The shutdown at Hamaoka raises the risk of power disruptions in the Chubu region, which is home to Toyota Motor Corporation and other manufacturers.

Companies in eastern and northeastern Japan served by Tokyo Electric Power Cooperation, and another quake-affected utility have already been asked to curb electricity usage this summer when demand peaks.

Some protesters said safety should not be compromised by economic calculations.

Makoto Takahashi, Protester, said, "Since the Fukushima nuclear power plant became such a trouble, I think we should just get rid of all nuclear plants in Japan. We already have a sufficient amount of electricity if we save right."

In the nearly two months since the massive disasters in Japan, the capital has been the scene of plenty of anti-nuclear protests. Most are held in front of the headquarters of TEPCO.

The company announced in April that it wanted a cold shutdown of the plant within six to nine months. However experts say this timeline will be tough to meet.

Meanwhile, although the closure was announced by the Prime Minister, the board of Chubu Electric Power Corporation is still holding discussions on whether they will agree to the suspension.