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HOME  > Past issues  > 2007 April 4 - 10  > TEPCO disguised N-plant parts to evade state inspection
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2007 April 4 - 10 [SOCIAL ISSUES]

TEPCO disguised N-plant parts to evade state inspection

April 8, 2007
Tokyo Electric Power Co. (TEPCO) secretly replaced a control rod drive actuator in the No. 4 reactor at its Fukushima No. 2 nuclear power plant and even had the plant maker, Hitachi, produce a device marked with the same production number of the spare parts used in the replacement, so that the replacement could be kept secret. TEPCO revealed this in a report which it submitted to the government on April 6.

According to TEPCO, a drive actuator was broken by mistake during the first regular inspection in October 1988. Reporting this to the state was a prerequisite for the replacement with a spare, but the company carried out the replacement without reporting it.

Before the second regular inspection scheduled for January 1990, TEPCO ordered Hitachi to produce a device with the same production number as the replaced spare in order to be consistent with the record on stocked spare parts. TEPCO said that this device was returned to Hitachi after the inspection had been completed.

The power company also ordered Hitachi to produce a device with the same production number as the broken one, and had it installed during the second regular inspection without reporting this to the state.

TEPCO said that the two devices that were secretly replaced are still in use and will be replaced with new ones during the regular inspection now under way.

Hayakawa Atsuo, representative of the Fukushima Prefectural Liaison Association for the Safety of Nuclear Power Plants, said, “The TEPCO report to the state clearly shows that TEPCO carried out the wrongdoing in collaboration with the plant maker, and the government, unable to see through this, has said for many years that nuclear power plants are safe. They share the responsibility.”

Hokuriku Electric muzzles criticality accident

It was revealed that when a criticality accident occurred at Hokuriku Electric Power Co.’s Shika nuclear power plant No. 1 reactor on June 18, 1999, a power company operator made an inquiry by phone to an engineer of the plant maker, Hitachi, about the reactor condition.

According to a report that Hitachi submitted to the government, the Hitachi engineer received a phone call at his home before dawn of June 18, immediately after the accident. The operator asked him for an analysis of the reactor condition when three control rods fell off, informing him of detailed information about the position of the rods and the condition of the fuel. Then, he went to his office and made an analysis together with his superior. They reached the conclusion that the reactor has reached criticality, and conveyed this to the Shika plant operator.

Without informing anyone of the criticality accident, the Shika plant operator asked the Hitachi engineer to not report their conversation to anybody, including his supervisor. Although the engineer suspected that a criticality accident might occur, the information was not disclosed in the company.
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