Safety is a perennial problem for nuclear power plants. The latest government report on nuclear safety, released earlier this month, focuses on assuring safety in the use of plutonium, particularly in the so-called pluthermal program, which uses plutonium as fuel in light-water reactors.
The report comes up short, however, following recent accidents resulting from technical failures at Chubu Electric Power Co.'s Hamaoka nuclear plant. These accidents, including pipe fractures and water leaks from beneath the reactor pressure vessel, have to do with mechanical fatigue, such as stress-corrosion cracks. Three decades after nuclear plants went into commercial operation here, addressing this problem of physical deterioration of the reactor structure is a top priority.
The pluthermal program involves the burning of mixed oxides (MOX), a mixture of plutonium extracted from spent nuclear fuel and regular uranium. The government and electric power companies originally planned to use this mixed fuel at 16 to 18 nuclear plants throughout the country by around 2010.