Tokyo Electric Power Co.’s inexact monitoring of contaminated water stored at Fukushima No. 1 may have led the company to overstate last week’s storage tank leak, according to the Nuclear Regulation Authority.
The loss of 300 metric tons that Tepco reported was based on an assumption that the tank had been full before the leak, Shunichi Tanaka, chairman of the NRA said Wednesday in Tokyo. That assumption may not have been reliable because there was no gauge measuring the tank’s water level, he said.
“We have no idea whether it’s actually 300 tons that leaked,” Tanaka said. “We need to look into this issue more.”
Tepco’s management of the contaminated water at the crippled nuclear plant has already drawn fire from Shinji Kinjo, leader of a disaster task force at the NRA, who has said the utility was careless in its monitoring of the storage tanks and failed to keep records of its inspections.
Managing the water, which is increasing at a rate of 400 tons a day, is a fundamental challenge for Tepco as it struggles with cleaning up the catastrophe, a process that could take as long as 40 years.
Tanaka’s remarks came hours after the NRA said it had finalized its ranking of the leak, based on Tepco’s reckoning, as a level 3 “serious incident” on the International Nuclear and Radiological Event Scale, or INES, in which level 7 is the most severe rating.
Tepco characterized the leak as small before determining, because of the change in the tank’s water level, that 300 tons of contaminated water had escaped. The leak may have started in July, Mayumi Yoshida, a Tepco spokeswoman, said Wednesday.
The NRA may reconsider its INES ranking should further studies show different amounts of water loss than those provided by Tepco, Tanaka said.
“It’s up to us to provide accurate data to the nation,” he said.
Another of Tepco’s challenges was highlighted Wednesday when Niigata Gov. Hirohiko Izumida said he would continue to resist the restart of the company’s Kashiwazaki-Kariwa nuclear power plant, which is located in his prefecture.
“There remain concerns about whether safe operations are possible or not,” said Izumida, who also accused the NRA of adopting too narrow a mission that neglects the safety of local residents.
Izumida’s approval is critical before Tepco can go ahead with plans for restarting some of the reactors at Kashiwazaki-Kariwa, the world’s largest nuclear power station by generating capacity.
Fukushima Gov. Yuhei Sato, who was also in Tokyo on Wednesday to meet with Minister of Economy, Trade and Industry Toshimitsu Motegi, asked that Tepco be strictly monitored by the central government as it pursues the cleanup. Sato also asked for a review of ocean monitoring conducted by Tepco and the government.
In Qatar on Wednesday, Prime Minister Shinzo Abe said his administration will take charge of the efforts to contain the disaster at Fukushima No. 1, following revelations of the toxic water leak.
“There is a need for the government to address the issue with a sense of urgency and not just leave it all up to Tokyo Electric Power Co.,” he said at a news conference.
Abe, who is in Qatar on the last leg of a trip to the Middle East and Africa, said the government will thoroughly disseminate to people in Japan and abroad information about the containment effort.
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