• Title/Summary/Keyword: 지르칼로이-4

Search Result 52, Processing Time 0.642 seconds

A Study on the Iodine-induced Stress Corrosion Cracking of Zircaloy-4 Cladding (I) (지르칼로이-4 피복재의 요드응력 부식 균열에 대한 연구)

  • W. S. Ryu;S. I. Hong;Y. Choi;Y. H. Kang;C. S. Rim
    • Nuclear Engineering and Technology
    • /
    • v.17 no.3
    • /
    • pp.193-199
    • /
    • 1985
  • Iodine-induced stress corrosion cracking tests of Zircaloy-4 cladding were undertaken using the modified infernal pressurization method. The effects of iodine concentration and applied stress were studied. The critical iodine concentration for SCC was found to be about 0.2 mg/$\textrm{cm}^2$ at 603$^{\circ}$K. The threshold stress was dependent on the test temperature and the mechanical properties of the specimen. The fracture surface showed that the crack propagated stepwise iron one grain to others until the material was unstable and then ruptured mechanically. The initial region showed the transgranular feature and the wedge-shaped cracks. As the crack proceeded, the transgranular and ductile-tearing mired feature appeared in the middle region.

  • PDF

Iodine Stress Corrosion Cracking of Zircaloy-4 Tubes

  • Moon, Kyung-Jin;Lee, Byung-Ho
    • Nuclear Engineering and Technology
    • /
    • v.10 no.2
    • /
    • pp.65-72
    • /
    • 1978
  • In this paper, it is attempted to investigate the phenomena of iodine stress corrosion cracking of Zircaloy-4 cladding failures in reactor through the results of similar out-of-pile test in iodine vapour. The main result of this experiment is a finding of the relation between the threshold stress which can lead to iodine stress corrosion cracking of Zircaloy-4 tube and the iodine concentration. The values of critical stress and the critical iodine concentration are also obtained. A model which relates failure time of Zircaley-4 tube to failure stress and iodine concentration is suggested as follows: log t$_{F}$ =5.5-(3/2)log$_{c}$-4log $\sigma$ where t$_{F}$ : failure time, minutes c: iodne concentration, mg/㎤ $\sigma$: stress, 10$^4$psi.

  • PDF

A Feasibility Study on the Brazing of Zircaloy-4 with Zr-Be Binary Amorphous Filler Metals (비정질 이원계 합금 Zr-Be 용가재를 이용한 지르칼로이-4의 브레이징 타당성 검토)

  • 고진현;박춘호;김수성
    • Journal of Welding and Joining
    • /
    • v.17 no.4
    • /
    • pp.26-31
    • /
    • 1999
  • An attempt was made in this study to investigate the brazing characteristics of Zr-Be binary amorphous alloys for the development of a new brazing filler metal for joining Zircaloy-4 nuclear fuel cladding tubes. This study was also aimed at the feasibility study of rapidly solidified amorphous alloys to substitute the conventional physical vapor-deposited(PVD) metallic beryllium. The $Zr_{1-x}Be_{x}$($0.3\leq$x$\leq0.5$) binary amorphous alloys were produced in the ribbon form by the melt-spinning method. It was confirmed by x-ray diffraction that the ribbons were amorphous. The amorphous. the amorphous alloys were used to join bearing pads on Zircaloy-4 nuclear fuel cladding tubes. Using Zr-Be amorphous alloys as filler metals, it was found that the reduction in the tube wall thickness caused by erosion was prevented. Especially, in the case of using $Zr_{0.65}Be_{0.35}$ and $Zr_{0.7}Be_{0.3}$ amorphousalloys, the smooth and spherical primary $\alpha$-Zr particles appeared in the brazed layer, which was the most desirable microstructure from the corrosion-resistance standpoint.

