Space propulsion fuel particle in TRISO testing 'first'

Wednesday, 15 March 2023

The test took place in the Compact Fuel Element Environmental Test facility at NASA's Marshall Space Flight Center, where the fabricated fuel was cycled rapidly and repeatedly to more than 2,000°C with the temperature fluctuating hundreds of degrees per minute and held at those temperatures to replicate conditions anticipated during space missions, while maintaining its integrity.

"The test was the first time TRISO-X's - or to TRISO-X's knowledge - any coated particle fuel was tested to these conditions," the company said.

TRISO - standing for TRIstructural-ISOtropic - fuel particles have a kernel of enriched uranium oxycarbide, encased in carbon and ceramic layers. According to TRISO-X, the US Department of Energy has described this type of fuel as the most robust nuclear fuel on Earth.

X-Energy Reactor Company subsidiary TRISO-X is developing key fuel fabrication processes as part of a team led by General Atomics Electromagnetic Systems for the first phase of the Defense Advanced Research Projects Agency's (DARPA) Demonstration Rocket for Agile Cislunar Operations (DRACO) programme which is just coming to an end. The phase has involved two tracks, for which contracts were announced in 2021. The contract for Track A, a baseline design of a nuclear thermal rocket, or NTR, was awarded to General Atomics. Blue Origin and Lockheed Martin were contracted to work independently on the Track B contract, to develop an operational system concept to meet operational mission objectives and a demonstration system design with a focus on demonstrating the propulsion subsystem.

"We are thrilled to meet this crucial milestone that will help to enable the prospective deployment of a nuclear-thermal-propulsion-based rocket," TRISO-X President Pete Pappano said. "The high-temperature resilience of our 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. This is a key demonstration of the robust properties and performance of our coated particle fuel, demonstrating the fuel's design to be melt-down proof under any foreseeable scenario."

The next two phases of the DRACO programme will culminate in a flight demonstration, which DARPA envisions will take place in fiscal 2027. The next phase of the project will involve a cold flow test of the rocket engine without nuclear fuel. The project's third phase involve assembly of the fueled NTR with the stage, environmental testing, and launch into space to conduct experiments on the NTR and its reactor.