Continuing to work
in the field of nuclear technology –
This is my
core and my guiding principle

Research Manager,
Service Engineering Department,
Research & Innovation Center,
Yuko Yamamoto REPORT #32

© School of Engineering, Tohoku University

You can’t say something is scary if you don’t even know about it Make your judgement after you get to know it

In September 1999, Japan’s first criticality accident occurred at a nuclear fuel processing facility in Tokaimura, Ibaraki Prefecture. Criticality occurs when a nuclear fission chain reaction continues at a certain rate. Even though criticality was brought under control about 20 hours after the incident, 3 workers were exposed to massive radiation, and more than 600 people, including residents of the surrounding area, were also exposed to radiation. This incident had a major impact on daily life, with evacuations, orders to stay indoors, train service suspensions, and road closures. Watching all these on the news was a high school student on a school trip. That student was Ms. Yuko Yamamoto, who later studied quantum energy engineering at the School of Engineering at Tohoku University and is currently a researcher at the Research & Innovation Center of Mitsubishi Heavy Industries, Ltd., a manufacturer of nuclear reactors. She says, “While on a school trip, I was watching TV and almost all of the news was about the criticality accident. The news reports on nuclear power were delivered with a scary tone, and my classmates were also saying how scary it was. At the time, I thought, ‘I don’t know much about nuclear power and I don’t understand it. But I don’t want to be afraid of it without knowing anything about it.’”

Ms. Yamamoto loved physics, and she was thinking of studying engineering at university, but she was still unsure about what to choose for her major. She explains, “Because of the accident, I felt a strong desire to understand nuclear power generation well enough to be able to explain it in my own words. If I were to be afraid of it, I want to be afraid of it after knowing the logic behind it.” Having narrowed down her choice to nuclear engineering, she began to look for a university. One of the few options was Tohoku University’s School of Engineering, Department of Quantum Science and Energy Engineering. Before taking the university entrance exam, she went on a trip to Sendai with her parents, and she visited the Aobayama Campus which housed the School of Engineering. “The campus on top of a mountain was huge, and I felt I could experience many other things aside from studying nuclear power. I also had a good impression on the city of Sendai,” she says.

The approach to research acquired in university laboratories

After being admitted to Tohoku University, Ms. Yamamoto joined the Student Friendship Association tennis club. During her 4 years of undergraduate studies, she devoted herself to tennis, participated in tournaments held in the Tohoku area, and played in regular matches with Hokkaido University. For her laboratory in her junior year, she chose a lab that aimed to develop a nuclear fusion reactor. Her reason was her interest and curiosity in nuclear fusion. She explains, “Nuclear power generation is a technology that is already being used in the world. In contrast, I thought that only at a university could I learn about power generation by nuclear fusion, which is a technology still under development.”

In contrast to nuclear power generation which uses energy generated during nuclear fission, nuclear fusion power generation uses energy generated when an atomic nucleus and another atomic nucleus are fused to form a new atomic nucleus. This is the same principle as how the sun works – it continues to burn through a nuclear fusion reaction of helium being produced when hydrogen nuclei fuse. Deuterium and tritium, which are the raw materials of nuclear fusion power generation, can be extracted from seawater, and the processing time of radioactive materials from nuclear fusion power generation is much shorter compared to conventional nuclear power generation, which is another advantage. However, an issue with nuclear fusion power generation is the reduction of costs for the nuclear fusion reactors’ construction and operation. Chiefly, the cost of superconducting magnets that confine high-temperature plasma (in which the atomic nuclei and electrons that comprise atoms are dispersed and fly about freely) in a nuclear fusion reactor is high. Ms. Yamamoto says, “During my four years of undergraduate and postgraduate studies, my research focused on dividing superconducting magnets to produce them more efficiently. This was one of the main research themes of our laboratory, and they are still working on this today.”

Research on the development of nuclear fusion power generation, a new technology, was embarking on a challenge into the unknown. Ms. Yamamoto explains, “In my research, I didn’t have an example or model to follow. That’s why, instead of mimicking someone else, I built my own devices for experimentation and plunged into experiments no one else has done before.” She says those experiences built the foundation of how she works now as a researcher. “Nuclear fusion power generation is not a technology that can be completed in the two to three years a student spends in the laboratory. That’s why it was a very good learning experience for me to imagine what meaning my research would have in the greater scheme of technological development, and where and how the results of my experiments are connected. I learned this approach of deciding on one’s goal and then creating a research plan based on a proper grasp of the research’s overall picture and ultimate goal during my time at the university laboratory,” she adds.


