Corrosion behavior of Si-enriched steels for nuclear applications in liquid lead–bismuth

The corrosion behavior of Si-enriched steels in liquid lead–bismuth was studied in order to develop accelerator driven systems for transmutation of long-lived radioactive wastes and lead–bismuth cooled fast reactors. The corrosion tests of 316SS, Si-enriched 316SS, Mod.9Cr–1Mo steel (T91) and Si-enriched T91 were conducted at 550 °C in liquid lead–bismuth at the two controlled oxygen levels. Both the additions of 2.5 wt.% Si to 316SS and 1.5 wt.% Si to T91 had the effect of reducing the thickness of oxide layer in liquid lead–bismuth at the high oxygen concentration (2.5 × 10−5 wt.%). Although the Si addition to 316SS reduced the depth of ferritization caused by Ni dissolution in liquid lead–bismuth at the low oxygen concentration (4.4 × 10−8 wt.%), it could not suppress the ferritization and the penetration of Pb and Bi completely. The Si addition to T91 did not have the effect of preventing the penetration of Pb and Bi in the liquid lead–bismuth at the low oxygen concentration. The oxide scales formed on both Si-enriched steels did not have sufficient corrosion resistance under the low oxygen condition.

► The corrosion behavior of Si-enriched steels in liquid lead–bismuth was studied.
► The corrosion tests were conducted at the two controlled oxygen levels.
► The Si addition reduces the scale thickness under the high oxygen condition.
► The Si addition has no significant effect under the low oxygen condition.