Japan restarts first nuclear plant

• A reactor at the Ohi Nuclear Power Plant in western Japan is set to restart Sunday
• All 50 of Japan's commercial reactors have been offline since May due to safety tests
• The reactors have been stress-tested in the wake of last year's Fukushima disaster
• Demonstrators protesting nuclear power gather outside the Ohi plant

Tokyo (CNN) -- Energy-starved Japan will regain nuclear-powered electricity on Sunday, when the first reactor to be switched on since last year's Fukushima disaster comes online.

Kansai Electric Power Co. Ltd. (KEPCO) said the No. 3 reactor at the country's Ohi Nuclear Power Plant will be activated. The reactor will start providing electricity to western Japan -- which includes Osaka, Japan's second biggest city, by Wednesday. Ohi's No. 4 reactor is scheduled to resume operations by July 24.

Throngs of protesters demonstrated outside the Ohi plant on Sunday, voicing their opposition to the No. 3 reactor from going online.

All 50 commercial nuclear reactors in Japan have been offline since May 5 for safety checks. The government has been conducting simulation tests for restarting its nuclear reactors in response to public concerns over their safety in the wake of the crisis at the Fukushima Daiichi nuclear plant last year.

Before the March 11 disaster, Japan had relied on nuclear energy for about 30% of its electricity needs, according to government figures.