Los Alamos National Laboratory is converting part of the waste stream from plutonium purification into a steady, sustainable supply of the coveted element americium, which is used for medical research, smoke detectors and more. This makes Los Alamos the nation's sole supplier-reducing dependence on other countries.
Americium is a household staple with space travel potential. Few people likely know it, but americium is found in almost every household as an essential component of smoke detectors. It is also being considered to power spacecraft on Mars and elsewhere, as an alternative to the plutonium-238 that is used for thermoelectric generators today.
The U.S. lost its sole domestic source of americium in 1984, when the Rocky Flats plutonium processing plant in Colorado ceased recovering waste americium from plutonium. Rocky Flats completely shut down in 1992, and by 2004 the U.S. became entirely dependent on international supplies, primarily from Russia, after fully depleting the domestic americium inventory.
Now, Los Alamos is processing americium for commercial applications for the first time in decades. The Lab shipped its first commercial batch for customers in 2020, and - following significant process improvements since 2021 - it's now ready to significantly ramp up americium production.
Americium-241 is used in smoke detectors (left), neutron moisture meters (center) and radioisotope thermoelectric generators for space exploration, such as an upcoming European Space Agency's mission on the moon (artist's impression, right).
A 'win-win'
Apart from mitigating the nation's dependence on foreign supplies, the program has multiple benefits, such as turning an unwanted plutonium impurity into a valuable commodity, while also removing it from nuclear waste streams, said Owen Summerscales, editor of the Lab's Actinide Research Quarterly magazine.
That helps protect the environment. And it saves money by eliminating americium from disposal drums shipped to the Waste Isolation Pilot Plant in southern New Mexico. Each WIPP drum shipment costs around $100,000, Summerscales wrote in a detailed article about americium in the ARQ magazine.
"Overall, resuming production of americium and mitigating dependency on sensitive countries has been beneficial to all parties involved: the U.S. nuclear complex, taxpayers and industry," Summerscales wrote. "A true win-win."
The chromatography process shown here extracts americium-241 from a waste product stream as part of the Lab's plutonium purification process, which uses chemical extraction techniques contained within radiological glove boxes.
Rebuilding americium production capacity
Scientists first discovered americium during the Manhattan Project. It's a byproduct, or ingrowth, that emerges as plutonium decays, generating about 1 gram of americium-241 over 20 years for every 1 kilogram of fresh weapons-grade plutonium.
Americium production is a complex process that begins with separating it from plutonium and then refining it into a commercial product.
First, aging plutonium is heated in furnaces as part of the purification process, leaving behind a pyrochemical residue. The plutonium and americium are then separated out in that residue through an aqueous chloride, or water-based, solution.
Once separated, the americium is further purified through a new glove box-contained process that they've developed to remove other unwanted elements or impurities. It's then calcinated through a thermal treatment process to create a more stable americium oxide that can be shipped to companies that use it for its numerous applications.
Said David Kimball, deputy group leader for Material Recovery and Recycling at the Lab's Actinide Material Processing and Power, "As plutonium used in the nuclear security complex ages, the source of americium only keeps growing. This program means we don't have to throw that away as a waste product."
Americium-241 is used in smoke detectors (left), neutron moisture meters (center) and radioisotope thermoelectric generators for space exploration, such as an upcoming European Space Agency's mission on the moon (artist's impression, right).
The chromatography process shown here extracts americium-241 from a waste product stream as part of the Lab's plutonium purification process, which uses chemical extraction techniques contained within radiological glove boxes.
