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2011年4月17日 (日)

地震国の原発 政策の大転換を図れ

(Mainichi Japan) April 16, 2011
Japan should change energy policy following nuclear power plant crisis
社説:震災後 地震国の原発 政策の大転換を図れ

Events that have occurred since the March 11 Great East Japan Earthquake have reminded us of the reality Japan faces -- another powerful earthquake could occur anytime and anywhere, and we have no way to predict it.



Fifty-four nuclear reactors are situated in coastal areas of Japan. Many experts have repeatedly pointed out how difficult it is to ensure the safety of nuclear power plants in this earthquake-prone country.

Some scientists had predicted that radiation could leak from a nuclear power plant if it was damaged by a powerful quake and ensuing tsunami. One of them, Kobe University professor emeritus Katsuhiko Ishibashi, called such a potential accident an "earthquake-triggered nuclear power plant disaster."

However, electric power suppliers as well as the government had dismissed such warnings as a "minority opinion." The consequences of this attitude are the serious crisis at the crippled Fukushima No. 1 Nuclear Power Plant operated by Tokyo Electric Power Co. (TEPCO).


The distortion of the earth's crust caused by the powerful quake has had a huge impact on various areas of Japan. No optimism can be justified for future seismic activity in the Japanese archipelago.

The government has no choice but to seriously consider whether quake-prone Japan can coexist with nuclear power stations, take prompt countermeasures and drastically change its nuclear energy policy.

The biggest problem with nuclear power plants is their lack of measures against tsunami. Measures to protect nuclear plants from tsunami are incorporated in the government's guidelines for the quake-resistance of nuclear power plants that were revised in 2006, but priority has not been given to anti-tsunami measures. Moreover, power suppliers have been slow to re-examine their nuclear plants in accordance with the amended guidelines. TEPCO has not even completed its re-examination.

On the other hand, some electric power companies strengthened measures to protect their nuclear plants from tsunami following the Chuetsu Offshore Earthquake in Niigata Prefecture in 2007. One of them is the Tokai No. 2 Nuclear Power Plant in central Japan.

It is not permissible to conclude that the crisis at the Fukushima plant was caused by an unexpected massive tsunami.

TEPCO's responses to the crisis are highly questionable. TEPCO was unprepared for a situation in which all external power sources were lost and it became impossible to cool down nuclear reactors for a long time. This is despite the fact that following the 1979 crisis at the Three Mile Island nuclear power station in the United States, countermeasures against serious nuclear power plant accidents were worked out in Japan to cope with the possibility of more catastrophic nuclear plant disasters.

Initial responses to a nuclear power station accident are extremely crucial. Nevertheless, TEPCO was slow in introducing power-supply vehicles to the crippled plant, ventilating the reactors and pouring sea water into the reactors to cool them down. This shows that TEPCO was unprepared to implement serious accident countermeasures.

Power suppliers should put priority on securing electric power sources at their nuclear power stations in case of emergency. Guidelines for measures to protect nuclear plants from tsunami and their quake-resistance need to be promptly reviewed.

The government has also come under mounting pressure to review its regulations on nuclear power plants and the system to supervise them.

We have repeatedly pointed out that it is contradictory that the Nuclear and Industrial Safety Agency that regulates and supervises nuclear power plants comes under the umbrella of the Economy, Trade and Industry Ministry that is promoting nuclear power generation. The government's responses to the accident have illustrated this contradiction. Furthermore, the accident has called into question the raison d'etre of the Cabinet Office's Nuclear Safety Commission (NSC). The government should reorganize these bodies into a completely independent regulatory organization.

But the implementation of these measures alone is not enough.

Following the crisis at the Fukushima plant, NSC Chairman Haruki Madarame remarked, "Nuclear power stations can't be designed without discarding the potential for some problems, but the accident shows the way the potential problems were disregarded was wrong."

His remarks have raised questions as to whether a catastrophic accident can be prevented if problems are conveniently disregarded and whether it is enough to strengthen safety regulations, improve equipment and work out measures to respond to any emergency situation.

Both the government and power suppliers had emphasized for many years that nuclear power plants are safe because they are protected by multiple safety devices. However, the latest crisis has illustrated the fragileness of the multiple protective devices.

In other words, the accident has demonstrated that complete safety can not be achieved even if far more protective devices are installed at nuclear plants, and that serious accident countermeasures, implemented following the Three Mile Island disaster, have been unable to quickly bring the potential for nuclear disaster under control.


There are arguments that aircraft and trains pose similar safety risks. However, a catastrophic accident involving a nuclear power plant has a far more serious and far-reaching impact over a far lengthier period. The risks posed by the coexistence of unpredictable major earthquakes and nuclear power plants should not be tolerated.

Considering such risks, extreme prudence should be exercised in considering whether to resume the operations of other nuclear power plants in quake-hit areas, such as the Onagawa plant in Miyagi Prefecture. It will be almost impossible to build new nuclear power stations from now on.

Based on these realities, we recommend that Japan take the opportunity of the Fukushima disaster to launch efforts to decrease its reliance on nuclear power plants from a long-term perspective. It is unrealistic to simultaneously dismantle all the existing nuclear power plants. Rather, Japan should gradually decrease its reliance on nuclear power generation by prioritizing the dismantling of nuclear power plants that are considered more vulnerable to disasters.

Top priority should be placed on decommissioning the Hamaoka Nuclear Power Plant in Shizuoka Prefecture that sits just above the probable focus of a Tokai quake that is believed certain to occur sooner or later.

In the latest disaster, the focus of several quakes simultaneously moved and caused a massive quake. The possibility cannot be ruled out that the focus of Tokai and Tonankai and Nankai earthquakes in central and western Japan will simultaneously move, causing a huge quake and tsunami.

Aging nuclear power plants are particularly vulnerable to earthquakes because the most advanced technology for ensuring safety of such power stations is not incorporated in them and the most advanced knowledge of seismology is not taken into account in their design.

Japan has relied on nuclear power generation for 30 percent of the total electric power consumed across the country. Many people think that nuclear power plants should be maintained as a stable source of electric power. Some have expressed concern that the Japanese economy could not survive without such power generators.

Still, we should understand that the "quake-triggered nuclear power plant disaster" occurred as a result of putting priority on the economy over safety. It is hoped that we will come up with ways to live affluent lives without relying on nuclear power plants even though the pros and cons of maintaining such plants should be decided by the whole nation.

The promotion of recyclable energy sources -- to which close attention is being paid as measures to prevent global warming -- and the achievement of a low-energy consumption society will be a key to breaking away from Japan's dependence on nuclear power. Now is the time for Japan to pursue electric power sources that are suitable for such an earthquake-prone country and adopt lifestyles that match the supply of electricity.

毎日新聞 2011年4月15日 0時07分


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