A damaged seawater hose had workers at the Fukushima power plant scrambling on Sunday when a shutdown of the cooling system on Reactor No 5 became necessary in order to replace the leaking plastic hose.
"Toyko Electric Power Company (TEPCO) said workers patrolling the Fukushima Nuclear Power Plant found a major crack in a polyvinyl chloride hose at the No.5 reactor over the weekend. Water was leaking around the outlet of a temporary pump sending seawater into the reactor's cooling system. TEPCO shut down the water to replace the hose. The reactor's cooling system automatically stopped 15 minutes later, meaning its cooling function was temporarily lost," reports NHK.
The temperature of the reactor was 43.1 degrees at the time of the cooling system shutdown. It continued to rise during the few hours that it took to replace the hose, but did not exceed 48 degrees overnight, TEPCO said.
To remain in cold shutdown the reactor temperature must stay below 100 degrees, according to the utility company.
If it the leak had not been spotted, the reactor would have reached the boiling point within 24 hours, causing all the water to evaporate, which would expose the rods, placing the reactor in danger of a core meltdown, according to Japan Times.
This was the first of two incidents over the past few days at the Fukushia Daiichi nuclear plant.
On Monday workers at the plant had to double the amount of water being injected into the No. 1 reactor after the water level decreased from 3.7 tons of water to 3 tons, setting off an alarm, according to NHK.
The problem was suspected to be caused by debris that had accumulated inside the hoses resulting in a clog that reduced the water flow.
TEPCO has blamed foreign and domestic parts, as well as the lack of preparation due to the speed of installing the cooling system, and human error following the March earthquake and tsunami, for the continued problems.