Interactive: A Visual Guide Inside Japan's Reactors

Workers at Fukushima Daiichi nuclear power plant in the northeastern coast of Japan have been struggling to keep reactors there from overheating. The troubles began March 11, when a massive earthquake and tsunami knocked out power at the facility, disabling cooling systems. Workers are now scrambling to cool the nuclear cores of three reactors, and there are new concerns about overheating in pools where spent nuclear fuel rods cool. Here's a visual guide to what's going inside the reactors.