In a development that could redefine how nuclear energy is deployed worldwide, California-based startup Deep Fission has begun drilling the first of three data acquisition wells for its revolutionary underground nuclear reactor project in Parsons, Kansas.
The milestone marks a critical transition—from theoretical design to physical implementation—for a technology that aims to place small modular reactors (SMRs) deep underground inside boreholes nearly a mile beneath the Earth's surface.
If successful, the concept could reshape nuclear power deployment by combining proven reactor technologies with drilling techniques borrowed from the oil, gas, and geothermal industries.
And perhaps more importantly, it could solve several of nuclear energy’s most persistent challenges: safety, land use, and construction costs.
A New Nuclear Architecture
Deep Fission’s approach is radically different from traditional nuclear plant designs.
Instead of constructing large, complex facilities on the surface, the company plans to install compact nuclear reactors deep underground in narrow boreholes.
The first well currently being drilled will reach approximately 6,000 feet (1,830 metres) and have a diameter of about eight inches (20 cm). Two additional wells will follow as part of the company’s three-well drilling program.
These wells are not yet for power generation.
Their purpose is to gather essential subsurface data, including:
- Geological properties
- Hydrological conditions
- Thermal characteristics
This information will help engineers refine the final reactor design, perform safety analyses, and guide regulatory approvals.
In essence, the drilling campaign is the scientific reconnaissance mission before nuclear deployment underground.
From Concept to Construction
According to Deep Fission CEO and co-founder Elizabeth (Liz) Muller, the drilling represents a turning point for the company.
“Drilling our first borehole is a major step forward for Deep Fission. It represents the shift from concept to construction and begins the process of demonstrating a fundamentally new approach to nuclear energy deployment.”
The company has already completed construction of the drilling pad at the Great Plains Industrial Park in Parsons, Kansas—an infrastructure milestone that allows drilling operations to proceed safely and efficiently.
Once the pilot project is validated, the site could host a full-scale commercial nuclear facility.
The Gravity Reactor Concept
At the center of the project is Deep Fission’s Gravity Reactor, a small modular reactor specifically designed to operate deep underground.
The reactor relies on conventional pressurised water reactor (PWR) technology and uses low-enriched uranium (LEU) fuel—both well-established elements within the nuclear industry.
Each underground reactor unit is expected to produce:
15 megawatts of electricity (MWe).
While that may sound modest compared to traditional nuclear plants, the design allows for extreme density of power generation.
For example:
- 10 reactors on one site could generate 150 MWe
- 100 reactors could produce 1.5 gigawatts (GWe)
This modular scaling offers flexibility for utilities and industrial users who may not require massive nuclear installations.
Why Go Underground?
The underground approach offers several potential advantages.
1. Passive Safety
The surrounding geology provides natural shielding and containment, significantly reducing risks associated with radiation exposure or external threats.
2. Smaller Surface Footprint
Traditional nuclear plants require large facilities and security perimeters. Underground reactors dramatically reduce land requirements.
3. Faster Construction
Using standardised borehole drilling techniques could accelerate reactor deployment compared to traditional plant construction.
4. Lower Capital Costs
By using off-the-shelf components and established drilling technologies, Deep Fission hopes to lower the enormous upfront capital investments typical of nuclear projects.
Where Nuclear Meets Geothermal Engineering
One of the most intriguing aspects of Deep Fission’s design is the cross-industry technology integration.
The company is combining knowledge from three sectors:
- Nuclear engineering
- Oil and gas drilling
- Geothermal well construction
For experts in geothermal drilling, the concept feels strikingly familiar.
Deep boreholes, subsurface thermal management, and complex geological characterisation are already routine in geothermal exploration. By borrowing this expertise, Deep Fission may significantly shorten the learning curve for underground reactor deployment.
It also highlights a broader trend: energy technologies are converging.
A Federal Push for Advanced Reactors
Deep Fission’s pilot project has also gained federal recognition.
In August 2025, the company was selected by the U.S. Department of Energy (DOE) as one of ten companies eligible for support under the Nuclear Reactor Pilot Program.
The program aims to accelerate advanced reactor development and achieve criticality for at least three reactor designs by July 4, 2026.
The initiative reflects growing urgency in the United States to deploy next-generation nuclear technologies that can complement renewable energy and provide reliable baseload electricity.
A Family of Nuclear Innovators
Deep Fission was founded in 2023 by Elizabeth and Richard Muller, a father–daughter team already known for pioneering unconventional nuclear solutions.
The pair previously co-founded Deep Isolation, a company focused on disposing of nuclear waste by placing sealed canisters deep underground in boreholes.
The experience gained in subsurface engineering and borehole safety is now being applied to power generation itself.
Instead of burying nuclear waste, Deep Fission aims to bury the reactor.
Could Underground Reactors Transform Nuclear Energy?
If the concept works at scale, it could unlock entirely new deployment possibilities.
Underground SMRs could power:
- Industrial parks
- Data centers
- Mining operations
- Remote communities
- Military installations
Because the reactors require little surface infrastructure, they may also face less public opposition compared to traditional nuclear plants.
Moreover, modular deployment could allow utilities to expand capacity gradually, rather than committing billions to a single massive facility.
The Challenges Ahead
Despite the promise, the technology faces significant hurdles.
These include:
- Regulatory approvals for underground nuclear reactors
- Long-term maintenance and accessibility
- Subsurface thermal management
- Public and environmental acceptance
Drilling wells for geological data is only the first step in a long journey.
The coming years will determine whether underground nuclear reactors remain an ambitious experiment—or evolve into a new pillar of the global energy system.
A Glimpse of the Future Energy Landscape
Deep Fission’s drilling campaign represents something larger than a single pilot project.
It signals a new wave of experimentation in nuclear engineering, where innovators are challenging the assumptions that have defined nuclear power plants for decades.
Just as geothermal developers learned to harness Earth’s internal heat through deep drilling, nuclear engineers may soon be tapping that same underground space to safely contain powerful reactors.
If that vision materialises, the future of nuclear power may not rise above the skyline.
It may lie deep beneath our feet.
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