US-based start-up Deep Fission, which plans to place small modular pressurised water reactors in boreholes one mile underground, has selected the Great Plains Industrial Park in Parsons, Kansas, as the site of its advanced reactor pilot project. Deep Fission plans to hold a ground-breaking ceremony marking a significant milestone in the Company’s first demonstration of the Gravity Nuclear Reactor.
Deep Fission and the Great Plains Development Authority signed a letter of intent (LOI), outlining their collaboration on the pilot and their intention to develop a full-scale commercial project at the same site. “This pilot is an exciting first step toward an energy-abundant America,” said Liz Muller, Co-Founder and CEO of Deep Fission. “Our Gravity reactor is designed to deliver safer, faster, and dramatically cheaper energy.”
In September Deep Fission selected its first three planned sites in Texas, Utah, and Kansas, signing Letters of Intent (LOIs) with partners at each location to pursue joint development projects. Deep Fission, founded in 2023 by father-daughter team Elizabeth and Richard Muller. The company announced its emergence from stealth mode in August 2024. Deep Fission went public in October through a reverse merger transaction with Surfside Acquisition, alongside a $30m private share placement.
Deep Fission is participating in the US Department of Energy’s (DOE’s) Reactor Pilot Program, which is designed to accelerate the deployment of advanced nuclear technologies through a streamlined regulatory pathway under the Atomic Energy Act. Pending DOE authorisation, the Company aims to complete construction of its first reactor and achieve criticality by 4 July 2026 in line with President Trump’s May Executive Order 14301, which set a target of having three reactors achieve criticality by that date.
“Kansas has long been a leader in energy production, and we’re continuing to diversify our portfolio with innovative technologies such as advanced nuclear,” said Lieutenant Governor and Secretary of Commerce David Toland. “As Deep Fission prepares to demonstrate its DOE-supported pilot reactor in Parsons, Commerce will support their efforts to integrate a thoughtful and transparent community engagement process that gives local residents clear avenues to ask questions and be part of the conversation.”
Great Plains Development Authority Chairman Robert C Wood welcomed Deep Fission, noting: “We are committed to supporting their work at the Kansas Proving Grounds in the Great Plains Industrial Park. Deep Fission’s pilot demonstrates a new level of energy innovation, showcasing Kansas’s potential to the world. The Board and I look forward to building a long-term relationship with Deep Fission and the positive impacts this collaboration will bring.”
The Great Plains Industrial Park, located on more than 14,000 acres in Labette County, Kansas, is an established site for industrial and energy development. It offers Deep Fission the unique opportunity to scale onsite and potentially grow with the Park for decades to come.
By placing reactors one mile underground, the surrounding geology provides billions of tonnes of passive shielding and natural containment enhancing safety and security while significantly reducing cost, surface footprint, and visual impact, the company said.
Deep Fission’s Gravity reactor is a small modular reactor designed to be placed underground in an optimised borehole one mile (1.6 km) deep. The reactor uses traditional pressurised water technology and low-enriched uranium (LEU) fuel and will generate 15 MWe. Its small footprint and dense power output means it will need a fraction of the land required for traditional surface nuclear.
The passive shielding and natural containment offered by the surrounding geology, and the combination of mature technologies from the nuclear, oil and gas, and geothermal industries, while using off-the-shelf parts and readily available LEU fuel, aims to improve safety and security and enable a faster, more cost-effective path to deployment.
Gravity reactors operate at the same roughly 315°C core temperature, while hydrostatic pressure from a one-mile-deep column of water provides the same 160 atmospheres of reliable pressure, safely and naturally. The heat produced is transferred to a steam generator at depth to boil water. This novel deployment approach applies proven geothermal components and processes for energy transfer. Non-radioactive steam rises rapidly to the surface, where a standard steam turbine converts the energy to electricity. Cables attached to the reactor allow it to be raised to the surface, if inspection is deemed necessary.
