The U.S. Department of Energy has announced that the Antares Mark-0 advanced nuclear reactor has successfully reached criticality at the Idaho National Laboratory (INL). This marks a significant milestone as it is the first privately developed U.S. nuclear reactor to achieve this milestone in over 40 years. The successful test, part of a Department of Energy pilot program, highlights a renewed focus on nuclear technology innovation. BWX Technologies played a crucial role, supplying the TRISO fuel that powered the reactor. The achievement paves the way for future advancements in nuclear energy, including small modular reactors and microreactors, potentially aiding efforts to establish sustainable energy solutions for various applications, including space exploration.