Architect: Uehara Haruo

Fukushima Daiichi Nuclear Power Plant is a disabled nuclear power plant located on an 860 acre site in the town of Okuma and Futaba in the Futaba District of Fukushima Prefecture, Japan.  The power plant was first commissioned in 1971, and it consisted of six boiling water reactors which drove electrical generators.  This made Daiichi one of the 15 largest nuclear power stations in the world [B].

The Daiichi Power Plant suffered major damage from the 9.0 earthquake and tsunami that hit Japan on March 11, 2011.  The fifteen meter tsunami disabled the power supply and cooling of three Daiichi reactors.  All three cores largely melted in the first three days.   The accident was rated 7 on the INES scale, due to high radioactive released over days 4 to 6.  Apart from cooling, the main task was to prevent release of radioactive materials, particularly in contaminated water leaked from the three units.  There were no deaths or cases of radiation sickness, but over one hundred thousand people had to be evacuated from their homes to ensure their safety [A].

The catastrophic accident at the power plant was the result of loss of offsite power caused by the earthquake, coupled with the loss of onsite power and the ultimate heat sink caused by the tsunami.  The first image shows where the earthquake happened.  Without a source of electrical power, the systems and components used to keep the fuel in the reactors cooled were not able to function.  Even though people tried to cool the reactors, they were unsuccessful in preventing the fuel from overheating and melting.  In addition, hydrogen generated during the accidents collected within the reactor building and caused explosions in the upper potions of the Units’ reactor buildings, this is shown in the second image.  There was significant damage to the top floors and exposure of the spent fuel pools to the environment.  The Nuclear Energy Agency member countries decided to alter the work priorities of the NEA standing technical committees in order to assess the accident and to identify safety lessons.  The NEA had devoted significant efforts to directly supporting the technical needs of the Japanese government, with this assistance primarily focusing on the recovery of land and decontamination, the development and implementation of national reviews and stress tests, and enhancements to the regulatory infrastructure [C].