Small, modular nuclear fission reactors are emerging as a resilient energy option, offering a scalable, cost-effective path to reliable power for remote or infrastructure-limited locations. However, these advanced reactor facilities typically run hotter and longer than conventional light water reactors, so they will require a new type of nuclear fuel tough enough to withstand harsher operating conditions.
Through a Strategic Partnership Project with micronuclear reactor startup AMPERA, Lawrence Livermore National Laboratory (LLNL) engineers are applying a novel metallic-particle manufacturing capability toward producing this robust nuclear fuel.
"Public-private projects like this show the value of connecting LLNL's world-class research capabilities with industry partners who have a clear technology need and sharp commercial focus," said Viktor Sukhotskiy, LLNL research engineer and principal investigator.
The Thorium UNimodal Droplet Ejection for Reactors (THUNDER) project aims to produce precursor thorium kernels for later processing into TRi-structural ISOtropic (TRISO) fuel. A fully encapsulated fuel particle made to prevent the release of radioactive fission products, TRISO fuel is designed for advanced reactors operating under challenging conditions.
"Lawrence Livermore National Laboratory has a long and distinguished record of translating advanced science into technologies of national importance," said AMPERA founder and CEO Brian Matthews. "We believe this collaboration can accelerate the technical foundation required to vertically integrate our fuel supply, reduce cost and supply-chain risk, and support the deployment of our compact subcritical nuclear energy systems."
THUNDER connects several key Department of Energy and Laboratory priorities, including domestic energy resilience. Small modular reactors can deploy to infrastructure-limited locations, offering a way to supply reliable power to isolated communities, military installations and industrial sites without placing demand on a centralized grid. This project also sustains Laboratory leadership in advanced manufacturing and demonstrates a technology-transfer pathway that spins out early-stage LLNL research into commercially relevant partnerships.
From liquid metal to nuclear fuel
Thorium, as a nuclear fuel material, offers several advantages: it is abundant, produces a less persistent waste stream and is more difficult to weaponize, adding a layer of proliferation resistance. Thorium-232 cannot sustain a fission chain reaction on its own, but when it absorbs a neutron, it decays into uranium-233, which is fissile. A thorium reactor therefore breeds its own fuel as it operates, though it still needs a "seed" of fissile material, typically uranium or plutonium mixed with the thorium, to start and sustain the reaction.
Each TRISO particle contains a fuel kernel enclosed in layers of carbon- and ceramic-based materials that help retain radioactive fission products. TRISO particles are resistant to neutron irradiation, corrosion, oxidation and high temperature - factors that impact fuel performance.
The THUNDER collaboration grew from PowderJet, an LLNL Laboratory Directed Research and Development project in which Sukhotskiy and his collaborators developed a unique approach for producing highly spherical, size-controlled metallic particles using droplet-on-demand liquid metal jetting.
"Project THUNDER shows how early LLNL investment in manufacturing and materials science can lead directly to external partnerships in strategically important technology areas," Sukhotskiy said. "PowderJet grew out of foundational work in liquid metal jetting, and we are now applying it to a challenging nuclear fuel problem with real commercial relevance."
In the TRISO fuel development pathway, tiny thorium kernels at the center must be produced with tight control over particle size, shape and composition. PowderJet can produce such metallic particles at scale with a level of uniformity that is difficult to achieve through conventional powder-production methods.
The work of the partnership will include computational modeling, materials and nozzle compatibility testing, high-temperature process development, particle characterization, safe radiological handling, and transfer of scalable process and design rules to support future commercialization.
The LLNL team includes Sukhotskiy, Joaquin Gonzalez, Jesse Ahlquist, Eric Elton, Andy Pascall, Alexander Baker, Christopher Walton, Luke Thornley, Ben Pham and Bassem El Dasher.
