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Editorial: Grave concerns remain over restart of Ikata nuclear plant

Shikoku Electric Power Co. has restarted the No. 3 reactor at its Ikata Nuclear Power Plant in Ikata, Ehime Prefecture, and begun generating and transmitting electric power. It is the fifth reactor that has been reactivated after passing safety screenings by the Nuclear Regulation Authority (NRA) -- following the No. 1 and 2 reactors at Kyushu Electric Power Co.'s Sendai plant in Kagoshima Prefecture and the No. 3 and 4 reactors at Kansai Electric Power Co.'s Takahama plant in Fukui Prefecture.

Ehime Gov. Tokihiro Nakamura told a news conference, "The best possible safety measures have been taken at the plant. An accident similar to that in Fukushima will never happen." His remarks appear to signify that the myth of the infallible safety of atomic power stations, which had been prevalent in the electric power industry and the government until the outbreak of the Fukushima nuclear crisis in March 2011, have been revived.

In particular, serious concerns remain about the Ikata plant from the viewpoint of preventing a nuclear disaster.

The biggest problem is that the power station is situated at the base of the Sadamisaki Peninsula, which is 40 kilometers long from east to west and about 800 meters wide at its narrowest location. Approximately 4,700 people live in areas west of the nuclear plant, but should a nuclear accident occur at the station, the escape route for local residents could be blocked.

Moreover, the median tectonic line fault, one of Japan's largest active faults, is situated only about 6 to 8 kilometers off the nuclear plant. A powerful Nankai Trough quake is feared to hit Shikoku Island where the power station is located. A complex disaster of a powerful earthquake and a nuclear accident could happen. The ground in some areas of the Sadamisaki Peninsula is fragile.

Under evacuation plans worked out by the prefectural and municipal governments, residents of areas west of the plant would escape from the peninsula in cars or boats if a nuclear accident were to occur.

However, if a complex disaster were to hit the peninsula, there are fears that residents might not be able to flee by land or sea. In such a situation, residents would be required to stay indoors at home or in evacuation shelters to avoid being exposed to radiation.

However, if the area were to be hit twice by a temblor registering 7 on the 7-point Japanese intensity scale just like in the Kumamoto Earthquake, it would be difficult to continue staying indoors.

Public evacuation shelters are not absolutely safe. There are seven radiation proof facilities in the town of Ikata. However, four of them are located in landslide caution zones.

The Ikata plant is Japan's only nuclear plant using mixed oxide (MOX)-fuel consisting of plutonium and uranium since operations at the Takahama Nuclear Power Plant have been suspended in response to a court order. It has been pointed out that MOX-fuel makes control rods more ineffective than conventional nuclear fuel. Furthermore, specifically how to dispose of spent MOX-fuel has not yet been determined.

Local bodies hosting nuclear plants are obligated to work out evacuation plans for local residents in case of a nuclear accident. Even if such plans are inadequate, the NRA still approves reactivation of nuclear plants because such plans are neither subject to screening by the NRA nor a precondition for restarting atomic power stations. A system under which a third-party organization would check the efficacy of evacuation plans before restarting nuclear plants needs to be established.

Shikoku Electric Power estimates that the operation of Ikata plant's No. 3 reactor will increase the company's annual profits by some 25 billion yen. However, power companies across the country have leeway to supply electricity to households and businesses this summer. There is no need to make haste to restart idled nuclear plants from the viewpoint of ensuring a stable supply of electric power.

The government and power companies' attempts to rely on nuclear plants while indefinitely postponing countermeasures against a possible complex disaster are unacceptable.

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