한국압력기기공학회 논문집 (Transactions of the Korean Society of Pressure Vessels and Piping)

한국압력기기공학회 (Korean Society of Pressure Vessels and Piping)
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응력 삼축성을 고려한 원자로 내부구조물 배플포머 집합체의 연성저하 평가

Ductility Degradation Assessment of Baffle Former Assembly Considering the Stress Triaxiality Effect

  • 투고 : 2016.11.12
  • 심사 : 2016.12.22
  • 발행 : 2016.12.30
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초록

The study presents structural integrity assessment of ductility degradation of a baffle former assembly by performing finite element analysis considering real loading conditions and stress triaxiality. Variations of fracture strain curves of type 304 austenitic stainless steel with stress triaxiality are derived based on the previous study results. Temperature distributions during normal operation such as heat-up, steady state, and cool-down are calculated via finite element temperature analysis considering gamma heating and heat convection with reactor coolant. Variations of stress and strain state during long operation period are also calculated by performing sequentially coupled temperature-stress analysis. Fracture strain is derived by using the fracture curve and the stress triaxility. Finally, variations of ductility degradation damage indicator with the fracture strain and the equivalent inelastic strain are investigated. It is found that maximum value of the ductility degradation damage index continuously increases and becomes 0.4877 at 40 EFPYs. Also, the maximum value occurs at top and middle inner parts of the baffle former assembly before and after 20 EFPYs, respectively.

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참고문헌

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