US firm begins drilling for world's first mile-deep nuclear reactor

Deep Fission, a California-based nuclear startup, has begun drilling the first of three data acquisition wells for its groundbreaking underground nuclear pilot project called the “Gravity” reactor. This small modular reactor (SMR) is designed to operate a mile beneath the Earth’s surface, specifically at the Great Plains Industrial Park in Parsons, Kansas. The initial well, drilled to about 6,000 feet deep and eight inches in diameter, aims to collect essential geological, hydrological, and thermal data. The project represents a shift from concept to construction and demonstrates a novel approach to nuclear energy deployment by leveraging natural geology for containment and pressure. The Gravity reactor’s design eliminates the need for massive surface containment structures by situating the reactor at the bottom of a deep borehole. At this depth, the water column provides the necessary 160 atmospheres of pressure, removing the need for expensive surface pressure vessels. Additionally, the surrounding bedrock offers natural shielding and containment, reducing the surface footprint and enhancing security. Deep F