NASA to test prototype Kilopower reactor

17 November 2017

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The National Aeronautics and Space Administration (NASA) will this month start testing uranium-fuelled Stirling engines for use in possible future missions to Mars. The technology has been developed as part of the Kilopower project.

The Kilopower reactor (Image: NASA)

The Kilopower reactor could produce 1-10 kilowatts of electrical power, continuously for ten years or more. The prototype power system uses a solid, cast uranium-235 reactor core. Reactor heat is transferred via passive sodium heat pipes, with the heat then converted to electricity by high-efficiency Stirling engines. Such engines use heat to create pressure forces that move a piston, which is coupled to an alternator to produce electricity.

NASA's Glenn Research Center in Cleveland has managed all phases of the Kilopower Project, from designing and building the hardware, with contributions from NASA's Marshall Space Flight Center in Huntsville, Alabama, through developing the test plan and operating the tests. The National Nuclear Security Administration's (NNSA's) Y12 National Security Complex in Oak Ridge, Tennessee, is providing the reactor core.

NASA is partnering with the US Department of Energy's Nevada National Security Site to carry out the tests, which will continue into early next year. The Kilopower hardware will undergo a full-power test lasting some 28 hours.

Lead researcher Marc Gibson said, "The upcoming Nevada testing will answer a lot of technical questions to prove out the feasibility of this technology, with the goal of moving it to a Technology Readiness Level of 5." He added, "It's a breadboard test in a vacuum environment, operating the equipment at the relevant conditions."

Patrick McClure, project leader on Kilopower work at the Los Alamos National Laboratory (LANL), said: "A space nuclear reactor could provide a high energy density power source with the ability to operate independently of solar energy or orientation, and the ability to operate in extremely harsh environments, such as the Martian surface."

David Poston, chief reactor designer at LANL, added, "The reactor technology we are testing could be applicable to multiple NASA missions, and we ultimately hope that this is the first step for fission reactors to create a new paradigm of truly ambitious and inspiring space exploration. Simplicity is essential to any first-of-a-kind engineering project - not necessarily the simplest design, but finding the simplest path through design, development, fabrication, safety and testing."

Lee Mason, principal technology for power and energy storage at NASA's Space Technology Mission Directorate, said: "The Kilopower test programme will give us confidence that this technology is ready for space flight development. We'll be checking analytical models along the way for verification of how well the hardware is working."

Space missions require reliable, long-lasting power sources both for propulsion once they are in space and to power experiments and equipment. Radioisotope thermoelectric generators (RTGs) have been widely used as power sources in satellites and other space vehicles such as the Mars rover Curiosity. However, virtually all RTGs are usually powered by plutonium-238, which is now in short supply.

Mason said, "What we are striving to do is give space missions an option beyond RTGs, which generally provide a couple of hundred watts or so. The big difference between all the great things we've done on Mars, and what we would need to do for a human mission to that planet, is power. This new technology could provide kilowatts and can eventually be evolved to provide hundreds of kilowatts, or even megawatts of power."

Researched and written

by World Nuclear News

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