Physicist and Daughter Develop Underground Nuclear Reactor Technology

Elizabeth Muller and Richard A. Muller, a physicist, have established a startup called Deep Fission to develop small nuclear reactors installed deep underground. The reactors are designed to be placed in boreholes a mile deep, using water pressure for operation.

Each reactor is expected to produce 15 megawatts of power, sufficient for 12,000 homes. The concept originated during walks in Berkeley, California, where the Mullers discussed ideas. Richard A. Muller, aged 82, previously taught at the University of California at Berkeley for 40 years and contributed to improvements in radiocarbon dating.

Elizabeth Muller, 47, worked in international finance in France before returning to Berkeley.

The design involves drilling a 30-inch-diameter borehole filled with water, into which a small reactor is inserted. The reactor boils water at the bottom, sending steam up a separate pipe to drive a turbine. The system operates under pressure from the water column, reducing the need for traditional containment structures.

Deep Fission estimates the cost at about six cents per kilowatt hour. The reactors use standard 5%-enriched uranium fuel assemblies, with control rods to manage fission reactions. The radioactive components remain isolated at the bottom, and the system recycles water in a closed loop.

The company has raised $122 million, with a post-money valuation of $1 billion. Elizabeth Muller holds a 19% stake, Richard A. Muller holds 10%, and 8VC, associated with Palantir cofounder Joe Lonsdale, owns 8%. Funds will support research, development, and a test reactor costing $84 million.

Department of Energy included Deep Fission in its Reactor Pilot Program, one of ten companies selected. Rian Bahran, deputy assistant secretary for nuclear at the DOE, stated that the program aims to test smaller reactors amid growing electricity demand from data centers.

Future Plans Deep Fission is drilling its first test borehole in Parsons, Kansas, at the Great Plains Industrial Park. The site, formerly used for munitions production during World War II, is zoned for heavy industry including nuclear activities. The company seeks an expedited license from the Nuclear Regulatory Commission to begin commercial power sales in 2027.

3 billion market cap; Aalo Atomics, which raised $136 million; Valar Atomics, with $150 million for a Utah reactor; and Kairos Power, constructing in Oak Ridge, Tennessee, to supply a Google data center.

Muller's earlier work included mentoring under Luis Alvarez, who collaborated with Robert Oppenheimer on the atomic bomb. After retiring, the Mullers started a nonprofit to study climate change, concluding nuclear power could reduce emissions in developed countries.

They later formed Global Shale with a former Shell Oil president to explore shale gas in China, partnering with Wuhan University, though the project was halted by authorities. Deep Fission represents their shift to nuclear energy innovation.