• 제목/요약/키워드: Leak-before-break assessment diagram

검색결과 2건 처리시간 0.016초

LEAK-BEFORE-BREAK ANALYSIS OF THERMALLY AGED NUCLEAR PIPE UNDER DIFFERENT BENDING MOMENTS

  • LV, XUMING;LI, SHILEI;ZHANG, HAILONG;WANG, YANLI;WANG, ZHAOXI;XUE, FEI;WANG, XITAO
    • Nuclear Engineering and Technology
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    • 제47권6호
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    • pp.712-718
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    • 2015
  • Cast duplex stainless steels are susceptible to thermal aging during long-term service at temperatures ranging from $280^{\circ}C$ to $450^{\circ}C$. To analyze the effect of thermal aging on leak-before-break (LBB) behavior, three-dimensional finite element analysis models were built for circumferentially cracked pipes. Based on the elasticeplastic fracture mechanics theory, the detectable leakage crack length calculation and J-integral stability assessment diagram approach were carried out under different bending moments. The LBB curves and LBB assessment diagrams for unaged and thermally aged pipes were constructed. The results show that the detectable leakage crack length for thermally aged pipes increases with increasing bending moments, whereas the critical crack length decreases. The ligament instability line and critical crack length line for thermally aged pipes move downward and to the left, respectively, and unsafe LBB assessment results will be produced if thermal aging is not considered. If the applied bending moment is increased, the degree of safety decreases in the LBB assessment.

원전 배관 파단전누설 평가를 위한 탄소성 파괴역학 평가 프로그램 개발 (Development of Elastic-Plastic Fracture Mechanics Evaluation Program for Leak-Before-Break Analysis of Nuclear Piping)

  • 박준근;허남수;김예지;이상민
    • 한국압력기기공학회 논문집
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    • 제16권2호
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    • pp.35-46
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    • 2020
  • In this paper, a fracture mechanics evaluation system which can be used to assess the leak-before-break (LBB) of nuclear piping is developed. Existing solutions for calculating the fracture mechanics parameters (J-integral and crack opening displacement) required for LBB evaluation were firstly presented. Then a module for calculating J-integral and COD was developed, with an additional module for predicting the critical load based on the crack driving force diagram to finally develop a fracture mechanics evaluation system. To confirm the validity of the proposed evaluation system, finite element (FE) analysis was performed, and the FE J-integral and COD results were compared with prediction results using the J-integral and COD estimations program. Furthermore, the critical load assessment module was verified by comparing the actual pipe test results (Battelle test data) with prediction results using the proposed program.