Revolutionizing Energy: Darpa Pursues Decades-Long Nuclear Power Pods

The Quest for Compact Nuclear Power: DARPA’s Rads to Watts Program

In an effort to overcome the significant challenges associated with nuclear power, the Defense Advanced Research Projects Agency (DARPA) has launched a multi-million-dollar program aimed at developing a new type of miniature power cell that can run for years or decades without recharging. Dubbed “Rads to Watts,” the initiative seeks to replace traditional AA batteries with a compact, high-energy source capable of powering everything from satellites in space to tactical radios and pacemakers.

Tabitha Dodson, program manager for DARPA’s Rads to Watts program, notes that the primary obstacles to achieving this goal are heat management and weight. “There’s an enormous amount of energy inside a nuclear reaction, whether it’s fission or radioisotope,” she explains. “But there is a lot of heavy and non-transportable hardware that deals with heat management for both fission and RTG systems.” This heat management piece has always been the roadblock to achieving transportable nuclear power.

To address this challenge, DARPA has funded seven competing teams through its Rads to Watts program. These teams are working on a range of approaches to radiovoltaics, which harness the energy from radiation to generate electricity without converting it into heat. This process is different from traditional nuclear reactors and RTGs, which create power by running hot and requiring bulky cooling systems.

Radiovoltaic power sources can be compact because they don’t require the conversion of radiation into heat. Instead, they capture the radioactive particles in a semiconductor, exciting electrons that are then converted into a usable electric current. This process is similar to how solar panels, which are photovoltaic devices, capture photons from sunlight.

However, there’s an inherent problem with harnessing intense energies: they can cause damage to electronic systems. In fact, the more energy a particle provides, the faster it can destroy the power cell built around it – a self-defeating outcome.

To overcome this issue, the competing teams are exploring different approaches. Some, like City Labs, are using weaker radiation sources, such as tritium, which emits beta particles. Others, like BWXT and Johns Hopkins University Applied Physics Laboratory, are using higher-energy radiation sources, such as alpha particles. These teams are relying on advances in materials science to design new kinds of semiconductors that can endure higher energies.

One team, led by City Labs, is taking a more conservative approach, packing tritium into a smaller volume to increase power output while maintaining safety. Another team, led by BWXT and Johns Hopkins University, is using alpha particles and exploring a wide range of novel semiconductor materials using AI simulations.

Avalanche Energy is also using alpha particles but takes a different approach. Instead of toughening up its semiconductor to absorb the alpha particles directly, they protect it with an absorbing layer of liquid metal. This allows the alpha particles to convert their intense energy into manageable electrons, which are then converted into electrical power.

Another team, led by Morgan State University and partnered with Sheehan’s Project Omega, is trying to get the best of both worlds by using a higher-energy beta particle source and novel materials to withstand it.

All these competing radiovoltaics have already demonstrated power outputs of at least 10 watts per kilogram, which is two to three times more efficient than traditional RTGs. However, the teams are confident that they can achieve much greater power densities, somewhere between 10 and 100 watts.

The teams will finalize their prototype power cells over the next 15 months, after which the best designs will proceed to a nine-month endurance test to see if they truly hold up under internal radiation and external environmental pressures. If successful, at least one candidate will be ready for large-scale deployment with the military.

DARPA’s Rads to Watts program has the potential to revolutionize the way we think about compact nuclear power. By harnessing the energy from radiation in a more efficient and safe manner, these miniature power cells could replace traditional batteries and become an essential component of future military operations, space exploration, and even medical devices.

The success of this program would not only provide a significant boost to DARPA’s efforts but also pave the way for innovative solutions in various fields. As the teams continue to work on their designs, one thing is clear: the quest for compact nuclear power is an exciting and ambitious endeavor that holds great promise for the future.

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