US firm's mile-deep underground nuclear reactors advance with fuel deal

Deep Fission, a California startup, is advancing its innovative approach to nuclear energy by developing small modular reactors (SMRs) installed a mile underground. The company recently secured a key fuel supply agreement with Urenco USA to purchase low-enriched uranium (LEU) from its New Mexico enrichment facility. This fuel will power testing and demonstration phases of Deep Fission’s initial “Gravity” reactor, supporting participation in the US Department of Energy’s Reactor Pilot Program and early commercial operations. The company also raised $80 million in new financing aimed at scaling production for AI-driven data centers and US electricity grids. The “Gravity” reactor design leverages natural geology by placing a 15 MWe reactor deep underground, where the Earth’s pressure and surrounding rock provide passive containment and shielding. This eliminates the need for expensive surface pressure vessels and containment structures, potentially reducing construction costs by up to 80% compared to traditional nuclear plants. The modular system is highly scalable, with the potential for 100 reactors on one