On September 3rd, in Fort Myers, Florida, Deep Fission lowered and retrieved a 30-inch reactor canister prototype inside a 34-inch borehole drilled to approximately 100 feet deep. The operation, carried out using Youngquist Brothers‘ equipment, was no paper study — it was a real mechanical test of installation and retrieval procedures, the first of its kind for the company’s underground reactor deployment program.
The partnership between the two companies aims to develop and refine the deep, large-diameter drilling techniques required for Deep Fission‘s deployment model. The plan calls for placing small pressurized water modular reactors — the Gravity Nuclear Reactor — approximately one mile below the Earth’s surface, leveraging natural geological formations for containment and cooling. The reactor runs on standard low-enriched uranium fuel, the same proven technology used in conventional PWRs, adapted to a radically different operating environment.
Youngquist Brothers, active in large-diameter drilling since 1971, has accumulated decades of hands-on experience with boreholes reaching depths of over 8,000 feet. It is precisely this operational expertise that led Deep Fission to choose them as a partner: no need to build capabilities from scratch, with proven technologies and machinery already battle-tested in the field. Deep Fission CEO and co-founder Liz Muller emphasized that working with an established commercial driller allows the company to move forward on the drilling side using tools that already exist.
The agreement fits into a program that is gaining real-world traction on multiple fronts. Deep Fission was selected by the U.S. Department of Energy under the Reactor Pilot Program and has already identified the site for its first pilot project: the Great Plains Industrial Park in Parsons, Kansas. The company is targeting commercial deployment by 2027. In January 2025, it announced a partnership with Endeavour Energy to co-develop 2 GW of nuclear power destined for data centers, with the first reactors expected to be operational by 2029.
The Fort Myers test was limited in depth — 100 feet versus the roughly one-mile operational target — but it was far from a symbolic exercise. It validated the real mechanics of lowering and raising the canister, aspects that at operational depths become one of the most demanding engineering challenges. The two companies plan to continue their joint work on drilling and testing as the program advances. A nuclear reactor installed a mile underground, retrievable and repositionable, fundamentally changes the variables in the siting equation: no cooling towers, no complex surface infrastructure, virtually no visual footprint. If large-diameter drilling proves viable at operational depths, Deep Fission’s model could open nuclear energy up to locations currently considered out of reach.
