The Reactors at Risk Act of 2026 requires the Secretary of Defense and the Under Secretary of Energy for Nuclear Security to jointly assess the dangers posed by nuclear reactors located in areas vulnerable to armed conflict. The report must evaluate risks to U.S. national security, allied interests, and civilian safety from reactors in regions that have experienced conflict in the past 25 years, contested areas likely to experience future conflict, and specific geopolitical hotspots including Ukraine, the Middle East, Eastern Europe, India-Pakistan, Taiwan, and the Korean Peninsula. The analysis must also identify steps the United States and its allies can take to prevent, prepare for, and reduce these risks. The report is due within 120 days of the bill's enactment and will be submitted to relevant congressional committees in unclassified form, though it may include classified details in a separate annex.