Space Flight System Demonstrated By Los Alamos Researchers
November 27, 2012

Stirling Engine Powered By Small Nuclear Reactor Could Be The Future Of Space Travel

April Flowers for - Your Universe Online

A research team from the Los Alamos National Laboratory and NASA has demonstrated a new concept for a reliable nuclear reactor that could be used on space flights.

The Demonstration Using Flattop Fissions (DUFF) experiment produced 24 watts of electricity, demonstrating the first use of a heat pipe to cool a small nuclear reactor and power a Stirling engine. A team of engineers from Los Alamos, the NASA Glenn Research Center and National Security Technologies LLC (NSTec) conducted the experiment at the Nevada National Security Site's Device Assembly Facility near Las Vegas.

Los Alamos scientists invented heat pipe technology in 1963. A sealed tube with an internal fluid and no moving parts, a heat pipe is efficient at transferring heat produced by a reactor.  A Stirling engine is a relatively simple closed-loop engine that uses a pressurized gas to move a piston, converting heat energy into electrical power. The team used the two devices in tandem to allow for the creation of a simple, reliable electric power supply that can be adapted for future space applications.

The DUFF experiment was configured on an existing experiment known as Flattop. This allowed for a water-based heat pipe to extract heat from uranium. The heat was then transferred to a pair of free-piston Stirling engines. The heat pipe and Stirling assembly was built by engineers from NASA Glenn who also operated the engines during the experiment. Las Alamos engineers under authorization from the National Nuclear Security Administration (NNSA) operated the Flattop assembly.

This experiment is the first demonstration since 1965 of a space nuclear reactor system in the U.S. It confirms the basic nuclear reactor physics and heat transfer for a simple, reliable space power system.

“The nuclear characteristics and thermal power level of the experiment are remarkably similar to our space reactor flight concept,” said Los Alamos engineer David Poston. “The biggest difference between DUFF and a possible flight system is that the Stirling input temperature would need to be hotter to attain the required efficiency and power output needed for space missions.”

“The heat pipe and Stirling engine used in this test are meant to represent one module that could be used in a space system,” said Marc Gibson of NASA Glenn. “A flight system might use several modules to produce approximately one kilowatt of electricity.”

Typically, our current space missions use power supplies that generate about the same amount of electricity as one or two household variety light bulbs. Making more power available could potentially boost the speed that mission data is transmitted, or increase the number of scientific instruments that could be operated simultaneously aboard a spacecraft.

“A small, simple, lightweight fission power system could lead to a new and enhanced capability for space science and exploration”, said Los Alamos project lead Patrick McClure. “We hope that this proof of concept will soon move us from the old-frontier of Nevada to the new-frontier of outer space”.

“Perhaps one of the more important aspects of this experiment is that it was taken from concept to completion in 6 months for less than a million dollars,” said Los Alamos engineer David Dixon. “We wanted to show that with a tightly-knit and focused team, it is possible to successfully perform practical reactor testing.”

Image 2 (below): John Bounds of Los Alamos National Laboratory's Advanced Nuclear Technology Division makes final adjustments on the DUFF experiment, a demonstration of a simple, robust fission reactor prototype that could be used as a power system for space travel. DUFF is the first demonstration of a space nuclear reactor system to produce electricity in the United States since 1965.