Part 2
After the rumbling mountain, there was a huge tremor rising from below and a long, violent lateral tremor one after another. March 11, 2011, 2:46 pm Sumio Konno (60), who came from Namie Town, Fukushima Prefecture, to the Onagawa Tohoku Electric Power Nuclear Power Plant (Miyagi Prefecture) to do instrument maintenance, recalled that moment. I was getting ready to go home in the office building when a magnitude 6 earthquake struck.
Sumio Konno talks about the situation at the Onagawa nuclear power plant (back) at the time of the Great East Japan Earthquake, in Onagawa Town, Miyagi Prefecture.
◆“It was like a picture of hell.”
“Let us go outside.” They screamed and opened the door, and everyone rushed out of the building immediately. A stern voice from the car radio said, “A tsunami is coming.” When I looked out to sea, I saw a black tsunami engulfing the islands of Onagawa Bay. Towards the reactor building, a huge heavy oil tank was overturned.
A bus carrying workers wearing protective gear came up the slope of the site, which was full of steps and cracks. After a short period of heavy snow that turned the area completely white, the landscape changed completely. There were fish and pieces of houses floating on the surface of the sea, which was glistening from leaking heavy oil, and cars were on the roofs of the buildings that were left on the beach. “It was like a picture of hell.”
That night, Mr. Konno heard from an employee of the main contractor that some of the cooling pumps in Unit 2 were no longer working, and asked if he could help, but he replied, “I’ll let a young person to do it. , please wait.”
Aerial photo of the Onagawa nuclear power plant (taken in 2011)
◆ Workers and employees narrowly avoided a major accident
The next day, we were informed that only one of the five external power lines was out of service due to the earthquake. “It was dangerous. We managed to hold out, but just barely. We were about to be the same as the Fukushima Daiichi Nuclear Power Plant.”
In fact, the Onagawa nuclear power plant was in a critical state. The height of the site where the reactor building is located was 14.8 meters, but the Oshika Peninsula itself sank by 1 meter due to the earthquake. A tsunami wave up to 13 meters high rolled in, approaching the site only 80 centimeters away.
At Unit 2, seawater entered through the tidal equipment connected to the sea, making the two emergency diesel generators unusable. At Unit 1, power equipment broke and a fire started. We lost external power and were relying on an emergency generator.
Onagawa nuclear power plant accident countermeasuresTohoku Electric Power has tightened the standard seismic motion used for seismic design of facilities from 580 gals before the earthquake to 1,000 gals, and set the estimated height of the tsunami from 13.6 meters, the highest water level height before the earthquake, to 23.1 meters. Construction began in 2013, and a new sea wall was built with a height of 29 meters and a total length of approximately 800 meters. A “vent with filter” was installed to reduce the pressure in the reactor containment vessel in the event of an accident to prevent damage, and a device was also installed to prevent the rise in hydrogen concentration to prevent a hydrogen explosion in the building. The construction cost was about 570 billion yen and was completed in May of this year.
Thanks to the hard work of the workers and employees, a major accident was narrowly avoided. Unit 2 was restored just 40 minutes before the earthquake, so the cold shutdown was quick, but Units 1 and 3 took until the early hours of the 12th. When interviewed by Tohoku Electric, an operator said, “The reactor has to be kept cool at all times, so it was tense weather.”
◆ “If an accident like Fukushima happens, you can’t escape.”
Nanao Abe (75), a former fisherman from Iikohama, Onagawa Town, about 1.5 kilometers west of the nuclear power plant, evacuated to the Onagawa nuclear power plant gymnasium and other facilities the day after the earthquake.
Their homes were washed away by the tsunami and roads were cut off. There was nowhere else to go. At the time, 364 people were evacuated. However, there was no explanation that the nuclear power plant was in crisis. Although the nuclear power plant has been praised for accepting evacuees, Abe says, “If I had known about the situation at the nuclear power plant, I might not have evacuated…If an accident like Fukushima happened, I wouldn’t be able to. to escape.”
