Comment on FR Doc # 2026-08550, NRC-2025-0379-0011, from Union of Concerned Scientists

Summary: The Union of Concerned Scientists opposes the proposed rule, arguing that it is unnecessary, lacks clear definitions for "microreactors," and risks allowing larger, higher-risk reactors to qualify for a more lenient licensing regime. They specifically criticize the fuel mass limits as being too high and call for more stringent entry criteria, including power rating limits and robust lifecycle security requirements.