Preliminary Study of Corrosion Mechanisms of Actinides Alloys: Calibration of FT-IR Spectroscopy
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1104-NN07-10
PRELIMINARY STUDY OF CORROSION MECHANISMS OF ACTINIDES ALLOYS: CALIBRATION OF FT-IR SPECTROSCOPY Véronique Magnien, Marx Cadignan, Olivier Faivret, and Gaelle Rosa Centre de Valduc, CEA, Is sur tille, 21120, France ABSTRACT
In situ analyzes of gaseous atmospheres could be performed by FT-IR spectroscopy in order to study the corrosion reactions of actinides. Nevertheless experimental conditions and the nature of studied species have a strong effect on IR absorption laws. Thus a prior calibration of our set-up is required to obtain an accurate estimation of gas concentration. For this purpose, the behavior of several air pure gases has been investigated according to their concentration from IR spectra. Reproducible results revealed subsequent increases of the most significant peak areas with gas pressure and small deviations from Beer Lambert’s law. This preliminary work allowed to determine precise absorption laws for each studied pure gas in our in situ experimental conditions. Besides our FT-IR set-up was well suitable to quantitative analysis of gaseous atmosphere during corrosion reactions. Finally the effect of foreign gas will be investigated through more complex air mixtures to obtain a complete calibration network. INTRODUCTION
Nuclear waste storage and corrosion reactions of nuclear materials in air conditions are current topics for industrial and fundamental laboratories to avoid a rupture of storage containers and a nuclear material release in environment. Thanks to a significant amount of works, reliable information were obtained on corrosion kinetics and mechanisms on various metallic materials [1-4]. Nevertheless the effects of atmosphere and experimental conditions still raise basic questions needing more parametric studies. As a matter of fact, understanding of corrosion processes in actinides has been hampered by a lack of in situ quantitative determination of gas composition especially. On the other hand, with numerous advantages as acquisition speed and none destructive character, FT-IR spectroscopy has proved its ability in atmosphere analysis of CO2, CH4, H2O, CO, SO2 or N2O for gas emissions from volcanos, for combustion or for emission due to agriculture [5-8]. Because this technique obeys a Beer Lamberts’s law relating absorbency to concentration, IR method could be applied for quantitative purposes [7, 9,10]. So our global purposes are: (1) to make a quantitative analysis of the evolution of gaseous atmosphere during actinides corrosion, (2) to get information on corrosion kinetics and mechanisms as rate-limiting steps, intermediate reactions and species. Our IR technique with a short time resolution and without disturbing reaction system could be a good mean to study those reactions. Nevertheless a calibration of FT-IR set-up must be firstly performed to reach straight quantitative estimation. The composition of air is roughly 78% of N2, 21% of O2, 0.9% of Ar, 0.03% of CO2, variable amounts of H2O and traces of CO, CH4, H2, He,…. FT-IR spectroscopy being not sensitive to hom
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