BBC News - Japan quake: Explosion at Fukushima nuclear plantA second explosion has hit the nuclear plant in Japan that was damaged in Friday's earthquake, but officials said it had resisted the blast.
TV footage showed smoke rising from Fukushima plant's reactor 3, a day after an explosion hit reactor 1.
Japan's nuclear safety agency said the blast was believed to have been caused by the build-up of hydrogen.
Government officials said the reactor core was still intact as they tried allay fears of a radioactive leak.
Technicians have been battling to cool three reactors at the Fukushima 1 plant since Friday, when the quake and tsunami combined to knock out the cooling system.