The radioactive fuel rods at the No. 2 reactor of the Fukushima No. 1 power station were fully exposed at one point Monday, Tokyo Electric Power Co. said, raising the possibility that it suffered a partial core meltdown.

The utility operating the Fukushima plant later said the level of coolant water in the reactor's container was raised 2 meters above the base of the rods — which are about 4 meters long.

However, it was not clear if Tepco was able to pump enough coolant into the containment vessel to cool it off. Nevertheless, Chief Cabinet Secretary Yukio Edano told a news conference Monday evening that the situation stabilized after cooling resumed.