• 제목/요약/키워드: SRO/LRO

검색결과 3건 처리시간 0.029초

원자력발전소 증기발생기 Alloy 690 전열관 재료의 규칙화 반응 (Ordering of Alloy 690 Steam Generator Tubings in a Nuclear Power Plant)

  • 황성식;최민재;김성우
    • Corrosion Science and Technology
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    • 제22권3호
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    • pp.214-219
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    • 2023
  • Considering the case in the United States where most nuclear power plants with an initial design life of 40 years continue to operate until 60 or 80 years after undergoing material soundness evaluation, it is time to plan a more robust long-term operation strategy for nuclear power plants in Korea. There are some reports that SRO/LRO might be formed when Alloy 690 is heat treated for 10,000 hours to 100,000 hours at 360 to 450 ℃. The possibility of LRO formation in Alloy 690 steam generator tubings of Kori nuclear power plant unit 1 (Kori-1) was investigated using existing research papers. The mechanism in which SRO/LRO occurred was also surveyed. Alloy 690 was found to be more likely to cause ordering than Alloy 600 in terms of alloy composition. The ordering could be evaluated through changes in material properties. However, it is difficult to evaluate it from a microstructural point of view. The likelihood of LRO in Alloy 690 of the Kori-1 plant operated at 320 ℃ for 19 years seemed to be low in terms of time and exposure temperature.

Processing of $Si_3N_4/SiC$ and Boron-Modified Nanocomposites Via Ceramic Precursor Route

  • Lee, Hyung-Bock;Rajiv S. Mishra;Matt J. Gasch;Han, Young-Hwan;Amiya K. Mukherjee
    • The Korean Journal of Ceramics
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    • 제6권3호
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    • pp.245-249
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    • 2000
  • Consolidation of amorphous powders is emerging as a route for synthesis of high strength composite materials. Diffusion processes necessary for consolidation are expected to be more rapid in amorphous state(SRO) than in the crystalline state(LRO). A new synthesis technique of exploiting polymeric ceramic precursors(polysilazane and polyborosilazane) is derived for Si$_3$N$_4$/SiC and boron-modified nanocomposites for extremely high temperature applications up to 200$0^{\circ}C$. The characterization methods include thermal analysis of DTA, and XRD, NMR, TEM, after pyrolysis, as a function of time and temperature.

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