How Did the Disaster at Fukushima Daiichi Happen?

The boiling water reactors at the Fukushima Daiichi nuclear power plant on the northeast coast of Japan are equipped with an elaborate set of systems designed to ensure that cooling of the fuel in the reactor core and spent fuel pool is maintained in the event of an accident or shutdown. Tragically, these systems proved unequal to the damage inflicted by the earthquake and tsunami that struck Japan on March 11, 2011.

In this slideshow presentation, David Lochbaum, Director of the UCS Nuclear Safety Project, explains in detail how the Fukushima reactors worked under normal conditions, and then describes how the events of March 11 crippled their safety systems, resulting in extensive fuel damage and a "tragedy of unprecedented scale."

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