A Dangerous Mix: Earthquakes and Nuclear Power Plants
By Mari Takenouchi
1961: A Confidential Document
In 1961, at the request of the Science and Technology Agency,
the Japan Nuclear Industry Committee came up with a report
called "The Possibility of a Nuclear Power Plant Accident
and the Ensuing Damage". The damage estimate was calculated
based on a power plant with an output of 160,000 kW, approximately
one-sixth of the output of the average plant today. It is
based on the assumption that 10 million curies, or 2% of the
radioactive materials, would be emitted into the environment.
This is approximately one thirtieth of the Chernobyl disaster.
If such an accident happened on a rainy day in Tokaimura,
where the criticality accident took place in September of
1999, 100,000 people would have to permanently leave their
homes. A total of 17.6 million would have to be temporarily
evacuated from cities and villages. Forty percent of the land
would have to be restricted from agricultural use at least
for one year. The estimated total amount of damage in the
report was 3.7 trillion yen (roughly $37 billion dollars),
more than double the national budget in those days. Yet, this
amount was greatly underestimated. It assumed that just 850,000
yen (US$8,500) would be paid for each death, and consideration
was only given to acute patients. All later health hazards,
such as cancer and leukemia, were ignored.
The 224-page text, from 1961, was kept confidential until
last year, with the exception of the 18-page summary that
did not include the maximum estimate of damage. The original
reason for preparing the report was to pass a law to ensure
coverage for compensation, using the national budget to protect
the industry, in case of a major nuclear accident. They needed
an estimate of the damage that might be caused by a nuclear
accident in order to pass the act.
In 1957, the United Kingdom, which has exported the Tokai
nuclear power plant for Tokaimura, announced that it could
not take responsibility for any nuclear power plant accidents,
due to faults with the technology. Lloyds of London, the famous
insurance company, also refused to cover Japanese nuclear
power plant in consideration of the possibility of a massive
earthquake. The Japanese government did not respond by giving
up the idea of promoting nuclear energy, however. Instead,
it decided to come up with alternative measures to promote
and protect the industry. This was the Atomic Energy Compensation
Act, which was adopted by the Diet in 1961. The Diet members
of the day carried out their deliberations based on the secret
document. According to the minutes, opinions were expressed
such as, "I do not think there is any place where we can build
nuclear power plants in this earthquake-prone country." "What
shall we do with the waste, and how shall we decommission
the plants?" "There aren't any permissible dose of radiation,
are there?" They were asking exactly the same questions as
people are asking today. They knew all this from the beginning.
Amazingly, however, the Act was adopted unanimously after
just two months.
A Deadly Mix
What if a nuclear power plant accident were to be caused
by an earthquake? The consequences would be truly catastrophic.
First of all, the evacuation of residents would be very difficult
and rescue operations would be made almost impossible because
of the high level of radioactive contamination. Thus, the
disaster site would have to be abandoned, and an uncountable
number of people would lose their lives right after the accident,
and for many years to follow.
Professor Ishibashi Katsuhiko of Kobe University has been
warning of this deadly mix for the last three years. He is
a renowned seismologist, who at the young age of 32 established
the Great Tokai Earthquake Theory. In 1994 he wrote Daichi-doran
no jidai (The Era of the Raging Earth), based on a theory
that was bashed as being too extreme at the time. His theory
was redeemed five month later, in the 1995 Great Hanshin Earthquake,
which left more than 6,000 dead.
Ishibashi points out that the study of earthquakes is not
a fully mature science even now and we should not underestimate
the possibility of disasters. But ignoring his warnings, the
government insists that all Japan's nuclear power plants are
safe, as they are in compliance with the earthquake resistance
guideline for nuclear facilities. But for two major reasons,
it is clear that the government estimate is far too optimistic.
The first problem derives from defects in the guideline itself,
in consideration of modern seismologic theory, and the second
problem involves safety concerns over nuclear power plant
construction, based on the opinion of a nuclear power plant
construction supervisor with more than 20 years of experience.
Obsolete Seismologic Theory
The government guideline calls for plants to be able to
withstand a magnitude 6.5-class earthquake with the epicenter
directly under the plant. This magnitude is calculated in
consideration of the length of active faults and their distance
from the power plant. However, active faults alone are not
always indicators of imminent earthquakes; thus it is obvious
that there is a big gap between the government's way of earthquake
"prediction" and modern seismologic studies.
