In 2011 a massive earthquake struck Japan triggering a destructive tsunami off the coast of the Miyagi prefecture. The earthquake was registered as a magnitude 9.0 (Baba, 2013). The news of the devastating earthquake spread rapidly across the world. Many watched in horror from their television screens and computer monitors as news outlets broadcasted images of a giant tsunami as it submerged large portions of the Tohoku region of Japan. According to an official police report 15,984 people were killed by the tsunami. Nearly half-a-million were eventually displaced. Infrastructure throughout the region was crippled.
Fourteen nuclear reactors at four nuclear power plants (NPPs) along the east coast of the island of Honshu were impacted by the events (Baba, 2013). Ten of those reactors were able to automatically reach a cold shutdown without incident (Baba, 2013), but four did not. Four of these reactors are located at the Fukushima-Daiichi NPP which houses six reactors. At the time of the earthquake reactors one, two and three were operating while reactors four, five and six had been shut down for a regularly scheduled inspection.
Reactors one, two and three automatically stopped and emergency generators as well as passive cooling systems began working, but the earthquake had already damaged the relief lines. Then, approximately 50 minutes later, the tsunami arrived rendering the emergency generators and seawater pumps useless (Baba, 2013). This left the plant, which is operated by Tokyo Electric Power Company (TEPCO), unable to cool the three reactors from the immense heat emitted by nuclear energy. The three reactors subsequently melted down.
Reactor four was empty at the time of the earthquake and tsunami, the fuel rods were in the spent fuel pool (SFP). March 15, four days after the initial disaster, a hydrogen explosion occurred in the reactor building (RB) housing reactor four and significantly damaged the structure. The explosion happened because of a hydrogen leak from neighboring reactor three (Baba, 2013). Despite minimal damage to the fuel rods in the SFP, the exposed nuclear waste no longer had an adequate containment vessel (CV) after the explosion. Consequently, radioactive materials escaped. This chain of events led to the infamous nuclear disaster at the Fukushima-Daiichi NPP. The disaster was rated a 7 which is considered to be a major accident according to the International Nuclear and Radiological Event Scale (INES).Only one other nuclear disaster has been given this status — Chernobyl.
Evacuation of the residents near the Fukushima-Daiichi NPP was complicated for two reasons, inadequate information and the inability to send communications due to infrastructure collapse. Initially, the evacuation zone was within 2 miles, then it grew to 6 miles and eventually as exposure to radioactive materials increased it expanded to 19 miles (Baba, 2013). The contamination from the nuclear disaster at the Fukushima-Daiichi plant spanned large areas of the country.
According to The Telegraph, Naoto Kan, Prime Minister at the time of the disaster, claimed that he was on the brink of evacuating Tokyo and surrounding areas. That would have meant the uprooting of 50 million people. Last week, Tsunehisa Katsumata, TEPCO chairman at the time of the disaster, was indicted on charges of criminal negligence. The charges come amid accusations that Mr. Katsumata was aware of the NPP’s vulnerability to a tsunami two years prior to the disaster and for his mismanagement of the disaster.
TEPCO is responsible for releasing radioactive waste into the ocean, despite having denied doing so in the aftermath of the Fukushima-Daiichi meltdowns.
TEPCO is responsible for releasing radioactive waste into the ocean, despite having denied doing so in the aftermath of the Fukushima-Daiichi meltdowns and exposure. The company later admitted that failures to launch key safety features allowed the meltdowns to occur in the wake of the tsunami. March 11, 2016 marks five years since a devastating tsunami struck the Tohoku region on the island of Honshu in Japan.
Baba, M. (2013). Fukushima accident: What happened?. Radiation Measurements, 55, 17-21.