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Research Papers: Nuclear Power

# Modeling of Fe–Cr Martensitic Steels Corrosion in Liquid Lead Alloys

[+] Author and Article Information
F. Balbaud-Célérier, L. Martinelli

CEA, DEN, DPC, SCCME, Laboratoire d’Etude de la Corrosion Non Aqueuse, Gif-sur-Yvette F-91191, France

J. Eng. Gas Turbines Power 132(10), 102912 (Jul 07, 2010) (9 pages) doi:10.1115/1.4000865 History: Received July 21, 2009; Revised September 16, 2009; Published July 07, 2010; Online July 07, 2010

## Abstract

Among the Generation IV systems, sodium fast reactors (SFRs) are promising and benefits of considerable technological experience. However, the availability and acceptability of the SFR are affected by the problems linked with the sodium-water reaction. One innovative solution to this problem is the replacement of the sodium in the secondary loops by an alternative liquid fluid. Among the fluids considered, lead-bismuth is at the moment being evaluated. Liquid lead-bismuth has been considerably studied in the frame of the research program on accelerator driven systems for transmutation applications. However, lead alloys are corrosive toward structural materials. The main parameters impacting the corrosion rate of Fe–Cr martensitic steels (considered as structural materials) are the nature of the steel (material side), temperature, liquid alloy velocity, and dissolved oxygen concentration (liquid alloy side). In this study, attention is focused on the behavior of Fe-9Cr steels, and more particularly, T91 martensitic steel. It has been shown that in the case of Fe–Cr martensitic steels, the corrosion process depends on the concentration of oxygen dissolved in Pb–Bi. For an oxygen concentration lower than the one necessary for magnetite formation (approximately $<10−8 wt %$ at $T≈500°C$ for Fe-9Cr steels), corrosion proceeds by dissolution of the steel. For a higher oxygen content dissolved in Pb–Bi, corrosion proceeds by oxidation of the steel. These two corrosion processes have been experimentally and theoretically studied in CEA Saclay and also by other partners, leading to some corrosion modeling in order to predict the life duration of these materials as well as their limits of utilization. This study takes into account the two kinds of corrosion processes: dissolution and oxidation. In these two different processes, the lead alloy physico-chemical parameters are considered: the temperature and the liquid alloy velocity for both processes and the oxygen concentration for oxidation.

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## Figures

Figure 1

Corrosion of Fe–Cr steel in stagnant liquid Pb–Bi (27)

Figure 2

(a) Presentation of the three fluxes governing the dissolution process; (b) iron concentration gradient in the concentration boundary layer

Figure 3

Variation in the corrosion rate mechanism as a function of the fluid velocity or the Reynolds number (4)

Figure 4

Ratio between the corrosion rate and (SFe−Cb) factor as a function of the angular velocity at 400°C(1), 470°C, and 540°C: experimental points and modeling

Figure 5

SEM-FEG picture in QBSD of cross section of T91 sample immersed 3600 h in oxygen saturated LBE at 470°C

Figure 6

Iron and chromium diffusion coefficient extrapolated from Refs. 22-23, as a function of oxygen activity

Figure 7

Oxygen activity gradient inside the magnetite and the Fe–Cr spinel layers

## Errata

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