Credit: Richard Mayes/ORNL, U.S. Dept. of Energy
A new method developed at Oak Ridge National Laboratory proves one effort’s trash is another’s valuable isotope.
One of the byproducts of the Department of Energy lab’s national plutonium-238 production program is promethium-147, a rare isotope used in nuclear batteries and to measure the thickness of materials.
It’s difficult and costly to dispose of waste containing radioactive elements left over after neptunium-237 targets are irradiated in the High Flux Isotope Reactor, a DOE Office of Science user facility, to produce Pu-238 for space exploration. But last year, a new ORNL project for the DOE Isotope Program began mining Pm-147 from the fission products left when Pu-238 is separated out of the target.
This effort’s primary goal is to reestablish domestic production of Pm-147, which is in short supply, and it has a side benefit: reducing the concentrations of radioactive elements in the waste, so that it can be disposed of safely in simpler, less expensive ways both now and in the future.
“In the process of recovering a valuable product that the DOE Isotope Program wants, we realized we can reduce our disposal costs,” said ORNL’s Richard Mayes, group leader for Emerging Isotope Research. “There’s some synergy.”
Pm-147 isn’t the only valuable metal in the Pu-238 production waste stream that is of interest to the DOE Isotope Program, but it’s the first Mayes’ team has successfully extracted. ORNL’s Susan Hogle wrote the original proposal to mine Pm-147 from Pu-238 waste and provides computational support detailing potential isotopes present in the solution, and Mayes has been working with Lætitia Delmau, interim group leader for Radiochemical Separations Science Group at ORNL, to develop a process to extract and purify it.
“Currently, we’re the only producers of Pm-147 in the U.S., and there’s a market for it,” Mayes said. Research indicates it could have additional applications in medical imaging and as a radioisotope to generate power for space probes.
Kristi Nelson Bumpus