June 5, 2002
By Kiyoo Mogi
(The former professor
at Tokyo University, the former chairman of Earthquake Prediction
Committee and Coordination Committee for Earthquake Prediction)
Power Plant Safety in View of Earthquake
Water leak accident at
Hamaoka Unit 2
At a little
over 2:00 am on May 25, a radioactive water leak was found
in the ECCS system at Hamaoka Unit 2 in Shizuoka prefecture,
resulting in the shutdown of the plant.
1 started its operation in 1976, and Unit 2 in 1978. Last
November, the operation of Unit 1 was suspended due to its
two accidents-pipe rupture caused by hydrogen explosion and
water leak from its reactor vessel. Following these accidents,
Unit 2, which has the same structure as Unit 1, had its operation
suspended and safety measures were implemented such as installing
valves on some pipes.
Since the Unit
1 accident, I have written three editorials, explaining how
risky it would be to have Hamaoka nuclear power plants being
constructed and operate. Since 1969, the seismologists have
been pointing out that a M8 earthquake could occur in Tokai
area (200km west of Tokyo). Consequently, the government enacted
a bill called Special Countermeasures on the Large Scale Earthquake
Act, and has established the Earthquake Prediction Committee.
I pointed out the danger of the Tokai Earthquake for the first
time in 1969, and since then, I have been working for the
mitigation of disasters to be caused by the Tokai Earthquake.
I had been a committee member of Earthquake Prediction Committee,
and the chairperson of the same committee, and become the
chairman of the Coordination Committee
for Earthquake Prediction.
However, Hamaoka nuclear
power plants are located in the very center of the earthquake
source region, and furthermore, the Unit 5 is still under
construction. It has been 30 years since the Great Tokai Earthquake
issue was announced for the first time. In the latter half
of these 30 years, I have been tackling this issue as an executive
member. Yet, the Chubu Electric Company has never sought for
my opinion regarding the siting or safety of the nuclear power
plants even for a single time.
There are many
nuclear power plants in the world, and most of them are in
advanced nations. The US is on the top, followed by France,
Japan, and Germany. However, most nuclear power plants are
in western nations. Japan, Korea, etc are exceptions. When
we take a look at the earthquakes more than M7 in the world
in this 100 years, there have been almost no earthquakes in
western nations with a number of nuclear power plants, and
thus, we can see that their lands are very stable. Even in
Korea, there is almost no prominent earthquake in modern age.
Overall Review is Necessary
other nations in the world, Japan is unique. Japan has the
third largest number of nuclear power plants in the world
and at the same time, it has seen a number of M7 or more earthquakes
occurring in such a small area. Moreover, there is no nation
that has four nuclear power plants on the middle of a region
where M8 (30 times more than M7 in energy level) earthquake
is predicted. It is simply ghastly.
I hear opinions
stating that there is no danger because of measures implemented
for earthquake resistance on nuclear power plants. I do not
understand why anybody can ensure such a theory. A Nuclear
power plant has a complex structure, which contains many weak
parts in regard to their strength. In the past, the earthquake
resistance standards have been revised each time unexpected
things took place. Nuclear power plant safety is no exception.
These are the
reasons why I insisted that a drastic review should be conducted
on Hamaoka nuclear power plants after the Unit 1 accident.
However, Chubu Electric did not listen to such kind of voices,
and resumed the Unit 2 operation only within six months after
the Unit 1 accident.
Nuclear and Industry Safety (ANIS) in Ministry of Economy,
Industry and Trade (METI) gave the approval on the inspection
result of the Unit 2, to which Hamaoka town and Shizuoka prefecture
were made to agree. It is not a surprising thing that voices
of criticism are gathering to Chubu Electric and ANIS after
the accident of Unit 2. In the worst case, an accident in
Hamaoka would affect almost all the areas of mainland Japan.
I would like to stress repeatedly, that Hamaoka issue needs
a drastic review from a wide point of view.