Book excerpt: This publication provides specific recommendations on research reactor instrumentation and control systems and software important to safety, including instrumentation and control system architecture and associated components, from sensors to actuators, operator interfaces and auxiliary equipment, to meet the relevant requirements of IAEA Safety Standards Series No. SSR-3, Safety of Research Reactors. The recommendations and guidance apply to both the design and configuration management of instrumentation and control systems for new research reactors and the modernization of the instrumentation and control systems at existing research reactor facilities. In addition, this Safety Guide provides recommendations and guidance on human factors engineering and human-machine interfaces, and for computer based systems and software for use in instrumentation and control systems important to safety. This Safety Guide is a revision of IAEA Safety Standards Series No. SSG-37, which it supersedes.