• 제목/요약/키워드: Nuclear structure

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후쿠시마 원자력발전소 지진 계측 기록 분석을 통한 지진파의 공간적 변화 특성 평가 (Spatial Variation Characteristics of Seismic Motions through Analysis of Earthquake Records at Fukushima Nuclear Power Plant)

  • 하정곤;김미래;김민규
    • 한국지진공학회논문집
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    • 제25권5호
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    • pp.223-232
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    • 2021

  • The spatial variation characteristics of seismic motions at the nuclear power plant's site and structures were analyzed using earthquake records obtained at the Fukushima nuclear power plant during the Great East Japan Earthquake. The ground responses amplified as they approached the soil surface from the lower rock surface, and the amplification occurred intensively at about 50 m near the ground. Due to the soil layer's nonlinear characteristics caused by the strong seismic motion, the ground's natural frequency derived from the response spectrum ratio appeared to be smaller than that calculated from the shear wave velocity profile. The spatial variation of the peak ground acceleration at the ground surface of the power plant site showed a significant difference of about 0.6 g at the maximum. As a result of comparing the response spectrums at the basement of the structure with the design response spectrum, there was a large variability by each power plant unit. The difference was more significant in the Fukushima Daiichi site record, which showed larger peak ground acceleration at the surface. The earthquake motions input to the basement of the structure amplified according to the structure's height. The natural frequency obtained from the recorded results was lower than that indicated in the previous research. Also, the floor response spectrum change according to the location at the same height was investigated. The vertical response on the foundation surface showed a significant difference in spectral acceleration depending on the location. The amplified response in the structure showed a different variability depending on the type of structure and the target frequency.

  • https://doi.org/10.5000/EESK.2021.25.5.223 인용 PDF KSCI

Microstructure analysis of pressure resistance seal welding joint of zirconium alloy tube-plug structure

  • Gang Feng;Jian Lin;Shuai Yang;Boxuan Zhang;Jiangang Wang;Jia Yang;Zhongfeng Xu;Yongping Lei
    • Nuclear Engineering and Technology
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    • 제55권11호
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    • pp.4066-4076
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    • 2023

  • Pressure resistance welding is usually used to seal the connection between the cladding tube and the end plug made of zirconium alloy. The seal welded joint has a direct effect on the service performance of the fuel rod cladding structure. In this paper, the pressure resistance welded joints of zirconium alloy tube-plug structure were obtained by thermal-mechanical simulation experiments. The microstructure and microhardness of the joints were both analyzed. The effect of processing parameters on the microstructure was studied in detail. The results showed that there was no β-Zr phase observed in the joint, and no obvious element segregation. There were different types of Widmanstätten structure in the thermo-mechanically affected zone (TMAZ) and heat affected zone (HAZ) of the cladding tube and the end plug joint because of the low cooling rate. Some part of the grains in the joint grew up due to overheating. Its size was about 2.8 times that of the base metal grains. Due to the high dislocation density and texture evolution, the microhardnesses of TMAZ and HAZ were both significantly higher than that of the base metal, and the microhardness of the TMAZ was the highest. With the increasing of welding temperature, the proportion of recrystallization in TMAZ decreased, which was caused by the increasing of strain rate and dislocation annihilation.

  • https://doi.org/10.1016/j.net.2023.07.025 인용 PDF