IAEA work in the area of research reactor operation and maintenance is aimed at enhancing the capabilities of Member States to utilize good engineering and management practices to improve research reactor reliability and availability. In particular, the IAEA supports activities addressing ageing management of research reactor instrumentation and control (I&C) systems. The purpose of this publication is to provide engineering guidance on the design, and operational aspects of digital I&C systems for the refurbishment of existing facilities and for new research reactors. Key areas addressed include codes and standards applicability, licensing issues, dealing with the change in human-system interface from analogue to digital technology, software verification and validation activities, periodic testing and inspection, and configuration management. The publication contains technical descriptions and summaries of available digital systems that have been utilized in both new research reactor designs, and in the upgrading of older analogue safety and control systems. This guidance is foreseen for the broad spectrum of research reactors types existing today.

• 1. INTRODUCTION
  • 1.1. Background
  • 1.2. Objective
  • 1.3. Scope
  • 1.4. Structure
• 2. GENERAL CONSIDERATIONS
  • 2.1. Rationale
  • 2.2. Analog versus digital technologies
  • 2.3. Challenges
  • 2.4. Modernization and new installation projects
• 3. IMPORTANT CONSIDERATIONS FOR I&C SYSTEM MODERNIZATION
  • 3.1. Graded approach
  • 3.2. Approaches to modernization
  • 3.3. Design basis documentation for modernization
  • 3.4. Basic design principles
    • 3.4.1. Codes and standards
    • 3.4.2. Safety demonstration
    • 3.4.3. Human factors assessment for human–system interface
    • 3.4.4. Classification and categorization
    • 3.4.5. Classification of structures, systems and components
    • 3.4.6. Categorization of I&C systems
    • 3.4.7. Defence in depth
    • 3.4.8. Reliability
    • 3.4.9. Single failure criterion
    • 3.4.10. Redundancy
    • 3.4.11. Independence
    • 3.4.12. Diversity
  • 3.5. Digital technology
    • 3.5.1. Commercial off the shelf components and qualification process
    • 3.5.2. Common cause failure
    • 3.5.3. Common mode software failure
    • 3.5.4. Human–system interface
    • 3.5.5. Security aspects
    • 3.5.6. Ageing management considerations
  • 3.6. Architectural approach
    • 3.6.1. Functional aspects
    • 3.6.2. Safety aspects
    • 3.6.3. Technological aspects
    • 3.6.4. Hybrid technical solution architecture as an alternative
    • 3.6.5. An iterative process of design
  • 3.7. Considerations during the preparation of the modernization project
    • 3.7.1. Planning
    • 3.7.2. Specific considerations
    • 3.7.3. Risk assessment
• 4. I&C PROJECT EXECUTION
  • 4.1. Overview of project phases
  • 4.2. Modernization project phases
    • 4.2.1. Feasibility phase
    • 4.2.2. Requirement specification phase
    • 4.2.3. Contractual arrangements
    • 4.2.4. Preliminary design phase
    • 4.2.5. Detailed design phase
    • 4.2.6. Implementation phase
    • 4.2.7. Integration and testing phase
    • 4.2.8. Installation and commissioning phase
    • 4.2.9. Handover phase
  • 4.3. Licensing process
    • 4.3.1. General principle for licensing
    • 4.3.2. Plan for the licensing process
    • 4.3.3. Major phases in the licensing process
    • 4.3.4. The safety case
  • 4.4. New facilities
• INTRODUCTION TO THE SUPPLEMENTARY FILES
• AppendixRELATED PUBLICATIONS
• REFERENCES
• ABBREVIATIONS
• CONTRIBUTORS TO DRAFTING AND REVIEW