De received a $1 million grant from the DTRA to create a multiscale model that simulates how different metals are affected by neutron irradiation. The model will simulate how irradiation impacts metals at the atomic level, but will also scale up, or “zoom out,” to illustrate how the atomic-level changes create chain reactions that can affect the overall integrity and mechanical properties of the metal. Credit: Rensselaer/Suvranu De

Researchers at Rensselaer Polytechnic Institute have received a $1 million grant from the U.S. Department of Defense (DoD) to model how different metals are affected by neutron irradiation.

The new three-year study, awarded by the DoD’s Defense Threat Reduction Agency and led by Suvranu De, associate professor in the Department of Mechanical, Aerospace, and Nuclear Engineering at Rensselaer, could lead to more effective, more predictable performance of electronic shielding materials in satellites and structural components in submarines and nuclear reactors.

“When satellites are exposed to radiation in space, neutrons impact the atoms of the satellite components, dislodging them from their original positions. These atoms then collide with others, starting a cascade that could ultimately lead to the metal becoming brittle,” De said. “You don’t want a brittle wall on a nuclear submarine, or the electronics in a satellite to be exposed to radiation, so we’re looking very carefully at how the mechanical properties of metals change over time when exposed to radiation. This should allow us to accurately predict the expected lifespan of these metals, and then design better devices.”

De and his team will build complex computational models to simulate the irradiation of different metals at the atomic level, and then scale up to see how the phenomena at the atomic level impact the overall mechanical properties of the material and device.

Starting at the nanoscale, and employing quantum mechanics, the model will look at the cause-and-effect of atomic events that last mere picoseconds — or one-trillionths of a second. That nanoscale model will inform a microscale model, which measures events in microseconds and nanoseconds, or one-millionths to one-billionths of a second. Similarly, the microscale model will feed into a larger model, which in turn will feed into the fourth, life-size model which measures the irradiation of metals in terms of seconds, days, and years.

The trick, De says, is developing code that allows the different models to “speak the same language” and correctly share information, in order to create the larger, self-consistent, multiscale model.

“Using quantum mechanics, we can predict what happens when a single neutron knocks out a few atoms from where they’re supposed to be, and then trace that chain reaction from the atomic scale to the microscale, mesoscale, and finally to the macroscale to see how that initial atomic fender bender leads to the eventual mechanical failure of the device,” De said. “We hope this research will lead to the design of self-healing metals that can withstand radiation for long periods of time without endangering their structural integrity or mechanical properties.

De is working on this study with Hanchen Huang, professor of mechanical engineering at the University of Connecticut.