The government’s nuclear energy report for 2004 is a dismal reminder that public confidence in nuclear safety remains low. The report, prepared by the Atomic Energy Commission, follows the accident last August in which five workers died because of exposure to bursts of superheated steam from a ruptured tube at Kansai Electric Power Co.’s (Kepco) nuclear plant in Mihama, Fukui Prefecture.
The white paper, titled “Toward Securing Understanding and Trust at Home and Abroad,” stresses the obvious: Accurate analyses of the causes of accidents, explanations of safety measures and risks, and repeated dialogues with residents are essential to the resumption or promotion of nuclear-energy activities. The title is a veiled admission that confidence-building efforts have not made much progress.
Public trust in the nation’s nuclear power program has been badly shaken not only by the Mihama accident but also by a number of earlier accidents, including a coolant leakage at the “Monju” prototype fast-breeder reactor in 1995 and an accidental critical-mass reaction at a uranium processing plant in Tokaimura, Ibaraki Prefecture, in 1999.
Unless the cycle of mistrust surrounding the nation’s nuclear energy program is broken once and for all, it will be impossible to secure the public’s understanding and trust. Yet the government and the nuclear power industry appear determined to continue a controversial nuclear-fuel recycling program that is designed to reprocess spent fuel from nuclear plants and use plutonium extracted from it as fuel. As things now stand, prospects for the program are uncertain at best.
The Japanese public is growing skeptical about the necessity of recycling spent fuel — a trend that was already evident when the previous report was published 14 months ago. Perhaps it is time to start reviewing the merits and disadvantages of the program on a long-term basis.
The reprocessing of waste fuel, a highly expensive operation, is bound to increase the overall cost of nuclear power generation. With threats of large-scale terrorism spreading around the globe, there is also an urgent need to safeguard nuclear materials at reprocessing and other facilities.
What’s more, the operation of Monju — the model for plutonium-burning reactors that would form the core of the fuel cycle — has been suspended since the 1995 accident. The next step toward commercial operation — the startup of a demonstration reactor — appears to be a long way off.
The alternative “pluthermal” program, designed to burn plutonium in existing light-water reactors, is also far behind schedule, due largely to a contractor’s fabrication of test data on MOX (mixed oxides) — uranium-plutonium fuel for pluthermal use — bound for a Kepco plant in 1999 and the concealment of technical defects by Tokyo Electric Power Co. between 1986 and 2001.
The 2004 report says the nuclear power program is showing “new signs of movement,” and refers to the scheduled startup of the reprocessing plant in Rokkasho-mura, Aomori Prefecture, in July 2006 and the decision by Kyushu and Shikoku Electric Power companies to introduce the pluthermal program. Optimism, however, is not warranted.
It seems that the nuclear power industry has yet to fully learn the lessons from past accidents. Consider the Mihama accident, the worst nuclear tragedy in terms of fatalities that the nation has experienced. Basically it was caused by human errors — particularly a failure by inspectors to detect corrosion in a pipe that conveyed extremely hot water. The corroded part ruptured under pressure, spewing tons of deadly steam.
According to the latest investigation, the corrosion occurred in a protruding part of the inside surface that was designed to adjust the flow of water. This particular part had been known to be more vulnerable to corrosion than other parts, yet it had been left unchecked for years.
It also has been revealed that the maintenance contractor that discovered the omission proposed that Kepco inspect the spot regularly, but that the power company postponed action because it did not immediately recognize the urgency. The investigation has revealed other disturbing episodes. For example, inspectors were aware of similar corrosion in other reactor systems years before the Mihama accident occurred, and some of those responsible were not adequately informed about uninspected spots.
All this and more suggests that something is fundamentally wrong with the maintenance and inspection system. A closer investigation focusing on the human factor is in order.
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