James E. Werner, the project leader at the U.S. Department of Energy (DOE), said that innovative fission technology for surface power applications is far different from the familiar terrestrial nuclear power stations, which sprawl over huge tracts of land and have cooling towers and other large structures.
An artistâ??s concept of a fission surface power system on the surface of the Moon. Credit: Galaxy Wire
A fission reactor itself is about 1.5 feet wide by 2.5 feet high, roughly the size of a carry-on suitcase, according to Werner. And there are no cooling towers.
"A fission power system is a compact, reliable, safe system that may be critical to the establishment of outposts or habitats on other planets. Fission power technology can be applied on Earth's Moon, on Mars, or wherever NASA sees the need for continuous power," said Werner.
Nuclear fission power in space is actually old news. In 1965, the U.S. launched SNAP-10A, which was a 45 kWt thermal nuclear fission reactor that produced 650 watts using a thermoelectric converter. (It operated for 43 days before it was shut down due to a satellite malfunction--but remains in orbit today.)
Nuclear fission works by splitting uranium atoms to generate heat that is then converted into electric power. A fission power system contains components that are similar to those found in the commercial reactors currently in use: a heat source, power conversion, heat rejection and power conditioning and distribution. For space applications, however, nuclear fission features a number of differences compared with commercial reactors.
"While the physics are the same, the low power levels, control of the reactor and the material used for neutron reflection back into the core are completely different," Werner said. "Weight is also a significant factor that must be minimized in a space reactor that is not considered in a commercial reactor."
Sunlight and fuel cells were traditionally the mainstays for generating electricity for space missions, but engineers realized that solar energy has limitations. Solar cells do a great job supplying electricity in near-Earth orbits and for satellite-borne equipment, but nuclear power offers some unique capabilities that could support manned outposts on other planets or moons.
The biggest difference between solar and nuclear reactors is that nuclear reactors can produce power in any environment. Fission power technology doesn't rely on sunlight, making it able to produce large, steady amounts of power at night or in harsh environments like those found on the Moon or Mars. A fission power system on the Moon could generate 40 kilowatts or more of electric power, approximately the same amount of energy needed to power eight houses on Earth. Nuclear power has the ability to provide a power-rich environment to the astronauts or science packages anywhere in our solar system and that this technology is mature, affordable and safe to use.
Werner contends that once the technology is developed and validated, it may prove to be one of the most affordable and versatile options for providing long-term base power for the space exploration programs.
The team is scheduled to build a technology demonstration unit in 2012.
The project is a collaboration between NASA and DOE.