Abstract
Developing repositories for low and intermediate-level nuclear waste (LILW) is crucial to Finland's nuclear waste management. Understanding the corrosion behavior and mechanisms of engineered steel used in these repository conditions is vital for isolating the waste from the surrounding environment and reducing the risk of radiation exposure to humans and the ecosystem during both operation and decommissioning.
Our previous study, conducted from 2021 to 2022, explored the role of microbially-induced corrosion (MIC) on the corrosion rate and mechanisms of carbon steel (CS, DC01* AmO) and stainless-steel alloys (SS, AISI 316L) under anoxic repository conditions at 10°C in a laboratory setting. The experimental setup involved both abiotic (biocide-treated) and biotic (microbial-enriched) natural groundwater sourced from a repository in a granite bedrock in Loviisa, Finland. Over approximately 8 months, a long-term laboratory corrosion test was performed, which included electrochemical measurements such as open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), and cyclic polarizations were performed to assess the corrosion behavior of two alloys in anoxic groundwater. Additionally, various steel surface characterization techniques, along with molecular biological analyses, were used to deepen our understanding of MIC under repository conditions.
The electrochemical measurements revealed that local corrosion, in the form of pitting, was observed intermittently in CS both employed abiotic and biotic groundwater. The biotic conditions seemed to inhibit corrosion of CS after five months due to biofilm formation, whereas SS AISI 316L also exhibited poorer corrosion resistance compared to abiotic groundwater, suggesting that local groundwater conditions influenced corrosion tendency and form in LILW repositories. Moreover, variations in microbial communities were detected depending on the groundwater conditions (abiotic and biotic) and steel materials. Factors such as microstructural state, alloying elements, chromium or molybdenum-depleted zones, and carbide precipitations can contribute to preferential corrosive attacks, but limited information is available on these aspects.
Building on the results from the presented study, our future project is expanding the focus on steel welds, considering groundwater ingress and microbial activities under conditions mimicking the Finnish LILW repository. We will focus on microbe-weldment interactions on steel surfaces and assess the role of varying weldment types, material combinations, and post-treatment methods on weld durability and corrosion resistance. The study is expected to provide new insight into the literature on corrosion in welds and affected zones under different conditions representing the evolutionary stages of the LILW repository.
Our previous study, conducted from 2021 to 2022, explored the role of microbially-induced corrosion (MIC) on the corrosion rate and mechanisms of carbon steel (CS, DC01* AmO) and stainless-steel alloys (SS, AISI 316L) under anoxic repository conditions at 10°C in a laboratory setting. The experimental setup involved both abiotic (biocide-treated) and biotic (microbial-enriched) natural groundwater sourced from a repository in a granite bedrock in Loviisa, Finland. Over approximately 8 months, a long-term laboratory corrosion test was performed, which included electrochemical measurements such as open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), and cyclic polarizations were performed to assess the corrosion behavior of two alloys in anoxic groundwater. Additionally, various steel surface characterization techniques, along with molecular biological analyses, were used to deepen our understanding of MIC under repository conditions.
The electrochemical measurements revealed that local corrosion, in the form of pitting, was observed intermittently in CS both employed abiotic and biotic groundwater. The biotic conditions seemed to inhibit corrosion of CS after five months due to biofilm formation, whereas SS AISI 316L also exhibited poorer corrosion resistance compared to abiotic groundwater, suggesting that local groundwater conditions influenced corrosion tendency and form in LILW repositories. Moreover, variations in microbial communities were detected depending on the groundwater conditions (abiotic and biotic) and steel materials. Factors such as microstructural state, alloying elements, chromium or molybdenum-depleted zones, and carbide precipitations can contribute to preferential corrosive attacks, but limited information is available on these aspects.
Building on the results from the presented study, our future project is expanding the focus on steel welds, considering groundwater ingress and microbial activities under conditions mimicking the Finnish LILW repository. We will focus on microbe-weldment interactions on steel surfaces and assess the role of varying weldment types, material combinations, and post-treatment methods on weld durability and corrosion resistance. The study is expected to provide new insight into the literature on corrosion in welds and affected zones under different conditions representing the evolutionary stages of the LILW repository.
| Original language | English |
|---|---|
| Publication status | Published - 2024 |
| MoE publication type | Not Eligible |
| Event | International Biodeterioration and Biodegradation Symposium IBBS19 - Federal Institute for Materials Research and Testing (BAM), Berlin, Germany Duration: 9 Sept 2024 → 12 Sept 2024 |
Conference
| Conference | International Biodeterioration and Biodegradation Symposium IBBS19 |
|---|---|
| Country/Territory | Germany |
| City | Berlin |
| Period | 9/09/24 → 12/09/24 |