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Critical Conditions for Initiation of Localized Corrosion of Mild Steels in Contact with Bentonite Used in Geological Disposal Packages of Nuclear Waste

Published online by Cambridge University Press:  01 January 1992

Guen Nakayama
Affiliation:
Research Institute, Ishikawajima-Harima Heavy Industries Co., Ltd. 3-1-15 Toyosu, Koto-ku, Tokyo 135, Japan
Masatsune Akashi
Affiliation:
Research Institute, Ishikawajima-Harima Heavy Industries Co., Ltd. 3-1-15 Toyosu, Koto-ku, Tokyo 135, Japan
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Abstract

In the current design of geological disposal of high-level nuclear waste, the use of bentonite to stand as an artificial barrier-cum-buffer between the host rock and the packages made of mild steel is being investigated. Although mild steels commomly have been considered to be passivity in alkaline environments, under certain circumstances, they become liable to localized corrosion, e.g., pitting corrosion and crevice corrosion. Since bentonite can turn the environment alkaline to a pH of approximately 10 when it is mixed with groundwater, critical conditions for the initiation of localized corrosion of mild steel must be known to evaluate the extremely long time integrity of disposal packages serving in such an environment. This paper presents and discusses the observations and results acquired in a series of critical conditions for the initiation of localized corrosion of mild steels in various groundwater-bentonite environments at 20C, with a deaerated aqueous solution of 1 mMol/L [HCO3−] +10 ppm [CI−], simulating the natural groundwater and varying the bentonite content.

Type
Research Article
Copyright
Copyright © Materials Research Society 1993

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References

REFERENCES

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