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It turns out that when constructing the Daiichi nuclear power plant at Fukushima over 40 years ago, Tokyo Electric Power Co. (Tepco) made one bad decision that resulted in the meltdown of three reactors after the earthquake and tsunami that struck the prefecture in 2011.
Official documents filed with Japanese authorities in 1967, show that when working on the construction of the new nuclear power plant, Tepco decided to reduce the natural, 35-metre seawall to just ten metres in height. A decision that left the facility vulnerable to the 14-15 metre tsunami that struck in March 2011.
A diagram showing the height of the 2011 tsunami (15 metres), the current sea wall elevation (10 metres), and the existing seawall elevation (35 metres).
When making the decision it had been agreed that typhoons, at no more than eight metres in height, were the biggest threat, and therefore leaving a ten metre seawall would be sufficient protection. “Most large waves in this coastal area are the product of strong winds and low pressure weather patterns, such as Typhoon No. 28 in February of 1960, which produced peak waves measured at 7.94 meters.”
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Masatoshi Toyota, an 88 year old, former executive at Tepco who was part of the decision making team back in 1967, explained that the decision was made based on two lines of reason. One, that reducing the cliff by 25 metres would make it much easier to deliver heavy equipment to the site, which was mostly delivered by sea; and two, that it was much easier to access sea water to cool the reactors from 10 metres above sea level, compared to 35 metres.
Mr. Toyota spoke to the Wall Street Journal to say that “it would have been a very difficult and major engineering task to lift all that equipment up over the cliff. For similar reasons, we figured it would have been a major endeavor to pump up seawater from a plateau 35 meters above sea level.”
Although not as commonly known, due to the fact that nothing happened, the Daiichi nuclear power plant is not the only facility along the Fukushima coastline. In the 1970s the Daini and Onagawa nuclear power plants were also built, however the seawalls were not destroyed here. When the massive earthquake and tsunami struck in March they were both able to achieve cold shutdowns, and no damage was suffered at either site.
The Wall Street Journal explained that the primary reason that neither of these plants were unharmed, was due to their higher elevations on top of the cliff.
By. Joao Peixe of Oilprice.com
Joao is a writer for Oilprice.com