Quake-hit nuclear plant shut down indefinitely

It may be on a major fault line, say experts

PHOTO: Toyko Electric Power Co.

19 July 2007—Three days after a deadly earthquake damaged the world’s most powerful nuclear complex, the woes for operator Tokyo Electric Power Co. (TEPCO) continue to multiply after experts determined that the Kashiwazaki Kariwa facility—about 200 kilometers north of Tokyo—may be located on a previously undetected extension of a major fault line. After reviewing the extent of the damage to the plant—some 50 separate incidents—the mayor of Kashiwazaki City, near where the plant is located in Niigata Prefecture, on the coast of the Sea of Japan, ordered a complete shutdown of the entire facility until its safety can be assured.

TEPCO officials estimate it could take until the end of August to repair the damage and carry out safety checks. But then the power company will have to convince authorities that the facility is safe to operate—no easy task when experts from the Japan Meteorological Agency are now saying the plant may be in an active part of the region’s earthquake zone.

At a press briefing Wednesday, Akira Fukushima, deputy director general for safety examinations at Japan’s Nuclear and Industrial Safety Agency, said: ”Because the earthquake was of a scale larger than the facility was built to withstand, the minister [of the Ministry of Economy, Trade, and Industry; METI] has directed that operation of the reactors not begin until their safety is assured.” He added that last September the Nuclear Safety Commission revised its guidelines for plant design, and TEPCO will have to take these new standards into consideration.

The facility was built to withstand a magnitude of 6.6, considerably lower than the 6.8-magnitude earthquake that struck at 10:13 Monday morning, killing 10 people and leaving scores of thousands without electricity and water. Given that magnitude is based on a base-10 logarithmic scale, a 0.2 increase represents a 200 percent jump in the amplitude of the earthquake’s vibrations and a greater than 600 percent increase in the energy released. So major structural reinforcements may be required to ensure the plant’s safety.

Meanwhile, TEPCO has come under strong criticism from authorities and growing anger from the local inhabitants after it was revealed that TEPCO bungled efforts to deal with the damage. It initially underreported the extent of the problems and delayed making its findings known.

Chief among the criticisms were TEPCO’s inability to deal with a fire in a power transformer outside one of the reactors and the late discovery that coolant containing a small amount of radioactive material had spilled and found its way into the sea. In addition, the utility initially reported that the quake had knocked over 100 barrels of low-level radioactive waste; the number was eventually found to be 400, and among those some 40 barrels had their lids dislodged. TEPCO says that because so many troubles arose simultaneously when the quake hit, it didn’t have the personnel to deal with all of them immediately and was also unable to inform authorities as quickly as it should have.

On a more positive note, four of the seven reactors in use at the time of the earthquake shut down automatically when the first tremors were felt; the other three reactors were already closed for maintenance. Both TEPCO and METI also say that the amounts of radioactive material that escaped had negligible impact on the environment. That hasn’t stopped hundreds of worried summer vacationers from canceling hotel reservations in the area, though.

Summer is the time of peak power demand, so TEPCO is planning to start up a number of fossil-fuel power stations not currently in operation to help cover the shortfall left by the closure of the 8.21 gigawatt complex. TEPCO is also asking six other regional power suppliers to provide it with electricity from their systems to help the area get through the hottest weeks.

For more about earthquakes in Japan

When the next big earthquake hits Tokyo, engineers bet even a few seconds can save lives, see ”How to Master a Seismic Disaster.”

The Japan Meteorological Agency is responsible for tracking earthquakes and other natural disasters in and around Japan. On its Web site, you can see a plot of earthquakes that have occurred there during the past week: http://www.seisvol.kishou.go.jp/eq/weekly_map/japan/weekly.shtml.

For a more global view, see the U.S. Geological Survey's weekly worldwide map of earthquakes. It shows disturbances with magnitudes of 4.0 or greater (or 2.5 or greater within the United States and adjacent areas): http://earthquake.usgs.gov/eqcenter/recenteqsww.

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