The Science and Technology Behind Stable Isotope Enrichment
Researchers at Oak Ridge National Lab are advancing enrichment science, developing modern separation technologies, and rebuilding the domestic capabilities needed to provide enriched stable isotopes for current and emerging U.S. needs.
Separating Nearly Identical Atoms
Stable isotope enrichment increases the concentration of a specific stable isotope within an element. Separating them requires technologies that find very small differences in mass or physical properties.
The result can be highly specialized materials that can’t be found in nature. They enable research, medical-isotope production, advanced electronics, quantum technologies, and other applications.
Tech + Stable Isotope Separation
Electromagnetic Isotope Separation (EMIS)
EMIS uses electric and magnetic fields to separate isotopes by mass. ORNL’s plasma-based systems can isolate and enrich multiple isotopes of an element.
Gas Centrifuge Isotope Separation (GSIS)
Gas centrifuge systems separate isotopes in gaseous compounds by exploiting small differences in molecular mass, providing an efficient approach for selected elements.
Advanced Separation Research
Researchers investigate additional physical and chemical separation methods to improve efficiency, precision, scalability, and access across the periodic table.
Reestablishing U.S. Stable Isotope Enrichment
For decades after the final Oak Ridge calutrons stopped operating in 1998, the United States lacked domestic stable isotope enrichment. DOE and ORNL have now re-established that capability using modern electromagnetic and gas-centrifuge isotope separation technologies.
For nearly a decade, a team at ORNL has been working to develop and demonstrate the next generation of gas centrifuges, technology that will restore a crucial capability the U.S. last had in 2013: to enrich uranium for defense-related missions.
Isotopes are forms of the same element with different numbers of neutrons. Stable isotopes do not undergo radioactive decay. Although they share nearly identical chemical properties, differences in their mass and nuclear characteristics can make individual isotopes valuable for medicine, research, computing, industry, and national security.
Most elements occur naturally as mixtures of isotopes. Enrichment increases the concentration of one selected isotope beyond its natural abundance. At ORNL, we develop technologies that separate nearly identical atoms so customers can obtain isotopic compositions and material forms suited to highly specialized applications.
Isotopes of an element behave almost identically in ordinary chemical processes. Separating them requires technologies capable of detecting and exploiting extremely small differences in atomic or molecular mass. ORNL combines physics, chemistry, engineering, materials science, modeling, and precision measurement to control these demanding processes.
ORNL’s isotope-enrichment history extends back to the electromagnetic calutrons developed at Oak Ridge during the 1940s. Today, our researchers are building on that foundation with modern electromagnetic, gas-centrifuge, and plasma-based technologies. ORNL serves as a national steward for the research, development, demonstration, and deployment of isotope-enrichment technologies.
Stable isotopes can serve as starting materials, or targets, for producing medical radioisotopes. For example, enriched ytterbium-176 can be irradiated to produce lutetium-177, a radioisotope used in targeted cancer therapies. Increasing the concentration of the desired target isotope can improve production efficiency and help reduce unwanted isotopic byproducts.
When Oak Ridge’s last production calutrons stopped operating in 1998, the United States lost a major domestic source of newly enriched stable isotopes. DOE and ORNL rebuilt that capability through sustained research and technology development. In 2018, ORNL enriched ruthenium-96—the first domestic enrichment of a stable isotope since the calutrons closed—and has continued expanding the nation’s production capabilities.
