Former GE engineer who helped build Fukushima nuclear plant says meltdown began before tsunami hit

http://www.atimes.com/atimes/Japan/MH12Dh01.html

Aug 12, 2011

What happened at Fukushima?

<snip>Kikuchi Yoichi, a former GE engineer who helped build the Fukushima nuclear power plant says unequivocally that, "the earthquake caused the meltdown not the tsunami.'' In his recent book Why I'm Against the Nuclear Plants I Helped Build, he explains that poorly maintained water pipes and circulation system failure were the cause of the triple meltdown:

''At Fukushima Daiichi Nuclear Power Plant, at first the plan was to use the water coffin approach. In other words, to fill the containment vessels with water and cool down the pressure vessel and ensure a safe and stable state. However, once (TEPCO) understood that the containment vessels had been damaged, they gave up this plan. Because water was probably leaking all over the place from the pipes, from the start this was an unreasonable scenario.''

Tanaka Mitsuhiko, a former nuclear power plant designer and science writer asserts that at least the Number One reactor melted down as a result of the earthquake damage. He describes it as a loss of coolant accident (LOCA). "The data that TEPCO has made public shows a huge loss of coolant within the first few hours of the earthquake. It can't be accounted for by the loss of electrical power. There was already so much damage to the cooling system that a meltdown was inevitable long before the tsunami arrived."

He says the released data shows that at 2:52 pm on March 11, before the tsunami had arrived, the emergency circulation equipment of both the A and B systems automatically started up. "This only happens when there is a loss of coolant." Between 3:04 pm and 3:11 pm the water sprayer inside the containment vessel was turned on. Tanaka says that it is an emergency measure only done when other cooling systems have failed.

By the time the tsunami arrived and knocked out all the electrical systems, circa 3:37 pm, the plant was already on its way to melting down.

I have not followed this closely and don't understand how this damage via earthquake compounded by the tsunami helps in this mess... Thanks.

Appears they were wrong.

Don

The claim was basically this: the plant could survive an earthquake, or a tsunami, or a fire, or the loss of the external generators, or two of those or possibly even three at once, but having all four happen at the same time was so improbable that it wasn't realistic to plan for that also.

By itself the argument is plausible (though it suggests that engineers no less than financiers overly discount the tail-heavy nature of actual probability distributions -- earthquakes, tsunamis, fires, and power loss are not distributed independently; if an earthquake happens a tsunami is much more likely to happen, etc.). But if the failure happened after only the first of the four, then there would have been a serious problem just from the earthquake, and the plant was necessarily underdesigned.

The tsunami didnt dislodge the pipes that were leaking, Really now, thats just silly. It was the quake.