Effect of a pre-oxide on the high temperature steam oxidation of Zircaloy-4 and M5Framatome alloys

• Published in: Journal of nuclear materials Vol. 518; pp. 386 - 399
• Main Authors: Le Saux, M., Brachet, J.C., Vandenberghe, V., Rouesne, E., Urvoy, S., Ambard, A., Chosson, R.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.05.2019; Elsevier BV
• Subjects: Air temperature; Alloys; Heat resistant alloys; High temperature; Kinetics; LOCA; Low temperature; M5Framatome; Oxidation; Oxidation in steam at high temperature; Pre-oxide; Reaction kinetics; Steam; Temperature effects; Thickness; Zircaloy-4; Zircaloys (trademark); M5Framatome; Zircaloy-4; LOCA; Oxidation in steam at high temperature; Pre-oxide
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2019.03.023

The effect of a pre-existing oxide layer formed at low temperature on the subsequent oxidation in steam at high temperature was studied for Zircaloy-4 and M5Framatome alloys. Various pre-oxidation conditions (air at 550 °C, steam at 415 °C, static and flowing water at ∼350 °C), pre-oxide thicknesses (3–60 μm) and high temperature oxidation conditions (850–1200 °C, 55–9500s) were investigated. Pre-oxide has an effect on the oxidation kinetics and the hydrogen uptake at high temperature, depending on the pre-oxide thickness, the pre-oxidation conditions, the alloy and the high temperature oxidation conditions. •Steam oxidation and hydrogen pickup at high temperature are influenced by a pre-oxide.•The effect of the pre-oxide depends on its thickness and pre-oxidation conditions.•Pre-oxide is partly reduced before a fresh oxide grows at high temperature.•Quantity of oxygen diffusing through the metal at high temperature is nearly the same either there is a pre-oxide or not.