Cooling device outage reported at Fukushima plant

The cooling system for an undamaged reactor at the Fukushima nuclear power plant temporarily stopped working Thursday, the plant’s operator said, as mysterious steam continued to rise from a broken unit.

While the outage only last two hours and there was no danger of a runaway nuclear reaction, the incident further underlined the precarious state of the plant more than two years after it was hit by a tsunami.

Four of the six reactors at the Fukushima Daiichi plant were battered by the waves of March 2011, with their cooling systems knocked offline, sending three of them into meltdown.