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A team of researchers, including engineers from Los Alamos National Laboratory, has demonstrated a new concept for a reliable nuclear reactor that could be used on space flights.
The research team recently demonstrated the first use of a heat pipe to cool a small nuclear reactor and power a Stirling engine at the Nevada National Security Site’s Device Assembly Facility near Las Vegas. The Demonstration Using Flattop Fissions experiment produced 24 watts of electricity. A team of engineers from Los Alamos, the NASA Glenn Research Center and National Security Technologies LLC conducted the experiment.
Heat pipe technology was invented at Los Alamos in 1963. A heat pipe is a sealed tube with an internal fluid that can efficiently transfer heat produced by a reactor with no moving parts. A Stirling engine is a relatively simple closed-loop engine that converts heat energy into electrical power using a pressurized gas to move a piston. Using the two devices in tandem allowed for creation of a simple, reliable electric power supply that can be adapted for space applications.
Researchers configured DUFF on an existing experiment, known as Flattop, to allow for a water-based heat pipe to extract heat from uranium. Heat from the fission reaction was transferred to a pair of free-piston Stirling engines manufactured by Sunpower Inc., based in Athens, Ohio. Engineers from NASA Glenn designed and built the heat pipe and Stirling assembly and operated the engines during the experiment. Los Alamos nuclear engineers operated the Flattop assembly under authorization from the National Nuclear Security Administration.
DUFF is the first demonstration of a space nuclear reactor system to produce electricity in the United States since 1965, and the experiment confirms 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.”