The well will be drilled to a depth of approximately 6,000 feet (1,830 metres) and will have a diameter of roughly eight inches (20 centimetres). The three planned wells represents the initial phase of site characterisation and engineering validation.
The data acquisition well will enable the company to gather critical geological, hydrological, and thermal data to inform final engineering design, safety analysis, and regulatory planning. The drilling campaign and subsequent testing programme will support a series of technical evaluations.
“The three-well drilling programme is expected to provide the subsurface data necessary to advance reactor demonstration and future commercialisation efforts,” Deep Fission said.
The company has also completed construction of the drilling pad at the Parsons site, preparing the location for safe and efficient drilling operations. Pad completion marks another key infrastructure milestone as the company advances from planning and engineering into active field development.
“Drilling our first borehole is a major step forward for Deep Fission,” said Liz Muller, CEO and co-founder of Deep Fission. “It represents the shift from concept to construction and begins the process of demonstrating a fundamentally new approach to nuclear energy deployment.”
Deep Fission’s Gravity reactor is a small modular reactor (SMR) designed to be placed underground in an optimised borehole one mile (1.6 km) deep. Using traditional pressurised water reactor technology and 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.
Deep Fission broke ground in December at the Great Plains Industrial Park in Parsons, Kansas, for its pilot project and plans to build a full-scale commercial plant there following the test reactor demonstration.
In August last year, Deep Fission was one of 10 companies selected by the US Department of Energy to receive support under its Nuclear Reactor Pilot Program, which aims to see at least three designs achieve criticality by 4 July 2026.
Deep Fission was founded in 2023 by father-daughter team Elizabeth and Richard Muller, who also co-founded Deep Isolation in 2016 to develop the concept of placing canisters of radioactive waste hundreds of metres underground via a borehole.
