NASA tests new small fission power plant for future space missions


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NASA has successfully completed a full test of a new small fission power plant that it hopes to use in future space missions.

The prototype power system uses a solid, cast uranium-235 reactor core, about the size of a paper towel roll. Passive sodium heat pipes transfer reactor heat to high-efficiency Stirling engines, which convert the heat to electricity.

According to David Poston, the chief reactor designer at NNSA’s Los Alamos National Laboratory, the purpose of the recent experiment in Nevada was two-fold: to demonstrate that the system can create electricity with fission power, and to show the system is stable and safe no matter what environment it encounters. “We threw everything we could at this reactor, in terms of nominal and off-normal operating scenarios and KRUSTY passed with flying colors,” said Poston.

The Kilopower team conducted the experiment in four phases. The first two phases, conducted without power, confirmed that each component of the system behaved as expected. During the third phase, the team increased power to heat the core incrementally before moving on to the final phase. The experiment culminated 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 team simulated power reduction, failed engines and failed heat pipes, showing that the system could continue to operate and successfully handle multiple failures.

This power plant appears similar in concept to the fission RTG nuclear fuel systems that have been used routinely for decades on unmanned planetary probes such as the two Voyager spacecraft, New Horizons, and on Curiosity. This new system however provides significantly more power, as much as ten kilowatts compared to the approximate two hundred watts provided by RTGs.

Such a system will be essential for future bases on both Mars and the Moon, where solar power is not the best option. I should also add that such a system might possibly have applications here on Earth. Developed properly, it could provide a practical power source for out-of-the-way locations not on the grid. If made cheap enough, it might also provide electrical customers a cheaper and competitive alternative that will allow them to remove themselves from the grid entirely.

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6 comments

  • Matt in AZ

    I’d like to know how KRUSTY’s weight and complexity compares to the ISS’s solar panel system. Hopefully it would be more cost effective and require less assembly and maintenance as a power supply for future stations.

  • Mitch S.

    “a solid, cast uranium-235 reactor core”
    Hmm, they didn’t say “enriched uranium” which would be U238 with a higher than natural quantity of U235. That would be what is used in many commercial reactors.
    U235 at higher than about 80% purity is considered “weapons grade” – the stuff at the heart of the Hiroshima bomb.
    It’s very expensive to separate U235 from U238 (that’s what the Iranians are trying to do with centrifuges) though there may be useful quantities in stock recovered from decommissioned nuclear weapons.
    But having quantities of U235 in unsecured facilities on earth doesn’t sound like a good idea.

  • pzatchok

    They used to make these things for general sale to the public 100 years ago.
    Sold as a safer alternative to a high power steam engine.

    To run one all you needed was an open fire.
    They did all sorts of low power, long running operations from pumping water to powering radios.

    I want to make an updated very very fuel efficient ‘hit skip’ motor to run a generator head.

  • Dave B

    Wow, Stirling engine. And we still come back to a piston engine, nuclear powered. A lot of moving parts though.

  • wayne

    …if this is the same thing— less parts than it sounds…

    “Small Reactor for Deep Space Exploration”
    November 2012
    Los Alamos Lab
    https://youtu.be/KobRfGqlpGc
    4:32

    “This is the first demonstration of a space nuclear reactor system to produce electricity in the United States since 1965, and an experiment demonstrated the first use of a heat pipe to cool a small nuclear reactor and then harvest the heat to power a Stirling engine at the Nevada National Security Site’s Device Assembly Facility confirms basic nuclear reactor physics and heat transfer for a simple, reliable space power system.”

  • wayne

    “Bringing Nuclear Power to Mars”
    Frank H. Shu SETI Talks 2016
    https://youtu.be/ZUgAYQc96is
    1:20:00

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