Posted on 05/15/2012 10:51:30 AM PDT by yank in the UK
Unit 2 we now know completely liquified. We’ve never seen this before in the history of nuclear power. A 100% liquification of a uranium core.
(Excerpt) Read more at enenews.com ...
Sad to think that in order to dig straight through to China, American kids would have needed to live in Chile. All that time and effort wasted.
We don’t know “for a fact” that the cores “had to” melt out through the bottoms of the RPV. There’s speculation that some of the core(s) might have gotten out of the RPV due to the radiation levels in the containment wells, but that can also happen as a result of material being flushed out of broken piping (when the fuel rods break, the fuel is now loose pellets), or excursion of molten fuel through existing penetrations of the RPV. The bottom of the RPV contains penetrations for control rods, sensors, etc. TMI-2 had some small excursion of corium through a few of these types of points, but that isn’t the same as a melt-through of the RPV floor.
Here’s a picture of the “final state” of the RPV at TMI-2:
http://www.americanhistory.si.edu/tmi/10-01.htm
Here’s the analysis of what happened to the RPV at TMI-2:
http://www.gl.iit.edu/govdocs/resources/NUREGCR6197part01.pdf
and the sequence of events at TMI:
http://www.gl.iit.edu/govdocs/resources/NUREGCR6197part01.pdf
TMI’s RPV wasn’t designed to hold back a molten core either... but it did.
TEPCO first thought that the RPV’s for 2&3 were compromised, then reversed themselves. Their assessment of reactor 1 is that they think the core might be extending out the control rod shafts at the bottom of the RPV. They still don’t know for certain, they’re still making estimations based on instrumentation.
On the flip side, at TMI, they didn’t think that the core had melted so extensively and the models of what happens in a LCA had to be adjusted as a result of TMI’s results. We heard all manner of “burn through the RPV” alarmism during TMI as well.
But let’s play devil’s advocate here: Let’s assume that the cores have dropped out the bottom of the RPV’s. What do the temperatures in the PCV’s tell us? They’ve achieved temps < 100C, which is “cold shutdown,” and there is no more self-sustaining reaction therein. The only way to get rid of the decay heat it to dump water across it. You can either carry the heat away, or the heat is absorbed by the water as it changed from liquid to gas phase. Overall, we should prefer a water cooling method that doesn’t involve the creation of steam.
The reality is that we won’t know exactly what happened until or unless they are able to section the bottom of the RPV, as they did with TMI years after the melt-down. The directly applicable experience we have (TMI-2) showed us that the core could melt down inside the RPV but not go through the bottom of the vessel.
For all the hysteria being offered by anti-nuke advocates and luddites the world ‘round, the physics of what goes on is pretty straightforward: When a core slags down, it takes in a whole lot of non-reactive stuff with it. The boron they’ve been dumping into the situation is a heavy neutron absorber, well known to poison fission reactions. There isn’t going to be some nice, uniform ball of fissile material in a runaway reaction, ready to head for the center of the earth. There’s going to be an ugly, molten mess of composite material that flows, solidifies and then cools. Even at Chernobyl, the core melt-down was contained within the reactor building as it slumped out of the reactor, combining with sand, steel, concrete and then cooling in the floors below the reactor. The most damaging thing about Chernobyl was the fire which spread isotopes over such a wide area.
On the subject of alarmism, here’s something useful to read:
http://fukushima.ans.org/report/Fukushima_report.pdf
If you read nothing else, start on p. 31 and continue to p. 33. NB the following passage on p. 32:
“A popular theoretical physicist and media personality made dozens of television appearances ridiculing the Japanese effort to cool the reactors and predicting the loss of the entirety of northern Japan unless the reactors were immediately entombed. There was no sustained counter view or strong challenge to these
claims—and perhaps, none was wanted.”
Seems as tho said TV personality is still offering observations of this sort today... despite his predictions not coming true to date.
