It's an exciting time for @DeepFission. ⚛️ What if the biggest barrier to expanding #nuclear energy isn't the reactor, but the way we deploy it? In this overview video, our CEO and co-founder Liz Muller shares about our deployment-first approach and progress toward commercialization, leveraging proven technology in a new way to help meet urgent demand for reliable, affordable power. Watch ⬇️

Our technology and evaluation process are designed to be adaptable to a range of geological and environmental conditions, not built around a single site. We conduct geological surveys, site characterization studies, drilling evaluations, and engineering analyses to better understand local subsurface conditions and inform borehole design, drilling methods, and site suitability assessments. Seismic analysis is part of that same process, with site suitability assessments considering applicable seismic conditions, geology, structural integrity requirements, and regulatory standards. But site evaluation also goes beyond the technical. We approach every community as a genuine partner and seek out those eager to work together to build what's next for their community's energy future. This is ongoing work, grounded in transparent communication and real dialogue — not a one-time conversation. From Parsons, Kansas, to potential future sites in Texas, Utah, and beyond, our approach adapts to each site's unique geology, while our commitment to genuine community partnership stays the same.

Many of the systems built around a traditional reactor exist to manage risks that come from being on the surface. Power outages that could disable cooling. Structures built to withstand external hazards. Exposure pathways between the plant and the public. These are surface problems, managed with massive and complex surface infrastructure. The Gravity™ Nuclear Reactor starts a mile down instead. That separation from the surface biosphere reduces potential exposure pathways and limits the impact of external hazards. That protection doesn't rely on one layer. The water column gives the reactor pressure balance and emergency core cooling. The surrounding geology adds a mile of distance between the core and the surface. The engineered well, cased the whole way down, adds a third layer in between. At Deep Fission, physics and geology do the jobs other reactors demand of the costly, complex infrastructure built around them.

Deep Fission's planned borehole design sits comfortably inside an established capability, not at the edge of a new one. Between 1959 and 1968, contractors drilled more than 500,000 feet of large-diameter boreholes across North America. The customers weren't oil and gas companies; they were the U.S. underground nuclear test program and the mining industry. When the test program wound down, the same drilling method carried forward into mining and wastewater work, which have kept drilling and lining wide holes with steel casing on a commercial basis for decades since. Large-diameter drilling is a proven technology, and another instance where Deep Fission's innovation is integration — not invention.

Deep Fission CEO Liz Muller joined @IGCom's The Long and the Short to talk about why we're building nuclear reactors a mile underground. Liz walks through our path to commercial power in Parsons, KS, and the customer demand behind our growing pipeline. youtu.be/3mhYG4X32DI

𝐓𝐡𝐞 𝐏𝐨𝐰𝐞𝐫 𝐨𝐟 𝐚 𝐌𝐢𝐥𝐞 𝐨𝐟 𝐖𝐚𝐭𝐞𝐫 The Gravity™ Nuclear Reactor sits inside a cased borehole roughly a mile underground, surrounded by a water column the same depth. That column does two jobs a conventional reactor normally needs a lot of steel, concrete, and machinery above ground to do. 𝐏𝐫𝐞𝐬𝐬𝐮𝐫𝐞. A mile of hydrostatic head creates roughly 160 atmospheres of pressure outside the reactor canister — nominally equal to the pressure inside it. Because pressure is balanced across the canister wall, the design minimizes the pressure differential that drives a classic loss-of-coolant accident, rather than relying on a large containment structure to contain one after the fact. 𝐄𝐦𝐞𝐫𝐠𝐞𝐧𝐜𝐲 𝐂𝐨𝐫𝐞 𝐂𝐨𝐨𝐥𝐢𝐧𝐠. That same water column functions as a large, continuously available heat sink. If decay heat ever needs to be removed beyond normal operation, the borehole water is intended to do so through natural circulation — where heated water rises and cooler water sinks to replace it — without pumps, offsite power, or operator action. This isn't just an engineering simplification. Containment domes, cooling towers, and the systems built around them are also some of the most capital- and time-intensive parts of building a conventional reactor. A mile of water is designed to take on key parts of that work passively instead.

