Father-Daughter Duo Deep Fission Set to Disrupt Nuclear Sector with Mile-Deep Borehole Reactors

Richard and Elizabeth Muller’s startup, Deep Fission, places small nuclear reactors a mile underground to cut costs by 80% and power AI data centers.

By: AXL Media

Published: Apr 3, 2026, 3:57 PM EDT

A Collaborative Vision Born in the Berkeley Hills

The foundation of Deep Fission was laid not in a laboratory, but during decade-long weekly hikes through the hills of Berkeley, California. Elizabeth Muller, 47, a business strategist with a background in international finance, successfully convinced her father, 82-year-old MacArthur "genius" award winner Richard A. Muller, to forgo retirement for one final commercial venture. Richard, a renowned physicist who revolutionized carbon dating, has spent four decades teaching at UC Berkeley. Together, they have transitioned from academic brainstorming to leading a startup that aims to solve the dual challenges of nuclear safety and high construction costs.

Engineering Simplicity: The Borehole Concept

Deep Fission’s approach departs radically from the massive, concrete-domed power plants of the 20th century. Their design involves drilling a 30-inch-diameter borehole one mile into the Earth’s crust. A small-scale nuclear reactor is lowered to the bottom, where it is submerged in water. Under the immense natural pressure of the Earth—roughly 160 times that of the surface atmosphere—the reactor boils the water to create steam. This steam is then transported back to the surface through a separate pipe to drive a conventional turbine.

Slashing Costs Through Geological Pressure

The primary innovation of the Deep Fission model is the elimination of the "containment" infrastructure that accounts for the vast majority of nuclear energy expenses. "We are using the gravity of the water to give the reactor the same pressure," Richard explains. By placing the reactor deep underground, the need for massive steel pressure vessels and reinforced concrete buildings is removed. The company estimates this will allow them to produce electricity at approximately six cents per kilowatt-hour, a price point that makes nuclear competitive with natural gas and renewables.