The New York Times reports that workers have been withdrawn from the Fukushima I site, indicating that not one, not two, but three complete core meltdowns are very likely. The withdrawal of workers came following what appears to be a breach of the steel containment structure, which encloses the core, on the #2 reactor. The withdrawal of the workers means all three cores are extremely likely to melt down fully.
At the very end of the New York Times quotes Princeton professor Frank von Hippel: “It’s way past Three Mile Island already. The biggest risk now is that the core really melts down and you have a steam explosion.”
I don’t know who von Hippel is or if he knows what he’s talking about, but the steam explosion he’s talking about sounds like what’s called the China Syndrome (hence the movie of the same name).
That’s when an out-of-control molten mixture of core material, melted cladding, melted machinery, melted control rods, melted steel containment vessel the concrete floor of the containment building (“a substance known as corium”) melts into the earth, hits groundwater, and causes a steam explosion and mushroom cloud. It’s supposed to be physically impossible. Nuke fans have been swearing up and down that such a thing can’t happen. At Chernobyl, a giant “elephant’s foot” of molten corium was found in the basement of the containment building, but it didn’t hit groundwater. (The explosion at Chernobyl was unrelated to the melting; it happened at the beginning of that disaster).
From the NY Times:
…The nuclear fuel in [the #2] reactor was exposed for many hours, increasing the risk of a breach of the container vessel and a more dangerous emissions of radioactive particles….By Tuesday morning, the plant’s operator, Tokyo Electric Power, said it had fixed the valve and resumed seawater injections, but that they had detected possible leaks in the containment vessel that prevented water from fully covering the fuel rods.
That means the containment vessel is leaking water; that means it’s been breached. The official reports hadn’t even acknowledge a problem at #2 until this morning.
More from the NY Times:
…An explosion at the most crippled of three reactors at the Fukushima Daiichi Nuclear Power Station damaged its crucial steel containment structure, emergency workers were withdrawn from the plant, and much larger emissions of radioactive materials appeared immiment…The sharp deterioration came after government officials said the containment structure of the No. 2 reactor, the most seriously damaged of three reactors at the Daichi plant, had suffered damage during an explosion shortly after 6 a.m. on Tuesday.
They initially suggested that the damage was limited and that emergency operations aimed at cooling the nuclear fuel at three stricken reactors with seawater would continue. But industry executives said that in fact the situation had spiraled out of control and that all plant workers needed to leave the plant to avoid excessive exposure to radioactive leaks.
If all workers do in fact leave the plant, the nuclear fuel in all three reactors is likely to melt down, which would lead to wholesale releases of radioactive material — by far the largest accident of its kind since the Chernobyl disaster 25 years ago.