  • PDF

Effect of High Temperature Steam Oxidation on Yielding of Zircaloy-4 PWR Fuel Cladding -Expanding Copper Mandrel Test- (가압경수형 핵연료 피복관 지르칼로이-4의 항복현상에 대한 고온 수증기 산화의 영향 -구리 맨드렐 팽창시험법-)

  • Kye-Ho Nho;Sun-Pil Choi;Byong-Whi Lee
    • Nuclear Engineering and Technology
    • /
    • v.21 no.2
    • /
    • pp.111-122
    • /
    • 1989
  • With the Zircaloy-4 tube oxidized in high temperature (1323 K) steam for 5, 10, 30 and 60 minutes, the expanding copper mandrel test was carried out over a temperature range of 673-l173k at $\varepsilon\;=\;3.0\times10^5S\;^1$. The oxidation parameters $(K_i)$ in the present study were linearly proportional to square root of time $(Ki= \delta_{kit})$ and their rate constants ($\delta_{ki}$) are 0.281, 2.82, and 2.313 for weight gain and thickness of Zr02 and $\alpha$(0) layer, respectively. Activation energy for high temperature (873-1073k) plastic deformation of Zircaloy-4 increases from 251 KJ/mol to 323 KJ/mol with increase in oxidation time from 5 minutes to 60 minutes due to the high strengthened Zr02. With the oxide layer thickness [K ; expressed in "Equivalent Cladding Reacted" (ECR,%)] and the yield stress obtained from the mandrel test, an empirical relation was derived as ($\sigma/C)^n=K^mexp$ (Q/RT) with n=6.9, m=5.7, C=0.155, 0.138, 0.051, and 0.046 MPa for Q=251, 258, 316, 323 KJ/mol, respectively.

  • PDF

지르칼로이-4의 고압 고온 수중기에서 산화 반응 속도

  • 박광헌;김규태
    • Proceedings of the Korean Institute of Surface Engineering Conference
    • /
    • 2000.11a
    • /
    • pp.35-36
    • /
    • 2000
  • 핵연료의 피복관은 핵분열로부터 발생하는 방사성 핵분열생성물이 외부로 유출되는 것을 차단하는 첫번째 방어막의 역할을 하며, 피복관의 건전성은 정상 상태는 물론 이고 사고시에도 위해한 핵분열생성물의 방출을 억제하는 역할을 충분히 수행할 수 있도록 유지되어야 한다. 단사정 산화막 영역에서만 수증기 압력에 의한 산화가속 효과가 존재하는데, 아직 이를 설명할 수 있는 산화속도 모형이 설정되어 있지 않은 상태이다. 본 연구에선 실험자료를 근거로 하여, 절실히 요구되는 $1000^{\circ}C$ 이하 영역에서 의 수증기 압력을 고려한 산화속도식을 개발하여, 보다 정확한 원전 사고해석이 가능 하도록 하는데 기여하려 한다.

  • PDF

Effect of Preoxidation on the Zircaloy-4 Oxidation Behavior in a Steam and Water Mixture between $700^{\circ}C$ and 85$0^{\circ}C$ (수증기와 물의 혼합 분위기에서 기산화층이 지르칼로이 -4의 산화 거동에 미치는 영향)

  • Yoo, Jong-Sung;Kim, In-Sup
    • Nuclear Engineering and Technology
    • /
    • v.19 no.2
    • /
    • pp.122-129
    • /
    • 1987
  • Experiments and numerical analysis have been performed to investigate the effect of preoxidation by oxidizing Zircaloy-4 specimens at a higher temperature after a period of exposure at a lower temperature. The oxidation experiments were performed between $700^{\circ}C$ and 85$0^{\circ}C$ after Preoxidation at $650^{\circ}C$ in a steam and water mixture for 600 seconds and 1,800 seconds. As the thickness of preoxidized layer increased, the oxidation rate of preoxidized specimens at higher temperature became lower than that of as-received claddings. A transition region of oxidation rate exist in the preoxidized specimens, and the region disappeared rapidly as the oxidation temperature increased. This effect appeared more clearly at lower temperatures. According to the results of numerical analysis performed in this study, the growth rate of oxide layer thickness and weight gains were similarly affected by the thickness of preoxidized layer.

  • PDF