The Japanese nuclear safety agency says explosion heard at Unit 2 of Fukushima Daiichi plant.
Earlier a cloud of radioactive dust billowed from the Fukushima Daiichi power plant after it suffered its second explosion in three days.
Government officials admitted that it was “highly likely” the fuel rods in three separate reactors had started to melt despite repeated efforts to cool them with sea water. Safety officials said they could not rule out a full meltdown as workers struggled to keep temperatures under control in the cores of the reactors.
The Fukushima crisis now rates as a more serious accident than the partial meltdown at Three Mile Island in the US in 1979, and is second only to the 1986 Chernobyl disaster, according to the French nuclear safety authority. After insisting for three days that the situation was under control, Japan urgently appealed to US and UN nuclear experts for technical help on preventing white-hot fuel rods melting.