Abstract

Modern nuclear reactors increasingly rely on advanced communication technologies to support instrumentation, control, monitoring, maintenance, and plant-wide coordination. As nuclear facilities become more digitalized, communication systems are no longer auxiliary components; they are now integral to the plant's instrumentation and control (I&C) architecture and therefore to operational safety and reliability. Recent research has identified 5G, wireless sensor networks, free-space optical communication, and other digital networking solutions as promising technologies for selected nuclear applications, particularly those requiring flexibility, mobility, and reduced cabling complexity. However, the introduction of these technologies into nuclear environments is constrained by severe requirements for reliability, environmental robustness, cyber resilience, and regulatory acceptance. This paper reviews the structure of nuclear reactors as it relates to communication design, examines modern communication technologies and their limitations, and focuses in particular on cybersecurity standards relevant to nuclear I&C systems. The analysis indicates that secure deployment requires a performance-based, defense-in-depth approach grounded in OT/ICS security standards such as NIST SP 800- 82 Rev. 3, IEC 62443, alongside functional safety standards including IEC 61513 and IEEE 7-4.3.2. Wired systems remain the preferred solution for safety-critical functions, whereas modern digital and wireless technologies are better suited to carefully qualified non-safety applications. A hybrid communication architecture combining robust wired backbones with carefully controlled wireless and optical technologies for support functions emerges as the most viable path forward.