This Safety Guide is a revision of IAEA Safety Standards Series No. SSG-24, which it supersedes. The current publication provides recommendations on how to meet the applicable safety requirements relating to the utilization and modification of research reactors. The recommendations focus on the categorization, safety assessment and approval of research reactor experiments and modification projects. The publication also incorporates the relevant lessons learned from the accident at the Fukushima Daiichi nuclear power plant and elaborates on interfaces between nuclear safety and nuclear security. Specific safety considerations in different phases of utilization and modification projects are covered, including pre­implementation, implementation, and post implementation phases. Guidance is given on operational safety of experiments, including the handling, dismantling, post-irradiation examination and disposal of experimental devices. The publication is intended to be of use to individuals within the operating organizations of research reactors, regulatory bodies, as well as the experimenters, technical support organizations and other persons involved in utilization and modification projects.

• 1. INTRODUCTION
  • Background
  • Objective
  • Scope
  • Structure
• 2. MANAGEMENT SYSTEM FOR THE UTILIZATION AND MODIFICATION OF A RESEARCH REACTOR
  • General
  • Management responsibility
  • Resource management
  • Implementation of a utilization or modification project
  • Measurement, assessment and improvement
  • Responsibilities of the project manager
  • Responsibilities of the reactor manager
• 3. CATEGORIZATION, SAFETY ASSESSMENT AND APPROVAL OF AN EXPERIMENT OR MODIFICATION
  • Categorization process
    • Experiments or modifications with a major effect on safety
    • Experiments or modifications with a significant effect on safety
    • Experiments or modifications with a minor effect on safety
    • Experiments or modifications with no effect on safety
  • Interface between nuclear safety and nuclear security for an experiment or modification
• 4. SAFETY CONSIDERATIONS FOR THE DESIGN OF AN EXPERIMENT OR MODIFICATION
  • General considerations
  • Specific considerations
    • Reactivity
    • Radiation protection
    • Safety devices
    • Heat generation and cooling
    • Pressure
    • Selection of materials
    • Neutron flux perturbations
    • Protection against external and internal hazards
    • Mechanical interaction of experiments and the reactor
    • Testability and ageing management
• 5. PRE-IMPLEMENTATION PHASE OF A UTILIZATION OR MODIFICATION PROJECT
  • General
  • Project initiation
  • Project definition
    • Categorization of the experiment or modification and selection of safety codes and standards
    • Data collection
    • Pre-design appraisal
  • Design
• 6. IMPLEMENTATION PHASE OF A UTILIZATION OR MODIFICATION PROJECT
  • General
  • Fabrication
  • Updating of safety documentation
  • Installation
    • Management
    • Safety aspects
  • Commissioning
• 7. POST-IMPLEMENTATION PHASE OF A UTILIZATION OR MODIFICATION PROJECT
  • Post-implementation safety evaluation and approval for routine operation
  • Updating of safety documentation
  • Special surveillance
• 8. OPERATIONAL SAFETY OF EXPERIMENTS AT A RESEARCH REACTOR
  • Radiation protection
  • Information necessary for the safe performance of experiments
  • Cooperation between experimenters and operating personnel
  • Operational changes in experiments
  • Responsibility for the safe operation of experiments
• 9. SAFETY CONSIDERATIONS IN THE HANDLING, DISMANTLING, POST-IRRADIATION EXAMINATION AND DISPOSAL OF EXPERIMENTAL DEVICES
  • General recommendations
  • Specific recommendations
    • Training
    • Storage
• 10. SAFETY ASPECTS OF OUT-OF-CORE INSTALLATIONS
• 11. CHANGES TO THE OPERATING ORGANIZATION
  • Organizational changes
  • Implementation of organizational changes
• REFERENCES
• Annex I EXAMPLE OF A CHECKLIST FOR THE CATEGORIZATION OF AN EXPERIMENT OR MODIFICATION AT A RESEARCH REACTOR
• Annex II EXAMPLE OF THE CONTENT OF THE SAFETY ANALYSIS REPORT FOR AN EXPERIMENT AT A RESEARCH REACTOR
• Annex III EXAMPLES OF MODIFICATIONS THAT CAN AFFECT THE SAFETY AND NUCLEAR SECURITY INTERFACE
• Annex IV EXAMPLES OF SAFETY FOCUSED QUESTIONS AND SECURITY FOCUSED QUESTIONS FOR USE IN ASSESSING A MODIFICATION TO A RESEARCH REACTOR
• Annex V EXAMPLES OF REASONS FOR A MODIFICATION AT A RESEARCH REACTOR
• CONTRIBUTORS TO DRAFTING AND REVIEW