Nuclear Engineering and Technology

Korean Nuclear Society (한국원자력학회)
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Failure simulation of nuclear pressure vessel under LBLOCA scenarios

  • Eui-Kyun Park (Mechanical Engineering, Korea University) ;
  • Jun-Won Park (Mechanical Engineering, Korea University) ;
  • Yun-Jae Kim (Mechanical Engineering, Korea University) ;
  • Kukhee Lim (Korea Institute of Nuclear Safety) ;
  • Eung-Soo Kim (Nuclear Engineering, Seoul National University)
  • Received : 2023.11.27
  • Accepted : 2024.02.26
  • Published : 2024.07.25
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Abstract

This paper presents the finite element deformation and failure simulation of a typical Korean high-power reactor vessel under a severe accident characterized by large break loss of coolant (LBLOCA) with in-vessel retention of molten corium through external reactor vessel cooling (IVR-ERVC) conditions. Temperature distributions calculated using Modular Accident Analysis Program Version 5 (MAAP5) as thermal boundary conditions were used, and ABAQUS thermal and structural analyses were performed. After full ablation, the temperature of the inner surface in the thinnest section remained high (920 ℃), but the stress remained relatively low (less than 6 MPa). At the outer surface, the stress was as high as 250 MPa; however, the resulting plastic strain was small owing to the low temperature of 200 ℃. Variations in stress, inelastic strain, and temperature with time in the thinnest section suggest that the plastic and creep strains are saturated owing to stress relaxation, resulting in low cumulative damage. Thus, the lower head of the vessel can maintain its structural integrity under LBLOCA with IVR-ERVC conditions. The sensitivity analysis of internal pressure indicates the occurrence of failure in the thinnest section at an internal pressure >9.6 MPa via local necking followed by failure due to high stresses.

Keywords

Acknowledgement

This work was supported by the Nuclear Safety Research Program through the Korea Foundation of Nuclear Safety (KoFONS) using the financial resources granted by the Nuclear Safety and Security Commission (NSSC) of the Republic of Korea (No. 2103079).

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