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, the first commercial reactor is targeted for operation by the end of 2027, with an initial capacity of 5 MWe, followed by a 15 MW-class unit in 2028. Deep Fission states that the underground configuration can leverage the approximately one-mile water column above to handle pressure, cooling, and heat transfer functions, thereby reducing the need for high-cost components found in traditional nuclear plants, such as reactor pressure vessels, containment domes, pressurizers, and emergency core cooling systems. The company also notes that drilling is expected to take approximately 60 days, and manufacturing of production reactor vessels takes about 6 months—if successfully replicated, this could help compress construction timelines and capital expenditures.

On the commercial front, Deep Fission says it has a committed customer demand pipeline of 18.5 GW, with early projects planned under a "build-own-operate" model and an expected payback period of under five years. The company believes demand for fast, reliable, low-carbon power is rising in the current electricity market, particularly from high-load users such as industrial parks and data centers, which could become potential buyers. However, capital markets remain cautious—the company's stock price is currently near its 52-week low, and analyst data suggests profitability remains elusive this year, reflecting lingering investor concerns over project execution, regulatory progress, and scalability.

Regulatory approval and site selection are critical to whether the plan can materialize. Deep Fission says its nuclear safety design protocol has been approved by the U.S. Department of Energy, and it is participating in the DOE's reactor pilot program, with the application covering a full commercial reactor rather than an experimental device. The company is simultaneously advancing both DOE and U.S. Nuclear Regulatory Commission pathways, and expects the new NRC Part 57 rule to be finalized by the end of 2026, potentially compressing future licensing timelines to 6–9 months. The project site is located at Great Plains Industrial Park in Parsons, Kansas, spanning approximately 13,000 acres, which has long been zoned for nuclear and industrial use and features existing infrastructure including roads, rail, and security perimeters.

From a supply chain perspective, Deep Fission seeks to combine the traditional nuclear industry with oil and gas drilling capabilities, with partners and suppliers including Halliburton, Day & Zimmermann, and Urenco. The company states it uses conventional PWR low-enriched uranium fuel and does not rely on supply-constrained fuels such as HALEU or TRISO, while reactor vessels are replaced in their entirety rather than refueled in the traditional manner. Meanwhile, the underground deployment still needs to demonstrate long-term sealing, heat dissipation, operations and maintenance, spent fuel management, and safety under extreme accident scenarios. The company has proposed storing spent vessels in an underground spent fuel pool at the bottom of the borehole, or further lowering them to greater depths for storage of 10 to 50 years, but these arrangements will still face multiple layers of scrutiny from regulatory, engineering, and public acceptance perspectives.