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Are there any conditions where corium would spread horizontally, or due to its weight does it always melt straight down? Am I correct in assuming corium to be extremely heavy?

@Bobby1 some people here have rubbished Busby. I'm keeping an open mind...

@jay : it goes straight down unless it finds a way less resistant, like a channel.

Am I understanding correctly that corium has likely melted thru the cement containment vessel, based on the scenarios in Dean's spreadsheet?

based on the assumptions from study of analyses yes Scilla

@UKVal Busby was right, it's based on isotopic ratios. He also says there is ongoing criticality. This would affect the current temperature of the corium.

thanks Dean..I think the circumstances of SFP 3 are somewhat mysterious. Perhaps a large amount of fuel was ejected...scary thought.

Following the hypothetical core meltdown accident, the drywell electric
penetration assembly seals have been identified as the most likely
leak pathway outside of the containment. The electric penetration seals
have been qualified for environmental conditions of 163°C (325°F) for
15 min followed by 138°C (281°F) for 3 hr at a pressure of 125 psig
(9.64 x 105 Pa). At tempera: ,.cs above 163°C (,'25°?), the penetration
materials lose their mechanical sealing integrity, and shortly thereafter
drywell venting occurs, releasing radioactive fission products outside the
containment. This venting occurs at a leak rate cf -^250 ft /min (118 i/hr)
and a pressure of V125 psig (9.64 * 10 Pa). Meanwhile, the temperature
and pressure inside the drywell continue., to increase. As the drywell
temperature exceeds 260°C (500°F), the penetration materials would become
sufficiently decomposed such that the penetration modules are physically
blown out of the containment wall. The initial leak rate through the
4
drywell electric penetration assemblies would be in excess of "v-6.50 x 10
ft3/min (3.07 x 104 fc/hr) at a pressure of ^130 psig (9.98 * 105 Pa) if
all of the modules failed simultaneously.

COULD BE LM

sorry the gremlin.

www.iaea.org elaine will you post this please

@UKVal You're right about 4. I was conjecturing about 3. It seems curious we've seen little steam from SFP area on 3 and more from the core area...that is, before the last few days. We know the pool was seriously damaged. If there isn't much fuel left I would think heat levels would be much less...but I'm no expert!

electrical penetration seal failure at temp.. bad deal ..

@Edano LOL. that was my question, is anything still hot enough to flow and move in May?

@Ian It's in a post of mine below at 2:50 PM Eastern time.

@LM sorry -not reading properly... still trying to digest all this

@LM : in a (bad) way, it is an historical event.

@edano Very true.

@Nancy That's a bit of good news.

Would they likely be trying to entomb if it weren't for the sfp's? I don't know how they would do it since things aren't wide open, but...

@Ian In short, Mar 16-17 readings:
A. Tc-99m 130,378
B. Te-132 25,177
C. I-132 35,700
D. I-131 55,607
E. Ba-140 542
F. La-140 1,521
A > B+C > D > E+F = nuke

@Edano Yes, this happened at the same time that corium was eating through the containment of #1. The concrete reaction doesn't explain the Tc-99m, which came from decay of Mo-99, which is released when neutrons bombard U-238.