The Revolution of Small Modular Reactors: A Vision for 2026
The nuclear industry has been on a quest for smaller, more affordable, and adaptable fission reactors, known as Small Modular Reactors (SMRs). A Californian startup, Deep Fission, is pioneering a groundbreaking approach that may just bring this vision to life: by burying the reactors underground.
Harnessing the Power of Pressure
A significant challenge for traditional commercial reactors is maintaining a pressurized water cooling system. Most existing reactors function above 300ºC, requiring immense pressures of around 150 to 160 atmospheres. This need for high pressure necessitates large, heavy, and expensive steel vessels.
Deep Fission’s innovative solution involves placing the reactor one mile underground within a water-filled well. The weight of the water itself generates a natural hydrostatic pressure of 160 atmospheres, effectively eliminating the need for complex pressure vessels. This design allows the reactor water to remain in a liquid state without excessive energy expenditure or the use of rare materials.
Natural Safety Features: Geological Advantages
Beyond overcoming pressure issues, Deep Fission’s design also takes advantage of the geological environment. Instead of constructing reinforced concrete containment structures to mitigate radiation risks during potential accidents, Deep Fission utilizes the solid rock surrounding the reactor. This rock acts as a natural barrier, providing a robust and enduring form of radiation protection.
Innovative Engineering Techniques
Deep Fission aims to use standard low-enriched uranium fuel, employing techniques adapted from petroleum engineering. By applying methods similar to hydraulic fracturing (fracking) and oil drilling, the company plans to extract heat from the reactor much like geothermal systems do.
The Gravity reactor developed by Deep Fission is a compact 15 MW module designed to fit into a drilling hole of just 76 centimeters in diameter. This innovative approach promises substantial economic benefits, with projected energy costs ranging from $50 to $70 per MWh and an 80% reduction in civil works, which can be completed in a matter of months.
Logistical Challenges Ahead
Despite the promising potential of Deep Fission’s design, there are challenges to address. With a portfolio of potential clients emerging in Texas and Kansas, the reactor’s design is not without flaws. While its underground position provides protection from disasters like tornadoes or terrorism, it creates logistical challenges for maintenance.
In most conventional plants, failures such as valve or sensor issues can be resolved with easier access. However, at 1.6 kilometers deep, any required repairs or refueling would necessitate hoisting the entire module to the surface, akin to maneuvering a miniature submarine.
The Path Forward: Regulatory Hurdles and Pilot Plans
Currently, there is no established regulatory framework for “deep well reactors” globally. However, Deep Fission is optimistic about the future. They aim to have a pilot project ready by July 2026, showcasing that innovative approaches, despite their hurdles, can pave the way for new solutions in the nuclear energy landscape.