A New Approach to Fusion Power Plant Materials

MIT PhD student Alexander O’Brien is working to deliver the next generation of fusion devices through research on additive manufacturing of metal-ceramic composites. “After years of knowing I wanted to work in green energy, but not knowing what that looked like, I very quickly fell in love with nuclear engineering.” 

When Alexander O’Brien sent in his application for graduate school at MIT's Department of Nuclear Science and Engineering, he had a research idea. The student from Arkansas wanted to explore the design of materials that could hold nuclear reactors together.

Dr. Ju Li, Battelle Energy Alliance Professor in Nuclear Engineering, wanted to explore AM for nuclear reactors and O’Brien seemed like the right candidate. Under the advisement of Ju Li, the fourth-year doctoral student now explores AM of ceramic-metal composites, materials that can be used to construct fusion power plants.

A fresh blueprint for fusion power plants

O’Brien’s current research at MIT's Department of Nuclear Science and Engineering (NSE) is important. As the design of new fusion devices kicks into gear, it’s becoming increasingly apparent that the materials just don’t hold up to the higher temperatures and radiation levels in operating environments, O’Brien says. Additive manufacturing “opens up a whole new realm of possibilities for what you can do with metals, which is exactly what you’re going to need to build the next generation of fusion power plants,” he says.

Metals and ceramics by themselves might not do the job of withstanding high temperatures (750 °C is the target), stresses, and radiation, but together they might get there. Although metal matrix composites have been around for decades, they have been impractical for use in reactors because they’re difficult to make with any kind of uniformity and really limited in size scale.

O’Brien’s work focuses on nickel superalloys like Inconel 718, which are especially robust candidates because they can withstand higher operating temperatures while retaining strength. To create the composites, first a mechanical milling process coats the ceramic onto the metal particles. The ceramic nanoparticles act as reinforcing strength agents, especially at high temperatures, and make materials last longer. The composite is then processed with a laser powder bed fusion system.