Kansas mile-deep reactor project has entered a new development phase after Deep Fission completed major testing and regulatory milestones. The $80 million pilot is under development at Great Plains Industrial Park in Parsons, Kansas.
Deep Fission broke ground on the project in December 2025. The company initially targeted reactor criticality by July 4, 2026. However, it did not meet that target and has shifted its focus toward engineering validation.
The project involves placing a small modular pressurized water reactor approximately one mile underground. The design uses established reactor technology with a different underground deployment model.
Deep Fission says the underground configuration could reduce surface infrastructure requirements. However, the pilot remains subject to further testing, regulatory approvals and technical validation.
Kansas mile-deep reactor project moves into proof-of-concept phase
The project has completed its first data acquisition well at approximately 6,000 feet. The well provides geological, hydrological and thermal information for the site.
Deep Fission has also completed fabrication and delivery of its prototype reactor canister. The company is now preparing for a commercial-scale borehole demonstration.
In September, Deep Fission demonstrated installation and retrieval of a full-scale prototype canister. The demonstration used a 34-inch borehole and reached approximately 100 feet.
The test used non-nuclear equipment and did not represent operation of an underground nuclear reactor. Instead, it validated elements of the planned installation process.
Deep Fission has also partnered with Youngquist Brothers to evaluate large-diameter drilling methods. The companies will test techniques needed to construct deep boreholes for the reactor system.
Youngquist Brothers has experience drilling large-diameter boreholes exceeding 8,000 feet. The collaboration could therefore support the project’s planned full-scale drilling program.
Kansas mile-deep reactor project receives DOE safety framework
The U.S. Department of Energy approved a Nuclear Safety Design Agreement for the Gravity reactor in August.
Deep Fission subsequently published the agreement in September. The document establishes the safety framework and regulatory approach guiding continued pilot development.
The DOE approval does not authorize nuclear operations at the Kansas site. Additional reviews and authorization remain necessary before the company can conduct nuclear testing.
Deep Fission is developing the pilot under the DOE Reactor Pilot Program. It is also pursuing a separate commercial licensing pathway with the U.S. Nuclear Regulatory Commission.
The company currently targets a commercial licensing application during the first half of 2027. It intends to convert the pilot reactor to commercial operation, subject to NRC approval.
The current project schedule therefore differs from the original July 2026 criticality target. Deep Fission now expects nuclear work at the site to progress into 2027.
The company also completed a $40 million public offering in June. It plans to use proceeds for engineering, research, development, licensing and construction activities.
Meanwhile, Deep Fission has raised additional private financing previously. The company announced $80 million in financing in February 2026.
The Kansas development forms part of Deep Fission’s wider strategy for deploying underground reactors. The company says potential commercial expansion would require additional regulatory approvals and successful pilot results.
As U.S. companies pursue new nuclear capacity for rising electricity demand, Amazon’s $3 billion Calvert Cliffs nuclear expansion in Maryland shows another route to expanding existing nuclear generation. The project will increase Calvert Cliffs’ output by about 190 MW under a 20-year power purchase agreement between Amazon and Constellation Energy.
Revolutionary “Gravity” Reactor Technology
The proprietary “Gravity Nuclear Reactor” design proposed by Deep Fission fundamentally reimagines the safety architecture of nuclear power by utilizing the earth itself as a primary containment vessel and radiation shield. By positioning the pressurized water reactor module a full mile underground, the system naturally achieves the necessary 160 atmospheres of operational pressure through the weight of the water column above it, removing the requirement for complex and costly mechanical pressurizers that are standard in surface plants.
This configuration ensures that all radioactive isotopes remain isolated deep within the bedrock, protected by billions of tons of passive geological shielding that renders the facility virtually impervious to surface-level threats such as tornadoes, aircraft impacts, or sabotage. The non-radioactive steam generated at depth is piped to the surface to drive standard turbines for electricity generation. This creates a closed-loop system that promises to deliver carbon-free baseload power with a significantly reduced physical footprint. In addition, it promises a projected levelized cost of electricity that could rival the affordability of natural gas.
Revitalizing the Great Plains Industrial Park
Selecting Parsons for this high-stakes demonstration highlights the strategic value of the Great Plains Industrial Park. A sprawling 14,000-acre complex that is actively transitioning from its mid-20th-century origins as a munitions manufacturing hub into a modern center for heavy industry and energy production. Furthermore, the site offers Deep Fission an ideal combination of existing heavy infrastructure and favorable geological conditions for deep drilling. Additionally, a supportive local administration eager to attract long-term high-tech investment to Southeast Kansas.
Local county commissioners and the Great Plains Development Authority have rallied behind the project. They recognize that a successful pilot could pave the way for a full-scale commercial deployment where multiple reactor modules are installed across the park to power energy-intensive tenants such as data centers or manufacturing plants. This “energy-first” development strategy positions the region to capitalize on the surging demand for reliable industrial power grids. Further, it creates a unique economic ecosystem where abundant, clean energy serves as the primary magnet for future tenants and job creation in Labette County.
National Implications for Energy Independence
The Parsons project is advancing under the auspices of the Department of Energy’s Reactor Pilot Program, a federal initiative designed to fast-track the deployment of novel nuclear technologies that can be built faster and cheaper than traditional large-scale plants—an ambition recently underscored as the Clinch River nuclear site in Tennessee gets $400M funding from DOE to deploy GE Vernova’s BWRX-300 reactors. Deep Fission’s approach addresses two of the most persistent criticisms of the nuclear industry; exorbitant construction costs and lengthy permitting timelines. By utilizing standard oil and gas drilling techniques and off-the-shelf reactor components that do not require custom fabrication.
If the Kansas pilot successfully demonstrates that a reactor can be taken from groundbreaking to criticality in under a year, validating a scalable model for rapid decarbonization that could be replicated across the United States. The regulatory data gathered from this project will be instrumental for the Nuclear Regulatory Commission as it establishes frameworks for subsurface reactors, potentially unlocking a new era where nuclear power can be safely integrated into populated or industrial areas with minimal visual or environmental impact.
Project Fact Sheet: Kansas mile-deep reactor
Project: Deep Fission Gravity Nuclear Reactor Pilot
Location: Great Plains Industrial Park, Parsons, Labette County, Kansas
Developer: Deep Fission
Project Value: $80 million
Reactor Technology: Gravity Nuclear Reactor
Reactor Type: Small modular pressurized water reactor
Planned Depth: Approximately one mile underground
Pilot Capacity: Approximately 15 MW
Data Acquisition Well: Approximately 6,000 feet deep
Current Phase: Engineering validation and proof-of-concept
Groundbreaking: December 9, 2025
Original Criticality Target: July 4, 2026
Current Commercial Target: 2027, subject to approvals
Site Area: Approximately 100 acres under long-term lease
Federal Programme: U.S. Department of Energy Reactor Pilot Program
Commercial Regulator: U.S. Nuclear Regulatory Commission
Current Status: In progress
Project Team
Developer: Deep Fission.
Site Partner: Great Plains Development Authority.
Drilling Technology Partner: Youngquist Brothers.
Federal Pilot Programme Authority: U.S. Department of Energy.
Nuclear Licensing Authority: U.S. Nuclear Regulatory Commission.
State Environmental and Well-Drilling Oversight: Kansas Department of Health and Environment.
State Energy Regulatory Authority: Kansas Corporation Commission.
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