Thursday, July 19, 2012

Reactor 4 at the Oi nuclear plant in Fukui Prefecture was reactivated Wednesday night and became the second to be restarted since the Fukushima nuclear crisis began in March 2011.

The reactor, capable of generating 1.18 million kw, is scheduled to begin transmitting power Saturday and commence full operation July 25, further easing power constraints in western Japan.

Kansai Electric Power Co. reactivated the plant's reactor 3 on July 1 and brought it to full operation July 9, prompting the government to lower summer power-saving targets for the service areas of four power suppliers in western Japan.

When reactor 4 begins full operation, the government plans to remove power-saving targets for Chubu Electric Power, Hokuriku Electric Power and Chugoku Electric Power, while further easing the target for Shikoku Electric Power from 7 percent to 5 percent. However, it intends to maintain the 10 percent target — recently reduced from 15 percent — for Kansai Electric.

Reactor 4 was idled July 22, 2011, for regular inspections and maintenance. It also had to pass disaster-stress tests introduced in light of the Fukushima crisis.

As was the case with reactor 3, Seishu Makino, senior vice minister of economy, trade and industry, observed unit 4's restart as part of the government's efforts to enhance monitoring to ease the public outcry over the Fukushima nuclear crisis.

Meanwhile, investigations into fault fracture zones, or soft layers also known as crushed zones, running under the Oi plant appear unavoidable after several members of an expert panel of the Nuclear and Industrial Safety Agency pointed Tuesday to the risk they pose.

Experts, including Toyo University professor Mitsuhisa Watanabe, said in June that the zones could move the surface of the ground by acting together with nearby active faults.

"We will immediately study countermeasures as experts' views are extremely important," a NISA official said.

But Kepco was more reserved. "We will make studies based on (experts') views," an official with the utility said.

The conflicting responses appeared to puzzle Oi residents.

"When building a nuclear power plant there, it must have been determined after consultations with experts that there was no problem," said a local business owner. "It is difficult to understand why they are saying now that another investigation is necessary."

Members of the NISA panel also called for investigations into Hokuriku Electric Power Co.'s Shika plant in Ishikawa Prefecture due to the possibility of active faults under the now-idled plant's reactor 1.

In a related development, a group of residents of Kyoto and Shiga prefectures presented the Cabinet Office and METI with around 23,000 signatures calling for the government to rescind its decision to allow the two reactors at the Oi plant to restart.

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