The production of 50 grams of plutonium-238 - roughly the mass of a golf ball -- marks the first demonstration in the US since the Savannah River Plant in South Carolina ceased production in the late 1980s, Nasa said.
Radioisotope power systems convert heat from the natural radioactive decay of the isotope plutonium-238 into electricity, the researchers explained.
"This significant achievement by our team mates at DOE signals a new renaissance in the exploration of our solar system," said John Grunsfeld, associate administrator for Nasa's Science Mission Directorate in Washington.
"Radioisotope power systems are a key tool to power the next generation of planetary orbiters, landers and rovers in our quest to unravel the mysteries of the universe," Grunsfeld said.
The success of the engineers and technicians at DOE's Oak Ridge National Laboratory (ORNL) in Tennessee comes two years after the project formally started with Nasa funding, building on many years of research and testing.
This demonstration of the key steps in fuel production will ensure that this vital space power technology will be available to provide electricity and heat for ambitious exploration missions of the solar system in this decade and beyond, the statement added.
"As we seek to expand our knowledge of the universe, the Department of Energy will help ensure that our spacecraft have the power supply necessary to go farther than ever before," Franklin Orr, under secretary for science and energy at DOE, noted.
"We are proud to work with Nasa in this endeavour, and we look forward to our continued partnership," Orr noted.
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