Tokyo Electric Power (Tepco) has revealed that on at least two occasions its staff rigged the results of inspections by manipulating main steam valves to reduce leak rates during containment testing in 1991 and 1992.
Tepco admitted the 'dishonest acts' in a press release issued in late October. During the two annual inspections at Fukushima Daiichi 1 (Fukushima I-1), plant staff knew that the containment leak rate was too high. When government inspectors carried out the leak tightness test the staff injected air via the main steam isolation valves to reduce the leak rate. Reportedly the actual rate was 2 per cent per day compared to the allowed maximum of 0.45 per cent per day. By manipulating the valve, the rate was reduced to 0.12 per cent per day.
Tepco said the plant had been shut down for additional leak rate inspections, and an external commission comprising five specialist lawyers had been assigned to oversee the investigation. The company could not say whether dishonest acts were conducted in the leakage inspections at all Tepco's nuclear power stations other than the above-mentioned two inspections; nor could it say whether other tests at that plant had been falsified. All the company's leak tests are now being examined. Once again, the power company found itself saying: "Tepco sincerely regrets and apologises that such dishonest acts were conducted." Tsunehisa Katsumata has taken over as head of Tepco following the resignation of Nobuya Minami, while Shigemi Tamura is to replace Hiroshi Araki as chairman.
At a press conference Katsumata said the data falsification was "the gravest crisis since the company was established", and that the company had lost so much "it should start again from zero".
l Japan's Nuclear and Industrial safety Agency has drafted revisions to the Electric Utility Law and Nuclear Reactor Regulation Law featuring imprisonment of up to three years for individuals and fines of up to 300 million yen for companies to try and prevent a recurrence of such scandals. The revisions will be presented to parliament in its next session.
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