Kansas site selected for underground reactor demo

The company said it intends to break ground for the demonstration project on 9 December, and - subject to authorisation from the US Department of Energy (DOE) - achieve criticality by 4 July 2026. It has signed a letter of intent with the Great Plains Development Authority outlining their collaboration on the pilot and the parties' intention to develop a full-scale commercial project at the same site.

Deep Fission's Gravity reactor is small modular reactor designed to be placed underground in an optimised borehole one mile (1.6 km) deep. Using traditional pressurised water reactor technology and low-enriched uranium (LEU) fuel, each reactor will generate 15 MWe, the company says, while its small footprint and dense power output means it will need a fraction of the land needed for traditional surface nuclear: ten reactors on the same site would deliver 150 MWe, or 100 reactors would produce 1.5 GWe. 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.

Earlier this year the project was announced by the DOE to receive support under its Nuclear Reactor Pilot Program, which aims to see at least three designs achieve criticality by 4 July 2026.

Great Plains Industrial Park was one of three three potential sites in Kansas, Texas and Utah shortlisted by Deep Fission as a potential project site in September. Located in Labette County, Kansas, the park was formerly the site of an army munition plant and is owned by the Great Plains Development Authority, a government administration company. As an established site for industrial and energy development, Deep Fission said it offers the "unique opportunity to scale onsite and potentially grow with the Park for decades to come".

"Great Plains Development Authority is excited to welcome Deep Fission, and we are committed to supporting their work at the Kansas Proving Grounds in the Great Plains Industrial Park," the Authority's Chairman Robert Wood said. "Deep Fission's pilot demonstrates a new level of energy innovation, showcasing Kansas’s potential to the world."

Deep Fission announced its selection after signing an Other Transaction Agreement (OTA) with the DOE to build and operate a test reactor as part of the Reactor Pilot Program.

"This pilot is an exciting first step toward an energy-abundant America," said Liz Muller, co-founder and CEO of Deep Fission. "We're proud to partner with the Great Plains Industrial Park and southeast Kansas to show what's possible with next-generation nuclear. Our Gravity reactor is designed to deliver safer, faster, and dramatically cheaper energy. We're grateful to the Administration for the opportunity to move from vision to reality through the programme."

Deep Fission went public in October through a reverse merger transaction with Surfside Acquisition Inc, alongside a USD30 million private share placement.