Tokyo Electric Power Co. failed to take anti-quake measures on about 600 important pieces of equipment at its Fukushima No. 1 nuclear power plant, even though revised safety guidelines in 2006 required such action.
TEPCO's lax practices were described Oct. 13 at a Nuclear and Industrial Safety Agency (NISA) meeting, in which nuclear experts were questioned. NISA officials said the utility did not conduct strength tests and implement reinforcement work on key equipment, including control rods in the No. 1 to 6 reactors that adjust the nuclear fission process within the reactors.
"TEPCO also did not conduct tests on a large majority of the piping" at the Fukushima No. 1 plant, Masaru Kobayashi, director of the Seismic Safety Office at NISA, said.
After the anti-quake guidelines were revised, TEPCO submitted an interim report to the central government in March 2008 in which it concluded that reinforcement work was not needed. It cited the results of tests on the pressure vessel and other important equipment.
TEPCO officials planned to include what would be done on the 600 or so other important pieces of equipment, such as those related to the control rods and other piping, in a final report.
At that time, TEPCO told NISA officials the final report would be submitted after autumn 2010.
According to Kobayashi, a document compiled by NISA in the summer of 2008 had wording that said reinforcement work was being implemented at the Fukushima No. 1 plant.
But on Oct. 7, TEPCO officials told NISA officials that the reinforcement work was never conducted.
It is unclear what led to the change on TEPCO's part because no records remain of communications exchanged in 2008.
"We assumed that an evaluation was being conducted, but we did not undertake a sufficient response. It is very regrettable," Yoshinori Moriyama, NISA's deputy director-general for nuclear accident measures, said at a news conference.
The Hamaoka nuclear plant of Chubu Electric Power Co. and TEPCO's Kashiwazaki-Kariwa plant are the only commercial nuclear plants for which final reports on the anti-quake measures have been submitted to the central government.
Operations were suspended at the Hamaoka nuclear plant after the March 11 Great East Japan Earthquake crippled the Fukushima No. 1 nuclear plant.
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