New nanomaterial exploits radiation to create more powerful nuclear reactors

An international team of researchers have created a nanoceramic material that not only can withstand the harsh effects of radiation, but that also becomes tougher when exposed to it.

The next generation nuclear systems, many of which are already being fielded by China will operate at higher temperatures and will have larger radiation fields than ever before which will let them produce energy more efficiently and economically.

Traditionally energy companies have used water as the primary coolant in reactors and while water poses fewer risks than some of the other coolants that are available, such as liquid metals like Sodium and Lead that can lead to increased levels of corrosion, they're often limited by their maximum operating temperatures and in advanced reactors increasing their temperature is the best way to increase energy production.

"There is a preferred use of metallic materials for structural components, but many of these materials cannot withstand high-temperature corrosion in advanced reactors," says Kumar Sridharan, a distinguished research professor in engineering physics and materials science and engineering at the University of Wisconsin-Madison.

"Corrosion is a surface phenomenon, so if you put coating on the surface, you need that coating to withstand high radiation doses without becoming embrittled."

Sridharan and collaborators at the Istituto Italiano di Tecnologia (IIT) in Milan, Italy, characterized an aluminium oxide nanoceramic coating – a new material that can withstand the harmful effects of these high-temperature liquid metals in advanced reactors and this material could be a huge boon to these systems. The researchers described it in their paper, "Radiation endurance in Al2O3 nanoceramics," published in the Nature journal Scientific Reports.

Many materials tend to harden and crack when exposed to radiation. However, aluminium oxide nanoceramic coatings toughen, ultimately benefitting from irradiation, says Fabio Di Fonzo, a team leader at the IIT Center for Nano Science and Technology.

"The pinpoint of our work is the demonstration that an amorphous or nanoceramic material can improve during irradiation, and this opens the path toward a different view of nuclear materials, specifically where coatings are concerned," he says.

Di Fonzo's lab has been producing aluminium oxide nanoceramics for a few years now, collaborating with Sridharan's group, who used transmission electron microscopes to analyse the new materials properties.

"Di Fonzo's lab developed the coating and exposed it to radiation, and we conducted analysis and helped them interpret the result," says Mairov. "We correlated changes they observed in the mechanical properties with changes in the nanoscale structure."

The researchers anticipate that this unique material will be able to make next-generation reactors more safe and economical overall, as well as perhaps finding its way one day into the space industry where it could help protect spacecraft, or even space habitats, against radiation in space.

"It's a paradigm shift in the field, because so far there has not been a material that actually exploits radiation," says García Ferré, "with this new material, we benefit from a radiation environment to tailor the evolution of the mechanical properties of the material. In particular, we are able to have a material that, by the end of its lifetime, has similar mechanical properties as when it was first exposed to radiation.