Japan's quake-tsunami disaster ( Photo 6 of 7 )

A TV grab shows smoke rising from Fukushima Daiichi nuclear power plant’s Unit 1 in Okumamachi, Japan on Saturday. The walls of a building at the nuclear power station crumbled on Saturday and smoke poured out. Japanese officials said they feared the reactor could melt down following the failure of its cooling system in the Friday’s earthquake and tsunami.