Source: C&EN | Wudan Yan, special to C&EN | July 27, 2020

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TerraPower plans to mine nuclear waste to capture actinium-225 for cancer clinical trials. This vial contains traces of actinium within a mixture of thorium and uranium.

A half hour north of Seattle in Everett, about 15 black barrels sit in a nondescript storage facility owned by the nuclear innovation company TerraPower. Each barrel is the size of a large trash can, around 110 L, and weighs over 350 kg. What’s held within is . . . complicated. Just inside the thick shell is a layer of foam padding. Within that padding sits a heavy-duty container, which in turn encloses a steel pipe capped on each end. Inside the pipe is a screw-top aluminum can, which holds a thick plastic bag, which encases a glass vial about the size of a tube of toothpaste. “It’s sort of your classic Russian doll,” says Jeff Latkowski, TerraPower’s senior vice president of innovation. That innermost glass vial holds half a gram of a yellow matter—a mixture of the radioactive elements uranium and thorium.

These smidgens of material would normally have been disposed as nuclear waste by the US Department of Energy (DOE) and its partner in disposal, the nuclear waste management company Isotek. Instead, TerraPower requested the samples so that Latkowski and his colleagues can unpack the Russian dolls and extract a valuable medical isotope: actinium-225, which results from radioactive decay of uranium and has shown promise in treating a range of cancers. TerraPower hopes that mining the waste will yield between 200,000 and 600,000 doses of 225Ac a year, 100 times the number of doses currently available globally. TerraPower’s efforts are part of a global push to increase actinium production to ensure a reliable supply for medical research and clinical use.

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