Fatigue is a major element in time limited ageing analysis for long term operation of nuclear power plants (NPPs). It is important to understand how cracks occur and grow as a result of fatigue, and then assess fatigue failure. In the design and operating phase of NPPs, it is essential to consider the concurrent loadings associated with the design transients, thermal stratification, seismically induced stress cycles, and all relevant loads due to the various operational modes. After repeated cyclic loading, crack initiation can occur at the most highly affected locations if sufficient localized micro-structural damage has accumulated. This publication provides practical guidelines on how to identify and manage fatigue issues in NPPs. It explains the mechanism of fatigue, identifies which elements are the major contributors, and details how fatigue can be minimized in the design phase for new NPPs.

• 1. INTRODUCTION
  • 1.1. Background
  • 1.2. Objective
  • 1.3. Scope
  • 1.4. Structure
• 2. MECHANISMS AND MAJOR CONTRIBUTIONS TO FATIGUE
  • 2.1. Basic mechanism of fatigue
    • 2.1.1. Stress/strain versus life diagram
    • 2.1.2. Initiation of fatigue crack and crack propagation
  • 2.2. Categories of fatigue
    • 2.2.1. High cycle fatigue
    • 2.2.2. Low cycle fatigue
  • 2.3. Influential factor
    • 2.3.1. Mean stress
    • 2.3.2. Stress concentration effects
    • 2.3.3. Size effects
    • 2.3.4. Surface finish
    • 2.3.5. Temperature
    • 2.3.6. Corrosion fatigue due to environmental effects
    • 2.3.7. Loading history effect
  • 2.4. Loading as a cause of fatigue failure
    • 2.4.1. Vibration fatigue
    • 2.4.2. Thermal fatigue
    • 2.4.3. Fretting fatigue
    • 2.4.4. Ratcheting
  • 2.5. Fracture mechanics approach to fatigue
• 3. FATIGUE ASSESSMENT IN NEW NUCLEAR POWER PLANT DESIGNS
  • 3.1. Codes for fatigue design
    • 3.1.1. Overview of design codes for nuclear power plants
    • 3.1.2. ASME Code rules for fatigue design
  • 3.2. Fatigue design loadings
    • 3.2.1. Design transients
    • 3.2.2. Thermal stratification
    • 3.2.3. Earthquake loads
    • 3.2.4. Vibratory loads
    • 3.2.5. Thermal oscillations in piping
    • 3.2.6. Other loadings
    • 3.2.7. Loading combinations
  • 3.3. Design considerations for avoiding possible fatigue failure
    • 3.3.1. Design consideration for vibration fatigue
    • 3.3.2. Design consideration for thermal fatigue
  • 3.4. Approach to fatigue assessment
    • 3.4.1. Design fatigue analysis
    • 3.4.2. Environmentally assisted fatigue analysis
    • 3.4.3. Piping vibration testing
    • 3.4.4. Transient and fatigue monitoring
    • 3.4.5. Vibration monitoring
    • 3.4.1. Current regulatory fatigue issues: EAF evaluation methods
• 4. FATIGUE ASSESSMENT IN OPERATING NUCLEAR POWER PLANTS
  • 4.1. Operating experience: general trends and issues
    • 4.1.1. Summary of Member State experiences
    • 4.1.2. Evaluation of survey results
  • 4.2. Experiences of fatigue failure and root causes
    • 4.2.1. Fatigue failure
    • 4.2.2. Flow induced vibration and acoustically induced vibration
    • 4.2.3. Other potential fatigue issues
  • 4.3. Ageing management application on fatigue
    • 4.3.1. Overview of fatigue screening criteria
    • 4.3.2. Overview on repair and replacement
    • 4.3.3. Current regulatory fatigue issues
• 5. ENVIRONMENTAL EFFECTS ON FATIGUE LIFE
  • 5.1. Outline of phenomena
  • 5.2. Methods for estimating environmental effects
    • 5.2.1. Basic principles
    • 5.2.2. Reference in-air fatigue curves
    • 5.2.3. Influence of strain rate
    • 5.2.4. Influence of temperature
    • 5.2.5. Influence of material composition and water chemistry
    • 5.2.6. Effect of strain amplitude
    • 5.2.7. Existing formulas for Fen
  • 5.3. Application to general loading conditions
  • 5.4. Reflection in design codes and regulations
    • 5.4.1. Development in Japan (Thermal and Nuclear Power Engineering Society (TENPES)/JSME guidelines)
    • 5.4.2. Development in the USA (NUREG report and ASME Code)
    • 5.4.3. Development in France
    • 5.4.4. Development in Germany
    • 5.4.5. Development in Finland
    • 5.4.6. Summary
  • 5.5. Environmental effects on fatigue crack growth
    • 5.5.1. Outline
    • 5.5.2. Ferritic steels
    • 5.5.3. Austenitic stainless steels
    • 5.5.4. Ni–Cr–Fe alloys
    • 5.5.5. Comparison of crack growth equations for different materials
  • 5.6. Summary
• 6. FATIGUE MONITORING AND RELATED SYSTEMS
  • 6.1. Fatigue monitoring strategies and technologies
    • 6.1.1. CBF
    • 6.1.2. SBF
  • 6.2. Monitoring locations
  • 6.3. General steps for implementation
    • 6.3.1. Generic steps
    • 6.3.2. Solutions for the cycle counting issue
    • 6.3.3. Using operational measurements
    • 6.3.4. Using local measurements (local fatigue monitoring approach)
  • 6.4. Commercially available fatigue monitoring systems
    • 6.4.1. Description of different systems
    • 6.4.2. Comparison of different systems
• 7. CONCLUSIONS AND GUIDANCE
• Appendix ISAMPLE FATIGUE EVALUATION OF VESSEL AND PIPING ACCORDING TO THE ASME CODE
• Appendix IINATIONAL AND INTERNATIONAL RESEARCH ACTIVITIES TO MANAGE FATIGUE
• Appendix IIISURVEY RESULT ON FATIGUE MONITORING AND ASSESSMENT
• REFERENCES
• ABBREVIATIONS
• CONTRIBUTORS TO DRAFTING AND REVIEW
• STRUCTURE OF THE IAEA NUCLEAR ENERGY SERIES