US-based X-Energy Reactor Company subsidiary TRISO-X has completed testing of its coated particle fuel for nuclear thermal propulsion applications. The work was undertaken as part of a team led by General Atomics Electromagnetic Systems for the first phase of the US Defense Advanced Research Projects Agency's (DARPA’s) Demonstration Rocket for Agile Cislunar Operations (DRACO) programme. The first phase included a baseline design of a nuclear thermal rocket, which was awarded to General Atomics.
The test took place at NASA’s Marshall Space Flight Centre in the Compact Fuel Element Environmental Test facility. The TRISO-X fuel was tested in extreme conditions representing those experienced in space. The fuel was cycled rapidly and repeatedly to more than 2,000 degrees Celsius with the temperature fluctuating hundreds of degrees a minute and held at those temperatures to replicate conditions anticipated during space missions, while maintaining its integrity.
The US Department of Energy (DOE) has described TRISO (TRIstructural-ISOtropic) particle fuel as “the most robust nuclear fuel on the planet”. TRISO fuel particles have a kernel of enriched uranium oxycarbide, encased in carbon and ceramic layers. DOE selected X-energy in 2020 for their Advanced Reactor Demonstration Program to receive up to $1.2bn of federal cost-shared funding to develop, license, build, and demonstrate operational advanced reactors and advanced nuclear fuel fabrication by the end of the decade. TRISO-X has leased research and laboratory space at the Oak Ridge National Laboratory campus in Oak Ridge, Tennessee, since 2016. TRISO-X broke ground last year in Oak Ridge on its commercial-sale Fuel Fabrication Facility, which is expected to be fully operational in 2025.
TRISO-X President Dr Pete Pappano said the high-temperature resilience of the coated particle fuel “bolsters TRISO-X’s position as the domestic leader in the fabrication, testing and commercialisation of coated-particle fuel systems for both power and space applications”. The test showed “the robust properties and performance of our coated particle fuel, demonstrating the fuel’s design to be melt-down proof under any foreseeable scenario”.