In addition to the Great East Japan Earthquake, the Onagawa Nuclear Power Plant has repeatedly experienced large earthquakes, including the Miyagi Prefecture-Oki Earthquake of 2005. Konno is worried.
“What damage has the disaster done? Is it okay to operate a nuclear power plant similar to the Fukushima Daiichi Nuclear Power Plant, whose cause of the accident has not yet been fully clarified? difficult to evacuate even if an accident occurs, so it is difficult to restart.
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Interview between Time.news Editor and Nuclear Safety Expert
Time.news Editor (E): Today, we’re delving into a critical moment in nuclear safety history, focusing on the Onagawa Nuclear Power Plant during the Great East Japan Earthquake of 2011. Joining us is nuclear safety expert, Dr. Akira Yamada. Welcome, Dr. Yamada!
Dr. Akira Yamada (Y): Thank you for having me. It’s a pleasure to discuss such an important topic.
E: The events of March 11, 2011, had a profound impact. Can you describe the condition of the Onagawa plant in the aftermath of the earthquake?
Y: Certainly. On that fateful day, the Onagawa Nuclear Power Plant experienced a strong tremor and then a massive tsunami. Remarkably, while external power lines were impacted, only one was disabled. The workers narrowly avoided what could have been a catastrophic accident, similar to the one in Fukushima, due to their quick reactions and preparedness.
E: That’s both fortunate and alarming. Could you elaborate on how the plant’s design helped mitigate the crisis?
Y: Absolutely. The height of the reactor building was originally designed to withstand certain seismic activities. However, after the earthquake, the site of the plant itself sank by one meter. The tsunami that hit was nearly 13 meters, coming alarmingly close to the reactors, which were only 80 centimeters above that incoming wave. Thankfully, because of emergency protocols, many crucial systems were preserved.
E: You mentioned that the Onagawa plant was in a critical state. How did the plant staff manage the crisis?
Y: The plant’s staff acted swiftly and decisively. For instance, Unit 2 had its cooling systems restored just before the earthquake struck, which was crucial in preventing overheating. The team understood the vital importance of maintaining cooling in the reactors, so there was a constant tension to ensure all systems were operational during the chaos.
E: Given these challenges, what major changes have been made in nuclear safety regulations since that event?
Y: In response to the disaster, Tohoku Electric Power undertook significant upgrades. They revised the seismic design standards from 580 gals to 1,000 gals and raised the estimated tsunami height from 13.6 meters to 23.1 meters. This involved constructing a new sea wall nearly 29 meters high, which is a substantial buffer against future tsunamis.
E: Building such infrastructure must be a massive undertaking. How has community sentiment changed since the earthquake?
Y: There’s understandably a mix of fear and resilience within the local communities. Many residents are still deeply aware of the potential dangers, as highlighted by individuals like Nanao Abe, a former fisherman from the area, who expressed concerns that if a similar disaster were to occur, there might be no escape. This ongoing anxiety underscores the importance of transparency and safety in nuclear operations.
E: That’s a crucial point. In your opinion, what lessons can other nuclear facilities worldwide learn from Onagawa?
Y: The most significant lesson is the importance of preparedness and adaptability. Continuous evaluation of risks and implementing advanced safety measures is critical. The onus is on nuclear operators to employ lessons learned from incidents like these to assure both their employees and the surrounding communities.
E: Dr. Yamada, thank you for shedding light on the vital importance of nuclear safety and the enduring impact of the 2011 earthquake. It’s clear that the Onagawa Nuclear Power Plant has implemented a range of measures to enhance safety, but the conversation around nuclear safety must continue.
Y: Thank you for having me. It’s a crucial dialogue that we must keep pursuing for the safety of all.
E: And with that, we conclude our interview. Thank you for joining us, and stay tuned for more insights on pressing issues shaping our world today.