Onagawa Nuclear Power Plant Resumes
Tohoku Electric Power Company restarted operation of the reactor #2 of Onagawa Nuclear Power Plant on October 29th. The plant suspended its operation after Great East Japan Earthquake (GEJE) in 2011, which caused severe accident in Fukushima Daiichi Nuclear Power Plant. While the power company built a great wall to protect the plant from tsunami, it still has concern about possibility of another great earthquake and evacuation of people around the site in emergency.
Resumption of a reactor in Onagawa plant marked thirteenth example of reactors in Japan after GEJE. One significance is that Onagawa is the first one in east Japan among those thirteen restarted reactors, inviting expectation for further stable power supply in the region. Another point is that the reactor #2 in Onagawa is the first boiled water reactor, which is the same type of reactor as in Fukushima Daiichi, to resume its operation.
The power company restarted the reactor by pulling control rod in the morning of October 29th. The reactor is going to reach a critical state and begin generating electric power in November 7th. It is expected to resume commercial operation in December, if it clears all the examinations.
Onagawa Nuclear Power Plant is located on a hill, 14.8 meters above the sea surface. In the wake of GEJE, a major tsunami of 13 meters high reached as close as 80 centimeters below the reactor. While the reactor could avoid severe accident as Fukushima experienced, some devices were broken by the impact of great quake.
Nuclear Regulation Authority (NRA) estimated possible biggest tsunami in the future as high as 23.1 meters. Tohoku Electric Power Co. built a wall with height of 29 meters against possible tsunami, and passed examination of NRA in 2020. Receiving approval for building some facilities to protect the reactors from terrorist attack, the plant needs to construct the facility by 2026 to continue its operation.
The Onagawa plant is standing on the edge of continental plates underground, where great earthquake frequently occurs. The region suffered from Jogan Earthquake in A.D. 869 and Meiji Sanriku Earthquake in 1896, which brought great tsunami in the coastal area.
Evacuation of 190 thousand people living within 30 kilometers from Onagawa plant is a major concern. As located in Oshika Peninsula, Onagawa plant can isolate the people living on the side of the cape in emergency of nuclear accident. In the earthquake of Noto Peninsula on January 1st this year, over 150 people around Shika Nuclear Power Plant were isolated for sixteen days with no land or sea transportation.
After unimaginably great tsunami washed the coast of east Japan, there is no longer an argument in Japan that all the nuclear reactor is completely safe. The policy of Japanese government for resumption of nuclear reactors based on compromises with needs of stable power for economy or households.
The government of Japan promotes energy plan which is taking advantage of nuclear power. Meanwhile, some experts argue that there is no such place where a nuclear power plant can be built on this land, which is the nest of earthquakes.
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