The high market-implied odds against a U.S. Nuclear Regulatory Commission license for a new commercial nuclear reactor in 2026 stem primarily from extended review timelines, even amid aggressive federal streamlining. While the Department of Energy has authorized multiple advanced test reactors to reach criticality this year and issued construction permits such as TerraPower’s Natrium in March, full combined operating licenses for grid-connected units involve detailed safety, environmental, and design reviews that historically span multiple years. Recent NRC proposals to modernize regulations and risk-informed approaches, along with early site work exemptions like Holtec’s at Palisades, signal policy momentum but have not yet produced completed commercial licenses. Realistic upside scenarios include expedited approvals for pre-reviewed designs if hearings conclude rapidly before year-end, though current dockets point to decisions in 2027 or later.