Deep Fission and Youngquist Brothers Team Up to Drill Mile-Deep Boreholes for Underground Nuclear Reactors

Deep Fission, a developer of the “Gravity Nuclear Reactor,” has partnered with commercial drilling firm Youngquist Brothers to create the large-diameter, one-mile-deep boreholes required for its underground reactor concept. The reactor would sit in a water-filled borehole, using surrounding rock and water for containment and cooling. The collaboration moves the effort from reactor design to solving the engineering challenge of drilling a borehole wide enough (approximately 34 inches) and deep enough to host the system.

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The underground deployment model builds on pressurized-water reactor technology and low-enriched uranium fuel. Earlier, on September 3, the teams lowered a 30-inch full-size prototype canister into a 34-inch borehole in Fort Myers, Florida, reaching roughly 100 feet before retrieving it—a test of installation and retrieval mechanics, not the full-depth drilling required for the final design. Youngquist Brothers has drilled large-diameter holes to depths exceeding 8,000 feet and has refined such methods since 1971. Deep Fission is also advancing its first reactor project in Parsons, Kansas, and has been selected for the U.S. Department of Energy’s Reactor Pilot Program.

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Liz Muller, CEO and Co-Founder of Deep Fission, emphasized that leveraging an established commercial driller allows the project to advance without developing new drilling technology from scratch. Harvey Youngquist, CEO of Youngquist Brothers, noted that the company’s long-standing expertise in deep, large-diameter drilling aligns directly with the reactor’s requirements. Both executives framed the partnership as a practical step toward meeting the borehole-construction milestone needed before commercial deployment, which Deep Fission targets for as early as 2027.

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• “Youngquist brings decades of hands-on drilling experience that maps directly onto what our deployment model requires,” — Liz Muller, CEO and Co-Founder of Deep Fission

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• “Large-diameter drilling to these depths is a method we’ve refined since 1971,” — Harvey Youngquist, to its CEO

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Deep Fission aims to complete the borehole-construction feasibility work with Youngquist Brothers in the coming years, after which the company plans to begin installing its first mile-deep reactor. Commercial rollout is projected for early 2027, contingent on successful drilling trials and continued DOE program support.

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