In this study, static thermo-structural integrity and environmentally assisted fatigue (EAF) behavior were evaluated according to housing thickness reduction (10 mm to 3 mm) for an i-SMR CRDM housing. Finite element analysis was conducted on the STS316L housing under operating conditions (325 °C, 15.5 MPa) and 200 transient cycles based on ASME Section III NB-3200. To account for the primary water coolant environment, an environmental fatigue correction factor (Fen = 6.03) derived from NUREG/CR-6909 Rev. 1 was applied. The air fatigue damage (Uair) remained at a negligible across all thickness conditions, confirming significant over-design in the baseline 10 mm model. Although the actual safety factor decreased from 33.60 (10 mm) to 12.21 (3 mm), the 3 mm design maintained a substantial safety margin well above 1.0. Considering environmental effects, the cumulative usage factor (CUFen) for the 3 mm design was , far below the ASME allowable limit of 1.0. Consequently, reducing the housing thickness to 3 mm ensures structural robustness and 60-year operational integrity.
목차
Abstract 1. 서론 2. 해석 모델 및 평가 방법론 2.1 Engineering data 2.2 ANSYS를 활용한 열-구조 결합 피로해석 2.3 피로 평가 지표의 정의 2.4 환경 피로(EAF) 평가 방법론 (Fen) 3. 유한요소해석 결과 및 고찰 3.1 대기 환경에서 피로 해석 결과 3.2 고온 수중 환경 피로 평가 4. Conclusions References