𝐏𝐫𝐨𝐠𝐫𝐞𝐬𝐬 𝐟𝐫𝐨𝐦 𝐭𝐡𝐞 𝐟𝐢𝐞𝐥𝐝: We put our prototype reactor canister into a 34” borehole this morning. Today a commercial drilling and rigging crew went to work with a full-size prototype of Deep Fission's reactor canister — the component that will eventually house Deep Fission's Gravity™ Nuclear Reactor core — in a wide borehole at a working drilling site. The crew has finished, and our engineers are now reviewing the data. We wanted to share this update as it happened. Next week we'll share the full result, our engineers' analysis, and what it means for Deep Fission's commercial momentum — along with a replay so you can see the operation for yourself. Stay tuned!

Groundwater protection isn't an afterthought. It's engineered into our design from the start. Our planned boreholes are designed with multiple engineered barriers, including steel casing and concrete, which add strength and uniformity to the borehole walls and support the long-term stability of the reactor canister within it. Construction follows a two-step sequence common to the drilling industry: a metal casing goes in first to add strength and keep the borehole walls uniform, then concrete is forced up from the bottom of the hole, surrounding the casing on the sides and bottom. Running the length of the borehole, this casing is designed to separate the interior of the well from the surrounding rock, so nothing inside comes into direct contact with the geological formations or any groundwater it passes through. This layered casing approach uses the same standard casing technology used in approximately four million existing boreholes in the U.S. One mile underground, a reactor canister engineered with corrosion-resistant materials, together with a heat exchanger, provides a separate layer of protection. The fuel is contained within the reactor canister at the bottom of the borehole. Water in the primary coolant loop circulates in a closed loop: from the canister, up through a connecting pipe, to the heat exchanger, and back down. At the heat exchanger, only heat crosses over into a separate secondary loop. That secondary loop carries the heat to the surface through a double-walled, insulated pipe, without direct contact with the primary loop or the fuel. Protection of water resources is further supported through site characterization, engineering analysis, monitoring, environmental review, permitting, regulatory oversight, and compliance with applicable environmental requirements. Learn more —> nrc.gov/docs/ML2611/ML26112A…

Most next-generation nuclear developers are betting on something new: a new reactor design, a new fuel type, a new supply chain to support it. Every one of those adds engineering risk, regulatory uncertainty, and time. We're taking a different approach: integrating three established technologies to deploy nuclear power a mile underground. Deep borehole drilling and casing, using well-completion techniques from across the U.S. drilling industry. Geothermal heat exchange, using components and processes already proven in that industry. And pressurized water reactor technology, paired with the same low-enriched uranium fuel that's already powering the global reactor fleet today — an established supply chain we don't have to wait on. That same principle shapes who we work with. Deep Fission brings together specialized partners and proven capabilities across drilling, fuel, engineering, manufacturing, and construction — not to build each discipline from scratch, but to build on existing legacy to redefine time to deployment. The goal: Fewer points of new. Fewer points of risk. A faster path to deployment.

Deep Fission welcomes ShawnTrell Scales as our first Chief People Officer. As we move from first-of-a-kind demonstration toward commercial deployment of the Gravity™ Nuclear Reactor, bold leadership matters. "What drew me here is the mission and the culture behind it — a team that believes in transparency and boldness, and in leaving things better than they found them," said ShawnTrell. She brings more than 20 years of HR leadership across energy, manufacturing, and agricultural technology — most recently as Chief Human Resources Officer at Farmer's Business Network, with earlier senior roles at Matthews International, LINN Energy, and QEP Resources. She's built people functions from the ground up in complex, highly regulated organizations. "We are still early in our journey, and the decisions we make about how we hire, develop, and support our people now will shape the company for decades," said Deep Fission CEO and Co-Founder Liz Muller. "ShawnTrell is exactly the kind of leader we need as Deep Fission enters this next chapter." As Chief People Officer, ShawnTrell will lead talent strategy, organizational design, employee relations, and culture as we scale our workforce toward delivering our first full-power reactor in 2027. Learn more —> deepfission.com/pr-media-kit…

Deep Fission $FISN has signed Letters of Intent with data centers, co-developers, industrial parks and strategic partners across multiple power sites, representing up to 18.5 GW of potential generation capacity. For us, this pipeline represents more than a number. It reflects growing interest in new sources of reliable, affordable power, and the potential role our Gravity™ Nuclear Reactor can play in meeting that demand. Each relationship gives us an opportunity to advance potential projects and build the commercial pathway for deploying #nuclear power at scale. Learn more: deepfission.com/sites