Pseudobinary zircaloy-oxygen phase diagram

Chung, H.M.; Kassner, T.F.

doi:10.1016/0022-3115(79)90172-7

Cited by 77 publications

(37 citation statements)

References 6 publications

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“…As the ductility of the prior-beta layer decreases with increasing oxygen content, the results suggest that the oxygen content in the beta layer reaches the solubility limit (0.38 wt.% [18]) at ≈15% CP-ECR, which corresponds to an equivalent isothermal time of ≈600 s. From 15% ECR (600 s) to 20% ECR (1065 s), the beta layer-thickness decreases to ≈300 µm, while the oxygen content and post-quench ductility of the prior-beta layer remain constant. Thus, neither oxygen-nor beta-layer-thinning-induced embrittlement was observed under these test conditions.…”

Section: ×17 Zry-4 Oxidized At 1000ºc and 1100ºcmentioning

confidence: 80%

“…The primary difference is the slow decrease in offset strain with ECR from 7.5% at 15% CP-ECR to 5.1% at 17% CP-ECR to 3.2% at 20% CP-ECR. The beta-layer oxygen-solubility at 1000˚C is less (0.24 wt.% [18]) than it is at 1100˚C, so higher ductility would be expected. However, 1000˚C is very close to the (alpha + beta) → beta phase transformation temperature.…”

Section: ×17 Zry-4 Oxidized At 1000ºc and 1100ºcmentioning

confidence: 99%

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Cladding embrittlement during postulated loss-of-coolant accidents.

Billone¹,

Yan²,

Burtseva³

et al. 2008

134

105

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The effect of fuel burnup on the embrittlement of various cladding alloys was examined with laboratory tests conducted under conditions relevant to loss-of-coolant accidents (LOCAs). The cladding materials tested were Zircaloy-4, Zircaloy-2, ZIRLO, M5, and E110. Tests were performed with specimens sectioned from as-fabricated cladding, from prehydrided (surrogate for high-burnup) cladding, and from high-burnup fuel rods which had been irradiated in commercial reactors. The tests were designed to determine for each cladding material the ductile-to-brittle transition as a function of steam oxidation temperature, weight gain due to oxidation, hydrogen content, pre-transient cladding thickness, and pre-transient corrosion-layer thickness. For short, defueled cladding specimens oxidized at 1000-1200ºC, ring compression tests were performed to determine post-quench ductility at ≤135ºC. The effect of breakaway oxidation on embrittlement was also examined for short specimens oxidized at 800-1000ºC. Among other findings, embrittlement was found to be sensitive to fabrication processes -especially surface finish -but insensitive to alloy constituents for these dilute zirconium alloys used as cladding materials. It was also demonstrated that burnup effects on embrittlement are largely due to hydrogen that is absorbed in the cladding during normal operation. Some tests were also performed with longer, fueledand-pressurized cladding segments subjected to LOCA-relevant heating and cooling rates. Recommendations are given for types of tests that would identify LOCA conditions under which embrittlement would occur. ForewordFuel rod cladding is the first barrier for retention of fission products, and the structural integrity of the cladding ensures coolable core geometry. In the early 1990s, new data from foreign research programs showed degraded cladding behavior for high-burnup fuel compared with low-burnup fuel in tests designed to simulate postulated accidents. Interim actions were taken, but it became clear that extrapolation from a low-burnup data base needed to be reassessed more carefully for regulatory purposes.One of NRC's central regulations used in plant licensing deals with postulated loss-of-coolant accidents (LOCAs). A portion of that regulation in 10 CFR 50.46(b) specifies criteria that were derived from tests with unirradiated Zircaloy cladding, and these criteria limit the peak cladding temperature and the maximum cladding oxidation during the accident. These two limits are known as embrittlement criteria. Their purpose is to prevent cladding embrittlement during a LOCA, thus ensuring that the general core geometry will be maintained and be coolable.In the mid-1990s, NRC sponsored a cooperative research program at Argonne National Laboratory to reassess these limits for the possible effects of fuel burnup. The program's industry partners included the Electric Power Research Institute, Framatome ANP (now AREVA), Westinghouse, and Global Nuclear Fuel; in general, the industry partners were responsible fo...

