Nuclear security prevention is the academic concept and research field focused on developing and implementing proactive strategies to avert intentional unauthorized acts involving nuclear materials, facilities, and transport. It investigates the threats, vulnerabilities, and risks associated with nuclear assets, analyzing the effectiveness of physical security systems, personnel reliability programs, intelligence measures, and international cooperation frameworks designed to prevent theft, sabotage, or unauthorized access. This field is critical for mitigating the catastrophic risks of nuclear terrorism and proliferation by establishing robust preventative barriers.