electricpete
Electrical
I don't know what they're using, but there was a related link in my post dated 16 Mar 11 7:47
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(2B)+(2B)' ?
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(2B)+(2B)' ?
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Fukushima No. 1 loss of coolant due to earthquake 7
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The workers at Fukushima are just wearing plastic suits and respirators to block intake of radioactive contaminants. They're probably also wearing safety glasses if not using a full-face respirator. Plastic sheet provides some protection from external beta, but negligible protection from external gamma.
External gamma shielding basically comes down to mass - a pound of tungsten provides no more protection than a pound of lead. Some applications use tungsten because it's denser, non-toxic and can somehow be mixed more easily with flexible plastics. No doubt there exists some tungsten aprons out there, but that weight would still slow you down too much to be useful. Better to get your job done quickly and get out of the radiation field. Also, lead aprons can become contaminated and carry the contamination around with you.
External gamma shielding basically comes down to mass - a pound of tungsten provides no more protection than a pound of lead. Some applications use tungsten because it's denser, non-toxic and can somehow be mixed more easily with flexible plastics. No doubt there exists some tungsten aprons out there, but that weight would still slow you down too much to be useful. Better to get your job done quickly and get out of the radiation field. Also, lead aprons can become contaminated and carry the contamination around with you.
For anyone still interested, here's a link to the Tokyo Electric Power Company's website providing information about Fukushima Dai-ishi.
Lots of pictures at the second URL (which can be reached from the first one; look under "Press Release")
Under the first URL, you can find the location of the monitoring points and the associated radiation levels at those points.
Patricia Lougheed
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Lots of pictures at the second URL (which can be reached from the first one; look under "Press Release")
Under the first URL, you can find the location of the monitoring points and the associated radiation levels at those points.
Patricia Lougheed
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electricpete
Electrical
That is informative stuff. Can someone explain the pressure and temeprature readings for Units 2 and 3 on slide 10/28:
Temperature > 100C, should have positive pressure at saturation.
Some kind of instrument error?
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(2B)+(2B)' ?
Temperature > 100C, should have positive pressure at saturation.
Some kind of instrument error?
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(2B)+(2B)' ?
Pete
I have no more information than what was provided here on a publicly available website, so your guess is as good as mine. Might it be due to the different locations where the readings are being taken?
Patricia Lougheed
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I have no more information than what was provided here on a publicly available website, so your guess is as good as mine. Might it be due to the different locations where the readings are being taken?
Patricia Lougheed
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The latest plant parameters still list the reactor water temperature as "Impossible collection due to low system flow rate," and most of the RPV temperatures and pressure are still "under investigation."
The highest RPV temperatures reported in all documents are from the main feedwater nozzle. This nozzle is relatively high on the RPV and is probably dry. I'm guessing that cooling water is only being injected through the Low Pressure Coolant Injection (LPCI) system, which feeds the recirculation loops below the main feedwater nozzle.
There's another set of published temperatures for the bottom head of the RPV, and these are around 110-120 C. We can expect the boiling point to be elevated by a couple metres of head and a lot of salt left behind from the seawater cooling. On top of that there could be some metastable superheating happening, or heat conduction could be keeping the metal temperature higher than the water temperature. And then there's always the possibility of sensor failure(s) as well.
The highest RPV temperatures reported in all documents are from the main feedwater nozzle. This nozzle is relatively high on the RPV and is probably dry. I'm guessing that cooling water is only being injected through the Low Pressure Coolant Injection (LPCI) system, which feeds the recirculation loops below the main feedwater nozzle.
There's another set of published temperatures for the bottom head of the RPV, and these are around 110-120 C. We can expect the boiling point to be elevated by a couple metres of head and a lot of salt left behind from the seawater cooling. On top of that there could be some metastable superheating happening, or heat conduction could be keeping the metal temperature higher than the water temperature. And then there's always the possibility of sensor failure(s) as well.
They've been negative since day one of the disaster. I'd guess they're bad sensors or sensor circuitry.
