From left, Devon Engle, Brian Anderson, Clint Ausmus, Brian Egle, Adam Stevenson, Leigh Ann Warner, Eva Hickman and Alan Tatum pose with a replica of the Little Boy bomb that was made with uranium enriched at the calutrons and dropped on Hiroshima during World War II.
Employees tour deteriorating Beta-3 to arrange for preservation of enrichment artifacts
In 1945, workers at the Beta calutrons at Y-12 had a crucial mission: to separate uranium used for the atomic bomb Little Boy that was dropped on Hiroshima, Japan, helping bring about the end of World War II.
For more than 50 years afterward, the calutrons had a peacetime mission: to separate isotopes of a variety of elements for research use and targets to produce radioisotopes.
Now, with the calutrons silent since the late 1990s, a group of isotopes employees last month toured Beta-3 with another mission: to preserve useful and historical artifacts from the deteriorating building.
On Nov. 13, F&O’s Wendell Ely led a tour for Brian Anderson, Clint Ausmus, Brian Egle, Devon Engle, Adam Stevenson and Alan Tatum, all of ESED, along with Eva Hickman of the National Isotope Development Center. The tour was requested by Egle and was arranged at the behest of Leigh Ann Warner, who supports ESED with document control and records management − and has a passion for preserving the history and legacy of enrichment at the lab.
“My main reason for the tour was to provide the opportunity to discover what remains of such a notable era in ORNL history,” Warner said. “Beta-3 houses many ‘enterprise’ assets that still have use and value. I believe we could use those artifacts to shine a light on how great the science is at ORNL, and why ORNL is a leader in isotope science.”
ORNL owns the contents of and manages Building 9204-3, which housed Beta-3 and is within the Y-12 Protected Area. It’s one of two facilities that are part of the Manhattan Project National Historical Park. But it’s in disrepair. The building is no longer temperature controlled, and the basement is flooded, raising the risk of mold inside.
“The reality is that the building is deteriorating, the documents are fragile, and we may lose access to the artifacts inside,” Warner said. “Now ESED can lay a claim on these artifacts and make plans for their use.”
UT-Battelle manages ORNL for DOE’s Office of Science, the single largest supporter of basic research in the physical sciences in the United States. DOE’s Office of Science is working to address some of the most pressing challenges of our time. For more information, visit energy.gov/science.

On the tour, employees saw records, tools, photos and museum-quality replicas, including one of Little Boy.
They saw the control room where DOE photographer Ed Westcott took his iconic photograph of the “Calutron Girls,” and saw a stool still there.
They saw the last remaining alpha source and collector display, and the display beta source and collector for the original uranium configuration, along with a variety of signage and components original to Beta-3’s operations.
Two of them, Hickman and Ausmus, had seen them in action decades ago.
A biochemist who now oversees stable isotope products for the NIDC, Hickman worked in calutron operations, spending several years of her early career enriching stable isotopes.
Ausmus, a process development engineer who now works on the modern isotope enrichment methods developed to replace the calutrons, started his career at Beta-3, after a job interview during which the late Joe Tracy shared the program’s vision in such a way that Ausmus was immediately hooked.
“Reflecting now, I realize I was transitioning from having a job to having a mission and a passion,” said Ausmus, who grew to recognize the global significance of the technology being developed and the work being done at his job.
The calutrons were a type of mass spectrometer. They worked by ionizing an element, which then produced an electric current when the ions collided with a plate. A magnetic field separated the different isotopes by mass.

“Beta-3 housed a critical technology that contributed to changing the lives of nearly everybody in the world – twice,” Ausmus said. “It was the last operating electromagnetic uranium enrichment facility of the Manhattan Project, and it was the primary facility for producing stable precursor isotopes in the development of specialized radioisotopes. Few understand that radioisotope development and production would have been significantly suppressed without the Beta-3 calutron facility – lives would have been lost, and technology would have been priced out of reality.”
Beta-3 was initially built to be a stopgap facility to produce enriched uranium until the improvement of gaseous diffusion, a then-newer technology in which DOE was investing.
“Instead, it was cleaned, modified and served the nation for five decades in stable isotope production,” Ausmus said. “Its five acres of floorspace housed post-war projects for the Air Force and early ORNL experiments, with the East track being used for research and development and actinide enrichment.”
Later, the building housed the ORNL Isotope Research Materials Laboratory and the Isotope Business Office, the precursor to the NIDC.
Ausmus and Tracy were working the evening shift on the very last calutron run, in 1998.
“We were enriching strontium-84 using pre-enriched feedstock worth about $1 million,” Ausmus said. “Collectively, across the shifts, the approach was to run as long and as stable as possible. The run had lasted well past the average run time, and output had begun to drop slightly.”
The filament that provided electrons for ionization had worn thin and burnt out from a slight overcurrent, he said.
The government decided to move forward with electromagnetic isotope separation devices, or EMIS. By 2011, a team that included Brian Egle, now section head of ESED’s Stable Isotope Research, Development and Production, and Kevin Hart, now retired, had a working EMIS prototype that could separate argon isotopes.
“I was so excited to get to ‘drive’ the new machine on its first day of operation that I forgot to eat lunch,” Ausmus said.
Now, several generations later, EMIS technology is being incorporated in the Stable Isotope Research and Production Center, which DOE is constructing on the ORNL campus to reestablish U.S. capability to enrich stable isotopes.
“As the program continues to grow to meet this national need, the people involved seem to share the same enthusiasm and sense of purpose that comes from participating in important missions,” Ausmus said.
He’d like to make sure the historical link between the calutrons and EMIS is documented for posterity. Tours of the building are no longer allowed, because of safety concerns, but a “virtual tour” of the facility is being filmed. The ESED team will then use it to identify items to be transferred to ORNL for preservation.
“As we are losing the best people to tell the story of Oak Ridge’s transition from the Manhattan Project era into the modern era, their stories and the associated physical artifacts become more valuable,” Ausmus said. “The story of the calutrons is sometimes limited to the scope of the Manhattan Project. The repurposing is not as well-known and is just as remarkable.
“I would like to say we were among the ones to preserve the precious few artifacts remaining, and to keep telling the full story.”
