Researchers ask industry to find new approaches to kilowatt-scale power generation from nuclear radiation

Summary points:

• Rads to Watts seeks to convert nuclear radiation directly into electricity for long-term, high-power military use in remote environments.
• Project focuses on next-gen radiovoltaics using radiation-hardened semiconductors to overcome degradation in high-radiation, high-power applications.
• Abstracts are due by 10 July 2025, and full proposals by 20 Aug. 2025.

ARLINGTON, Va. – U.S. military researchers are asking industry to find ways of converting nuclear radiation directly to electricity for long-term unattended power in military applications where refueling and other support is impractical.

Officials of the U.S. Defense Advanced Research Projects Agency (DARPA) in Arlington, Va., issued a solicitation (DARPA-PS-25-27) on Monday for the Rads To Watts program.

Rads to Watts will explore new approaches to power generation from nuclear radiation, without taking the interim step of converting radiation to heat before converting it to electricity.

The project focuses on radiation voltaics -- also called radiovoltaics -- which converts the energy from ionizing radiation directly into electricity using semiconductor materials. The radiation excites electrons and creates electron-hole pairs in the semiconductor to generate an electrical current.

Radiation to kilowatts

Specifically, Rads to Watts seeks to convert high-power nuclear radiation into kilowatts of electrical energy to create long-term high-power sources for military applications that must operate in harsh and remote areas.

Radiation-induced defects in radiovoltaics can degrade the performance and lifespans of today's radiovoltaics at the materials and device levels when exposed to high-power radiation sources.

Instead, Rads to Watts will encourage contractors to go beyond typical low-power radiovoltaic architectures and semiconductors with low-fluence tolerance for long-lived high power conversion. Rads to Watts seeks to develop prototype radiovoltaic cells scalable to radiovoltaic arrays or stacks of unit cells.

Operations in space, under the sea, and other isolated locations are limited by low-power systems with short lifetimes, researchers explain. Challenges like radiation-induced degradation, environmental degradation, and chemical incompatibility have kept today's power electronics technologies from high-power long-duration applications. Overcoming this is the primary focus of Rads to Watts.

New semiconductor materials

Today's silicon and gallium arsenide radiovoltaic semiconductor materials can be damaged in high-radiation energy environments like space. Potential solutions involve new materials, self-healing and annealing materials, and advances in thin film fabrication.

DARPA researchers are looking for companies able to combine radiation-hardened materials with new radiovoltaics architectures that will lay the groundwork for radiation-tolerant high-power long-life systems that can achieve kilowatt-scale power.

Companies interested should submit abstracts no later than 10 July 2025 to the DARPA BAA Tool online at https://baa.darpa.mil. Submit full proposals no later than 20 Aug. 2025 to the DARPA BAA Tool online at https://baa.darpa.mil.

Email questions or concerns to DARPA at [email protected]. More information is online at https://sam.gov/opp/f655dbe2fb434ba89678b17f247f48bc/view.