TerraPower looks to turn DOE’s waste uranium into actinium-225

August 5, 2020, 10:12AMAround the Web

This vial contains traces of actinium within a mixture of thorium and uranium. Photo: Isotek

An article recently published in Chemical & Engineering News describes TerraPower’s efforts to extract actinium-225, a radioisotope with therapeutic potential, from highly radioactive uranium-233 owned by the Department of Energy and slated for disposal. While others are working to ramp up production of Ac-225 by using a linear accelerator or cyclotron, TerraPower hopes to harvest between 200,000 and 600,000 doses a year from U-233 to increase the global supply.

Disease-fighting potential: Ac-225, with a half-life of 10 days, is currently being studied in clinical trials for cancer treatment that make use of the alpha particles emitted from its radioactive decay. Because alpha particles travel only a short distance through the body—about the diameter of two or three human cells—there’s minimal risk of damage to tissues beyond the target. And attaching Ac-225 to drugs or antibodies that target diseased cells can deliver the radiation to where it is needed. No actinium-based drugs have yet been approved by the U.S. Food and Drug Administration. Currently, Ac-225 is produced in small amounts at Oak Ridge National Laboratory, Brookhaven National Laboratory, and Los Alamos National Laboratory.

Milking the thorium cow: Isotek has been contracted by the DOE to eliminate the nation’s remaining stores of highly radioactive U-233, which has a half-life of 160,000 years and decays to thorium-229, which itself has a half-life of 8,000 years, decaying to Ac-225. Isotek isolates Th-229 and ships it to TerraPower. TerraPower plans to scale-up an ORNL-developed method of producing Ac-225 called “milking the thorium cow.”

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