NASA and NNSA engineers lower the wall of the vacuum chamber around the Kilowatt Reactor Using Stirling TechnologY (KRUSTY system). The vacuum chamber is later evacuated to simulate the conditions of space when KRUSTY operates. Credits: Los Alamos National Laboratory
A new nuclear reactor power system developed by NASA and the U.S. Department of Energy’s National Nuclear Security Administration (NINSA) could enable long-duration missions to the Moon, Mars and other far-reaching destinations in space.
On May 2, NASA officials announced the results of the Kilopower Reactor Using Stirling Technology (KRUSTY) experiment, which demonstrated that the system can create electricity with fission power and is stable and safe regardless of the environment. The demonstration took place after extensive experiments conducted at the NNSA’s Nevada National Security Site from November 2017 to March 2018.
“We threw everything we could at this reactor, in terms of nominal and off-normal operating scenarios and KRUSTY passed with flying colors,” David Poston, the chief reactor designer at NNSA’s Los Alamos National Laboratory, said in a press statement.
KRUSTY is a small, lightweight fission power system capable of providing up to 10 kilowatts of electrical power—enough to run several average households—continuously for at least 10 years.
The new system uses a solid, cast uranium-235 reactor core that is about the size of a paper towel roll, where passive sodium heat pipes transfer reactor heat to high-efficiency Stirling engines, converting the heat to electricity.
Officials believe this type of system could be used for traveling to the Moon, where power generation from sunlight is difficult due to lunar nights, a period where it stays dark for the equivalent of two weeks on Earth.
“Kilopower gives us the ability to do much higher power missions, and to explore the shadowed craters of the Moon,” Marc Gibson, lead Kilopower engineer at Glenn, said in a press statement. “When we start sending astronauts for long stays on the Moon and to other planets, that’s going to require a new class of power that we’ve never needed before.”
The first two phases of the four-phase experiment were conducted without power to confirm that each component of the system behaved as expected. During the third phase, the researchers increased the power to heat the core incrementally and in the fourth and final phase, the team conducted a 28-hour, full-power test that simulated a mission including reactor startup, ramp to full power, steady operation and shutdown.
Throughout the experiment, the team simulated power reduction, failed engines and failed heat pipes, showing that the system could continue to operate and successfully handle multiple failures.
“We put the system through its paces,” Gibson said. “We understand the reactor very well, and this test proved that the system works the way we designed it to work. No matter what environment we expose it to, the reactor performs very well.”
The team is now developing mission concepts and performing additional risk reduction activities as they prepare for future flight demonstrations.
“Safe, efficient and plentiful energy will be the key to future robotic and human exploration,” Jim Reuter, NASA’s acting associate administrator for the Space Technology Mission Directorate (STMD) in Washington, said in a press statement. “I expect the Kilopower project to be an essential part of lunar and Mars power architectures as they evolve.”
The project will remain a part of the STMD’s Game Changing Development program with the goal of transitioning to the Technology Demonstration Mission program in 2020.
The Kilopower project is led by Glenn, in partnership with NASA’s Marshall Space Flight Center in Huntsville, Alabama, and NNSA, including its Los Alamos National Laboratory, Nevada National Security Site and Y-12 National Security Complex.
