U.S. Restarts Plutonium Production for Powering Space Probes

March 19, 2013 Updated: April 3, 2013

The U.S. Department of Energy has produced its first batch of non-weapons grade plutonium, since a nuclear reactor shutdown 25 years ago, NASA officials said on Monday. According to a Reuters report, this will be used to power future space probes.

As plutonium-238 naturally radiates heat, it can be used to warm the spacecraft and be converted into electricity by a device called a radioisotope thermoelectric generator. Plutonium-239 is the isotope used in nuclear weapons.

Russia has been meeting the plutonium requirements till now but that supply has run out, and U.S. has not produced plutonium-238 after the environmental disaster at Savannah River Site.

Since the last forty years, NASA has been flying nuclear-powered probes including the Mars rover Curiosity, the Saturn-orbiting Cassini spacecraft, Pluto-bound New Horizons and the twin Voyager probes, which are leaving the solar system.

“The new plutonium is very important to us,” Jim Green, the head of NASA’s planetary science division, said during a briefing at a Lunar and Planetary Science Conference in Houston.

The Oak Ridge National Laboratory in Tennessee partnered with NASA to successfully produce a small amount plutonium. NASA aims to produce about 3.3 to 4.4 pounds (1.5 to 2 kg) of plutonium-238 per year.

“The new material when we add with our old plutonium, which is more than 20 years old in some cases, really allows us to get the appropriate energy density out,” Green said. Newly made plutonium has the ability to revive the older plutonium.

NASA also has been working on a more energy efficient generator, called the Advanced Stirling Radioisotope Generator, which can produce four times more electrical power per kilogram of plutonium-238.