Tokyo (CNN) -- Japan restarted nuclear power production Sunday for the first time since shutting down all the country's reactors in the wake of the Fukushima Daiichi meltdown after last year's devastating tsunami.

Kansai Electric Power Co. Ltd. (KEPCO) began an operation to restart the Ohi nuclear plant's No. 3 reactor on Sunday night, it said, despite protests from raucous demonstrators at the site.