SINGAPORE – Japan’s nuclear crisis is a nightmare, but it is not an anomaly. In fact, it is only the latest in a long line of nuclear accidents involving meltdowns, explosions, fires, and loss of coolant – accidents that have occurred during both normal operation and emergency conditions, such as droughts and earthquakes.
Nuclear safety demands clarity about terms. The Nuclear Regulatory Commission in the United States generally separates unplanned nuclear “events” into two classes, “incidents” and “accidents.” Incidents are unforeseen events and technical failures that occur during normal plant operation and result in no off-site releases of radiation or severe damage to equipment. Accidents refer to either off-site releases of radiation or severe damage to plant equipment.
The International Nuclear and Radiological Event Scale uses a seven-level ranking scheme to rate the significance of nuclear and radiological events: levels 1-3 are “incidents,” and 4-7 are “accidents,” with a “Level 7 Major Accident” consisting of “a major release of radioactive material with widespread health and environmental effects requiring implementation of planned and extended countermeasures.”
Under these classifications, the number of nuclear accidents, even including the meltdowns at Fukushima Daiichi and Fukushima Daini, is low. But if one redefines an accident to include incidents that either resulted in the loss of human life or more than $50,000 in property damage, a very different picture emerges.