Damage to Japan's nuclear power plants could result in sickness and dislocation for hundreds of thousands more.

Japanese media said an explosion blew the roof off the reactor, raising fears of a disastrous meltdown at a nuclear plant damaged in the massive earthquake that hit Japan.

The explosions and meltdown fears at Fukushima Daiichi nuclear-power plant that followed Friday's earthquake have increased concerns in Japan about the safety of nuclear power.