NASA is developing a mini nuclear power-generating plant that is the size of a suitcase, says a research scientist involved in leading the project on behalf of NASA and the Department of Energy.
The compact fission technology for surface power applications would be used by colonists or unmanned missions to the moon, or Mars — or any place else NASA decides to send a spaceship that can’t rely on the sun for power.
James Werner, who manages reactor technologies for the Space Nuclear Systems division at DOE’s Idaho National Laboratory, described the new system Sunday at the 242nd Meeting of the American Chemical Society in Denver.
Describing the new technology at the conference, Werner said: “People would never recognize the fission power system as a nuclear power reactor. The reactor itself may be about 1-1/2 feet wide by 2-1/2 feet high, about the size of a carry-on suitcase. There are no cooling towers.”
The system would provide energy for outposts or colonies on land where solar power is impractical. Unlike photovoltaic cells, a fission system could operate on the dark side of moons or the polar areas of planets, in caves or shaded craters, and in stormy and dusty conditions such as those on Mars.
Fuel cells are another power option for space operations, but this new nuclear reactor system would pack more energy into a relatively small and lightweight space, two key advantages to consider when packing for a very long, very expensive flight.
The small size of the reactor is enabled in part by the relatively modest energy needs of a space outpost.
According to NASA, a fission power system would provide only a tiny portion of the levels of energy generated by a full-scale nuclear reactor on Earth, but those levels could generate more than enough power for a typical lunar space outpost with about 40 kilowatts of electric power — or enough for about eight homes on Earth.
In addition to powering life support and other stationary equipment, a fission technology system would also charge batteries for rovers and other mobile devices such as mining equipment.
After the initial setup, modular-designed systems could be linked together as needed to provide more power for a growing colony.
The system would convert heat from the reactor to electricity by using technology that is almost 200 years old, the Stirling engine.
The basic principle behind a Stirling engine was established in 1816. In contrast to the familiar internal combustion engine that burns fuel within a chamber to turn a piston, a Stirling engine works by the expansion and contraction of a gas (typically hydrogen or helium) within a chamber, as it is heated by an exterior source, then cooled.
The external set-up enables a Stirling engine to run on practically any heat source, including solar energy. That also makes it an ideal candidate for converting energy from a miniature nuclear reactor to electricity.
By using a Stirling converter, the fission technology for surface power applications system reduces the amount of uranium fuel needed – an important consideration for cutting costs and reducing risks in case of accident, as well as eliminating excess weight.
In a recent test at NASA’s Marshall Space Flight Center, a pumped liquid metal was used to replicate the conditions under which Stirling engines would interact with the fission technology for surface applications system. Sandia National Laboratories has also tested the ability of a Stirling alternator to operate under exposure to radiation.
NASA’s Glenn Research Center in Cleveland and the Los Alamos National Laboratory in New Mexico are also contributing to the design of the device, along with a number of private sector partners including the Stirling engine manufacturer Sunpower, Inc. of Georgia.
The next step is a demonstration unit of 12 kWe (kilowatts of electrical energy), which should be ready for action in 2012.
