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Deep Fission Discloses Safety Design Agreement for Kansas Nuclear Pilot Project

Deep Fission, the company building a nuclear reactor one mile underground in Parsons, Kansas, made its federally approved safety report public on Monday. The U.S. Department of Energy approved the company's safety design for its Gravity nuclear reactor in July of this year. A press release stated that the company publicly released the report, with only a very small number of details involving safety privacy redacted. Liz Muller, co-founder and CEO of Deep Fission, said in the press release that the company disclosed the complete Nuclear Safety Design Agreement because they believe the public has the right to see the true safety...

2026-09-18

US-based Deep Fission Completes Full-Scale Reactor Vessel Deployment and Retrieval Demonstration Using Commercial Drilling Equipment

On September 3, 2026, advanced nuclear energy development company Deep Fission, Inc. (stock ticker: FISN) announced that it had completed a deployment and retrieval demonstration of a full-scale non-nuclear prototype reactor vessel using standard commercial drilling and hoisting equipment. The company is developing a technology pathway that deploys small modular pressurized water reactors in boreholes approximately 1 mile deep underground. In this demonstration, a commercial drilling and hoisting team lowered a 20-foot-long prototype reactor vessel into a 34-inch-diameter, 100-foot-deep borehole, and after completing alignment, retrieved it to the surface. Deep Fission stated that the equipment used in the demonstration was all standard equipment already in commercial...

2026-09-11

Deep Fission Details 'One-Mile-Deep PWR' Roadmap at Canaccord Conference, Targeting First Commercial Operation by End of 2027

On August 11, Deep Fission (FISN) unveiled a differentiated nuclear commercialization pathway at Canaccord Genuity's 46th Annual Growth Conference: rather than reinventing nuclear fission technology, the company aims to deploy mature pressurized water reactors in underground boreholes approximately one mile deep. CEO Liz Muller emphasized that the core approach is to change where reactors are deployed, not to adopt an entirely new reactor physics model. Given that PWR technology has been used in commercial nuclear power for decades, the company hopes to shorten the validation cycle by leveraging mature technology and avoid the new fuel, new material, and new design licensing hurdles faced by some advanced nuclear projects. According to the company's plan...

2026-08-12

US DOE Approves Nuclear Safety Design Agreement for Deep Fission Underground SMR

Deep Fission, a US advanced nuclear energy company, announced on August 6 that the US Department of Energy (DOE) has approved the Nuclear Safety Design Agreement (NSDA) for its Gravity reactor. The company stated that this milestone means its reactor design meets the requirements for continued advancement under the DOE's Reactor Pilot Program. Deep Fission is developing a small modular pressurized water reactor concept, with plans to place the reactor in a borehole approximately 1 mile, or about 1.6 kilometers, underground. The approved Nuclear Safety Design Agreement will serve as the safety framework for subsequent reactor development work. According to the company's plans, the project will proceed into the DOE authorization process...

2026-08-07