Quantum Key Distribution Secures Nuclear Reactor Communications Over Extended Distances

Quantum key distribution (QKD) secured real-time communication over distances up to 140km within a fully digital nuclear reactor, PUR-1. The system achieved a 320 kbps key rate with 3.8% bit error at 54km, utilising both one-time pad (OTP) and advanced encryption standard (AES) encryption. Dynamic key pooling ensured sustained availability.

The increasing digitisation of critical infrastructure, including nuclear reactors, necessitates robust communication security. Conventional cryptographic methods rely on mathematical complexity, leaving them vulnerable to advances in computing power. Researchers are now exploring quantum key distribution (QKD), a technique leveraging the principles of quantum mechanics to guarantee secure communication. A collaborative team from Purdue University, Toshiba Europe Ltd, and Oak Ridge National Laboratory have demonstrated a fully functional QKD system integrated within a working nuclear reactor. Konstantinos Gkouliaras, Vasileios Theos, True Miller, Brian Jowers, George Kennedy, Andy Grant, Terry Cronin, Philip G. Evans, and Stylianos Chatzidakis detail their work in a recent publication titled ‘Demonstration of Quantum-Secure Communications in a Nuclear Reactor’, reporting successful real-time encryption and decryption of data over distances up to 140km utilising both one-time pad (OTP) and advanced encryption standard (AES) methodologies.

Quantum Key Distribution Secures Reactor Communications Over Significant Fibre Distances

Advanced nuclear systems increasingly depend on digital technologies, necessitating robust and secure communication protocols. Researchers are actively investigating quantum key distribution (QKD) as a potential solution for safeguarding sensitive data within these complex environments. A recent investigation details the successful integration of QKD into a functional nuclear reactor control system – Purdue University’s PUR-1 – demonstrating real-time encryption and decryption of up to 2,000 signals transmitted over optical fibre distances reaching 80 km.

The QKD system consistently maintains a stable secret key rate of 320 kbps with a bit error rate of 3.8% at 54 km, indicating robust performance under realistic operating conditions and validating its ability to handle a substantial data load. Researchers found that deploying multiple QKD systems provides redundancy, bolstering resilience against potential system failures.

The study explored the trade-offs between security and resilience, discovering that lower key refresh frequencies coupled with larger key pools demonstrably extend system uptime following a QKD failure. Employing QKD for initial key establishment significantly improves security. Switching to Advanced Encryption Standard (AES) markedly extends uptime compared to the One-Time Pad (OTP).

The team successfully achieved OTP-based communication over a range of 130 km with a core set of 68 signals, highlighting its potential for high-security, short-range applications. Extending this range to 140 km with AES demonstrates its suitability for longer-distance communication.

A dynamic key pool implementation ensures continued operation for several hours even during potential QKD downtime, crucial for maintaining operational continuity. While OTP introduces minimal latency, AES and ASCON encryption schemes offer increased key efficiency, enabling the encryption of a greater number of signals. A larger key pool consistently improves uptime, while the choice between OTP and AES/ASCON depends on specific application requirements and the acceptable balance between security and efficiency. The observed decrease in uptime with increasing communication distance aligns with expectations, as longer distances introduce greater signal degradation and increase the likelihood of QKD system failure.

Future work will focus on enhancing the robustness of the QKD system itself and investigating adaptive key management strategies that dynamically adjust key refresh rates and pool sizes based on real-time system conditions.