Kansai Electric Power Co. is planning to reactivate an idled nuclear reactor on the Sea of Japan coast on May 17 at the earliest, sources close to the matter said Tuesday.

The planned restart of the reactor 4 at the Takahama plant in Fukui Prefecture is expected to bring the total number of online commercial nuclear reactors across Japan to four.

Reactors 3 and 4 passed the stricter safety standards introduced after the 2011 Fukushima No. 1 meltdowns and restarted in February last year. But immediately after that, unit 4 was shut down due to a technical problem.

The operation of reactor 3 was also suspended in March 2016 after the Otsu District Court in a neighboring prefecture of Shiga ordered the utility to shut it down. The two reactors have remained offline for more than a year since then.

But Kansai Electric has stepped up its efforts to reactivate the two reactors as the Osaka High Court reversed the lower court ruling in March.

Kansai Electric also plans to reactivate reactor 3 unit in early June, the company said earlier.