Renewable energy sources such as solar and wind will, and should, continue to grow, but conventional wisdom in energy circles identifies nuclear power as one of the most reliable, portable, and green baseload energy sources to support a comprehensive modern energy grid. The negative perception of high-profile accidents such as Three Mile Island and Fukushima highlight outdated nuclear technology when advanced materials and their methods of manufacture weren’t available.
Organizations like Ultra Safe Nuclear Corporation (USNC) use advanced manufacturing to make safe, controlled, and reliable nuclear energy a reality. Binder jet 3D printing plays a fundamental role in USNC’s innovative fuel design that allows the company to control nuclear fission and prevent accidents altogether.
The key to their approach is Fully Ceramic Micro-encapsulated (FCM) fuel, the manufacturing of which is enabled by Desktop Metal innovative X-Series binder jet systems and their ability to 3D print heat-resistant ceramic particles in unique geometries that can safely surround a standard type of nuclear fuel particle known for its safety.
Today, USNC is using the novel approach to fuel its extremely reliable and safe micro modular reactor (MMR™) energy systems. Application of Desktop Metal binder jet 3D printers facilitates a key step in manufacturing of USNC’s fuel, which is vital to executing the organization’s underlying innovation.
Traditionally, nuclear fuel microspheres are put into a soft graphitic matrix. However, these were not structurally strong and served as a poor barrier to radionuclide release.
USNC’s answer was to replace this graphitic matrix with a refractory ceramic: silicon carbide (SiC). SiC is a technical ceramic material with extreme environmental stability that is often used in aerospace, armor, plasma shield, and high-temperature applications. The conditions within a nuclear reactor are some of the harshest in all of industry, yet SiC doesn’t shrink or excessively swell like the traditional graphitic matrix and has a very high resistance to oxidation and corrosion, offering unique stability under all the demanding conditions of the nuclear reactor core.
“Through exploiting fundamental laws of nature, we’ve created a design for a passively safe reactor, so you don’t need a concrete dome, exclusion zone, or big water reservoir because it’s inherently safe,” Terrani said, explaining the idea behind USNC’s approach. We’re leveraging a high-temperature resistant fuel with multiple inherent barriers to radiation release at the center of our reactor system. That is the essence of the Ultra Safe Nuclear approach.”
The 3D printed SiC fuel forms may have complex geometries that act as shells for the nuclear fuel particles. Silicon carbide will often be infiltrated with silicon or other matrices for densification; however, this is not an option in a nuclear environment. “Radiation will affect one material one way and another differently, so material uniformity and homogeneity is key,” Terrani said.
By marrying binder jetting with chemical vapor infiltration to fill the porous SiC structure with more high-purity crystalline silicon carbide, USNC is able to realize highly complex, near-net shapes without the need to sinter the SiC material, apply any pressure, or introduce secondary phases.
“There was a whole host of additive manufacturing methods out there, but a large portion of those rely on a high-temperature process during deposition,” Terrani explained. “With metals they’re melting the particles to connect them together, but you can’t do that with the high melting point of silicon carbide. Binder jet technology is unique because it really relies on the physical characteristics of the powder, and it’s essentially highly agnostic to the chemical and phase structure of the material. So, we can select highly pure, highly crystalline carbide feedstock powder, nuclear grade powder, and then form these really complex geometries, and that just wasn’t previously possible.”
Binder jet 3D printing directly from digital design files without the need for tooling allows the USNC team to iterate their designs quickly and create unique shapes not otherwise manufacturable. Beyond performance, the ability to create unique designs en masse with 3D printing allows USNC to add an additional layer of quality assurance to its mission of safe, responsible nuclear energy.
“We print an ID on these parts, so from the moment of birth we track the reactors’ manufacturing DNA throughout production, operational lifetime, and upon their discharge,” Terrani said. “Binder jetting allows us to create a new paradigm of safe, reliable, carbon-free nuclear energy for use by industry and remote communities.”
Download the complete case study to learn how USNC 3D prints technical ceramics to create safe nuclear fuel cells with Desktop Metal X-Series binder jet machines:
