Arab News Japan
TOKYO: The No. 2 reactor at the Onagawa Nuclear Power Plant resumed operations on Tuesday, 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 that suffered a major meltdown following the 2011 earthquake and tsunami.
The Citizens’ Nuclear Information Center (CNIC) says the Onagawa plant has serious safety problems.
“The Onagawa Nuclear Power Plant was the plant that was hit by the strongest ground tremor among all of Japan’s nuclear power plants at the time of the 2011 Great East Japan Earthquake and tsunami,” the CNIC said.
“It narrowly escaped a major direct hit from the massive tsunami and consequent major destruction but suffered severe damage due to seawater flowing backward through a culvert, causing the failure of emergency diesel generators.”
“More than 1,000 cracks appeared in the concrete wall of the Unit 2 reactor building, causing a significant decrease in strength. It is doubtful if repair work has been carried out to ensure sufficient strength against a large earthquake that might occur in the future. It may be unable to withstand an earthquake of the expected scale.”
The CNIC says the operator’s calculations for predicting seismic shaking may not be accurate, as was the case at the Shika Nuclear Power Plant during the 2024 Noto Peninsula earthquake, a seismic event that was more than twice the estimate previously calculated by the power company.
“Another concern is a hydrogen explosion,” CNIC says. “At the Fukushima Daiichi Nuclear Power Station, Units 1, 3 and 4 experienced explosions powerful enough to cause serious damage to their buildings. Countermeasures against hydrogen explosions are yet to be developed.”
“Restarting the nuclear power plant after more than 13 years in a state of shutdown is a major safety concern. The occurrence of minor accidents in recent months, such as water leaks from the control rod hydraulic drive system in the reactor building and malfunctions in the emergency gas treatment system, indicate that hidden safety issues exist.”
Tohoku Electric invested 570 billion yen ($3.7 billion) to construct a seawall 29 meters above sea level to guard against tsunamis. The company also conducted seismic reinforcement work on the reactor building, among other safety measures.
The Onagawa plant is the first to restart operations in eastern Japan. The government is looking to nuclear power to reduce the burden of imported energy.