부하추종 과도 운전 조건 하 i-SMR CRDM 하우징의 열-구조 연성 과도 해석 및 환경피로(EAF) 건전성 평가
Transient Thermo-Structural Analysis and Environmentally Assisted Fatigue (EAF) Integrity Assessment of i-SMR CRDM Housing under Daily Load-Following Transients
This study evaluated the thermo-structural integrity and environmentally assisted fatigue (EAF) behavior of an i-SMR CRDM housing under daily load-following transients (100%→50%→100% power) based on ASME Section III NB-3200. Sequentially coupled 2D FEA on a 3 mm STS316L housing showed a maximum von-Mises stress of 232.79 MPa at 100% power and 217.68 MPa at 50% power, yielding a cyclic stress range of 15.11 MPa. For a 60-year design life (200cycles), the air fatigue damage (Dair) was with a minimum safety factor of 3.384. Applying an NUREG/CR-6909 Fen factor of 6.03 resulted in a cumulative usage factor (CUFen) of , well below the 1.0 limit. These results confirm that the thermal stress induced by load-following transients is significantly mitigated by the thin-walled design, ensuring structural robustness and substantial safety margins over the 60-year design life.
목차
Abstract 1. 서론 2. Finite Element Modeling & Transient Analysis 2.1 Geometry and Material Properties 2.2 Load-Following Transient Profile & Boundary Conditions 2.3 Transient Thermal-Structural coupled Analysis Boundary Conditions 3. Finite Element Analysis Results 3.1 Transient Equivalent Stress Distribution 3.2 Fatigue Life and Cumulative Damage Results 3.3 Environmental Fatigue Consideration (Fen) 4. Conclusions References