When I’ve checked into the credentials of those being interviewed by the press, or offering these alarmist claims, very, very few of them have any science or engineering background. One guy who is well known for his alarmism from a DC “think tank” who is a supposed “spent fuel pool expert,” is, in fact, a music studies drop-out. Let’s get this understood: He wasn’t a music major... he dropped out of a music program. I’m not saying that being a music major is easy - I have friends who were graduates of serious music schools and they hardly had a cake-walk. But then again, none of my friends who were music majors a) dropped out, b) are trying to hold forth technical opinion on nuclear power, or c) were ever arrested for growing dope in their basement while holding a government job with a clearance.
The least the press should try to do is find some people who have passed a few physics and math classes. Just a few. Let’s say, three semesters of calc, three semesters of physics. They don’t even have to finish a degree. I’ll accept someone who dropped out of a BS program by the end of their sophomore year over some of the “experts” the press is parading around.
The ANS report also alludes on p. 32 to the hysteria disseminated by the chair of the NRC concerning the fuel pool at reactor 4. This is where the hysteria about the fuel pool(s) started, with his comments to Congress. Well, while he has some credentials in physics, let’s see what his tenure at the NRC has been:
http://www.politico.com/news/stories/1211/70427.html
And for other amusing stories:
http://www.politico.com/tag/GregoryJaczko
Not what I’d call a calm, cool individual.
—If it makes you feel any better, we gave it to China.—
Whew! Thank you. I’ve unloaded the shotgun and tore up the letter.
That was close!
Inside the core, in the upper region of the core during the loss of coolant period, temperatures might have reached in the vicinity of 1,700 to 2,000C. This is based on forensic examination of what happened inside TMI-2 years after the core was sampled.
When that material would have slumped lower in the core and met water levels, it would have cooled fairly quickly.
TMI-2 also showed that these peak temps were reached only in the very central region of the core, and not uniformly across the core. The outer regions of the fuel rods didn’t reach anywhere near those temps, even when not covered with water.
As I’ve said before, the fear people (especially women) have of things “nuclear” is irrational in the classic, numerical sense.
I have no more fear of anything resulting from Fukushima than I have fear of dying from a blood clot as a result of stubbing my toe.
At the same time, because I am a highly numerate person, skilled in higher mathematics, I have a rational and supportable aversion to allowing the radon evac system in my basement to fall into disrepair. I check the system every where, because in the county where I live, over 60% of homes sampled show radon levels higher than the 4pC/l recommended limit, and there are levels that have been found in basements in this county into the 20+ pC/l region. So making sure that we have a radon evac system and that it works is a rational concern for me.
Ephemeral increases in background radiation from the other side of the planet? Pfah. I’ve already been exposed to more from above-ground testing after-effects in Nevada from when I lived in Nevada.
That said, I’ve been reading papers of late where biologists are studying wildlife in the Chernobyl region. One big question arises: Why are humans so special? Or, put another way, where are all the supposed deleterious health effects on the wildlife in the region?
should read:
“I check the system every week...”
Ex-Vessel Corium Coolability and Steam Explosion Energetics in Nordic Light Water Reactors
Perhaps their main point was the amount of liquidity that occurred. Normal Corium is not 100 % liquid. It retains some solid within the melt mix. So it is partially solid and partially liquid. It can be quantified by how liquid or solid that its physical components are overall. Obviously the more liquid, the less the density. The more solid, the greater the density. More liquid means it should travel farther and faster then more solid. My guess is Kaku stated something he was not supposed to state. Probably national security/classified material that he read on a private wire service. Probably coming out of Japan or through the NRC. Need some more FOIA requests.
Thanks - glad you came back to question...
:)
Because in bureaucrat thinking, if 10 is bad and 5 is better, then none must be perfect.
Attempting to make a germ free environment doesn’t keep you from getting sick, it ruins your body’s ability to develop immunity.
Radiation is a normal part of life on earth. So it is illogical to assume that it’s best to receive no radiation at all.
Wrong accident. TMI was a Pressurized Water Reactor. The control rods on PWRs are all through the vessel head, not the bottom of the reactor. There are no control rod penetrations at the bottom of a PWR reactor vessel. And what the hell is a solenoid seal?
The core melt at TMI did damage in-core instrumentation penetrations at the bottom of the vessel, but the melt never extended beyond the vessel, and even if it had, the containment structure was never violated.
