The reactor core is the central part of a nuclear reactor where nuclear fission occurs. It consists of four basic systems and components: the fuel (including fuel rods and the fuel assembly structure), the coolant, the moderator and the control rods, as well as additional structures such as reactor pressure vessel internals, core support plates, and the lower and upper internal structure in light water reactors. This Safety Guide provides recommendations on meeting the safety requirements established in IAEA Safety Standards Series No. SSR-2/1 (Rev. 1), Safety of Nuclear Power Plants: Design, applied to the design of the reactor core for nuclear power plants. The publication addresses the safety aspects of the core design and includes neutronic, thermohydraulic, thermomechanical and structural mechanical aspects. Other aspects considered are those relating to reactor core control, shutdown and monitoring, and core management.

• 1. INTRODUCTION
  • Background
  • Objective
  • Scope
  • Structure
• 2. GENERAL SAFETY CONSIDERATIONS IN THE DESIGN of THE REACTOR CORE
  • Management system
  • Design objectives
    • Fundamental safety functions
    • Adequate design based on the concept of defence in depth
    • Proven engineering practices
    • Safety assessment in the design process
    • Features to facilitate radioactive waste management
  • Design basis for structures, systems and components of the reactor core
    • Plant states and postulated initiating events
    • External hazards
    • Design limits
    • Safety classification aspects of the reactor core
    • Engineering design rules
    • Design for reliability
    • Operational limits and conditions
  • Design for safe operation
  • Reactor core safety analysis
• 3. SPECIFIC SAFETY CONSIDERATIONS IN THE DESIGN OF THE REACTOR CORE
  • General
    • Fuel type
    • Coolant
    • Moderator
  • Neutronic design
    • Design considerations
    • Nuclear design limits
  • Thermohydraulic design
    • Design considerations
    • Thermohydraulic design limits
  • Thermomechanical design of fuel rods and fuel assemblies
    • Design considerations
    • Fuel design limits
  • Mechanical design of core structures and components
    • Design considerations
    • Design limits for the mechanical design of core structures and components
  • Reactor core control, shutdown and monitoring systems
    • Reactor core control system
    • Reactor shutdown system
    • Partial trip system
    • Operating limits and set points
    • Core monitoring system
  • Core management
    • Design considerations
    • Core management design limits
    • Special core configurations
    • Impact of fuel design and core management on fuel handling, transport, storage, reprocessing and disposal
• 4. QUALIFICATION AND TESTING
  • General
  • Design qualification
  • Inspection
  • Testing including prototype assemblies and lead use assemblies
• REFERENCES
• Annex ISUPPLEMENTARY TECHNICAL INFORMATION
• Annex II ASPECTS TO BE ADDRESSED IN THE DESIGN OF THE FUEL ROD, FUEL ASSEMBLY, REACTIVITY CONTROL ASSEMBLY, NEUTRON SOURCE ASSEMBLY AND HYDRAULIC PLUG ASSEMBLY
• CONTRIBUTORS TO DRAFTING AND REVIEW