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Section: ×17 Zry-4 Oxidized At 1000ºc and 1100ºcmentioning

confidence: 80%

Section: ×17 Zry-4 Oxidized At 1000ºc and 1100ºcmentioning

confidence: 99%

Cladding embrittlement during postulated loss-of-coolant accidents.

Billone¹,

Yan²,

Burtseva³

et al. 2008

134

105

View full text Add to dashboard Cite

show abstract

“…It has been developed by IRSN to address LOCA induced oxidation [10]. The oxygen concentration profile is calculated by solving the Fick's 2nd law diffusion equation in cylindrical coordinates according to equation (1). The left side is considered to be the oxygen accumulation and the right side the space change of the diffusion flux F r .…”

Section: Oxygen Concentration Profiles Modelingmentioning

confidence: 99%

Oxygen segregation in pre-hydrided Zircaloy-4 cladding during a simulated LOCA transient

Torres

Desquines

Guilbert

et al. 2017

EPJ Nuclear Sci. Technol.

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Abstract. Oxygen and hydrogen distributions are key elements influencing the residual ductility of zirconiumbased nuclear fuel cladding during the quench phase following a Loss Of Coolant Accident (LOCA). During the high temperature oxidation, a complex partitioning of the alloying elements is observed. A finite-difference code for solving the oxygen diffusion equations has been developed by Institut de Radioprotection et de Sûreté Nucléaire to predict the oxygen profile within the samples. The comparison between the calculations and the experimental results in the mixed a+b region shows that the oxygen diffusion is not accurately predicted by the existing modeling. This work aims at determining the key parameters controlling the average oxygen profile within the sample in the two-phase regions at 1200°C. High temperature steam oxidation tests interrupted by water quench were performed using pre-hydrided Zircaloy-4 samples. Experimental oxygen distribution was measured by Electron Probe Micro-Analysis (EPMA). The phase distributions within the cladding thickness, was measured using image analysis to determine the radial profile of a(O) phase fraction. It is further demonstrated and experimentally checked that the a-phase fraction in these regions follows a diffusion-like radial profile. A new phase fraction modeling is then proposed in the cladding metallic part during steam oxidation. The modeling results are compared to a large set of experiments including the influence of exposure duration and hydrogen content. Another key outcome from this modeling is that oxygen average profile is straightforward derived from the proposed modeling.

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“…The oxygen concentrations (8 and (9 at the a!ß-phase boundary were taken hom the pseudo-binary diagram for Zircaloy-oxygen. The expressions published by (hung et al [20] for the oxygen concentrations in weight per cent in the Q-and ß-phase boundaries are:…”

Section: In Tomentioning

confidence: 99%

“…The lines represent Ds (eq. 11) and the Arrhenius functions (20) which fit best to the points. Interface concentrations Cl and C2.…”

Section: Bayoglu Andmentioning

confidence: 99%

New determination of the UO2/Zircaloy reaction kinetics and calculation of the oxygen diffusion coefficients

Hofmann

Uetsuka

Garcı́a

et al. 1992

Journal of Nuclear Materials

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SummaryThe results of the isothermal U02/Zircaloy interaction experiments were corrected with respect to the actual annealing temperature and the reaction time. This was done by comparison of the Zr02 and Q-Zr(O) reaction layer thicknesses of the U02/Zircaloy fuel rod segments, which reacted under oxidizing conditions, with that of Zircaloy cladding oxidation experiments performed in a tube furnace under weil controlled temperature conditions. The reactions which took place during the heatup and cooldown period were taken into consideration by the determination of a so-called equivalent isothermal annealing time which was added to the actual isothermal annealing time.

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Pseudobinary zircaloy-oxygen phase diagram

Cited by 77 publications

References 6 publications

Cladding embrittlement during postulated loss-of-coolant accidents.

Cladding embrittlement during postulated loss-of-coolant accidents.

Oxygen segregation in pre-hydrided Zircaloy-4 cladding during a simulated LOCA transient

New determination of the UO2/Zircaloy reaction kinetics and calculation of the oxygen diffusion coefficients

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