USA | Fateful Move Exposed Japan Plant

Posted on July 12, 2011



Tokyo Electric Lowered Elevation of Land Before Building Nuclear Facility, Weakening Tsunami Defense

TOKYO–When Tokyo Electric Power Co. broke ground on the now defunct Fukushima Daiichi nuclear-power station 44 years ago, the utility made a fateful construction decision that raised the plant’s vulnerability to the tsunami that ultimately crippled its reactors.


ReutersThe tsunami flooded the Fukushima Daiichi plant on March 11, reaching five meters above the reactor floors.



In 1967, Tepco chopped 25 meters off the 35-meter natural seawall where the reactors were to be located, according to documents filed at the time with Japanese authorities. That little-noticed action was taken to make it easier to ferry equipment to the site and pump seawater to the reactors. It was also seen as an efficient way to build the complex atop the solid base of bedrock needed to better protect the plant from earthquakes.

But the razing of the cliff also placed the reactors five meters below the level of 14- to 15-meter tsunami hitting the plant March 11, triggering a major nuclear disaster resulting in the meltdown of three reactor cores.

“It’s a typical act based on the thinking of the high-growth era. People were attracted to the idea of ‘reforming the land’ back then,” said seismologist Kazuo Oike, a former president of Kyoto University who now serves on a government committee investigating the Fukushima accident. “When you inflict significant change to nature, nature will eventually get back at you with a significant force.”

In the 1960s Tepco began purchasing the land needed for the plant in coastal Fukushima, the largest chunk of which was a former Imperial Japanese Army air base during World War II. At the time, a 35-meter seaside cliff running the length of the property was a prominent feature of the site.

But Tepco outlined its intention to clear away about two-thirds of the bluff in its official request for permission from the government to build its first nuclear plant, according to a copy of the application reviewed by The Wall Street Journal.

“While the tsunami countermeasures at Fukushima Daiichi were considered sufficient when the plant was constructed, the fact that those defenses were overwhelmed is something that we take very seriously,” said Kouichi Shiraga, a public-affairs official at Japan’s Nuclear and Industrial Safety Agency. “It was common practice at the time to build on bedrock, but that is no longer the case today as long as the ground meets standards for firmness.”

In the application, the company said it wanted to build the Daiichi facility on bedrock to stabilize it and help it absorb vibrations from earthquakes and aftershocks, a process that required significant excavation of topsoil.

“The important thing is that the plant was built on a solid foundation of bedrock,” said Tepco spokesman Hiro Hasegawa, noting the decision was made by employees who have long since retired. “It would appear that height was one factor, but not necessarily the only—or even the biggest—factor involved in where to build.”

The destruction of that natural tsunami barrier at the Fukushima Daiichi site contrasts starkly with later decisions in the 1970s to build the nearby Fukushima Daini and Onagawa nuclear-power plants at higher elevations. Despite being rocked by the massive March earthquake, both of those plants’ reactors achieved “cold shutdowns” shortly after the tsunami struck and thereby avoided the damage wreaked upon the crippled Daiichi plant.

Both of those plants, located along the same coastline as Daiichi, survived primarily because they were built at higher elevations, on top of floodwalls that came with the landscape. As a result, the tsunami didn’t result in an extended loss of power at those plants, allowing their operators to quickly cool active reactors and avoid meltdowns.

Tepco’s 1966 application for permission to start construction at Daiichi—stretching more than 1,000 pages—devotes much space to the threat posed by earthquakes, but makes relatively few references to tsunami. The document states a solid base of bedrock was detected at 10 meters above sea level and explains that building upon that firmament would reduce the impact from any earthquakes.

Even so, it notes confidently that “there is no recorded history of a severe earthquake in the immediate vicinity” of the plant.

The document included no discussion of tsunami-dedicated defenses, though it did review tsunami history in a three-page list of seismic activity dating from 1273. In that chart, Tepco does reference a tsunami of unspecified height that struck the immediate area of Daiichi in 1677. It destroyed 1,000 homes and killed 300 people.

The application cites typhoons as the bigger threat, noting an 8-meter-tall wave generated in 1960. “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,” it stated.

A former senior Tepco executive involved in the decision-making says there were two main reasons for removing the cliff. First, a lower escarpment made it easier to deliver heavy equipment used in the plant, such as the reactor vessels, turbines and diesel generators, all of which were transported to the site by sea. Second, the design of the plant required seawater to keep the reactor cool, which was facilitated by a shorter distance to the ocean.

“It would have been a very difficult and major engineering task to lift all that equipment up over the cliff,” says Masatoshi Toyota, 88 years old, the former top Tepco executive who helped oversee the building of the reactors at Fukushima Daiichi. “For similar reasons, we figured it would have been a major endeavor to pump up seawater from a plateau 35 meters above sea level,” he said in a telephone interview.

To this day, Tepco doesn’t consider that method of construction to be inherently flawed, noting that, before March 11, there were no records of major tsunami hitting in the immediate vicinity of the town where the plant was located in at least 300 years.

“The plant met all government standards at the time of its construction,” said Mr. Hasegawa, the Tepco spokesman.

But critics say that reflects a certain arrogance by the engineers involved at the time. “Of course there is no record of big tsunami damage there because there was a high cliff at the very same spot” to prevent it, said Mr. Oike, the seismologist on the investigation committee.

And Daiichi’s lower elevation contrasted with plants that were built in the following years along the same coast.

The newer Fukushima Daini plant, where construction began in 1975, is located seven miles south of Daiichi, and stands three meters higher: at 13 meters above sea level. The size of the tsunami that struck there on March 11 measured from 6.5 to 7 meters, Tepco said in an April 9 report.

Tepco officials said the Daini plant was not built at the higher elevation out of acute fear of tsunami, but rather that the elevation was a feature of the land that the plant was built upon.

But the Onagawa site, 60 miles north of Daiichi, was selected in large part because of its height beyond the reach of any recorded tsunami, according to a former executive at a Japanese manufacturer involved in the work.

The reactors stand at 13.8 meters above sea level, according to plant operator Tohoku Electric Power Co., which started construction in 1980. The March tsunami reached 13 meters in Onagawa, according to an April 7 report from the utility. The Onagawa plant’s construction permit specified a minimum height of 9.1 meters above sea level, according to the Japanese government’s official June 7 report to the International Atomic Energy Agency.

Yet in 2002, the Japan Society of Civil Engineers calculated a tsunami risk near the Onagawa plant of 13.6 meters based on a magnitude 8.3 earthquake in 1896, the Japanese government report said. The foresight to build higher than required by permit proved to be a critical distinction with the Daiichi plant.

Another Tohoku Electric’s dated April 7 states the lower floors of the building housing Onagawa’s reactors were constructed below ground level to reach the bedrock, thus retaining much of the natural seawall for protection instead of shearing the wall away.

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