Skip to comments.[Japan]TEPCO: Melted fuel eroded containment vessel floor at Fukushima reactor [diagram inside]
Posted on 11/30/2011 11:29:57 PM PST by TigerLikesRooster
TEPCO: Melted fuel eroded containment vessel floor at Fukushima reactor
December 01, 2011
Most of the fuel rods that melted in the pressure vessel of the No. 1 reactor of the stricken Fukushima nuclear power plant ate into the containment vessel, according to Tokyo Electric Power Co.
It said on Nov. 30 the melted fuel did not breach the containment vessel but partially eroded its concrete floor.
As for the No. 2 and No. 3 reactors, most of the melted fuel stayed within the pressure vessel, TEPCO added.
Water levels have submerged the fuel rods at all three reactors, which is helping to cool them, the plant operator said.
TEPCO said its latest findings were based on water levels in the containment vessels, temperature readings and other data.
It admitted earlier that melted fuel partially breached the reactors, a potentially catastrophic development.
During the 1979 accident at the Three Mile Island nuclear power plant in the U.S. state of Pennsylvania, a core meltdown occurred but the pressure vessel was not breached.
(Excerpt) Read more at ajw.asahi.com ...
Thanks for that image. So it is 10.2 meters from the top of the concrete to the bottom ? I was guessing 15 meters on another thread.
This is largely consistent with what was seen at TMI.
But it looks like the containment building did its job and held the nuclear material.
Depends if the concrete is not cracked and can hold water.
Also, once the corium has dug itself a hole it prevents any coolant (water) from getting to it and is free to heat up via internal reactions.
In reality they are still not sure where the corium is and these are just educated guesses. No one can go near to find out either with a visual inspection. Even bots can take only so much exposure to radiation and there are literally tons and tons of the stuff in each unit now in corium form, radioactive blobs.
“But we do know that the corium was and may still be eating its way through the concrete core catcher.”
But (unless I’m misunderstanding) the article admits (I say ‘admits’ because it’s dramatized in a way that tortures the truth, i.e., “China Syndrome”) that the rods are still contained in the steel structure, ie, they are not in contact with the concrete superstructure.
In #1 the rods and the RPV internals have almost completely melted and have dripped out of the RPV. Actually under pressure it can actually partially jet out the bottom of the RPV. That molten mass is now eating the drywell floor and has yet to get to the last steel wall which is called the dry wall. There is concrete on the dry well floor above the dry steel wall. That is the concrete that Tepco admits the corium (melted rods and stuff) is eating through.
Now that Tepco has admitted a significant amount of concrete floor erosion, there is another problem that must also be occurring. Gets much more technical and has to do with the drywell sumps and suppression chambers. Basically the corium mass could have flowed across the drywell floor and down the downcomers into the suppression pools. That is where the wet wells are located. That can cause a steam explosion and may have been what happened in Unit #2.
Having spent many hours over many years in seceral different drywells around the country, I would like to applaud you for your synopsis. Factual and clear.