Internal hazards have to be considered in the design of items important to safety in a nuclear power plant. The objective is to provide appropriate features to prevent internal hazards and mitigate their effects to ensure that safety is not compromised. This Safety Guide provides recommendations to regulatory bodies, nuclear power plant designers and licensees on hazard assessment (including for combinations of hazards) and design concepts for protection against internal hazards in nuclear power plants, in order to meet the requirements established in IAEA Safety Standards Series No. SSR 2/1 (Rev. 1), Safety of Nuclear Power Plants: Design. The following internal hazards are reviewed in this Safety Guide: fires, explosions, missiles, pipe breaks, flooding, collapse of structures and falling objects with a focus on heavy load drop, electromagnetic interference and release of hazardous substances originating from within the site boundary.

• 1. INTRODUCTION
  • Background
  • Objective
  • Scope
  • Structure
• 2. GENERAL CONSIDERATIONS
• 3. GENERAL DESIGN RECOMMENDATIONS FOR PROTECTION AGAINST INTERNAL HAZARDS
  • Identification and characterization of internal hazards and hazard combinations
  • Prevention of internal hazards and of the effects of the hazards
  • Mitigation of the effects of internal hazards
  • Assessment, verification and success criteria
  • Specific aspects of design for protection against internal hazards
• 4. RECOMMENDATIONS FOR SPECIFIC INTERNAL HAZARDS
  • Internal fires
    • General
    • Identification and characterization of fire hazards
    • Fire prevention
    • Fire mitigation
    • Mitigation of secondary fire effects
  • Internal explosions
    • General
    • Identification and characterization of explosion hazards
    • Prevention of explosion hazards
    • Mitigation of the effects of explosions
  • Internal missiles
    • Identification and characterization of missile hazards
    • Prevention of missile hazards
    • Mitigation of the effects of missile hazards
  • Pipe breaks (pipe whip and jet effect and flooding)
    • Identification and characterization of pipe breaks
    • Prevention of pipe breaks
    • Mitigation of the consequences of pipe breaks
    • Specific jet hazard considerations
  • Internal flooding
    • Identification and characterization of internal flooding hazards
    • Prevention of internal flooding hazards
    • Mitigation of internal flooding and the effects of internal flooding
    • Specific flooding hazard considerations
  • Heavy load drop
    • Identification and characterization of heavy load drop
    • Prevention of heavy load drop
    • Mitigation of the effects of heavy load drop
  • Electromagnetic interference
    • Identification and characterization of electromagnetic interference hazards
    • Prevention of electromagnetic interference hazards
    • Mitigation of the effects of electromagnetic interference hazards
    • Specific electromagnetic interference hazard considerations
  • Release of hazardous substances inside the plant
    • Identification and characterization of hazards from releases of hazardous substances within the plant
    • Prevention of hazards from releases of hazardous substances within the plant
    • Mitigation of the consequences of hazards associated with releases of hazardous substances within the plant
    • Specific considerations for releases of hazardous substances
• Appendix IHAZARD COMBINATIONS
• Appendix IIDETAILED GUIDANCE ON INTERNAL FIRES
• REFERENCES
• CONTRIBUTORS TO DRAFTING AND REVIEW