Unit 4 of the Ohi nuclear power plant in Japan's Fukui Prefecture began supplying electricity to the grid again on May 11, according to Kansai Electric Power Co.

The news came just as the Japanese government released the country's medium-to-long term energy policy. The policy is reviewed every three years, and outlines targets to 2050 in line with the Paris climate accord.

The energy plan aims to reduce Japan's generating costs for renewable energy in order to make renewables the country's main source of power. The continued use of nuclear energy is included as one way to achieve a carbon-neutral society.

The plan puts renewable energy resources at 22 to 24 percent of the total energy mix, and nuclear power at 20 to 22 percent. It also puts thermal generation from coal and natural gas resources at about 56 percent.

Officials say they will seek comments on the plan, and aim for official approval as early as July.

All of Japan's reactors were ordered shut after the March 2011 accident at the Fukushima Daiichi plant, following an earthquake and tsunami. Ohi 3 and 4 were given permission to resume operation in August 2012. The two 1,180 MW pressurized water reactors were taken offline again for Nuclear Regulation Authority (NRA) inspections in September 2013.

The NRA announced in May 2017 that the two units met safety standards introduced in July 2013. The governor of Fukui Prefecture approved the restart of Ohi units 3 and 4 in November 2017.

Ohi 3 was restarted in mid-March, and returned to commercial operation on April 10.

Fuel loading was completed at unit 4 in early April. The reactor was restarted on May 9 and reached criticality on the 10th.

Ohi 4 is the eighth of Japan's 39 operable reactors to have cleared inspections, according to World Nuclear News. The others are Kyushu's Sendai units 1 and 2 and Genkai unit 3; Shikoku's Ikata unit 3; and Kansai's Takahama units 3 and 4. Another 17 reactors have applied to restart.