While scientists can tag migrating birds, mammals, and other animals to track their movements, the precise migration patterns of butterflies and other insects too small for tagging evaded scientists’ scrutiny for decades. That changed in 1996, when Leonard Wassenaar and Keith Hobson, working at the time as isotope scientists for Environment Canada, demonstrated that isotopic techniques could be used to determine the origin of individual monarch butterflies and deduce the species’ annual migration routes. Now, the same technique is being used to study other butterfly species.

Technicians use a manipulator arm in a shielded cave in ORNL’s Radiochemical Engineering Development Center to separate concentrated Pm-147 from by-products generated through the production of Pu-238. Photo: Richard Mayes/ORNL, DOE

A method developed at Oak Ridge National Laboratory is allowing the Department of Energy to cull promethium-147 from plutonium-238 produced for space exploration. Under an ORNL project for the DOE Isotope Program that began last year, the lab has been mining Pm-147, a rare isotope used in nuclear batteries and to measure the thickness of materials, from the fission products left when Pu-238 is separated out of neptunium-237 targets. The Np-237 targets are irradiated in Oak Ridge’s High Flux Isotope Reactor, a DOE Office of Science user facility, to produce the Pu-238.

According to the DOE, the primary goal of the project is to reestablish the domestic production of Pm-147, which is in short supply. As a side benefit, the project is 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 Richard Mayes, group leader for ORNL’s Emerging Isotope Research. “There’s some synergy.”

The Monday session “Advancement in Medical Isotopes Production and Applications” of the 2020 ANS Virtual Winter Meeting was sponsored by the Isotopes & Radiation Division and co-chaired by Lin-Wen Hu of Massachusetts Institute of Technology and James Bowen of Pacific Northwest National Laboratory.

Radioisotopes produced from nuclear reactors and accelerators are widely used for medical diagnostics and cancer therapy. Technetium-99m (decay product of molybdenum-99), for example, is used in more than 80 percent of nuclear medicine diagnostic procedures. The session featured speakers who discussed the advancement and status of domestic production and applications of medical isotopes.

The Department of Energy is awarding up to $16 million in new funding to advance research and development of isotope production. The funding opportunity is part of a federal program that produces critical isotopes that are otherwise unavailable or in short supply for U.S. science, medicine, and industry. The effort is aimed at sustaining longstanding U.S. leadership in the vital field of isotope production, research, and development, according to the DOE.