NASA/DOE Developing Surface Nuclear Fission Power

(Above) An artist’s concept of a fission surface power system on the surface of the moon. The nuclear reactor has been buried below the lunar surface to make use of lunar soil as additional radiation shielding. The power system would transmit a steady 40 kW of electric power, enough for about eight houses on Earth, to the lunar outpost.

NASA and the Department of Energy have completed tests on several fission surface power components within the last few weeks. The agencies are researching technologies that could enable possible use of nuclear power on the surface of the moon and Mars. Nuclear power is part of the range of options that are being examined for potential human missions on the moon and Mars.

A fission surface power system could use a small nuclear reactor, about the size of an office trash can, and Stirling power generators to produce 40 kilowatts of energy, enough electricity to power a future lunar or Mars outpost. The electricity produced could be used for life support, performing experiments, recharging rovers and mining resources.

Don Palac, NASA Glenn Research Center’s fission surface power system project manager, observed, “This recent string of technology development successes confirms that the fission surface power project is on the right path.”

One successful test occurred at Glenn in Cleveland, where a lightweight composite radiator panel was successfully tested in a vacuum chamber that replicates the hard vacuum and extreme cold temperatures that would be seen in space, with temperatures as low as minus 125 degrees C. The radiator, approximately 6 feet by 9 feet, represents one of 20 panels that would be needed to cool the notional fission surface power system. By performing this test, the team showed the radiator panel could reject the required heat at the proper temperature under realistic lunar conditions.

The radiator panel was designed and built by Material Innovations, Inc., Huntington Beach, Calif., with help from Thermacore, Inc., Lancaster, Pa. and Materials Research and Design, Inc., Wayne, Pa.

According to Glenn lead engineer David Ellis, “This was a tremendous accomplishment and a giant step toward proving out the radiator technology. We can now proceed toward a system-level technology demonstration with confidence.”

A second achievement occurred at NASA’s Marshall Space Flight Center, Huntsville, Ala. For the first time, Stirling engines were heated with a pumped liquid metal, replicating how heat could be delivered from a reactor to the converter. This was a major accomplishment on the road to demonstrating technical feasibility of fission surface power.

Glenn developed the data and control system for the Stirling engines, which were designed and built by Sunpower, Inc., Athens, Ohio. Glenn also designed the Stirling heat exchangers that were fabricated by Mound Advanced Technology Center in Miamisburg, Ohio. The test loop at Marshall included an electrically heated reactor simulator designed by Los Alamos National Laboratory, Los Alamos, NM and an electromagnetic pump supplied by Idaho National Laboratory, Idaho Falls, Idaho.

Steve Geng was the Glenn lead for the test. He said, “The engines performed flawlessly producing over 2 kilowatts of electricity at a gross thermal efficiency of about 32 per cent with liquid metal temperatures as high as 550 degrees C.”

At Sandia National Laboratories in Albuquerque, NM, a Stirling alternator was operated while being exposed to radiation levels similar to those that would be experienced with a reactor. The alternator survived a cumulative radiation dose 20 times the current fission surface power surface design requirement, during 26 hours of radiation exposure in the DOE Gamma Irradiation Facility at Sandia. There was no change in electrical power input required to maintain alternator operation, which would have been a possible indication of radiation damage.

The Stirling alternator was developed by Sunpower, Inc., Athens, Ohio. The diagnostics and control rack was assembled by Glenn. Testing was conducted by a team that included Sandia, Glenn and a University of Florida doctoral student.

“The pace of progress exhibited by these three achievements in the same time period is exciting,” said Lee Mason, Glenn’s principal investigator for the fission surface power project. “It has built the team’s confidence and prepared them for challenges that lay ahead.”

The next major step is a non-nuclear system level technology demonstration where all of the major elements will be combined in one test. This test is scheduled to begin in 2012.

The Fission Surface Power Project is managed by Glenn for NASA’s Exploration Technology Development Program Office at NASA’s Langley Research Center, Hampton, Va.