Shadows spreading to the far north and south - Japan's crisis drawn by the 250-kilometer evacuation line (2011)

Shadows spreading to the far north and south - Japan's crisis drawn by the 250-kilometer evacuation line (2011)

In March 2011, the worst-case scenario presented to the government as the Fukushima Daiichi nuclear accident progressed drew an unprecedentedly vast evacuation zone across the Japanese archipelago. If multiple reactors were to experience a chain reaction of severe conditions and continue to emit large amounts of radioactive materials for an extended period of time, the evacuation zone would cover a radius of 250 km from the Fukushima Daiichi Nuclear Power Plant. Morioka City, Iwate Prefecture is located at the northern end of the circle, and Yokohama City, Kanagawa Prefecture is located at the southern end. To link such distances into a single danger zone was more than just a geographical figure; it represented the possibility that most of the functions on which Japanese society depended might be shaken.

The Tokyo metropolitan area was then home to some 35 million people, and its economy was the center of the nation's support. If this population were to be evacuated from the entire area, the very foundations of society, including administration, finance, logistics, and medical services, could come to a halt in one fell swoop. The reason why this situation could not be announced as a realistic political decision was not only the fear of triggering a panic, but also the potential for a crisis on a scale that could shake the entire nation. Although the worst-case scenario was a scientific estimate, it carried the weight of involving diplomacy, social psychology, and even economic structure.

Behind this assumption was the wind direction bias observed in the early stages of the accident: around March 15, it was pointed out that radioactive materials could flow southward, and in fact trace amounts of radioactive materials were detected in Ibaraki, Chiba, Tokyo, and Kanagawa. Depending on weather conditions, a wide area from Tohoku to Kanto could be affected by long-term contamination. The U.S. government had already recommended evacuation from the 80-kilometer zone, and the seriousness of the situation was shared internationally. External precautions were another factor supporting the reality of a 250-kilometer evacuation line.

The single evacuation line from Morioka to Yokohama was also a boundary that symbolized how the failure of a large-scale technological system would affect the nation. The accident exposed the fragility of an energy policy built around nuclear power and how the safety of society had been built on an unstable foundation, and it caused a rethinking of the very concept of "safety" in Japan. More than 10 years have passed since then, but the question posed by the 250-kilometer shadow has not disappeared. What is the coexistence of giant technology and society? How should we prepare for a national crisis? The evacuation line drawn in 2011 still quietly lingers in the air.