TerraPower breaks ground on Ac-225 isotope facility

TerraPower Isotopes has broken ground on a $450M actinium-225 manufacturing facility in Philadelphia’s Bellwether District, according to the company.

The 250,000-square-foot Bellwether Laboratory will serve as TerraPower Isotopes’ flagship East Coast current good manufacturing practice, or cGMP, facility for Ac-225 production. The company said the site is intended to support targeted alpha therapy and precision medicine development.

Combined with expanded capacity at TerraPower Isotopes’ laboratory in Everett, WA, the Philadelphia facility is expected to increase global Ac-225 production capacity 20-fold. TerraPower said the project is intended to address a supply constraint that has limited development of targeted alpha therapies for cancer treatment.

Ac-225 is a rare radioisotope used in targeted alpha therapy, a class of radiopharmaceutical treatments that link radioactive isotopes with targeting molecules to deliver localized radiation to cancer cells. TerraPower said its Ac-225 is already being used in human clinical trials worldwide.

“Breaking ground today on the Bellwether Laboratory represents a defining chapter,” said Chris Levesque, president and CEO of TerraPower.

The project is expected to create at least 225 full-time jobs and about 500 construction jobs, according to the Pennsylvania Department of Community and Economic Development. The state said it supported the project with a $10M investment.

Philadelphia was selected after TerraPower Isotopes evaluated more than 350 potential sites across the U.S., including 49 site visits in 8 metropolitan areas. The company cited the Bellwether District’s scale, infrastructure access, and proximity to life sciences and medical institutions as reasons for the location.

The facility was first announced March 17, when TerraPower Isotopes said production of cGMP Ac-225 is expected to begin in 2029 as part of a multiyear buildout.

State officials said the Bellwether District is a 1,300-acre redevelopment of the former Philadelphia Energy Solutions refinery into a commercial, advanced manufacturing, and innovation hub.

The project comes amid growing interest in radiopharmaceutical therapy and nuclear medicine supply chains. Ac-225 has attracted attention because alpha-emitting radiopharmaceuticals may deliver highly localized radiation, but isotope availability has remained a bottleneck for drug developers and clinical trials.

TerraPower Isotopes is part of TerraPower, a nuclear innovation company founded by Bill Gates and others to develop nuclear science applications across energy and healthcare. The isotope business focuses on supplying radioisotopes for targeted alpha therapy development.

Further milestones will depend on construction progress, cGMP qualification, and the company’s planned production start in 2029.