TerraPower Isotopes announced plans to build an actinium‑225 production facility in Philadelphia with a projected $450 million cost and production start targeted for 2029. The company said the plant will scale supply of Ac‑225, a short‑lived alpha emitter crucial to next‑generation targeted radiotherapies. The lead sentence: TerraPower is expanding into medical isotopes to address a critical shortage for radiopharmaceutical development. The announcement follows site selection from 350 candidates and underscores industry concerns about stable access to medical radioisotopes for alpha‑particle therapies. Actinium‑225 is a limiting reagent for several alpha‑emitter drug programs; scaling domestic production could accelerate clinical development and commercialization for companies developing targeted alpha therapies. Investors, drug developers and regulators will track licensing, isotope purity standards, and distribution logistics given the isotope’s short half‑life and complex supply chain requirements.