Fuel rods at the Number Two reactor at a power plant in quake-hit Fukushima Prefecture remain exposed.
Earlier, the Tokyo Electric Power Company said the valve to vent steam and reduce pressure inside the reactor closed at 11 PM on Monday.
It said the increased pressure at the reactor made it impossible to pump water in. The water level dropped sharply, possibly fully exposing the fuel rods.
The company managed to open the valve to reduce pressure and let seawater into the reactor at around 1 AM on Tuesday.
But as of 3 AM, the water level remains low and the fuel rods remain exposed.
The company says there has been no pressure increase inside the reactor, and no major change in radioactivity levels on the edge of the plant's compound.
A company official says there is no imminent danger.
A similar problem hit the reactor earlier on Monday, but the company managed to reactivate the pump, bringing the water level to the middle of the fuel rods.
The company is battling to raise the water level, as the protracted exposure of the fuel rods could cause them to melt. Tuesday, March 15, 2011 07:48 +0900 (JST)
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