Deep Fission has signed a binding 25-year Master Energy Purchase Agreement with the Great Plains Development Authority in Parsons, Kansas, converting our December 2025 letter of intent into a definitive contract for a planned commercial project at the site of our U.S. Department of Energy pilot. The initial phase is anticipated to be 150 MW, with a target commercial operation date of September 30, 2028. Later phases could grow the project to a total of 2,000 MW, pending further demand growth. With Deep Fission’s Gravity™ Nuclear Reactor, we aim to provide reliable, carbon-free, 24/7 power. Read the full release in the comments. Thanks for following $FISN. #AdvancedNuclear #NuclearEnergy #CleanEnergy

Can you drill a well wide and deep enough to hold a nuclear reactor? The answer goes back more than 60 years. Swipe through the timeline, from the surge in large-diameter drilling in the 1960s, to the injection wells still being drilled today. Our Gravity™ Nuclear Reactor’s deployment plan builds on that record. Our commercial well plan calls for 64-inch casing to 600 feet, 54-inch to 2,300 feet and 44-inch to 6,000 feet, squarely within what the industry has already done. We are not this hole’s first customer. We are its next one. Read the full white paper in the comments. Thanks for following $FISN

“We are excited to find ways for our students at USD 503 Parsons District Schools to learn more about the work Deep Fission is doing in the nuclear industry," shared Assistant Superintendent Jeff Pegues, a member of Deep Fission's Community Advisory Group. "I’ve really enjoyed getting to know the Deep Fission team and the professionals working to bring this project to commercialization. I have been thoroughly impressed by everyone I’ve met with the organization—their knowledge, professionalism, and passion for their work are evident. I also appreciate the time and effort they have made to connect with our community and create meaningful opportunities for our students to learn more about the work they are doing.” Our CAG helps provide a consistent forum for two-way communication between Deep Fission and local community representatives, focused on sharing information, listening to community perspectives, and building mutual understanding. The group’s objective is to support informed, respectful dialogue on project progress, safety, environmental stewardship, construction activities, and operations. Visit the link in comments to learn more. Thanks for following $FISN

Want to take a deep dive on large diameter drilling? We published a white paper covering the 60+ year record of this capability, and how it supports our Gravity™ Nuclear Reactor's commercial deployment plan. Some key facts: —Between 1959 and 1968, contractors drilled about 500,000 linear feet of holes over 36 inches wide across North America —In 1968, a 54-inch casing string weighing about 5 million pounds was run to 5,600 feet —Our commercial well plan calls for 64-inch casing to 600 feet, 54-inch to 2,300 feet and 44-inch to 6,000 feet, squarely within the historical record Visit the link in comments to read more. Thanks for following $FISN.

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!

"We aren't inventing new nuclear physics or new drilling technology," writes Deep Fission CEO and Co-Founder Liz Muller in her latest piece. "We're prioritizing deployment innovation over reactor invention, integrating proven expertise, discipline by discipline, with a goal of delivering firm, commercial power from a mile underground." Visit the link in comments to read the full article.

Today we announced a collaboration with Youngquist Brothers to advance and test methods for constructing large-diameter, deep boreholes for Deep Fission's underground deployment model. Youngquist has been drilling large-diameter boreholes since 1971, to depths of more than 8,000 feet. "Working with an established commercial driller lets us advance the drilling side of our approach using equipment and expertise that already exist in the field, rather than starting from scratch," said Liz Muller, CEO and Co-Founder of Deep Fission. On September 3, our teams completed a related equipment demonstration in Fort Myers, Florida, lowering our 30-inch full-size prototype reactor canister into a 34-inch borehole to a depth of approximately 100 feet, then retrieving it. The demonstration focused on installation and retrieval mechanics, distinct from the full-depth drilling work intended to be covered by the collaboration. "What Deep Fission requires for its nuclear application is the same discipline we've always applied," said Harvey Youngquist, CEO of Youngquist Brothers. Visit the link in comments to learn more

"While the components of Deep Fission's model aren't novel, combining them is," writes Vanessa Bates Ramirez in a piece for @newscientist. "The company says its design will not only work, but improve safety and reduce costs compared with conventional nuclear power projects. Putting the reactor 1600 metres underground means the surrounding rock will serve as a built-in containment structure, and the weight of the water column above will create a pressure of 160 atmospheres — high enough to keep water in liquid form at ultra-high temperatures and eliminating the need for a pressuriser that is a necessary component of ground surface reactors." Visit the link in comments to read the full article.