A JAPANESE expert on nuclear safety warned more than three years ago that the policy of building large numbers of reactors in the middle of a volatile earthquake zone could lead to catastrophe. As the authorities battled to avert a meltdown at the Fukushima plant, it emerged that a senior figure in Japan's nuclear community resigned in protest from a safety panel saying guidelines to protect atomic power plants from earthquake damage were too lax.
Ishibashi Katsuhiko, a professor at Kobe university, said seismic guidelines brought in to protect Japan's 55 reactors in 2006 were "still seriously flawed".
He pointed out that big quakes had taken place in "close proximity" to three nuclear power plants in Japan from 2005 to 2007. In each case, the ground motion caused by the quake was stronger than that for which the plants had been designed.
A tremor at the Kashiwazaki Kariwa plant, about 300km across the main island from Fukushima, had experienced a tremor with ground motion of 993 gal (a measure of ground movement), far beyond its design value of 450 gal.
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"Not only are the new design guidelines defective but the system to enforce them is in a shambles," wrote Professor Katsuhiko after his resignation. He said it was just a matter of luck that the epicentre of each earthquake had not been nearer.
In an article in 2007 explaining his resignation, Professor Katsuhiko said almost all of the Japanese archipelago had entered a period of brisk seismic activity since the Kobe earthquake of 1995.
"Unless radical steps are taken now to reduce the vulnerability of nuclear power plants to earthquakes, Japan could experience a true nuclear catastrophe in the near future," he wrote.
