(Refiles to fix word in paragraph 59)
* Tokyo Electric ignored own study on tsunami risk
* Utility decided safety issues, not regulators
* Kept vulnerable vent systems despite quake data
* Tokyo Electric cited the most for safety violations
By Kevin Krolicki, Scott DiSavino and Taro Fuse
TOKYO, March 29 Over the past two weeks,
Japanese government officials and Tokyo Electric Power
executives have repeatedly described the deadly combination of
the most powerful quake in Japan's history and the massive
tsunami that followed as "soteigai," or beyond expectations.
When Tokyo Electric President Masataka Shimizu apologised to
the people of Japan for the continuing crisis at the Fukushima
Daiichi nuclear plant he called the double disaster "marvels of
nature . that we have never experienced before".
But a review of company and regulatory records shows that
Japan and its largest utility repeatedly downplayed dangers and
ignored warnings -- including a 2007 tsunami study from Tokyo
Electric Power Co's senior safety engineer.
"We still have the possibilities that the tsunami height
exceeds the determined design height due to the uncertainties
regarding the tsunami phenomenon," Tokyo Electric researchers
said in a report reviewed by Reuters.
The research paper concluded that there was a roughly 10
percent chance that a tsunami could test or overrun the defenses
of the Fukushima Daiichi nuclear power plant within a 50-year
span based on the most conservative assumptions.
But Tokyo Electric did nothing to change its safety planning
based on that study, which was presented at a nuclear
engineering conference in Miami in July 2007.
PDF of this special report: r.reuters.com/pum78r
Special Reports on Japan [ID:nL3E7EN0C6]
Latest news story [ID:nL3E7ET0PZ]
Graphic on nuclear crisis link.reuters.com/pek78r
Reactor graphic link.reuters.com/ram78r
Meanwhile, Japanese nuclear regulators clung to a model that
left crucial safety decisions in the hands of the utility that
ran the plant, according to regulatory records, officials and
Among examples of the failed opportunities to prepare for
disaster, Japanese nuclear regulators never demanded that Tokyo
Electric reassess its fundamental assumptions about earthquake
and tsunami risk for a nuclear plant built more than four
decades ago. In the 1990s, officials urged but did not require
that Tokyo Electric and other utilities shore up their system of
plant monitoring in the event of a crisis, the record shows.
Even though Japan's Nuclear and Industrial Safety Agency,
(NISA) one of the three government bodies charged with nuclear
safety, cataloged the damage to nuclear plant vent systems from
an earlier earthquake, it did not require those to be protected
against future disasters or hardened against explosions.
That marked a sharp break with safety practices put in place
in the United States in the 1980s after Three Mile Island, even
though Japan modeled its regulation on U.S. precedents and even
allowed utilities to use American disaster manuals in some
Ultimately, when the wave was crashing in, everything came
down to the ability of Tokyo Electric's front-line workers to
carry out disaster plans under intense pressure.
But even in normal operations, the regulatory record shows
Tokyo Electric had been cited for more dangerous operator errors
over the past five years than any other utility. In a separate
2008 case, it admitted that a 17-year-old worker had been hired
illegally as part of a safety inspection at Fukushima Daiichi.
"It's a bit strange for me that we have officials saying
this was outside expectations," said Hideaki Shiroyama, a
professor at the University of Tokyo who has studied nuclear
safety policy. "Unexpected things can happen. That's the world
we live in."
He added: "Both the regulators and TEPCO are trying to avoid
Najmedin Meshkati, a professor of civil and environmental
engineering at the University of Southern California, said the
government's approach of relying heavily on Tokyo Electric to do
the right thing largely on its own had clearly failed.
"The Japanese government is receiving some advice, but they
are relying on the already badly stretched resources of TEPCO to
handle this," said Meshkati, a researcher of the Chernobyl
disaster who has been critical of the company's safety record
before. "Time is not on our side."
The revelation that Tokyo Electric had put a number to the
possibility of a tsunami beyond the designed strength of its
Fukushima nuclear plant comes at a time when investor confidence
in the utility is in fast retreat.
Shares in the world's largest private utility have lost
almost three-fourth of their value -- $30 billion -- since the
March 11 earthquake pushed the Fukushima Daiichi nuclear plant
into crisis. Analysts see a chance the utility will be
nationalized by the Japanese government in the face of mounting
liability claims and growing public frustration.
AN 'EXTREMELY LOW' RISK
The tsunami research presented by a Tokyo Electric team led
by Toshiaki Sakai came on the first day of a three-day
conference in July 2007 organized by the International
Conference on Nuclear Engineering.
It represented the product of several years of work at
Japan's top utility, prompted by the 2004 earthquake off the
coast of Sumatra that had shaken the industry's accepted wisdom.
In that disaster, the tsunami that hit Indonesia and a dozen
other countries around the Indian Ocean also flooded a nuclear
power plant in southern India. That raised concerns in Tokyo
about the risk to Japan's 55 nuclear plants, many exposed to the
dangerous coast in order to have quick access to water for
Tokyo Electric's Fukushima Daiichi plant, some 240 km (150
miles) northeast of Tokyo, was a particular concern.
The 40-year-old nuclear complex was built near a quake zone
in the Pacific that had produced earthquakes of magnitude 8 or
higher four times in the past 400 years -- in 1896, 1793, 1677
and then in 1611, Tokyo Electric researchers had come to
Based on that history, Sakai, a senior safety manager at
Tokyo Electric, and his research team applied new science to a
simple question: What was the chance that an
earthquake-generated wave would hit Fukushima? More pressing,
what were the odds that it would be larger than the roughly
6-meter (20 feet) wall of water the plant had been designed to
The tsunami that crashed through the Fukushima plant on
March 11 was 14 meters high.
Sakai's team determined the Fukushima plant was dead certain
to be hit by a tsunami of one or two meters in a 50-year period.
They put the risk of a wave of 6 metres or more at around 10
percent over the same time span.
In other words, Tokyo Electric scientists realised as early
as 2007 that it was quite possible a giant wave would overwhelm
the sea walls and other defenses at Fukushima by surpassing
engineering assumptions behind the plant's design that date back
to the 1960s.
Company Vice President Sakae Muto said the utility had built
its Fukushima nuclear power plant "with a margin for error"
based on its assessment of the largest waves to hit the site in
That would have included the magnitude 9.5 Chile earthquake
in 1960 that killed 140 in Japan and generated a wave estimated
at near 6 meters, roughly in line with the plans for Fukushima
Daiichi a decade later.
"It's been pointed out by some that there could be a bigger
tsunami than we had planned for, but my understanding of the
situation is that there was no consensus among the experts,"
Muto said in response to a questi