Researchers at NASA and the Department of Energy recently tested key technologies for a lunar nuclear reactor that might power an outpost on the moon or Mars:
To generate electricity, the researchers used a liquid metal to transfer the heat from the reactor to the Stirling engine, which uses gas pressure to convert heat into the energy needed to generate electricity. For the tests, the researchers used a non-nuclear heat source. The liquid metal was a sodium potassium mixture that has been used in the past to transfer heat from a reactor to a generator, says Palac, but this is the first time this mixture has been used with a Stirling engine.“They are very efficient and robust, and we believe [it] can last for eight years unattended,” says Lee Mason, the principal investigator of the project at Glenn. The system performed better than expected, Palac says, generating 2.3 kilowatts of power at a steady pace.
The researchers also developed a lightweight radiator panel to cool the system and dissipate the heat from the reactor. The prototype panel is approximately six feet by nine feet–one-twentieth the size required for a full-scale system. Heat from a water-cooling system is circulated to the radiator where it dissipates.
The researchers tested the radiator panel in a vacuum chamber at Glenn that replicates the lack of atmosphere and the extreme temperatures on the moon–from over 100 degrees Celsius during the day to below 100 degrees Celsius at night. The panel dissipated six kilowatts of energy, more than expected–a “very successfully test,” says Palac. On the moon, the panel must also survive the dusty environment cause by the regolith.
Lastly, the researchers tested the performance of the Stirling alternator in a radiation environment at Sandia National Laboratories in Albuquerque, NM. The objective was to test the performance of the motor, ensuring that the materials would not degrade. The alternator was subjected to 20 times the amount of radiation it would expect to see in its lifetime and survived without any significant problems.
Mason says that the tests are very important in showing the feasibility of the system and that the next step is for the researchers to conduct a full system demonstration, by combining a non-nuclear reactor simulator with the Stirling engine and radiator panel. He says that these tests should be completed in 2014.
(Hat tip to Nyrath.)