Oklo Inc.’s Groves Isotope Test Reactor in Texas achieved first criticality on August 5, 2026, reaching a controlled, self-sustaining nuclear chain reaction. It became the fifth reactor authorized under the U.S. Department of Energy’s Reactor Pilot Program to reach that milestone and the first to do so on private land. Facility Solutions Group joined the project in April 2026, with Century Construction serving as general contractor, and provided electrical, instrumentation, controls, testing and verification work. The low-power reactor is intended to support domestic commercial isotope production and demonstrate accelerated deployment of advanced nuclear projects. The milestone also supports Oklo’s broader plans for fast fission plants and a domestic fuel-recycling supply chain, although its commercial reactor and recycling businesses remain years from operation.