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Engineering  2010 

Hydrogen Pick up in Zircaloy-4: Effects in the Dimensional Stability of Structural Components under Nuclear Reactor Operating Conditions

DOI: 10.4236/eng.2010.28073, PP. 573-579

Keywords: Thermal Analysis, Dimensional Change, Hydrides, Zircaloy-4

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Abstract:

In the present work, the expansion coefficient due to hydrogen incorporation was measured for the axial direction of a Zircaloy-4 cooling channel, similar to that installed in the Atucha I PHWR, Argentina, trying to simulate the nuclear power reactor operating conditions. As a first step, the solubility curve of hydrogen in Zircloy-4 was determined by two techniques: differential scanning calorimetry and differential dilatometry. The comparison with classical literature curves showed a good agreement with them, although the calorimetric technique proved to be more accurate for these determinations. Dilatometry was able to detect the end of hydride dissolution from concentrations around 60 wppm-H up to 650 wppm-H, where the eutectoid reaction: α + δ→α + β takes place (at 550oC). We assume that this ability is a good indicator of the aptitude of the technique to measure dimensional changes in the given hydrogen concentration range. Then, the expansion of Zircaloy-4 homogeneously hydrided samples was measured at 300oC, the typical operating temperature of a nuclear power reactor, obtaining a relative expansion of 2.21 * 10-4% per wppm-H. Considering the relative expansion observed for Zircaloy-4 at room temperature due to hydriding, starting from a hydrogen free sample, the total relative expansion rate is calculated to be 5.21 * 10-4% per wppm-H.

References

[1]  J. C. Ovejero, A. D. Banchik and P. Vizcaíno, “Axial/ Tangen-tial Expansion Coefficients of Zircaloy-4 Channels Due to the Hydrogen Pick up,” Advanced in Technology of Materials and Materials Processing Journal, Vol. 10, No. 1, 2008, pp. 1-8.
[2]  C. P. Fagundez, P. Vizcaíno, D. Bianchi and A. D. Ban- chik, “Dilatometría del Sistema Zr-H,” Proceedings of the Congress SAM/CONAMET 2005, Mar del Plata, 18-21 October 2005.
[3]  J. P. Giroldi, P. Vizcaíno, A. V. Flores and A. D. Banchik, “Hydrogen Terminal Solid Solubility Determinations in Zr-2.5 Nb Pressure Tube Microstructure in an Extended Concentration Range,” Journal of Alloys and Compounds, Vol. 474, No. 1-2, 2009, pp. 140-146.
[4]  D. Khatamian and V. C. Ling, “Hydrogen Solubility Limits In ?- and ?-Zirconium,” Journal of Alloys and Compounds, Vol. 253-254, No. 20, 1997, pp. 162-166.
[5]  A. McMinn, E. C. Darby and J. S. Schofield, “The Terminal Solid Solubility of Hydrogen in Zirconium Al-loys,” Proceedings of the 12th International Symposium of the Zirconium in the Nuclear Industry, ASTM STP 1354, 2000, pp. 173-195.
[6]  Z. L. Pan and M. P. Puls, “Precipitation and Dissolution Peaks of Hydride in Zr-2.5 Nb during Quasistatic Thermal Cycles,” Journal of Alloys and Compounds, Vol. 310, No. 1-2, 2000, pp. 214-218.
[7]  D. Khatamian and J. H. Root, “Comparison of TSSD Results Obtained by Differential Scan-ning Calorimetry and Neutron Diffraction,” Journal of Nuclear Materials, Vol. 372, No. 1, 2008, pp. 106-113.
[8]  P. Viz-caíno, A. D. Banchik and J. P. Abriata, “Calorimetric Determi-nation of the ?-Hydride Dissolution Enthalpy in Zircaloy-4,” Metallurgical and Materials Transactions A, Vol. 35A, No. 8, 2004, pp. 2343-2349.
[9]  J. Kearns, “Terminal Solubility and Partitioning of Hydrogen in the Alpha Phase of Zirconium,” Journal of Nuclear Materials, Vol. 22, No. 3, 1967, pp. 292-303.
[10]  E. Zuzek, J. P. Abriata and A. San Martín, “H-Zr (Hydrogen-Zirconium),” Bulletin of Alloy Phase Dia-grams, Vol. 11, No. 4, 1990, pp. 385-395.
[11]  P. Vizcaíno, A. D. Banchik and J. P. Abriata, “Solubility of Hydrogen in Zir-caloy-4: Irradiation Induced Increase and Thermal Recovery,” Journal of Nuclear Materials, Vol. 304, No. 2-3, 2002, pp. 96-106.

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