2024/10/04

National Research and Development Agency Japan Agency for Marine-Earth Science and Technology
General Incorporated Foundation Electrical Utilities Central Research Institute
National Research and Development Agency Japan Atomic Energy Agency
Nippon Steel Corporation

1. Key Points of the Presentation
The annual cost related to metal corrosion exceeds 6 trillion yen and the evaluation of microbial influence has not been conducted.
Initiate large-scale diagnostic technology development for microbial corrosion of metals through industry-academia collaboration system.
The developed technology can be deployed not only for the safe decommissioning of the Fukushima Daiichi Nuclear Power Plant but also for general industries.
2. Overview
A research team led by Yohei Yamato, Director of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), and represented by Senior Researcher Akatsuki Wakai (Cutting-Edge Research and Development Department, specializing in applied microbiology), has been selected for the commission research project "Promotion Project for Nuclear Science and Technology and Human Resource Development by Bringing Together Wisdom" operated by the Japan Atomic Energy Agency (JAEA) under the Ministry of Education, Culture, Sports, Science and Technology. In this research project, a collaboration team of JAMSTEC, the National Institute for Materials Science (NIMS), the Central Research Institute of Electric Power Industry (CRIEPI), Nippon Steel Corporation, and JAEA will conduct research and development titled "Data-Driven Onsite Diagnostic Technology: Microbial Corrosion Risk Prediction to Ensure Long-Term Soundness.
In the field of microbial corrosion of metals (microbial corrosion), the influence of microorganisms has gradually become clear in recent years. However, diagnostic technologies have not yet been established, and efforts are mostly made post-occurrence of corrosion cases. This research and development will focus on the behavior of microbial populations and develop technologies for risk management to predict the occurrence of severe corrosion in advance.
The research results will not only be provided as necessary technology for the safe decommissioning of the Tokyo Electric Power Company Holdings, Inc. Fukushima Daiichi Nuclear Power Plant (referred to as "Unit 1F") associated with the Great East Japan Earthquake but also contribute to the preservation of oil and chemical plants, as well as the infrastructure that supports our lives.
[Glossary]
*1 Microbial corrosion of metals (microbial corrosion): An abnormal phenomenon where the corrosion of metal materials is significantly accelerated by microbial activity.
3. Background
Microbiologically induced corrosion is a known phenomenon, but research on the causative microorganisms is still in progress. At JAMSTEC, by evaluating microbes as a community, they have succeeded in capturing changes in the microbial community during the progression of microbial corrosion, which has long been a black box (previously reported on June 4, 2022). The research team has successfully developed various element technologies necessary for this research project, such as specific methods of accumulating highly corrosive microorganisms, isolating novel corrosive microorganisms, identifying bio markers related to corrosion, and determining environmental conditions in which microorganisms exhibit high corrosiveness, and aims to further develop these aspects towards practical applications.
Microbiologically induced corrosion can occur mainly in aquatic environments, and is observed in industrial water environments using river water and environments utilizing seawater. As one of the environments that want to prevent the occurrence of microbiologically induced corrosion, there are various aquatic environments in 1F, including various water environments (treatment water tanks, inside nuclear reactor buildings, sub drains). However, with current technology, predicting the risk of microbiologically induced corrosion in these water environments is difficult, and there is an urgent need to establish diagnostic techniques to ensure long-term integrity. In this research, the aim is to establish and provide a protocol for innovative on-site diagnostic technology that can predict microbiological corrosion risks with high accuracy by making full use of data-driven statistical analysis through the development of microbiologically induced corrosion analysis methods that can test multiple samples simultaneously, simulation tests that mimic field environments, and tests simulating accident reactor environments.
[Glossary]
*2 Biomarker: Biological information that performs specific biological functions targeted (specific gene sequences, proteins, etc.)
4. Research Plan
The research team, led by Senior Researcher Wakai, who has been conducting research on microbiologically induced corrosion in various environments, will collaborate with NIMS to develop a multi-sample simultaneous corrosion test evaluation system, with Chudenken carrying out experiments using a corrosion test reactor that simulates the 1F environment, Nippon Steel conducting statistical analysis of metal corrosion and microbial community structure data, and JAEA conducting corrosion tests under radiation environments. By integrating data accumulated from various corrosion environments and corrosion data in the 1F simulated environment, they will proceed with the development of a technology to detect corrosive microorganisms with correlation to metal corrosion activity (Figure 1).

At NIMS, we explore highly corrosive microorganisms in environmental samples, including the 1F surrounding environment, using a rapid aggregation method of electrically active microorganisms already developed, as well as a unique multi-sample simultaneous corrosion testing and evaluation system. Additionally, with the multi-sample simultaneous corrosion testing and evaluation system, the effects of various agents used for corrosion protection are evaluated using microbial corrosion activity as an indicator. This testing system allows for consideration not only in decommissioning environments but also in general industrial environments, making it a research topic with high ripple effects.
At the Institute of Electrical Power Research, we will conduct microbiological corrosion tests simulating the on-site environment based on the environmental information already published, by constructing a reactor mimicking the 1F building interior. This testing system allows for tests simulating environmental fluctuations that may occur during decommissioning processes and is an important research topic for confirming long-term safety in future decommissioning processes.
At JAEA, we study the distribution of microorganisms in corrosion products and microbial corrosion in radioactive environments. While it is known that a sufficient amount of microbial DNA can be recovered from corrosion products, how these microorganisms are distributed within the corrosion products is not yet clear. To elucidate the corrosion mechanism, it is essential to clarify the distribution and actions of microorganisms. Various microbial corrosion activities have been identified, but the assessment of whether corrosion actually progresses in radioactive environments remains unexplored. Both research aspects are crucial research topics.
Nippon Steel has statistical analysis techniques for identifying important water treatment microorganisms from complex and diverse microbial populations in the field of wastewater treatment. Therefore, a comprehensive genetic analysis will be conducted by JAMSTEC on microbial populations in various culture conditions under investigation at NIMS, IEP, and JAEA. The obtained information on microbial corrosion activity and microbial population will be analyzed using Nippon Steel's statistical analysis techniques to extract microbial information affecting metal corrosion from over thousands of microbial species.
At JAMSTEC, in addition to conducting comprehensive community structure analysis of microbial populations in the aforementioned cultures, metagenomic analysis will be performed on highly corrosive microbial populations, identifying biomarkers that can associate metal corrosion activity with biological information. DNA extraction protocols usable at the site level have already been established. Based on information such as biomarkers, the development of a technology to predict corrosion risks rapidly and easily on-site will be conducted.

【Glossary】
※3 Metagenomic analysis: A method of collectively analyzing the genetic information of microorganisms present in the environment.
5. Ripple effect of research
The developed technology can be applied not only to the primary target facility of the research project, 1F water environment, but also to chemical plants, petroleum-related facilities, and microbial corrosion risk prediction of infrastructure in water environments. In addition, the multi-sample simultaneous microbial corrosion analysis method developed in this research can also be applied to the development of corrosion protection techniques necessary after predictive diagnosis (effect verification), making it an important technology to reduce various issues related to microbial corrosion.
References:
1 Corrosion Cost Survey Committee, Corrosion Costs in Japan, Materials and Environments Journal, Vol. 69, pp. 283-306 (2020)
2 Patent No. 7299485 'Method for identifying microbial groups'

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