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NASA successfully tests a nuclear reactor that works in space

NASA and the Department of Energy’s National Nuclear Security Administration (NNSA) have successfully demonstrated a new nuclear reactor power system that could enable long-duration crewed missions to the Moon, Mars, and destinations beyond.

NASA announced the results of its Kilopower Reactor Using Stirling Technology (KRUSTY) experiment, during a news conference Wednesday at its Glenn Research Center in Cleveland, Ohio. The Kilopower experiment was conducted at NNSA’s Nevada National Security Site from November 2017 through March of this year.

 “Safe, efficient and plentiful energy will be the key to future robotic and human exploration,” said Jim Reuter, NASA’s acting associate administrator for the Space Technology Mission Directorate (STMD) in Washington. “I expect the Kilopower project to be an essential part of lunar and Mars power architectures as they evolve.”
 NASA and NNSA engineers lower the wall of the vacuum chamber around the Kilowatt Reactor Using Stirling TechnologY (KRUSTY system). NASA/Los Alamos National Laboratory

The Kilopower project

 In December last year, Digital Journal reported that NASA was pushing forward on its Kilopower project, with testing of its reactor prototype that was finished in September 2017. The prototype is small. and is designed to produce up to 1 kilowatt of electric power and is about 6.5 feet tall (1.9 meters).

Testing of the prototype began in November after being tested against analytical models for hardware verification. The prototype power system uses a solid, cast uranium-235 reactor core, about the size of a paper towel roll. Reactor heat is transferred via passive sodium heat pipes, with that heat then converted to electricity by high-efficiency Stirling engines.

KRUSTY control room during the full-power run, Marc Gibson (GRC/NASA) and David Poston (LANL/NNSA) in foreground, Geordie McKenzie (LANL/NNSA) and Joetta Goda (LANL/NNSA) in background. (NASA)

Stirling engines use heat to create pressure forces that move a piston, which is coupled to an alternator to produce electricity, sort of like an automobile engine.

The reactor technology is capable of providing 10 kilowatts of electrical power – enough to run several average households – continuously for at least 10 years. Four of the power systems would provide enough power for an outpost on the moon, where solar arrays are difficult to use because lunar nights are equal to 14 Earth days.

Testing was in four phases

In addition to proving the prototype could produce electricity through fission technology, NASA wanted to show the power system would be safe and stable in any environment. For this reason, the testing was done in four phases.

“We threw everything we could at this reactor, in terms of nominal and off-normal operating scenarios and KRUSTY passed with flying colors,” said David Poston, the chief reactor designer at NNSA’s Los Alamos National Laboratory

The Kilopower Stirling engine assembly. (NASA)

The first two test phases were conducted without any power and confirmed that each component of the system was functioning properly. During the third phase, the team increased power to heat the core little-by-little before moving on to the final phase.

Phase four ended with 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 NASA team threw out all kinds of possible problems that could be encountered, including a simulated power reduction, failed engines and failed heat pipes, and the results showed the system could continue to operate and successfully handle multiple failures.

“We put the system through its paces,” said Marc Gibson, lead Kilopower engineer at Glenn. “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.”

Source: Digital Journal