In a major milestone for Japan’s nuclear industry, after 13 years of dormancy Tohoku Electric restarted the No. 2 reactor at Onagawa NPP (825 MW) on October 29. In addition to bringing more carbon-free capacity online, the event marks the first restart of a boiling water reactor (BWR), the same type that was in use at Fukushima Daiichi NPP.

Along with Fukushima, Onagawa NPP was hit hard during the earthquake that shook the Pacific coastal area of northeast Japan in March 2011. Located close to the epicenter, Onagawa withstood the earthquake’s full force and a subsequent 13-meter tsunami. Still, the NPP had to be mothballed.

Onagawa’s restart has sparked hopes that other BWR reactors will soon follow. For example, Chugoku Electric’s Shimane NPP Unit 2 (in Matsue City) has completed loading nuclear fuel and plans to restart on December 7. Also, TEPCO’s Kashiwazaki-Kariwa Unit 7, also a BWR, has passed regulatory review and awaits local approval.

The restart of these BWR reactors in East Japan lags behind the already restarted pressurized water reactors (PWRs) in West Japan. The first PWR reactor to restart was Kyushu Electric’s Sendai NPP Unit 1 in August 2015, followed by Sendai NPP Unit 2 a few months later. Since then, ten other PWRs have restarted.

The Onagawa restart comes at a critical time for Japan’s energy policy. Despite Prime Minister Ishiba taking a cool stance on nuclear energy during his recent election campaign, the new government seems intent on following former PM Kishida’s target of nuclear power providing 20%-22% of the national power mix by 2030.

That means the number of operating reactors will need to double from the current level, accounting for just under 8% of the national energy mix.