Japan. March 11, 2011. 2:46 P.M. The biggest earthquake in Japan's history—and one of the world's five most powerful since 1900—devastated the Tohoku region, 320 kilometers (200 miles) northeast of Tokyo. It triggered a huge tsunami that left crippling damage in its wake. More than 13,000 people drowned, and thousands of buildings and homes were reduced to rubble.

As people assessed the damage, they made the most frightening discovery of all: the Fukushima #1 nuclear power plant was seriously damaged and three of its six reactors were heading for meltdowns. Workers tried desperately—but unsuccessfully—to save them. Explosions and fires released radioactivity into the air. Within days the Japanese government declared a 20-kilometer (12-mile) evacuation zone. The future of the plant, the long-term health of those exposed to radiation, and the effects on the environment remained uncertain.

Learn more about this massive catastrophe as Dr. Fred Bortz examines both the human tragedy and the scientific implications of the nuclear meltdown. Compare this disaster to similar nuclear events in the United States and in Ukraine, and move ahead with Dr. Bortz as he explores the global debate about the future of nuclear power and alternative sources of energy.