“Now there is a big difference between partially melted rods and a melt down. But once the rods get exposed you are looking at a massively more expensive cleanup. You can’t just pull the rods out for disposal any more since once they melt they tend to get stuck in place. So you have to dispose of the entire reactor vessel as a unit like they did at Three Mile Island. Getting this thing safely disposed of is going to be a seriously no fun engineering problem. Certainly one more than the Japanese need a the moment.”
So far, this is the big problem. The reactors are ruined and are going to be very expensive for the Japanese to clean up.
But we are still a couple of big steps away from a nuclear disaster. The rods have to actually melt down. The rods are radioactive material enclosed in a metal alloy. The radioactive stuff can produce 3000 degrees and the rods can only take 2200 degrees—that’s why they are desperate for water to cool the rods. So the rods staying intact is the first protection. If they are talking about how covered up the rods are in percentages, the rods have not melted down substantially (although the radioactive Cesium release suggests the exposed portions of the rods may have started that process). Then steel containment container has to breach and that takes a full meltdown (and I haven’t heard any evidence it has breached). In addition, once breached, the concrete and steel container compartment drains into a concrete torus below the container that spreads the melted materials out and contains them. So that third level of containment must be breached also for there to be a nuclear accident of the kind FREEPERS are worrying about.
It could still happen, especially if the concrete containment or the Torus were shattered by another major quake. But we’re still a long way from that result from the current state of the news.
Japanese officials say the nuclear fuel rods appear to be melting inside all three of the most troubled nuclear rreactors - AP
I’m reading the Ticker Forum thread, someone quoted this from the UK Guardian NewsBlog. I know the Guardian is a leftist rag but the info seems factual. TF thread about Japan nuke plants link:
http://tickerforum.org/akcs-www?post=182121&page=34
Robert Alvarez, a senior policy expert at the institute of Policy Studies, said satellite pictures of the Fukushima plant showed evidence of damage to the spent fuel pool. “There is clear evidence that the fuel cask cranes that haul spent fuels to and from the reactor to the pool both fell. They are gone,” he said. “There appears to be copious amounts of steam pouring out of the area where the pools are located.”
He said there was no evidence of fire but described the situation as “worrisome”.
“What we don’t know is whether or not explosions or the quake or the tsuanmi or a combination of things might have damaged support structures or compromised the pool,” Alvarez said.
http://www.guardian.co.uk/world/blog/2011/mar/14/japan-tsunami-nuclear-alert-live