By YOSHIKATSU NAKAJIMA/ Staff Writer
October 30, 2024 at 17:11 JST
The No. 2 reactor building, front left, resumes operations at the Onagawa nuclear power plant in Ishinomaki, Miyagi Prefecture, on Oct. 29. (Masaaki Kobayashi)
ISHINOMAKI, Miyagi Prefecture--The No. 2 reactor at the Onagawa nuclear power plant resumed operations here on Oct. 29, the first reactor damaged in the 2011 Great East Japan Earthquake and tsunami to be restarted.
The plant utilizes boiling water reactors (BWR), the same type as the Fukushima No. 1 nuclear power plant, which suffered triple meltdowns following the earthquake and tsunami.
The resumption marks the first restart of this type of reactor following the 2011 quake.
On Oct. 29 at 7 p.m., Tohoku Electric Power Co. workers reactivated the No. 2 reactor by withdrawing the control rods that suppress nuclear fission.
After confirming that the reactor has reached a critical state where nuclear fuel is sustaining a fission chain reaction, the reactor will start generating electricity as early as Nov. 7.
Commercial operations are scheduled to resume from around December.
Tohoku Electric submitted an application to the Nuclear Regulation Authority to receive the mandated safety review to restart its No. 2 reactor in 2013.
The NRA approved the use of the reactor in 2020. Miyagi Mayor Yoshihiro Murai announced that he agreed to the restart.
Tohoku Electric invested 570 billion yen ($3.7 billion) to construct a seawall reaching 29 meters above sea level to guard against tsunami. The company also conducted seismic reinforcement work of the reactor building among other safety measures.
Before the 2011 earthquake and tsunami, 54 reactors were operating nationwide.
However, all suspended their operations following the Fukushima accident. In 2013, new regulatory safety requirements took effect.
In 2015, the Sendai nuclear power plant operated by Kyushu Electric Power Co., located in Kagoshima Prefecture, resumed operations, marking the first since the Fukushima accident. Since then, a total of 12 reactors of Kansai Electric Power Co. and Shikoku Electric Power Co. have been restarted.
The Onagawa plant is the first to restart operations in eastern Japan.
The government is intent on relying more on nuclear power generation for securing electricity starting with the Onagawa reactor’s resumption.
It aims to restart other nuclear power plants as well, including the Kashiwazaki-Kariwa nuclear power plant of Tokyo Electric Power Co., located in Niigata Prefecture.
Meanwhile, in the 2011 earthquake, a 13-meter tall tsunami reached the Onagawa nuclear power plant, which is situated about 14 meters above sea level.
Although no reactors were flooded, more than a thousand cracks were found in the building of the No. 2 reactor, which was in operation, and a portion of the facilities to cool the reactor became unusable.
In addition, following the New Year’s Day earthquake in the Noto Peninsula, some of the evacuation routes around the Shika nuclear power plant of Hokuriku Electric Power Co. were disrupted in succession.
These disruptions highlighted the difficulties of evacuating when a major earthquake and an accident at a nuclear power plant occur at the same time.
The Onagawa plant is located on a peninsula, the same as the Shika plant, where subduction zone earthquakes often occur off the coast.
Residents around the Onawaga plant continue to have lingering concerns, as experts point out the vulnerability of local evacuation plans.
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