Oklo’s Groves Isotope Test Reactor in Lockhart, Texas, has become the fifth reactor to achieve criticality under the U.S. Department of Energy’s Reactor Pilot Program (RPP), and the first under the program to do so on private land. The low-power test reactor reached criticality at 9:19 p.m. Groves adds a distinct case, given that it is a privately financed isotope test reactor sited on private land in Texas, rather than a power-reactor demonstration or a reactor hosted inside existing national laboratory infrastructure. While Groves is a low-power, water-cooled test reactor focused on isotope-production development, Aurora-INL is a sodium-cooled power reactor intended for commercial energy production.” In May, the company said it had built the Groves test reactor facility in 229 days and was targeting criticality by July 4.