What is it about?
In this review article, we decribe the state-of-the-art regarding crevice corrosion issues of candidate nickel-based alloys for the corrosion-resistant barrier of high-level nuclear waste containers. We explain the different types of repositories, the engineering barrier system and the role of the waste container providing a period of absolute containment to the waste. Most of the reviewed articles are about alloy 22 (Hastelloy C-22, UNS N06022) for the proposed Yucca Mountain repository (USA). We focus on the effects of the most relevant metallurgical and environmental variables on the crevice corrosion susceptibility of nickel-based alloys.
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Why is it important?
This is a summary of the present knowledge on this topic. What we have lerned from the behavior of alloy 22 and other related materials on crevice corrosion in anticipated repository environments is very useful for other applications of passive alloys. Dealing with such large time scales (thousands of years) on localized corrosion and passive behavior has led to the development of novel testing techniques along with very conservative criteria for localized corrosion occurrence. The discussion herein is very useful for regular applications of any passive metallic material which may suffer localized corrosion in service.
Perspectives
Ni-Cr-Mo alloys are used in many applications and they do not suffer pitting corrosion, in most of cases, but the main concern is about crevice corrosion. The Yucca Mountain repository project is likely to be resumed in the near future. The performance of the engineered barrier system, and particularly the corrosion-resistant barrier, will be revisited. We think this arcticle is a good starting point for assessing the issue of localized corrosion of the waste container.
Dr Martín A Rodríguez
Comision Nacional de Energia Atomica
Read the Original
This page is a summary of: Crevice corrosion of nickel-based alloys considered as engineering barriers of geological repositories, npj Materials Degradation, October 2017, Nature,
DOI: 10.1038/s41529-017-0010-5.
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