Chubu Electric Power Co. on April 28 disclosed a plan to resume by July the operation of the No. 3 reactor in its Hamaoka nuclear power plant in Shizuoka Prefecture. The reactor has been under regular check and observation since November 2010. The plant sits inside a zone where a magnitude-8 earthquake — referred to as the Tokai Earthquake — is expected to occur with high probability.

In view of the Fukushima nuclear power plant accidents, the firm should rethink its plan. Chubu had assumed that the quake would cause a tsunami up to 8.3 meters high. After the Fukushima accidents occurred, it announced that it will build a bulwark 15 meters or more in height from sea level behind a 10-to-15-meter high dune facing the sea and lying in front of the plant, Chubu’s only nuclear power station.

Chubu president Akihisa Mizuno says that the plant is sufficiently safe. One cannot but see he is overconfident. One question is whether the bulwark can withstand a tsunami.

Also a tsunami could hit the plant from two rivers flowing on either side of it. The fact remains that the Hamaoka plant, which has five reactors, sits above a fault that could cause a major quake.

Strong tremors may make it difficult to insert control rods into reactor cores or may break pipes necessary in cooling the reactors.

Mr. Katsuhiko Ishibashi, a seismologist, says that if the Tokai Earthquake occurs, the site of the plant will rise one to two meters, making the site uneven. This may destroy the bulwark.

In addition, the plant currently has no emergency power sources that can sufficiently cool the reactors in the event of a major accident. Under a simulation, if a large amount of radioactive materials is released from the plant, they will reach Tokyo in about half a day.

Chubu plans to increase the nuclear share of its power generation from less than 20 percent at present to 50 to 60 percent. This plan represents an effort toward an undesirable goal. The government should quickly adopt a policy of encouraging the creation of a low-energy-use society that will use safe, renewable energy sources while reducing dependency on nuclear power, although it may take long-term efforts.

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