On April 12, one month after the initiation of the tragedy at the Fukushima Daiichi I nuclear power plant, the Japanese government labeled the event a level seven accident-the most severe rating on the International Nuclear Events Scale (INES). This announcement heightened international concerns about the severity of the event and the potential for circumstances to worsen. This posting is intended to provide some clarification about these events in historical context.

Improvements are needed in explaining the significance of the numbers to the public