A reactor at the world¡¯s largest nuclear power plant was shut down Thursday due to a malfunctioning alarm less than a day after it was restarted.

Tokyo Electric Power Company Holdings (Tepco), the operator, said that the reactor is safe and that there is no danger of radiation leaks.

Unit No. 6 at the Kashiwazaki-Kariwa nuclear power plant in Niigata Prefecture was switched on Wednesday, 13 years after being shut down following the meltdown at the Fukushima No. 1 power plant.