Fukushima: How TEPCO Manipulated Diet Inspection

Hideaki Kimura | Asahi Shimbun

Fukushima Daiichi

“(TEPCO’s explanation) was absolutely false and seriously obstructed the investigation,” Mitsuhiko Tanaka, a former member of the now-disbanded Diet commission, said in a statement submitted to the chiefs of the two Diet chambers on Feb. 7.

Tanaka asked the Diet to inspect the No. 1 reactor building to see if isolation condensers–key safety components at nuclear plants–were damaged by the Great East Japan Earthquake of March 11, 2011.

If the emergency cooling system was damaged by the magnitude-9.0 earthquake, stricter quake-resistance standards would be required for nuclear power plants, further delaying the restarts of idled reactors around the country.

The isolation condensers stopped working soon after the earthquake struck, which is believed to have contributed to the early meltdown of the No. 1 reactor.

TEPCO has denied they were damaged by the quake.

Tanaka, a former reactor design engineer, was responsible for on-site inspections for the Fukushima Nuclear Accident Independent Investigation Commission.

He and other commission members planned to visit the plant on March 5-6 last year after receiving reports that subcontracted workers had seen water on the fourth floor of the No. 1 reactor building following the earthquake. Two tanks and piping were holding water for the isolation condensers.

But Tanaka gave up on that plan after TEPCO said the reactor building was pitch-black and dangerous to enter.

In reality, a cover over the building transmitted 10-16 percent of sunlight. It was also equipped with powerful mercury lamps.

Toshimitsu Tamai, then chief of TEPCO’s corporate planning department, visited Tanaka at a Lower House annex building around 7 p.m. on Feb. 28. Others were present during the meeting that lasted for more than one hour.

Tamai said the fourth floor had no lighting, and he repeatedly emphasized the potential dangers of wandering around in the dark, according to an audio recording obtained by The Asahi Shimbun.

“If you got lost, you would run into areas with dreadfully high levels of radiation,” Tamai said. “You would face a considerable danger and could be thrown into a panic.”

Tamai also cited other risks, such as the debris scattered around the site and the heavy dosimeters visitors must carry.

During the meeting, Tamai showed an image of a modestly lit fourth floor of the No. 1 reactor building, whose roof was blown off in a hydrogen explosion. He said it was taken before a cover was installed to keep radioactive materials from spreading.

Tamai never said TEPCO would reject the inspection, but he urged Tanaka to withdraw the plan.

“I might say it would be better if you would not go ahead with something that reckless,” Tamai said.

Tanaka eventually chose not to visit the plant after Tamai asked him to make a decision on that day.

“We concluded that it would be dangerous to carry out the inspection at a completely dark site,” Tanaka said in the statement to the chiefs of the two Diet houses. “We had no choice but to give up the inspection.”

The Diet commission was authorized to ask the Diet to use its powerful investigation rights to uncover the causes of the Fukushima nuclear crisis. TEPCO was supposed to cooperate with the panel.

A TEPCO spokesman admitted that the utility gave wrong information to the Diet commission but said it did not intentionally make false reports.

The image shown during the meeting was actually taken four days after the cover was installed over the reactor building in October 2011. Tanaka and others in October found the image with the correct date on TEPCO’s website.

The spokesman said the TEPCO officials who gave the explanation to the Diet commission mistakenly believed that the image was taken before the cover was installed.

The Asahi Shimbun found that the cover was equipped with lighting while checking a story in a construction industry magazine featuring cover installation work in January.

A set of five mercury lamps, as bright as the headlights of more than 40 vehicles, has been operational on the cover’s ceiling since October 2011. An additional set of five mercury lamps is on standby.

An isolation condenser condenses steam into water that flows down into a reactor. It can lower pressure within the reactor and cool it even without a power source.

Although the Diet commission suspected the isolation condensers were damaged by the quake, a separate investigation panel set up by the government said it is reasonable to believe the condensers’ functions were not lost in the disaster.

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