The U.K.'s National Cyber Security Centre (NCSC) has released new guidance on operational technology (OT) security for nuclear reactors, emphasizing the need for robust connectivity principles to mitigate potential breaches. This move comes as 22% of critical infrastructure firms have reported OT incidents, with external access being a primary driver of these breaches. The NCSC's guidance outlines four key principles to enhance the nuclear ecosystem's cyber resilience, aiming to prevent costly retrofits and compliance issues down the line. By embedding these principles, utilities can better protect their OT systems from vulnerabilities such as CVE-2022-33891, which has been exploited in similar contexts. The guidance is particularly relevant given the increasing reliance on digital systems in nuclear reactors, which creates new attack surfaces for malicious actors to exploit. As the nuclear industry continues to evolve, the implementation of these principles will be crucial in ensuring the long-term security and reliability of these critical infrastructure systems1. This matters to security practitioners because implementing these guidelines can significantly reduce the risk of OT breaches, which can have devastating consequences for public safety and national security.