The rapid expansion of artificial intelligence has intensified demand for reliable, carbon-free electricity, prompting renewed interest in advanced nuclear technologies. One of the most unconventional approaches comes from Deep Fission, a startup founded by physicist Richard Muller and his daughter, Elizabeth Muller. Their idea is to place compact nuclear reactors about a mile underground inside narrow boreholes, using the Earth’s natural pressure and rock formations to improve safety while reducing construction costs, tells Forbes.com.
Rather than building large, above-ground nuclear plants with massive containment structures, Deep Fission proposes drilling 30-inch-wide boreholes and lowering small pressurized water reactors into them. Water circulating through the borehole is heated by the reactor and brought back to the surface to drive conventional steam turbines. Each underground reactor is expected to generate about 15 megawatts of electricity, and clusters of dozens of reactors could collectively power gigawatt-scale AI data centers or industrial facilities.
The design combines proven reactor technology with decades of experience in deep drilling from the oil, gas, and geothermal industries. By placing reactors far below ground, the surrounding rock acts as a natural containment barrier, while the depth provides continuous cooling and additional protection against external hazards. The simplified infrastructure could also shorten construction timelines and lower capital costs compared with traditional nuclear plants.
Deep Fission has already attracted significant interest. The company has been selected for the U.S. Department of Energy’s Reactor Pilot Program and reports commitments from prospective customers seeking enough generating capacity to power large-scale AI operations. The growing electricity demands of data centers have made alternative energy sources increasingly attractive, especially those capable of providing uninterrupted baseload power without carbon emissions.
Although the concept remains in the development stage and must still overcome regulatory and engineering challenges, the Mullers believe underground nuclear reactors could redefine the economics of nuclear energy. If successful, their approach would demonstrate that innovative deployment methods, rather than entirely new reactor designs, may offer one of the fastest paths toward expanding clean, dependable power generation for the AI era.