Further approvals will be needed before the restart, along with the consent of local authorities.
The three-unit station in Miyagi Prefecture, northern Japan, was hit by the March 2011 tsunami that resulted in meltdowns at Fukushima-Daiichi to the south, but survived with its cooling system intact, saving its reactors from the threat of meltdowns.
The basement floors of the Onagawa-2 unit were flooded and Tohoku Electric has been building a 30-metre-high sea wall to protect the complex.
The company filed a restart application for Onagawa-2 in 2013, but according to industry group the Japan Atomic Industrial Forum, has not yet made a decision on whether to restart Onagawa-3. Last year Tohoku Electric confirmed that it plans to decommission Onagawa-1.
All three Onagawa units are boiling water reactors. Onagawa-1 is an older 498-MW BWR-4 model that began commercial operation in 1984 and was permanently shut down in 2018. Onagawa-2 and -3 are 796-MW BWR-5 units that began commercial operation in 1995 and 2002.
Japan has a total of 62 nuclear power units, but shut down all 42 that were operating at the time after the Fukushima-Daiichi accident.
Thirty-three units have a licence to operate although before units return to service they need to meet stricter safety standards introduced following Fukushima-Daiichi.
Nine units have returned to service. They are Genkai-3 and -4, Ikata-3, Ohi-3 and -4, Sendai-1 and -2, and Takahama-3 and -4.
Two units – the Ohma and Shimane-3 advanced boiling water reactor units – are under construction.
According to the International Atomic Energy Agency, the country’s nuclear share in 2018 was about 6.2%. Before Fukushima, Japan generated about 30% of its electricity from nuclear and planned to increase that to 40%.
A recent energy white paper adopted by the Cabinet called for further efforts to cut carbon emissions by keeping to a nuclear generation target of 20% to 22%.
In August, Four of Japan’s major energy and nuclear power companies signed an agreement to discuss potential collaboration on boiling water reactor projects – a move that could lead to construction of a new nuclear power plant at Higashidori in the north of the country.
