This Safety Guide considers the application of a graded approach throughout the lifetime of a research reactor (site evaluation, design, construction, commissioning, operation and preparation for decommissioning), including utilization and experiments that are specific features of research reactor operation. A major aspect of this Safety Guide involves the use of a graded approach in the application of the safety requirements for the design and operation of research reactors, so that the fundamental safety objective to protect people and the environment from harmful effects of ionizing radiation is achieved. It is intended for use by operating organizations, regulatory bodies and other organizations involved in the design, construction and operation of research reactors. This Safety Guide is a revision of IAEA Safety Standards Series No. SSG-22, which it supersedes.

• 1. INTRODUCTION
  • Background
  • Objective
  • Scope
  • Structure
• 2. BASIC ELEMENTS OF A GRADED APPROACH FOR RESEARCH REACTORS
  • General considerations for applying a graded approach to research reactors
  • Description of the use of a graded approach in the application of safety requirements for research reactors
    • Step 1: Categorization of the research reactor in accordance with potential hazards
    • Step 2: Analysis and application of a graded approach
• 3. USE OF A GRADED APPROACH IN THE REGULATORY SUPERVISION OF RESEARCH REACTORS
  • The use of a graded approach in the legal and regulatory infrastructure for research reactors
  • The use of a graded approach in the organization and functions of the regulatory body for research reactors
  • The use of a graded approach in the authorization process for research reactors
    • Safety analysis report
  • The use of a graded approach in inspection and enforcement for research reactors
• 4. USE OF A GRADED APPROACH IN THE MANAGEMENT AND VERIFICATION OF SAFETY OF RESEARCH REACTORS
  • A graded approach to management responsibilities for safety for research reactors
  • Safety policy for research reactors
  • The use of a graded approach in the application of the requirements for the management system for a research reactor
  • The use of a graded approach in the verification of safety at a research reactor
    • Safety assessment
    • Reactor safety committee
• 5. THE USE OF A GRADED APPROACH IN SITE EVALUATION FOR RESEARCH REACTORS
• 6. THE USE OF A GRADED APPROACH IN THE DESIGN OF RESEARCH REACTORS
  • The use of a graded approach in the principal technical requirements for the design of research reactors
    • Main safety functions
    • Radiation protection
    • Design
    • Application of the concept of defence in depth
    • Interfaces of safety with security and the State system of accounting for, and control of, nuclear material
    • Proven engineering practices
    • Provision for construction
    • Features to facilitate radioactive waste management and decommissioning
  • The use of a graded approach in the general requirements for the design of research reactors
    • Safety classification of structures, systems and components
    • Design basis for items important to safety
    • Postulated initiating events
    • Internal hazards and external hazards
    • Design basis accidents
    • Design limits
    • Design extension conditions
    • Engineered safety features
    • Reliability of items important to safety
    • Single failure criterion
    • Common cause failures
    • Physical separation and independence of safety systems
    • Fail-safe design
    • Qualification of items important to safety
    • Design for commissioning
    • Calibration, testing, maintenance, repair, replacement, inspection and monitoring of items important to safety
    • Design for emergency preparedness and response
    • Design for decommissioning
    • Design for radiation protection
    • Design for optimal operator performance
    • Provision for safe utilization and modification
    • Design for ageing management
    • Provision for long shutdown periods
    • Prevention of unauthorized access to, or interference with, items important to safety
    • Prevention of disruptive or adverse interactions between systems important to safety
    • Safety analysis of the design
  • The use of a graded approach in specific requirements for the design of research reactors
    • Buildings and structures
    • Means of confinement
    • Reactor core and fuel design
    • Provision of reactivity control
    • Reactor shutdown systems
    • Design of reactor coolant systems and related systems
    • Emergency cooling of the reactor core
  • The use of a graded approach in instrumentation and control systems for research reactors
    • Provision of instrumentation and control systems
    • Reactor protection system
    • Reliability and testability of instrumentation and control systems
    • Use of computer based equipment in systems important to safety
    • Control room
    • Supplementary control room
    • Emergency response facilities on the site
    • Electrical power supply systems
    • Radiation protection systems
    • Handling and storage systems for fuel and core components
    • Radioactive waste systems
  • The use of a graded approach in supporting systems and auxiliary systems for research reactors
    • Performance of supporting systems and auxiliary systems
    • Fire protection systems
    • Lighting systems
    • Lifting equipment
    • Air-conditioning systems and ventilation systems
    • Compressed air systems
    • Experimental devices
• 7. THE USE OF A GRADED APPROACH IN THE OPERATION OF RESEARCH REACTORS
  • The use of a graded approach in organizational provisions for a research reactor
    • Responsibilities of the operating organization
    • Structure and functions of the operating organization
    • Operating personnel
    • Training, retraining and qualification of personnel
  • The use of a graded approach in operational limits and conditions for a research reactor
    • Safety limits
    • Safety system settings
    • Limiting conditions for safe operation
    • Requirements for maintenance, periodic testing and inspection
    • Administrative requirements
    • Violations of operational limits and conditions
  • The use of a graded approach in the performance of safety related activities at a research reactor
  • The use of a graded approach in commissioning of a reseach reactor
  • The use of a graded approach in the operation of a research reactor
    • Operating procedures
    • Main control room, supplementary control room and control equipment
    • Material conditions and housekeeping
    • Maintenance, periodic testing and inspection
    • Core management and fuel handling
    • Fire safety
    • Non-radiation-related safety
    • Emergency preparedness
    • Records and reports
    • Utilization and modification of a research reactor
    • Radiation protection programme
    • Management of radioactive waste
    • Ageing management
    • Extended shutdown
    • Feedback of operating experience
• 8. USE OF A GRADED APPROACH IN THE PREPARATION FOR DECOMMISSIONING OF RESEARCH REACTORS
• 9. USE OF A GRADED APPROACH IN THE INTERFACES BETWEEN SAFETY AND SECURITY FOR RESEARCH REACTORS
• REFERENCES
• CONTRIBUTORS TO DRAFTING AND REVIEW