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 gigantic earthquakes.

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 vulnerable.

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 are safe?

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.

Obsolete Plants

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.