Nearly 10 years in
the making,
the development
of a thin and bendable
ultrasonic sensor

When choosing her career path after completing her master’s degree, Ms. Yamamoto says she went back to the intention she had when she was first admitted to university. Intending to work in the field of nuclear power, whether with a plant manufacturer, or an electric company that powers a plant, she interned at Mitsubishi Heavy Industries during the summer of the first year of her master’s program. There she learned of the existence of the Quality Assurance Department. She says, “The Quality Assurance Department uses various methods to inspect the safety and proper operation of nuclear power plant equipment and obtains data to show that they are safe and reliable. By working in quality assurance that guarantees safety, I can convey to those who are afraid of nuclear power generation that it isn’t necessarily scary. That’s why I chose to work in my current job.”

During her first three years at Mitsubishi Heavy Industries, Ms. Yamamoto was assigned to the Quality Assurance Department of the Nuclear Power Division, her first choice when she first joined the company, and was put in charge of after sales service for nuclear power plants. As the “last bastion” for guaranteeing safety, her duties in the department included conducting periodic power plant inspections, suggesting inspection equipment to electric companies, and having discussions (which sometimes included people from the Research & Innovation Center) about consultations for inspections from electric companies. She says, “In a power plant, there are many people who care about inspection data and methods, each one looking at such data and methods from their own points of view – from those working onsite, those in charge of planning at the electric power company, to the materials and design engineers who evaluate inspection results. Aside from technical requirements, the viewpoints and opinions of workers and creators must all be considered. This made me realize the magnitude of the actual work, and at the same time, it made me realize that the research I was doing at university was on such a small scale and that I was only seeing what I was developing.

In her fourth year with the company, Ms. Yamamoto reached a turning point, which was a transfer to the Research & Innovation Center, where she is still working. “I was put in charge of developing a sensor for monitoring the integrity of piping inside nuclear power plants, which was a job I took over from someone more senior than me who was changing jobs. It was a new kind of conceptual research for developing an ultrasonic sensor that could be used continually for a long period of time at a high temperature of 200℃, utilizing ceramics synthesis technology owned by a research institute overseas,” she explains. It was her first time working on an ultrasonic sensor, and she first approached it by asking what materials should be used for cables and electrodes which will continually be used in a high-temperature environment, and what adhesives should be used to affix the sensor in place. The company’s in-house materials and chemistry labs also worked with her in her research. In the process, she also conducted joint research with Tohoku University and other universities. The thin film ultrasonic (UT) sensor that she was in chiefly charge of developing was highly acclaimed within and outside the company and was ultimately commercialized. Nearly ten years had passed since she first began her research until the product launched.

Male or female – it doesn’t matter As long as I have friends and colleagues, I can do anything

After the thin film ultrasonic (UT) sensor was commercialized, Ms. Yamamoto was transferred to the Service Engineering Department in 2020. Her role also changed to being a coordinator of the development of measurement technology, including sensors. She says, “In addition to generating data and technical reports on the experiments I am responsible for, I am now in a position where I need to envisage a major technological development roadmap from the viewpoint of what measurement technologies are needed by our company’s business division, what issues exist, and what steps should be taken to resolve these issues. In this sense, I believe I have grown and raised the level a little of the work that I do. Ultimately, research conducted in a company must contribute to the business and result in profits. But unlike academic research conducted in universities, the technology we develop is brought to reality by our design and production departments, and I can see the outcome of our work with my own eyes. I think this is where the fun of research conducted in companies lies. My goal for the future is to be able to make more efficient and strategic technological development plans. I want to work on the kind of development that skillfully combines technologies from other fields and industries to create new technologies and jump-starting such initiatives using ideas unique to our Research & Innovation Center. I’m sure I’ll have the opportunity to do this because our company has many products and is rich in human resources.”

Three years in a division that directly dealt with nuclear power plants, then developing new inspection technology as a researcher in the Research & Innovation Center, and finally shifting to a coordinating role for the development of measurement technology. While her career has advanced smoothly, has Ms. Yamamoto experienced any trouble or felt discomfort as a female engineer? She answers, “When I first joined the company, I was hoping I could have a senior female engineer as a role model, but there were only a few female engineers who were older than me. When I mentioned this to a female director, she said I didn’t need a role model, and that it’s enough to have friends and colleagues. Hearing those words, I began to think that gender doesn’t matter; as long as I have friends and colleagues, I can do anything in the years to come.”

Ms. Yamamoto, who says that continuing to work in the field of nuclear technology is her core and guiding principle, ventured into the field because of the reaction of people after the criticality accident who said that nuclear power is scary. She says, “There are many key words to keep in mind when considering a career path, whether it’s “scary,” “interesting,” or “cool.” From there, dig deeper and think about what’s ‘scary,’ ‘interesting,’ or ‘cool’ – that might become a catalyst. But having said that, one of the appealing things about engineering is the multitude of choices after being admitted to university. As their senior, the advice I would give to university students is that it’s ok even if their interests change or they become interested in more things.”