A quantitative model for embedding quantum-secure communications and evaluating communication autonomy in industrial control systems

Industrial control systems would increasingly depend on remote operation, online monitoring, and potentially autonomous control. This creates new requirements for secure, low-latency communications, and introduces new operational constraints on secret key availability, communication autonomy, and resilience under normal and abnormal conditions. We present a time-dependent quantitative model for embedding quantum-secure communications in an industrial control system and demonstrate its implementation on Purdue’s fully-digital 10-kWth research reactor (PUR-1). Using a phase-encoding decoy-state-BB84 Quantum Key Distribution (QKD) system we propose and evaluate three communication autonomy metrics: dynamic key pool size, lead time, and post-failure uptime. We establish quantitative relationships linking physical-layer QKD performance metrics, such as secret key rate (SKR) and quantum bit-error-rate (QBER), to industrial control-level communication demands defined by sampling rate, data precision, and reporting frequency. We show that for the most demanding configuration, 20 Hz sampling at 120 km, QKD coupled with AES-256 encryption required a minimum of 24 min lead time, while distances below 95 km required less than 10 min, regardless of the number of signals. These results establish experimentally verified bounds for integrating quantum cybersecurity within real-time control architectures and provide a foundation for designing quantum-resilient communication frameworks for next-generation reactors and other safety-critical industrial systems.