Outrage over Japan nuclear reactor coverup http://www.reuters.com/article/wtMostRead/idUST7529420070315
Thu Mar 15, 2007
By Ikuko Kao
TOKYO (Reuters) - A Japanese power company admitted on Thursday that it had covered up a 1999 incident in which mishandling of nuclear fuel rods led to an unintended self-sustaining nuclear fission chain reaction for 15 minutes. Anti-nuclear activists expressed outrage over Hokuriku Electric Power Co.'s failure to report the accident, although the company said the mishap was relatively minor.
The news of the 15-minute "criticality" -- an unintended self-sustaining nuclear fission chain reaction -- is likely to further dent public confidence in Japan's nuclear power industry, already undermined by safety scandals over the past decade.
An official with Hokuriku's nuclear team admitted the company had not reported the incident, which took place during a test while the unit was offline for a planned inspection.
"There was a cover-up," Toshihiko Takahashi told a news conference, bowing deeply. He added that the incident may have breached laws governing nuclear plant regulation.
"We deeply apologize for worrying everyone." In one of Japan's worst nuclear accidents, two workers were killed in September 1999, when workers at a nuclear facility in Tokaimura, northeast of Tokyo, set off an uncontrolled nuclear chain reaction by using buckets to mix nuclear fuel in a lab.
Hokuriku Electric said the mishandling of nuclear fuel rods caused the company's Shiga No. 1 nuclear unit in central Japan to go into a "critical state" for 15 minutes in June 1999.
The unit was shut down manually after an automatic shut-down function failed.
Hokuriku Electric's Takahashi said the mishap was not that serious because it boosted the activity of the nuclear unit by less than 1 percent of its total capacity of 540,000 kilowatts and took place in the reactor core, shielded by multiple thick concrete walls.
ACTIVIST OUTRAGE
One of the shields covering the top of the reactor was open, the common practice when a utility conducted inspections.
"It happened at around 2 or 3 a.m., so people probably thought no one would notice," Hokuriku Electric President Isao Nagahara told reporters after apologizing for the affair.
Activists were outraged, citing a long history of previous incidents such as Tokaimura or the leak of high-pressure steam that killed four workers at a nuclear power plant in 2004.
"In a worst-case scenario, there might have been some radiation leakage to the outside," said Chihiro Kamisawa, a staff researcher at the Citizen's Nuclear Information Center.
"We were not looking at a Three Mile Island, but this accident highlights some serious technical problems," he added, referring to a 1979 accident at a U.S. nuclear plant that led to a partial meltdown.
The Hokuriku incident, which was not written up in the utility's operational diaries, came to light after the company conducted an internal investigation, the Ministry of Economy, Trade and Industry (METI) said. Officials from Ishikawa Prefecture, where the plant is located, began inspecting it on Thursday afternoon.
Hokuriku has two nuclear power generation units at its Shiga plant. The other No. 2 unit, which has been shut since July 5 for inspections, has been undergoing planned inspections, with the restart of the unit expected in the first half of May.
The utility started shutting down the No. 1 unit at 6 p.m. (0900 GMT) to conduct a thorough check of safety measures there after being ordered to do so by METI.
But activists said more needed to be done. "There needs to be much stronger punishment imposed, say the kind of punishments that firms in other industries face -- something that really has an impact on profits," Masako Sawai, at the Citizens' Nuclear Information Center, said.
"Unless something like that is done, nothing will ever get better. The power companies don't take criticism to heart."
(Additional reporting by Osamu Tsukimori and Elaine Lies)
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