Active Faults-the Imperfect Indicator of Earthquakes
The entire Japanese archipelago is prone to large-scale
earthquakes, regardless of whether there are active faults
in the specific location or not. Active faults are sometimes
invisible. When an earthquake takes place with a very deep
epicenter, active faults are not visible on the surface. Not
only this, but if there has been a long time span between
the last major earthquake in a specific region, active faults
can be hidden due to land erosion. The government guideline,
however, only takes into consideration active faults that
are younger than 50 thousand years. This is an unrealistic
assumption. In 1945, a magnitude 6.8 earthquake struck Mikawa
(Aichi prefecture) with an active fault that was more than
50,000 years old. It left 1,961 dead.
There are many examples of earthquakes striking areas without
any visible active faults: the M 7.3 Kita-tanba (northern
Kyoto) earthquake of 1927, which left 2,925 dead, and the
1943 M 7.2 Tottori earthquake, which left a death toll of
1,083. It is common knowledge in modern seismology that M7
class earthquake can occur even in places where no active
faults are visible.
"Genpatsu Ginza" on the Mobile Belt and the Underestimate
of Active Faults
Given this reality, locations even with small active faults
need to be monitored extra caution. This includes the areas
of "concentrations of nuclear power plants." (They are called
"Genpatsu Ginza" in Japan. "Genpatsu" is the word for nuclear
plants, and Ginza is a section of Tokyo that is crowded with
restaurants and shops.) These areas include Fukui, with its
15 plants, Niigata with seven plants, and Shimane with two.
Given the possibility of a major earthquake being triggered
by the simultaneous effects of multiple active faults joined
together, as has often been the case, these areas are clearly
vulnerable to massive earthquakes.
Experts say that the coastal area of the Sea of Japan (where
many nuclear power plants are located) is a mobile belt where
crustal strain occurs rather slowly, and where major earthquakes
come after long intervals of time. And this mobile belt is
now entering a stage of increased activity. Accordingly, nuclear
sites even in coastal areas without any recent record of big
earthquakes can also be in great danger. This means that Niigata,
Fukui, and Shimane are in a perilous situation.
Lawsuit in Shimane
Another important issue regarding active faults is that
their lengths, which are often taken as an indicator of possible
damage, do not necessarily reflect the actual sizes of earthquake
faults. In the case of the 1943 Tottori Earthquake which left
1,083 dead, the length of the earthquake source fault plane
was about 35 km. The scale of the earthquake was M7.2. However
the length of the registered active fault was only 8 km, in
accordance with visual observations made in 1998. This active
fault is situated within 3 km of two of the nuclear power
plants located in Shimane. However, the maximum assumption
of an earthquake scale is M6.5, with an epicenter directly
below. A lawsuit has now been launched by citizens' groups
to prevent the construction of a third power plant on the
site, given the danger of the possible occurrence of an earthquake.
Professor Ishibashi may not be a prophet, but his theories
are consistently vindicated. He warned that a major earthquake,
greater than M7, could lead to devastation at the Shimane
plants. His theory was actually shown to be true on October
6, when a M7.3 class earthquake took place in Tottori, next
to Shimane prefecture, and just 45 km away from the Shimane
nuclear power plants. There were no visible active faults
above the epicenter. Due to extraordinary luck, no damage
as reported at the Shimane nuclear reactors. They had been
shut down for annual check-ups. But who can guarantee that
there will be no catastrophe triggered by a massive earthquake
in this area?
Established Theory: The Slab Earthquake
Another recent theory that has been totally ignored in the
government's guidelines concerns a type of earthquake called
a "slab earthquake." A slab is the section of an oceanic tectonic
plate that has been subducted beneath a continental plate
and is dipping toward the earth's interior. Many earthquakes
take place in these slabs, ranging from small to big. Recently,
there has been a slew of earthquakes, ranging up to magnitudes
of greater than 7.8, with epicenters at depths of between
40 to 100 km. These have included the M7.8 Kushiro-oki earthquake
of 1993, the M8.1 Guam earthquake in the same year, and the
M8.1 Hokkaido Toho-oki Earthquake of 1994. But the mechanisms
of this type of earthquake are yet to be fully explained.
Of course, no active faults appear in this type of quake.
The Science and Technology Agency is aware of the possibility
of this kind of earthquake, and published a pamphlet including
the theory, called "an earthquake within the oceanic plate,"
indicating nearly the same theory under different name. But
the Agency does not consider this theory when it comes to
the construction of nuclear power plants. Nuclear sites such
as Onagawa in Miyagi, Fukushima, Tokai in Ibaragi, and Rokkasho
in Aomori, which are along the Pacific Ocean Slab, and Ikata
in Ehime on the Philippine Slab, are vulnerable to potential
Great Danger at Hamaoka
In the case of the Hamaoka nuclear power plants in Shizuoka,
seismologists say that a big earthquake could hit at any time.
