Deep Fission: Using Boreholes to Cut Nuclear Costs and Deliver 24/7 Clean Electricity

What if the fastest path to reliable clean electricity is not a new reactor design, but a new place to put one? In this conversation, Paul Shapiro speaks with Elizabeth Muller, CEO of Deep Fission, about a plan to place a conventional pressurized water reactor roughly a mile underground to use geology, gravity, and groundwater for containment, pressure, and emergency cooling, potentially cutting total nuclear costs by as much as 80%. They unpack how a narrow borehole reactor could serve always-on demand from data centers and industrial users, what "proven tech combined in a new way" really means, how safety and groundwater concerns are handled through regulation and engineering practices, and the practical milestones from pilot to commercial operation so listeners can evaluate what it would take for underground nuclear to scale. Things You Will Learn

1. How putting a conventional reactor in a mile-deep borehole can replace major above-ground systems and cut nuclear cost drivers.
2. How Deep Fission thinks about worst-case scenarios, groundwater protection, and regulatory proof points.
3. What milestones convert LOIs into power purchase agreements, and what timelines look like for early deployment.

Tools & Frameworks Covered

1. Geology-as-infrastructure – Uses rock, gravity, and water to replace containment and pressurization systems.
2. Mature-tech recombination – Combines proven reactors, drilling, and geothermal heat transfer to speed time to market.
3. Pilot-to-commercial pathway – Separates "go critical" demonstration from commercial electricity generation milestones.

Episode Timestamps04:55 – Why a mile underground could cut nuclear costs by about 80% 08:47 – Borehole size, reactor dimensions, and how the hardware fits 09:31 – Replacement strategy, sealing, and stacking long-term operations 19:45 – Groundwater and safety concerns, what regulators need to see 21:43 – Timeline to power, DOE pilot program, and moving toward commercialization #BusinessForGood #CleanEnergy #NuclearEnergy #EnergyInnovation #ClimateSolutions