Kansai Electric Power Co. restarted Tuesday a reactor at its Takahama plant on the Sea of Japan coast that had been suspended by a court decision in March last year, aiming to resume its commercial operation in early July.

After reactivation, the No. 3 reactor at the plant in the central Japan prefecture of Fukui is expected to reach criticality on Wednesday and start producing electricity around Friday.

The reactor remained offline along with the No. 4 reactor at the Takahama plant after the Otsu District Court decided against their operation in March last year, citing safety concerns. It was the first injunction ever issued in the country to stop operating nuclear reactors.

But the decision was repealed by the Osaka High Court in March this year, enabling the latest restart. The No. 4 reactor was restarted on May 17 and is set to start commercial operation in mid-June.

Kansai Electric will likely cut electricity rates as early as this summer after the resumptions of operation at the Nos. 3 and 4 reactors.

The two reactors passed screening in February 2015 after Japan introduced stricter safety requirements in the wake of the March 2011 Fukushima nuclear disaster.

Both reactors will run on mixed oxide fuel or MOX -- which is created from plutonium and uranium extracted from spent fuel -- under the "pluthermal" project.

There are a total of 157 fuel rod assemblies, including 24 of MOX fuel, inserted in the No. 3 reactor.

As of last week, four of Japan's 42 commercial reactors nationwide were operating -- the No. 4 reactor at the Takahama plant, the Nos. 1 and 2 reactors at Kyushu Electric's Sendai plant in Kagoshima Prefecture, southwestern Japan, and the No. 3 reactor at Shikoku Electric Power Co.'s Ikata plant in Ehime Prefecture, western Japan, according to the Agency for Natural Resources and Energy.

 Takahama No. 3 reactor to be reactivated