US underground nuclear firm partners to deploy scalable reactor tech

Nuclear energy technology firm Deep Fission and engineering and construction company Day & Zimmermann (D&Z) have announced a formal partnership to construct an underground nuclear reactor facility.

Under the terms of the agreement, D&Z will manage pre-construction planning and execute all above-ground construction for Deep Fission’s proprietary “Gravity Nuclear Reactor.”

The corporate partnership combines Deep Fission’s subsurface design with D&Z’s years of experience in nuclear quality control, safety protocols, and Nuclear Regulatory Commission compliance.

D&Z also brings specific experience in natural gas plant construction under ISO 9001 quality standards, which is a required capability for building the non-nuclear, above-ground turbine generator systems for the project.

“Deep Fission’s advanced reactor technology, combined with Day & Zimmermann’s quality program and nuclear expertise, will bring first-of-a-kind nuclear construction to reality,” said Ross McConnell, D&Z Chief Nuclear Officer.

“For more than 40 years, the power industry has trusted our operational discipline and process-driven approach to quality, safety, and project execution while reliably and safely navigating the Nuclear Regulatory Commission’s complex oversight.”

Project development and reactor engineering

The announcement follows Deep Fission’s formal operational transition from the design concept phase into active field construction earlier this year. The California-based startup company recently began drilling operations on the first of three scheduled data acquisition wells for its pilot facility.

Located at the Great Plains Industrial Park in Parsons, Kansas, the project is officially part of the US Department of Energy’s Reactor Pilot Program, which selected Deep Fission as one of ten program participants.

Deep Fission’s design utilizes a 15-megawatt small modular reactor placed in a deep borehole approximately one mile beneath the surface of the Earth. While the core system relies on standard pressurized water reactor technology, its subsurface placement eliminates the structural need for large surface containment buildings by utilizing natural geological conditions to support core containment functions.

By placing the reactor a mile beneath the surface, the engineering design achieves two distinct operational objectives. First, the weight of the water column directly above the reactor naturally produces the 160 atmospheres of hydrostatic pressure needed for standard operation, which completely eliminates the need for expensive surface pressure vessels.

Second, the surrounding bedrock provides natural geological containment and radiation shielding, reducing the overall surface footprint of the facility and enhancing physical security against external threats.

Scaling according to energy requirements

“Partnering with Day & Zimmermann will bring proven nuclear construction expertise and execution discipline to Deep Fission’s deployment,” concluded Mike Brasel, Chief Operating Officer at Deep Fission.

“Their track record supports our aim to deliver a new model for low-carbon, reliable power that is simpler to build, inherently safe, and scalable to meet growing energy demand.”

The borehole configuration allows the modular system to scale according to local energy requirements. While a single borehole generates 15 megawatts of electricity, up to 100 reactors can be co-located on a single industrial site to produce a combined 1.5 gigawatts of electricity.

This configuration can support large industrial hubs or data complexes while using less land than conventional surface-level nuclear power plants.