February 26, 2014
Hinman Remembers: Fukushima Daiichi
by Eve Hinman
This month we remember the earthquake and tsunami which occurred almost three years ago on March 11, 2011 off the Pacific coast of Japan in Tohoku. It was the largest earthquake known to occur in Japan and the fifth largest on record since about 1900. However, it is most remembered because of the disaster it triggered at the Fukushima Daiichi nuclear power facility. It was the largest nuclear incident since the 1986 Chernobyl disaster. Japan recently reported that the event left 15,884 dead, 6,147 injured and 2,636 missing. It collapsed a total of 127,590 buildings, with more than a million others damaged. Insured losses are estimated in the US $14.5 to US $34.6 billion range. The World Bank estimated the total economic cost at US $235 billion, making it the costliest natural disaster in world history. The event is still unfolding; this week a radioactive leak was found under the reactors, which may have contaminated the groundwater.
This accident has so much to teach those of us dedicated to disaster mitigation. To start with, the Fukushima nuclear power plant was located on the coast near sea level in a part of the world known for large seismic events. Encouraging nearby communities on the surrounding hillside to move close to the nuclear plant by providing jobs and subsidized housing did not help the situation. Providing only a narrow winding access road along the coast to the area was also unfortunate. This plant is in an area with a population of roughly 1,000,000 within an 18 miles radius.
Now that I got that out of my system, I can focus on the actual event. For me this is a textbook example of a cascading event. It was initiated by an earthquake measuring 9.0 Mw that occurred at 2:46 pm on March 11, 2011. The Fukushima plant was able to handle this size quake and structurally performed well. Three of the six reactors were operating at the time and automatically shut down, but still needed cooling. The power was lost but the emergency diesel generators activated to keep the plant operating. Unfortunately, the plants were not designed to handle the tsunami that followed. The plant was protected by a three- meter flood wall, but the tsunami that hit the building nearly an hour after the earthquake was a whooping 15 meters above sea level and failed a portion of the flood wall. The main plant, 10 meters above sea level, became inundated by the tsunami. Eleven of the twelve generators in two of the three units, as well as the batteries, failed after the tsunami hit. Even had emergency power systems had been maintained, the sea water pumps used to cool the reactors below the buildings were flooded and inoperable. At this point the plant became a ticking time bomb because there was no way to cool the core. A series of hydrogen explosions occurred within a four day period as the reactors continued to heat up. The reactor that failed first was the oldest -- constructed in the 1960’s -- at the end of its useful life, and functionally obsolete. The workers desperately worked to mitigate the situation as best they could but radiation was released and continues leaking to this day.
It is difficult to untangle all the events that occurred during this disaster but it is safe to say that the owner of the plant, TEPCO, did not expect such a large earthquake and was ill prepared for the incident, though there were indications that Japan was due for a very large earthquake. Because of this, the event is widely considered to be a man-made disaster. In a past blog post, I mentioned that resiliency is the road to allow us some level of control over our world which is changing. Resilience management can help us be better prepared to protect ourselves against blast, earthquakes and other natural hazards, such as the events that occurred at the Fukushima Diiachi nuclear power plant.