Hamaoka now has four nuclear power plants in operation, with
a total output of 3.6 million kW. In 1971 and 1974, construction
began on two nuclear power plants, just before the modern
theory of seismologic activity in this area, regarding the
occurrence of the so-called "Tokai Earthquake," was developed
in 1976 by Professor Ishibashi. The young researcher's theory
carried substantiating data, and gained the acknowledgement
of mainstream seismological experts. Based on his theory,
the "Great Earthquake Law" was legislated in 1978. According
to this theory, a magnitude 8-class earthquake could take
place at any time in the area around the Hamaoka nuclear power
plants, which are situated in the boundary of the Eurasian
(Amurian) Plate and the Philippine Sea plate.
There are two factors that make the situation even graver
and more complicated. The first is the possibility of the
simultaneous occurrence of several major earthquakes, an event
caused by an uneven destruction of gaps on the major fault
plane of the plate boundary. A multiple epicenter-quake of
this kind would generate short-cycled but strong motion, to
which solid structures such as nuclear power plants are very
The second factor is the transmission of movement to small
branch faults in the shallow area caused by the destructive
slip of the major fault plane of the plate boundary. Geologically,
the area is made up of sedimentary rocks that are rather soft
and have many small branch faults. Depending on the location,
these branch faults can bring devastating earthquakes to nuclear
power plant sites, with the epicenter directly below them.
This would result in even larger-scale motion and land upheaval.
In fact, these small branch faults caused the Ansei-Tokai
Earthquake of 1854, which had aftershocks with magnitudes
of 7 to 7.5. In this type of earthquake, again, the existence
of active faults is no indication of what will happen.
The assumed maximum acceleration of earthquakes for nuclear
power plant construction in Japan is estimated at just between
380 to 600 gals, a measurement used to measure the acceleration
of movement. However, in the 1995 Great Hanshin Earthquake,
the maximum acceleration in some areas was measured at more
than 800 gals! Takagi Jinzaburo, the late chairman of the
Citizens' Nuclear Information Center, and Japan's most renowned
nuclear power plants expert, wrote in his book that, "When
I saw this number in the newspaper after the Hanshin Earthquake,
I became speechless with fear." Who could possibly guarantee
that same type of motion would not strike a nuclear power
plants sites in the future?
These factors clearly show how obsolete and imperfect the
government guideline is for the construction of nuclear power
plants, in the light of modern seismology. It is improbable
to assume that all of the 53 nuclear power plants along the
coasts of Japan will be miraculously spared from major earthquakes
in the future.
The 1995 Great Hanshin Earthquake
Before the 1995 Great Hanshin Earthquake, people generally
believed that important facilities, such as nuclear power
plants, high-speed rail lines and expressways, were totally
safe because they were built and checked in accordance with
strict government regulations. But this belief turned out
to be unfounded. After the Hanshin Earthquake, it was revealed
that a concrete support pillar on the Shinkansen (bullet train)
rail line contained a molded block of wood chips. It was also
found that the welding seams on one of the steel supports
of an expressway were so badly deteriorated that all the welded
parts had come off. How could something like these happen?
If this was the reality for these important facilities, can
it really be said that all Japan's nuclear power facilities
A Voice from Insider
According to the late Hirai Norio, a piping specialist and
supervisor for nuclear power plant construction for 20 years,
the earthquake resistance of nuclear power plants is very
much in doubt. He pointed out various types of dangers, based
on his many years of work and empirical knowledge. Hirai wrote
that the basic cause of the weakness of these important infrastructures,
which seem to be earthquake resistant, is that there is a
lot of emphasis on the planning stage, but that not enough
attention is given to the actual construction process. He
further stressed that the same thing could be applied to the
construction of nuclear power plants.
Designed by Professionals, Built by Amateurs
Even when the design and blueprints are perfect, things
cannot be done well if there are not enough professionals
on the site. With regard to nuclear power plant construction
sites, there is almost no discussion of what kinds of people
are doing the actual work. Advertisements are run in newspapers
recruiting people who have no experience at all. Many seasonal
workers, whose main jobs are in agriculture or fishery, and
sometimes even homeless people, are hired.
