Amazon invests in TRISO fuel for safer nuclear reactors powering AI

Amazon is investing in next-generation nuclear technology to power its AI and cloud infrastructure. At the core is tristructural isotropic (TRISO) fuel — millimeter-scale particles that act as miniature containment systems. Each TRISO particle has a uranium kernel surrounded by porous carbon and three ceramic layers: inner pyrolytic carbon, silicon carbide (SiC), and outer pyrolytic carbon. The SiC layer, with a melting point above 2700°C, acts as a pressure vessel and chemical barrier, maintaining integrity beyond worst-case accident conditions. Data from the U.S. Department of Energy's Advanced Gas Reactor Fuel Qualification Program, involving over 500,000 particles since 2002, shows that TRISO fuel exhibited no detectable failures when subjected to 1600°C for 300 hours, with an upper-bound failure fraction of ≤6.6×10⁻⁵.

TRISO fuel enables novel reactor designs like pebble-bed configurations, where particles are embedded in graphite spheres. This allows online refueling, real-time monitoring of fuel consumption, and reduces unburnt uranium in spent fuel. Amazon's involvement with the Xe-100 reactor at the Cascade Energy Center signals a shift toward inherently safe nuclear power to meet the rising energy demands of AI inference and training. Beyond operational efficiency, TRISO coatings preserve long-term stability in spent fuel for up to 100,000 years, addressing waste concerns. With kilogram-scale production already active, this technology could reshape how tech giants source carbon-free baseload power for compute-heavy workloads.