JAPAN'S quake-hit nuclear power plant Fukushima No.1, about 250km north-east of Tokyo, "may be experiencing nuclear meltdown", local media says.
The report via Kyodo News, citing the nation's Nuclear Safety Commission, follows yesterday's devastating 8.9-magnitude earthquake and tsunami in the area, with a commission official suggesting that even if there was a meltdown it would not affect humans beyond a 10km radius.
Parts of the reactor's nuclear fuel rods were briefly exposed to the air after cooling water levels dropped through evaporation, and a fire engine was pumping water into the reactor, Jiji news agency reported.
The rods, which create heat through a nuclear reaction, can release radioactivity when exposed to the air. Without water the rods cannot be cooled properly, Fox News reported.
The water levels are recovering, operator Tokyo Electric Power Company (TEPCO), told Jiji. In addition a TEPCO spokesman said that "we believe the reactor is not melting down or cracking. We are trying to raise the water level."
But moments later Kyodo News reported that radioactive caesium had been detected near the Fukushima plant, citing information from the nuclear safety agency.
Earlier today, the Japanese Government declared an atomic emergency amid growing international concern over its reactors.
As an industrial powerhouse nation poor in energy resources, Japan draws about 30 per cent of its total power from its 53 nuclear plants.