In Development
Natrium
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TerraPowerTerraPower Isotopes (Actinium-225)
Active
Medical-isotope business producing actinium-225 (Ac-225), a rare alpha-particle-emitting isotope used in targeted radiotherapeutics for cancers including prostate, breast, colon, and neuroendocrine cancers, melanoma, and lymphoma.
Latest update Sep 18, 2026
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Current status
Producing Ac-225 at commercial scale via weekly production runs since October 2024, supplying pharmaceutical partners for radiopharmaceutical development and human clinical trials from its Everett, Washington facility. A second, larger cGMP facility (the Bellwether Laboratory in Philadelphia, $450M investment, 250,000 sq ft) broke ground May 6, 2026 and is intended to expand global Ac-225 capacity twentyfold, with production starting in 2029. TerraPower's isotopes page, re-verified September 18, 2026, still describes the Philadelphia plant as under construction with a twentyfold capacity increase. TerraPower Isotopes sources its thorium-229 feedstock from DOE contractor Isotek Systems at Oak Ridge; a new Isotek analytical lab opened August 21, 2026 speeds Th-229 delivery and supports the decay-based technique TerraPower uses to extract Ac-225.
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Specifications3
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Upcoming milestones1
Announced next steps from TerraPower that mention TerraPower Isotopes (Actinium-225).
2029
Bring Bellwether Laboratory (Philadelphia) online
Complete construction of the $450M, 250,000-square-foot Bellwether Laboratory in Philadelphia's Bellwether District (groundbreaking May 6, 2026) and begin cGMP actinium-225 production there, expanding TerraPower Isotopes' global Ac-225 capacity twentyfold alongside its existing Everett, Washington site. Not yet online as of September 18, 2026; TerraPower's isotopes page still describes the Philadelphia plant as under construction with a twentyfold capacity increase, and no delay to the 2029 production-start target has been reported.
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