Deep Fission Successfully Tests Underground Nuclear Reactor Deployment Technology

Deep Fission, a company developing small modular reactors (SMRs) for deployment at depth of over 1.5 kilometers, has announced the successful testing of its technology. The team successfully lowered a full-scale prototype reactor canister into a borehole and retrieved it safely.

During the demonstration, the drilling crew lowered the 6-meter canister into a borehole (86 cm in diameter) to a depth of about 30 meters, centered it, and brought it back up to the surface. This exact sequence of operations forms the basis of Deep Fission’s reactor deployment model.

The test’s key feature was that the specialists used standard, off-the-shelf drilling equipment. According to Liz Muller, the CEO and co-founder of Deep Fission, the team did not need to invent, custom-build or adapt any equipment for the nuclear industry as all the necessary drilling and rigging equipment is commercially available.

The canister prototype used is an exact, non-nuclear replica of the Gravity reactor vessel. It contained no nuclear fuel. This successful test is just one step in a broader commercial validation program, encompassing drilling, system integration, obtaining regulatory approvals and ultimately reaching the stage of commercial operation.

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The company’s concept combines commercial drilling with time-tested pressurized water reactors (PWRs). Drilling boreholes of the required diameter and depth, as well as using equipment for lowering and retrieving loads, is routine work for the commercial drilling industry. Rather than creating parallel structures, Deep Fission relies on the existing supply chain, skilled workforce, and equipment fleet. Furthermore, the developed Gravity pressurized water reactor represents the most common reactor type in the world and operates useing standard low-enriched uranium (LEU) fuel. Deep Fission only changes the location of the reactor, not its fundamental physics or fuel cycle.

Placing the reactor at a depth of about 1.6 km underground in a water-filled borehole allows the water column and surrounding rock to act as a containment structure, while also providing the necessary operating pressure, effective heat removal, and natural emergency cooling.

This approach significantly simplifies the power plant design and eliminates the need for the extensive surface infrastructure typical of conventional nuclear power plants (NPPs). The company expects this will improve overall facility safety, accelerate deployment, and significantly reduce capital construction costs.

According to Deep Fission