Mile-Deep Nuclear Reactor Infuriates State – Construction Begins

A nuclear reactor the size of a small delivery van is headed a mile straight down into the Kansas dirt, and the federal government just gave it the green light to keep going.

Story Snapshot

The Department of Energy approved a Nuclear Safety Design Agreement for Deep Fission’s Gravity reactor on August 6, 2026.
The 15-megawatt pressurized water reactor will sit at the bottom of a borehole one mile underground near Parsons, Kansas.
The project runs through a new DOE pilot pathway created by a Trump White House executive order, separate from standard Nuclear Regulatory Commission licensing.
Deep Fission still needs Nuclear Regulatory Commission authorization to convert the pilot unit into a commercial power plant.

What The Federal Approval Actually Covers

Deep Fission announced that the Department of Energy signed off on the safety design for its Gravity reactor, calling it “a major regulatory milestone” for the company. The agreement locks in the safety framework engineers will follow as they build the pilot unit. It is the first of several required approvals before the reactor can legally operate at the Great Plains Industrial Park site outside Parsons.

Deep Fission is a Berkeley, California company founded in 2023 that builds small modular pressurized water reactors meant to be installed a mile below the surface. The Gravity reactor generates 15 megawatts, enough to power thousands of homes, and gets lowered into a borehole rather than housed in a traditional above-ground containment building.

Why Builders Want Reactors Underground

Putting a reactor deep in bedrock is not a new idea. Government and academic studies going back decades have looked at underground siting as a way to cut the risk of radioactive release during an accident, arguing that rock and soil act as a natural containment shield around the core. Federal research has specifically found that an underground plant, paired with a pressure relief system, can sharply reduce the severity of a hypothetical core-melt event.

Deep Fission is leaning on that same logic. Company materials describe the borehole design as a way to shrink the surface footprint of the plant and add a layer of physical protection that traditional reactors do not have. The Kansas Department of Health and Environment is working alongside federal regulators on the site.

The Trump-Era Pilot Program Behind The Project

Deep Fission’s path to this approval runs through the Department of Energy’s Reactor Pilot Program, created after an executive order President Trump signed in May 2025. The program lets private companies build and test full-scale advanced reactors under direct DOE authorization instead of waiting years for a Nuclear Regulatory Commission license. The stated goal was to get at least three test reactors to criticality, the point where a nuclear chain reaction becomes self-sustaining, by July 4, 2026.

That deadline was met. Three companies in the program, Antares Nuclear, Valar Atomics and Aalo Atomics, reached criticality on or before July 4, 2026, making the United States the first country to hit that mark with three different advanced reactor designs in a single stretch. Deep Fission’s Kansas project is aiming for its own construction and criticality milestones on a similar accelerated timeline.

Ground Broken, Hardware Already Moving

Deep Fission broke ground on the Parsons site in December 2025, just one day after signing its initial agreement with the Department of Energy. Chief executive Liz Muller called that agreement a major milestone toward getting the project built. Since then, drilling crews have started sinking the borehole itself, and the company has shipped a prototype reactor canister to the Kansas site as part of its proof-of-concept work.

Deep Fission still has to clear the Nuclear Regulatory Commission’s separate licensing process before it can sell electricity from the reactor commercially, and the company has acknowledged that pending federal authorization, timing for full construction and criticality is not locked in. One nuclear watchdog group has pushed back on how the company frames the approval, arguing it reflects sign-off on a design drawing rather than proof of a working reactor.

For Parsons, a small town near the Oklahoma border, the stakes are straightforward. A working underground reactor would mark the first of its kind built on American soil under this new streamlined federal pathway, and it would test whether burying nuclear power really does make it safer, cheaper, and faster to build than the plants of the last fifty years.