Strengthening Network Security in Safety-Critical I&C Systems of Nuclear Reactors: Design and Implementation of a Robust Data Diode

This paper presents a data diode solution designed to enhance the network security of safety-critical Instrumentation and Control (I&C) systems used in nuclear reactors, specifically Fast Breeder Reactors (FBRs). Emphasizing high dependability over speed, the solution addresses the demands of safety-critical nuclear applications, such as high reliability, fail-safeness, fault tolerance, online maintainability, and security. Our solution achieves a robust hardware-enforced unidirectional TCP/IP network isolation barrier between high and lower safety class systems, employing an ingeniously minimalist design. We are able to achieve real-time performance with a maximum latency of 20ms per kilobyte data transaction. The paper initially outlines the primary requirements for a safety-critical nuclear data diode solution and then discusses the proposed architecture and process adopted for hardware and software design and development.

I. Introduction

The International Atomic Energy Agency (IAEA) and India’s Atomic Energy Regulatory Board (AERB) categorizes instrumentation and control (I&C) systems important to safety of nuclear reactors in various safety classes and security levels . Among these safety-critical systems are assigned the highest safety class (safety class 1) and security level (security level 1). Stringent control over physical and logical access to computer security level 1 zones is essential, with robust barriers, access control, intrusion detection for physical access, and a fail-secure, unidirectional data communication pathway like a data diode, for logical access [3].