They managed to destroy a Billion Dollars worth of equipment at TIM, but it was never a China Syndrome. That was just a stupid Jane Fonda movie.
” - - - temperatures might have reached in the vicinity of 1,700 to 2,000C.”
Thanks. Sorry for the vague previous question.
Worst case: < 2 X the MP of Basalt, +/- MP of good Steel = max. penetration into Basalt Crust would be < 1/10 km IF there was NO conductive heat loss down to the top of the Basalt crust.
Most likely case: Rapidly increasing conductive heat loss for such a small amount of heat energy @ 2300 K = <1/10 km substrate penetration.
Test of the above speculations: compare to melt (not fracture) depth of Atomic Bombs.
BTW, ping me if I have bombed out.
The stainless steel welds connecting the control rod box to the RPV bottom. Inside the control box is solenoids for moving the control rods up and down.
Thanks for the corrections. Knew it was a seal at the bottom of the RPV, which basically means weld. You can find complete detailed descriptions for TMI damage in the papers I linked above.
Bottom line - a seal on the bottom of the RPV broke at TMI.
And, you know, if we end up with a molten core and then you talk about the time for the concrete to disassociate, you know, that NUREG says it’s a couple of inches an hour, you know. And, of course, that Mark 1 containment is the worst one of all the containment's we have, and it’s literally, you know, this NUREG tells you that in a station blackout you’re going to lose containment. There’s no doubt about it.
But, anyhow, I just would highlight that that is a valuable resource, that NUREG. I think it’s — is it 6150, CR-6150, Perspectives on Nuclear Safety? It completely walks all of this down. It’s already been thought out. It’s already been reviewed, looked at, modeled, everything.
So, the one thing the NUREG doesn't really do is tell you how to stop it, how to mitigate it, other than keeping water on it.
I’m not wagering my life on anything. There’s no threat to my life from Fukushima whatsoever, under any condition. I used to live in Nevada downwind of the test range, talked to people who lived and ranched in the “downwind” area of the NTS, and they’re pretty sanguine about nukes as well. They’re more worried about winter precip levels than they are about any nuclear fallout.
And there will be another bottom bolted onto that flange, BTW.
That’s what I’ve tried to communicate over and over, but people here in the US now seem to want to worry about things that are no reason for them to worry, while ignoring things that they SHOULD be worried about.
What you SHOULD be worried about is the rapidly accelerating debt load in the US and the hollowing out of the US economy, with no prospects or plan from either political part on how to reverse the situation. Then people should be worried that the major trading partners of the US are working on plans to replace the US dollar as the world’s reserve currency, which when accomplished, will make oil prices shoot to the moon in a couple months’ time. When (not if) that happens, the US economy will go into free-fall and the US consumer will see huge devaluation of the dollar vs. tangible goods (read as: “Food.”) in a very short period of time.
What we’re now getting closer and closer to a point-of-no-return for the US economy. I estimate that, unchecked, our macro-economic conditions are close to a point of no return within the next two to three years. After that, we will be in a situation where our economic future becomes one like Japan - decade upon decade of low to no growth, high non-participation in the labor force by youth and unskilled, huge transfer payments from the productive class to the deadbeat class, capital fleeting our markets.
Romney so far has not articulated a plan to reverse this course. The GOP keeps harping on Ryan’s “plan” but it is nothing but window dressing.
Fukushima? Pfah. I’m literally more concerned about weeds in my yard than Fukushima. It’s a huge mess, the results of which may eventually collapse the Japanese economy, but for us, the upside from that is that the US will lose a major economic competitor. The downside is that the Japanese buy a lot of US debt, and they simply won’t have the money to do that any more - they’ll be too busy trying to prop up their own economy. Their idiotic idea of shutting down all their nuke plants will (not might, but will) result in macro-economic declines for their country for the foreseeable future. They don’t have natural hydrocarbon resources (eg, coal), or natural gas that they can burn to replace their nukes.
Yea, that’s probably a good SWAG estimate, backed up by evidence from the “natural reactors” in Gabon.
The point is that the bottom looks more like the top of a salt shaker. Obviously it was never ever designed to stop a near complete meltdown of the core.
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