Nuclear Engineering and Technology

Korean Nuclear Society (한국원자력학회)
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Constraint-corrected fracture mechanics analysis of nozzle crotch corners in pressurized water reactors

  • Kim, Jong-Sung (Department of Nuclear Engineering, Sejong University Seoul) ;
  • Seo, Jun-Min (Department of Mechanical Engineering, Graduate School, Korea University Seoul) ;
  • Kang, Ju-Yeon (Dassault Systemes Korea Corporation) ;
  • Jang, Youn-Young (Dept. of Mech. System Design Engineering, Seoul National University of Science and Technology) ;
  • Lee, Yun-Joo (Korea Electric Power Company Engineering & Construction) ;
  • Kim, Kyu-Wan (Korea Electric Power Company Engineering & Construction)
  • Received : 2021.08.30
  • Accepted : 2021.11.28
  • Published : 2022.05.25
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Abstract

This paper presents fracture mechanics analysis results for various cracks located at pressurized water reactor pressure vessel nozzle crotch corners taking into consideration constraint effect. Technical documents such as the ASME B&PV Code, Sec.XI were reviewed and then a fracture mechanics analysis procedure was proposed for structural integrity assessment of various nozzle crotch corner cracks under normal operation conditions considering the constraint effect. Linear elastic fracture mechanics analysis was performed by conducting finite element analysis with the proposed analysis procedure. Based on the evaluation results, elastic-plastic fracture mechanics analysis taking into account the constraint effect was performed only for the axial surface crack of the reactor pressure vessel outlet nozzle with cladding. The fracture mechanics analysis result shows that only the axial surface crack in the reactor pressure vessel outlet nozzle has the stress intensity factor exceeding the low bound of upper-shelf fracture toughness irrespectively of considering the constraint effect. It is confirmed that the J-integral for the axial crack of the outlet nozzle does not exceed the ductile crack initiation toughness. Hence, it can be ensured that the structural integrity of all the cracks is maintained during the normal operation.

Keywords

Acknowledgement

The authors would like to express our deepest gratitude to Prof. Yun-Jae Kim of Korea University and Prof. Nam-Su Huh of Seoul National University of Science & Technology for their comments and supports on this study.

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