The radiation level at a quake-hit nuclear power plant in Japan's Fukushima Prefecture has again exceeded the legal limit, according to a report by Kyodo news agency Monday morning.

The operator and owner of the Fukushima plants, Tokyo Electric Power Co., said the Fukushima No. 1 nuclear plant has been shut down since the devastating magnitude-9 quake struck northeastern and eastern Japan on Friday, but some of its reactors have lost their cooling functions.

The No. 3 reactor at the plant lost its ability to cool the reactor core early Sunday, becoming the sixth reactor that lost the function. And a hydrogen explosion is possible at the No. 3 reactor, Japanese Chief Cabinet Secretary Yukio Edano said Sunday.