• 제목/요약/키워드: Zirconium Alloy

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핵연료 피복관의 산세 공정 시 Nb 함량에 따른 SMUT 특성 (Evaluation of SMUT Properties according to Nb Content in the Pickling Process of Nuclear Fuel Cladding Tube)

  • 문종한;이영준;이진행;홍종원;이종현
    • 한국재료학회지
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    • 제29권8호
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    • pp.483-490
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    • 2019
  • Currently, the Korean nuclear industry uses ZIRLO as material for nuclear fuel cladding(zirconium alloy). KEPCO Nuclear Fuel is in the process of developing a HANA alloy to enable domestic production of cladding. Cladding manufacture involves multistage heat treatments and pickling processes, the latter of which is vital for the removal of defects and impurities on the cladding surface. SMUT that forms on the cladding surface during such pickling process is a source of surface defects during heat treatment and post-treatment processes if not removed. This study analyzes ZIRLO, HANA-4, and HANA-6 alloy claddings to extensively study the SEM/EDS, XRD, and particle size characteristics of SMUT, which are second phase particles that are formed on the cladding surface during pickling processes. Using the analysis results, this study observes SMUT formation characteristics according to Nb concentration in Zr alloys during the washing process following the pickling process. In addition, this study observes SMUT removal characteristics on cladding surfaces according to concentrations of nitric acid and hydrofluoric acid in the acid solution.

마그네슘용탕의 니켈 함량에 미치는 알루미늄, 망간 및 지르코늄의 영향 (Effect of Aluminum, Manganese, and Zirconium on the Content of Nickel in Molten Magnesium)

  • 정대영;문영훈;문병기;박원욱;손근용
    • 한국주조공학회지
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    • 제35권1호
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    • pp.8-14
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    • 2015
  • Variations of nickel contents and microstructures in molten magnesium alloys on the addition of aluminum, zirconium, and manganese have been investigated. Specimens were prepared by melting under $SF_6$ and $CO_2$ atmosphere and casting into a disc of 29 mm diameter with 7~10 mm thickness from the melt acquired at the top of crucible. Before casting, the molten metal was stirred for 3 minutes after each addition of alloying elements and maintained for 30 minutes for settling down. Results showed that zirconium did not significantly affect the content of nickel while aluminum remarkably reduced it by forming $Al_3Ni_2$ phase. When manganese are added to Mg-1wt%Ni alloy along with aluminum, both elements remarkably reduced the content of nickel. The addition of 1.5 wt% manganese to Mg-1wt%Ni alloy containing aluminum further reduced the content of nickel by more than 30%, during which an additional intermetallic phase $Al_{10}Mn_3Ni$ was precipitated in the molten magnesium.

THE EFFECT OF HYDROGEN AND OXYGEN CONTENTS ON HYDRIDE REORIENTATIONS OF ZIRCONIUM ALLOY CLADDING TUBES

  • CHA, HYUN-JIN;JANG, KI-NAM;AN, JI-HYEONG;KIM, KYU-TAE
    • Nuclear Engineering and Technology
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    • 제47권6호
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    • pp.746-755
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    • 2015
  • To investigate the effect of hydrogen and oxygen contents on hydride reorientations during cool-down processes, zirconium-niobium cladding tube specimens were hydrogen-charged before some specimens were oxidized, resulting in 250 ppm and 500 ppm hydrogen-charged specimens containing no oxide and an oxide thickness of $0.38{\mu}m$ at each surface. The nonoxidized and oxidized hydrogen-charged specimens were heated up to $400^{\circ}C$ and then cooled down to room temperature at cooling rates of $0.3^{\circ}C/min$ and $8.0^{\circ}C/min$ under a tensile hoop stress of 150 MPa. The lower hydrogen contents and the slower cooling rate generated a larger fraction of radial hydrides, a longer radial hydride length, and a lower ultimate tensile strength and plastic elongation. In addition, the oxidized specimens generated a smaller fraction of radial hydrides and a lower ultimate tensile strength and plastic elongation than the nonoxidized specimens. This may be due to: a solubility difference between room temperature and $400^{\circ}C$; an oxygen-induced increase in hydrogen solubility and radial hydride nucleation energy; high temperature residence time during the cool-down; or undissolved circumferential hydrides at $400^{\circ}C$.

Effects of Hafnium, Boron and Zirconium on the Ductility of Ni$_3$(Al, Fe) Intermetallic Compounds

  • Lim, S.H.;No, J.Y.;No, K.S.;Wee, D.M.
    • 한국재료학회지
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    • 제2권4호
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    • pp.306-310
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    • 1992
  • Effects of hafnium, boron and zirconium on the ductility of Ni$_3$(Al, Fe) intermetallic compounds were studied using tensile test and SIMS analysis. Ni$_3$(Al, Fe) alloy with 0.1 at.% Hf, 0.05 at.% B and 0.1 at.% Zr additions showed maximum elongations of about 30% at 300K, 10% at 300K and 14% at 473K, respectively. The fracture mode of the alloy without the additive was the mixture of intergranular and transgranular fractures, but the addition of Hf, Zr or B changed the fracture mode to transgranular only. SIMS analysis showed that the beneficial effects of Hf, Zr or B segregation on the grain boundary strength are consistent with the grain boundary cohesion theory.

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원자력발전 설비의 소재와 용접방법에 대한 최신 기술동향 (Recent study of materials and welding methods for nuclear power plant)

  • 유호천
    • Journal of Welding and Joining
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    • 제33권1호
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    • pp.14-23
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    • 2015
  • Recent developing tendency of nuclear power plant are studied by searching of NDSL, KIPRIS, Science Direct and so on. Welding materials such as low alloyed steels, stainless steels, nickel-based alloys, zirconium alloy and welding methods such as narrow gap welding, laser beam welding, friction stir welding, overlay welding are investigated.