Japan’s turbulent history of war and natural catastrophe has already given the world a terrifying vocabulary of death: tsunami, kamikaze, Hiroshima.

But the country now stands on the brink of unleashing its most chilling phrase yet: genpatsu-shinsai – the combination of an earthquake and nuclear meltdown capable of destroying millions of lives and bringing a nation to its knees.

The phrase, derived from the Japanese words for “nuclear power” and “quake disaster”, is the creation of Katsuhiko Ishibashi, Japan’s leading seismologist and one of the Government’s top advisers on nuclear-quake safety. He said that the world may never know how close it came to its first genpatsu-shinsai this week. Luck, as much an anything else, helped to avert it.

A 6.8 magnitude quake, which shook Niigata on Monday and left thousands of homes uninhabitable, was three times more powerful than the designers of the nearest nuclear power plant – Kashiwazaki-Kariwa – had prepared for, or even imagined.

The unfolding crisis at Kashiwazaki has renewed calls for the immediate closure of the five atomic reactors at Hamaoka – an old plant in Shizuoka built directly above a geologically active fault about 100 kilometres (60 miles) west of Tokyo. Despite claims by its operators, Chubu Electric, that the plant meets government standards, seismologists said yesterday that it was “almost impossible” to ensure the safety of a nuclear plant in that location. The Hamaoka plant, said Mitsuhei Murata, a former diplomat and professor at Tokai Gakuen University, presents Japan with its biggest risk of genpatsu-shinsai.

A quake there, he said, could smash the reactor and send a radioactive cloud over Tokyo within eight hours: “We would be looking at 24 million victims and the end for Japan.”

The seismology community agrees that the Tokai region, which includes Tokyo and Hamaoka, is due for a massive quake. The Tokyo metropolitan government has drawn up disaster plans that assume an 87 per cent probability of a magnitude 8.0 quake within 30 years. But power companies have been allowed to prepare for much smaller quakes when building nuclear plants. If the epicentre of Monday’s quake had been 10 km further to the southwest, the seismology research team at Kobe University calculates that the reactor could have split and unleashed a “terrible, terrible disaster”.

As it is, the Tokyo Electric Power Company (Tepco) has admitted to a worrying series of problems since the quake, including the stunning revelation that the Kashiwazaki plant was constructed on top of an active fault – despite Tepco’s firm denials in court that this was the case. Vital reactor data on the minutes immediately after the quake have already been lost by Tepco. Numerous leaks of radiation have been detected.

The Times learnt yesterday that one of the exhaust ducts continued to pump radioactive particles into the air for nearly three days after the reactors were shut down. Professor Ishibashi has fought the Government unsuccessfully for urgent reviews of quake-proofing standards throughout Japan’s nuclear industry. A member of the Government’s own panel on nuclear safety, he criticised the Government and the Japanese public yesterday for their failure to recognise how close the country was to genpat-su-shinsai. Since 1969 seismology advisers to the Government have given warning of the danger of building atomic plants, but were officially ignored. “It’s not that people carefully consider my arguments and then decide against higher standards of safety. They just don’t give the possibility of disaster a moment’s thought,” Professor Ishibashi told The Times.

“Before World War II there were many Japanese who were against the idea of a war with America but they ended up just marching blindly towards it. I think Japan today is much like it was before the atom bomb was dropped on Hiroshima.”

Citizens’ groups, a handful of corporate leaders and former government officials are fighting for a review of Japan’s nuclear reliance. Mounting evidence of radiation leaks, unprepar-edness and deception over the dangers of the plant’s location mean that the problems at Kashiwazaki will reopen a court showdown over the plant at Hamaoka.

The Government has underplayed the risk of disaster. For this, Professor Ishibashi and others blame the “nuclear village” – corporate interests, politicians with links to the industry and academics who owe their salaries to power companies. All 55 of Japan’s nuclear reactors pose a genpatsu-shinsai risk, Professor Ishibashi said.

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