Oak Ridge’s Isotek dramatically increases world supply of Th-229

While 15 grams might not sound like much, it represents a 1,500 percent increase in the world’s supply, according to the DOE, which noted that there is currently only 1 gram of the isotope available worldwide outside of Oak Ridge, Tenn.

“We are incredibly proud to have reached this milestone,” said Sarah Schaefer, Isotek president and project manager. “This is the result of years of hard work and great attention by the operations team.”

A medical isotope: Begun in 2019 as a public-private partnership among TerraPower, Isotek, and OREM, the Thorium Express Project has been recovering Th-229 from downblended uranium-233 that has been in storage at Oak Ridge National Laboratory for decades.

Through the partnership, Isotek employees extract Th-229 from the U-233. The Th-229 is then delivered to TerraPower to produce actinium-225, an alpha-emitting isotope used in a promising cancer treatment called targeted alpha therapy, while the downblended and stabilized U-233 is shipped off-site for permanent disposal (primarily to the Nevada National Security Site).

Last year, TerraPower announced that it has enough Th-229 to produce Ac-225 at a commercial scale, making the medical isotope available to the pharmaceutical industry through weekly production runs.

U-223 inventory: Originally created in the 1950s and 1960s for potential use in reactors, U-233 proved to be an unviable fuel source due to trace quantities of unstable U-232. Eliminating the inventory of U-233 is OREM’s highest cleanup priority at ORNL, as it is stored in the world’s oldest operating nuclear facility and is very costly to keep safe and secure, the DOE said.

When Isotek began extracting medical isotopes in 2019, crews processed lower-radiation canisters in gloveboxes. When processing operations began on the higher-dose canisters in hot cells in 2022, employees saw a boost in the amount of isotopes they could extract and provide to TerraPower.

“As we progress through the inventory, we’ll have opportunities to extract greater amounts of thorium,” Schaefer said. “We continue to refine our processes to keep our extraction efficiency as high as possible.”

According to the DOE, Isotek has processed and removed approximately 40 percent of the remaining inventory of U-233 stored at ORNL. By the end of the project, Isotek expects to have extracted 40 grams of Th-229, enough to create 100 times more treatment doses annually than is currently available worldwide.