The seawater pump in the cooling system for the Fukushima power plant’s No. 5 reactor broke down Saturday evening, prompting repair crews to install a backup pump 15 hours later on Sunday afternoon, Tokyo Electric Power Co. said.
Tepco discovered the pump had stopped at 9 p.m. Saturday but didn’t announce it to the public until Sunday morning.
The beleaguered utility said it notified the local and central governments of the situation on Saturday evening.
The seawater pump was set up after the reactor’s original pumps were knocked out by the March 11 earthquake and tsunami. It was part of the critical Residual Heat Removal System that was later used to safely ease the reactor into a cold shutdown on March 20.