A decade after Niigata’s nuclear close call via The Japan Times

Jeff Kingston

On July 16, 2007, a 6.8 magnitude earthquake rattled the world’s largest nuclear power complex at Kashiwazaki-Kariwa in Niigata Prefecture. This was on a site that the government and Tokyo Electric Power Co. had insisted was seismically safe.

Two years earlier, the Tokyo High Court had ruled against local plaintiffs backed by scientists who insisted the authorities were wrong and that there was an active fault line adjacent to the site. In 2007, Mother Nature overruled the judge, raising questions about relying on old evaluations by institutions favoring nuclear energy in assessing site safety, particularly given subsequent advancements in seismic science.

The good news is that the reactors shut down automatically and the plant withstood tectonic shocks way beyond what anyone had anticipated when designing the structures. The bad news trickled slowly out of Tepco, but an NHK special shortly afterwards aired a startling revelation. The plant manager told NHK that it was very lucky that everything worked as planned and that there was no serious accident — especially considering that the door of the control center had been jammed and nobody could get in. This meant that if there had been a crisis, nobody would have been able to manage it because the emergency controls were inaccessible.

The door was stuck because the land subsided due to the earthquake. It is hard to anticipate every contingency, and that is precisely why accidents happen. If the safety systems had not functioned as planned, Kashiwazaki might have spun out of control, but luckily it was just a close call.

Also worrisome was the transformer fire that took an age to put out because the water pipes had ruptured due to the earthquake. And why was there a nine-hour delay in informing local authorities about the situation, including some radiation leaks? Apparently the plant workers were preoccupied with setting up whiteboards in the parking lot as an improvised control center and using their mobile phones to communicate with each other. Tepco also downplayed how much radioactive water had leaked, a spill that Asahi reporters spotted workers mopping up with paper towels.

At Kashiwazaki-Kariwa there are seven reactors with an 8,200 megawatt capacity, enough for 16 million households. This clustering of reactors means that if there was an accident, it could cascade into a major disaster.

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