Japan suspends restart of world’s largest nuclear plant hours after it began
TEPCO halted the Kashiwazaki-Kariwa restart after a monitoring alarm sounded, but confirmed the reactor is stable with no radioactive impact

But its operator, the Tokyo Electric Power Company (Tepco), said that “an alarm from the monitoring system … sounded during the reactor start-up procedures”, causing them to suspend operations.
“We were investigating the malfunctioning electrical equipment,” spokesperson Takashi Kobayashi said, adding that “once it became clear that it would take time, we decided to reinsert the control rods in a planned manner”.
The reactor “is stable and there is no radioactive impact outside”, he said.

Control rods are a device used to control the nuclear chain reaction in the reactor core, which can be accelerated by slightly withdrawing them, or slowed down or stopped completely by inserting them deeper.