Outline of the TEPCO Fukushima Dai-ichi Nuclear Power Plant accident.

The 2011 Off the Pacific Coast of Tohoku Earthquake struck the northeast part of Japan at 14:46 JST on 11 March 2011, triggering a tsunami with over 10m-height. The earthquake caused serious damages to the TEPCO Fukushima nuclear power plants (NPPs). Although the reactors at the NPPs automatically had shut down after the earthquake, the cooling systems and its power supply were damaged. The troubles in the cooling systems led to hydrogen explosions and core melting, resulting in a large amount of radioactive materials being released into the environment. The deposition of major radioactive materials, I-131, Cs-134 and Cs-137, on the ground induced the high ambient dose of radiation around the NPP, especially within 20 km radius, and even further distance in the northwest direction. Therefore, many people had to evacuate or stay indoors. Various agricultural and marine products were contaminated with radioactive materials; radioactive concentrations in some of them exceed over the provisional regulation values. Thus, the situation caused an anxiety among public