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N-plant seismic data lost ; more radiation emitted

The Yomiuri Shimbun

Tokyo Electric Power Co. said Thursday that data was lost from 63 seismometers at the Kashiwazaki-Kariwa nuclear power plant in Niigata Prefecture following the Niigata Prefecture Chuetsu Offshore Earthquake that hit the facility Monday.

The company also said air containing radioactive substances was emitted from one of the reactors for two days.

These new revelations came after TEPCO was found to have committed various errors in its initial efforts to deal with problems arising from the effects of Monday’s earthquake. Among 97 seismometers at the power plant, TEPCO lost parts of data from 63 older types of seismometers, the company said.

The seismometers were supposed to constantly transmit data to Tokyo over phone lines, but the lines became overwhelmed immediately after the quake, and data were overwritten with a series of aftershocks before the previous transmissions were completed, it said. Up to 1-1/2 hours of data were lost from some of the devices.

Although data from 30 newer seismometers were transmitted during the initial quake, the loss of the other raw data may impact the investigation of the quake resistance security check, observers said.

Meanwhile, TEPCO said Thursday radioactive iodine had been emitted for two days until noon Wednesday from an exhaust fan at the plant’s No. 7 reactor.

After the plant stopped reactor operations, it failed to stop the fan on the turbine that generates electric power, and air containing radioactive substances was emitted from the turbine area, the company said.

There were no filters to eliminate radioactive substances in the pathway that connects the fan and the exhaust pipe, it said.

But the amount of the radiation was small and there is no danger to the environment or the residents in the area, it added.

The power plant stopped the fan on Wednesday, but it will not be known until Friday if the emission of the radioactive iodine was fully stopped.

TEPCO said it did not detect radiation around the plant, but the government said it will keep a closer watch on the facility.

The company also confirmed that water leaked again from a damaged part of an fire-extinguishing duct. The total number of problems and instances of damages has so far increased to 63, TEPCO said.

The Nuclear Safety Commission and the Nuclear and Industrial Safety Agency, an organization under the Economy, Trade and Industry Ministry, said Thursday they found the government’s preparedness against disasters and preventive measures insufficient after the officials investigated the plant.

They said the plant’s failure to learn from mistakes at other plants was a problem.

Hokuriku Electric Power Co. had a similar problem at its Shika nuclear power plant when a temblor hit the Noto Peninsula in Ishikawa Prefecture in March.

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Plants told to speed up checks

Chief Cabinet Secretary Yasuhisa Shiozaki told Vice Economy, Trade and Industry Minister Takao Kitabata on Thursday to ensure electric power companies complete checking safety levels at the nation’s nuclear power plants ahead of schedule, government officials said.

The Nuclear and Industrial Safety Agency revised the seismic resistance guideline for nuclear plants in September and requested electric power companies use the new guideline to check their safety levels by the end of December 2007.

The government, however, decided to push up safety checks and take immediate preventive measures in the wake of Monday’s earthquake.

"We want [electric companies] to check [their levels of safety] as soon as possible," Shiozaki said during a press conference.
(Jul. 20, 2007)

http://www.yomiuri.co.jp/dy/national/20070720TDY01005.htm