Tokyo Electric Power Co. provided false information last year to a panel commissioned by the Diet to investigate the nation’s worst nuclear plant catastrophe, according to sources.
The misinformation led the now-defunct panel to cancel an on-site inspection of the building housing reactor 1 at Tepco’s Fukushima No. 1 nuclear plant, after it was wrecked by the March 2011 quake and tsunami.
In February 2012, a Tepco official told the panel it was too dark to conduct an inspection because the reactor building, heavily damaged by a hydrogen explosion, was encased in a cover to prevent radioactive materials from leaking.
However, the utility’s officials have now admitted there was light inside the structure.
A Tepco spokesman claimed Thursday the official in question had simply misread the situation inside the building and had not intended to mislead the panel.
But Mitsuhiko Tanaka, a member of the Diet panel, said Tepco had deliberately misinformed the group to block its activities. On Thursday, he requested the heads of both Diet chambers to green-light further probes.
The panel was disbanded last July.
The investigation team had hoped to check on the status of isolation condensers, which are used to cool reactors in emergencies, during its visit to the plant in March last year.
The condensers for reactor 1, one of three that experienced a core meltdown following the Great East Japan Earthquake, are located on the fourth floor of the building.
The panel suspected the condensers may have been damaged by the 9.0-magnitude earthquake before the tsunami swept ashore and crashed into the Fukushima No. 1 power station.
According to the utility’s officials, the then-head of Tepco’s corporate planning department told Tanaka last Feb. 28 that radiation levels inside the building were high, at around 60-70 millisieverts per hour, and that there was a large amount of debris.
Tanaka was shown video footage from an Oct. 18, 2011, Tepco inspection of the isolation condensers.
Tepco’s official told Tanaka that it would be far darker inside the reactor once the cover over the building was in place.
However, the cover had been completed four days before. And 10 days after the inspection, Tepco installed lighting on the fifth floor. Tanaka said he was told by the official that the darkness inside the building could lead to panic.
The official went on to say that Tepco did not want to provide personnel to support the inspection because of the risk of injury and exposure to high radiation levels, according to Tanaka, and the panel canceled the inspection because of the perceived dangers.
“Tepco blocked our investigation though it was legally obligated to cooperate with us,” said Chuo University Graduate School of Law professor Shuya Nomura, who was also a member of the Diet panel.
Further research should be conducted because the Nuclear Regulation Authority cannot establish new nuclear safety standards without a full analysis of the causes of the catastrophe, and the watchdog is considering an inspection of the fourth floor of the reactor 1 building, officials said.