In fact, there are many cases of human errors in nuclear
power plant construction. In one incredible incident, a worker
dropped a piece of wire into a Fukushima nuclear reactor,
but the person who dropped the wire did not inform anybody
of it. The reactor had been operated with the wire inside,
which could have lead to a Chernobyl class accident. The person
who dropped the wire had no recognition what kind of trouble
it could have caused. The same mechanism was embodied in the
JCO accident. There have been other cases where tools have
been left in the piping systems of nuclear power plants.
Experts will respond by saying that if they conduct inspections
properly after the construction, there is not great concern.
This is wrong. Many of the inspectors are unprofessionals,
assigned from governmental offices, and they only check the
documents and finished products. But this is inadequate. If
welding on the product needs to be checked, the process of
welding should be observed, not the finished products. Checking
the documents has little value at all.
Nuclear power plants are only inspected on a regular basis
approximately once every year, which is again quite unreliable.
This type of work involves radioactive contamination, so experienced
workers, who are exposed to their permissible doses during
the year, are not used. As a consequence, unskilled workers
end up taking these skilled workers' jobs. But it is difficult
to hand down the technical skills from professionals to laymen,
showing the detailed process of works. A great number of workers
who perform inspections are not professionals. Even for experts,
it is very difficult to do a good job wearing protection suits,
masks and alarm bells. Nuclear power plants are very unique
job sites, even for workers.
Hirai gave one example of how such a process could go wrong.
Once, a loose screw was found in a nuclear reactor. The screw
was placed in a highly radioactive place. Thirty workers were
called up, and they lined up to dash to the location, seven
meters away from the door, and turn the screw. But their alarm
bells would go off within 3 seconds. In the end, 160 people
worked to tighten the one screw, at a cost of 4 million yen
(40,000 dollars). During the operation, they didn't stop the
operation of the reactor, since that would have cost much
more: hundreds of million yen (some million dollars).
The Piping System-a Source of Danger
Nuclear power plants are truly fearsome installation. Each
has a network of several thousands of pipes and connections,
and every one of these connections is vital to the operation
of the plant. The total length of the pipes amounts to 80
km. The electric wires stretch to 1,440 km. There are 25,000
welded joints, and including screws and bolts, 100,000.
Recently, there was an accident at a Fukushima nuclear power
plant. A screw joint part of a pipe was broken, and radioactive
gas was leaked. This was caused by an earthquake that measured
just 4 on the Japanese scale - a moderate size - and with
its epicenter 100 km away. This accident is quite significant
when we think of the danger of a nuclear disaster caused by
an earthquake, because a major accident could be caused by
the breakage of a single pipe joint.
There is another scary example of the danger of a joint
breakage at a nuclear power plant in Fukui. In 1991, there
was an accident in Mihama plant, where a Chernobyl class disaster
nearly took place because of a broken heat-transfer tube.
Fortunately, although it was on the weekend, an experienced
worker was on duty. He turned off the reactor manually, using
the ECCS (emergency core cooling system). The ECCS is the
very last mean to stop the occurrence of serious accident,
and is only used when all the other safeguards have failed.
It is said that if he had waited 0.7 seconds longer, Mihama
would have become the world's second Chernobyl.
There is another case where the piping system didn't fit
well. This was the notorious Monju fast breeder reactor. When
Mr. Hirai checked the piping system, he found that different
manufactures, such as Hitachi, Mitsubishi, and Toshiba, had
provided the parts. These manufacturers had used different
design standards. For example, Hitachi was rounding down 0.5
mm, while Toshiba and Hitachi were rounding up 0.5 mm. Though
each deviation is very small, collectively the gaps can become
huge, In many cases different companies fail to communicate
adequately with each other in order to keep industrial secrets.
The scariest thing, on top of all the other problems, is
that all nuclear power plants are aging, causing a deterioration
of these piping and joints parts, which are always exposed
to strong radiation and heat. The number of accidents is increasing
year by year. But in spite of this, the durations of annual
check-ups are being cut, and the procedures simplified, due
to economical reasons. This is another deadly mix. There were
67 reported accidents last year alone in Japan.
Considering these factors, nuclear catastrophe is not an
unrealistic prospect. If we think seriously about the grave
consequences, nuclear power plants and related facilities
should be phased out as soon as possible. We should stop building
more plants and facilities. For the existing ones, we should
evaluate the potential danger of each site, and stop operations
in accordance with priority. People should be informed of
these dangers, and be provided measures for disaster prevention
for a catastrophe that might take place even tomorrow. Otherwise,
we might experience another radioactive catastrophe, like
Hiroshima and Nagasaki. Only this time, it will be in the
name of the "peaceful use" of nuclear power.