NASA completes cold-flow tests of flight-scale reactor unit at Marshall

NASA has completed a cold-flow test campaign of the first flight reactor engineering development unit since the 1960s at the agency’s Marshall Space Flight Center in Huntsville, Alabama, advancing nuclear propulsion capabilities for deep space missions. Teams at Marshall conducted more than 100 tests over several months in 2025 on a 44-inch by 72-inch unit built by BWX Technologies of Richmond, Virginia.

The full-scale, non-nuclear, flight-like development test article, the size of a 100-gallon drum, simulates propellant flow throughout the reactor across a range of operational conditions. "Nuclear propulsion has multiple benefits including speed and endurance that could enable complex deep space missions," said Greg Stover, acting associate administrator of NASA’s Space Technology Mission Directorate at NASA Headquarters in Washington.

"By shortening travel times and expanding mission capabilities, this technology will lay the foundation to explore farther into our solar system than ever before.