DARPA backs U.S. team to turn strontium-90 waste into long-life power cells

DARPA has awarded a research contract to a consortium led by Morgan State University to explore a nuclear-waste-derived power source called SYMPHONEE. The concept relies on a betavoltaic cell that transforms the beta radiation emitted by strontium-90 into electric current, similar to how sunlight powers a photovoltaic cell. Strontium-90, with a half-life of about 29 years, could supply a low-level but steady output for many years, making it suitable for devices that operate in inaccessible locations such as space probes, deep-sea platforms and remote sensors.

Laboratory experiments using simulated radiation achieved conversion efficiencies between 16 and 19 percent, indicating the principle works, but a complete battery delivering sustained watts-per-kilogram power has not yet been realized. The approach requires careful extraction, purification and encapsulation of the isotope to address safety and health concerns, as strontium-90 can be hazardous if inhaled or ingested. While the technology would not eliminate the need for nuclear waste storage, it could reclaim valuable isotopes and reduce reliance on conventional chemical batteries for niche applications.