Keith Cress
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Keith Cress
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I'm guessing that Keith is referring to the RPV gauge pressures? They're slightly negative, but only by 1% or so of the full operating pressure. That's probably within the normal instrument error band. I'm guessing that the RPV's in units 2 and 3 are fully vented to the atmosphere, and the true gauge pressure is zero.
Didn't see these posted, maybe I overlooked them but thee photos are amazing.
Zogzog (and others): Tokyo Electric has a website devoted to the Fukushima Daiishi reactor recovery ( If you scroll down, about 3/4 of the way down, there is a clickable link "Photos for Press."
A bunch of amazing pictures, including the ones shown above.
Patricia Lougheed
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A bunch of amazing pictures, including the ones shown above.
Patricia Lougheed
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Nice Patricia!
Now I just need something to download them all so it doesn't take me a week of watching them all crawl down the screen..
Keith Cress
kcress -
Now I just need something to download them all so it doesn't take me a week of watching them all crawl down the screen..
Keith Cress
kcress -
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Concur. Due to its design, the fuel assemblies (rods?) at Chernobyl actually smelted themselves and released evaporated radioactive elements, including metals, directly into the air. This was due to it using graphite for a moderator. It burned, the steam piping ran in vertical openings in the graphite pile, and the burning graphite got a pretty effective chimney effect going.
3-Mile Island melted at least the upper half of the fuel rods, due to lack of cooling water. Moron operator keept turning off pumps when they automatically came on. He was trained in-house by the utility. First-rate Navy-trained operators cost too much for them, so they got a $6-billion cleanup bill.
At Fukushima, they lost offsite power due to the eatrhquake, and internal power due to automatic shutdown because of the earthquake. Then the 6-15 foot tall wave drown out their diesel generators. Pathetic engineering, as this was a readily forseeable scenario. Japan holds tsunami drills all the time.
Without power, the decay heat of the used fuel boils off the water. If you don't replace the water, the fuel melts. One small firetruck could have delivered enough make-up water by suctioning from the seawater intake canal, and pumping into the the steam system. It all would have run back into the reactor. The firetruck method has actually been tried at a BWR before: look up "Brown's Ferry fire".
My guess is that the main problem in Japan was an inability to make a decision in a timely manner. The Japanese culture is to mull problems over for days, hold several meetings, discuss it over drinks, and finally achieve some sort of consensus -- in a week or three.
"Reactor desparately needs water NOW -- pump water into reactor. Only have seawater, and it will ruin the entire system -- system will be ruined tomorrow by the impending meltdown -- start pumping seawater."
It just took them too long to acknowledege the inevitable. And we in the USA may have that same lack of alacrity in a big emergency, if the utilities persist in training for Normal Ops, and leaving out ugly emergencies. The Navy trains for the hard stuff first, thus they develop superb operators.
"It ain't Rocket Science, it's just a big teakettle with some pecularities"
3-Mile Island melted at least the upper half of the fuel rods, due to lack of cooling water. Moron operator keept turning off pumps when they automatically came on. He was trained in-house by the utility. First-rate Navy-trained operators cost too much for them, so they got a $6-billion cleanup bill.
At Fukushima, they lost offsite power due to the eatrhquake, and internal power due to automatic shutdown because of the earthquake. Then the 6-15 foot tall wave drown out their diesel generators. Pathetic engineering, as this was a readily forseeable scenario. Japan holds tsunami drills all the time.
Without power, the decay heat of the used fuel boils off the water. If you don't replace the water, the fuel melts. One small firetruck could have delivered enough make-up water by suctioning from the seawater intake canal, and pumping into the the steam system. It all would have run back into the reactor. The firetruck method has actually been tried at a BWR before: look up "Brown's Ferry fire".
My guess is that the main problem in Japan was an inability to make a decision in a timely manner. The Japanese culture is to mull problems over for days, hold several meetings, discuss it over drinks, and finally achieve some sort of consensus -- in a week or three.
"Reactor desparately needs water NOW -- pump water into reactor. Only have seawater, and it will ruin the entire system -- system will be ruined tomorrow by the impending meltdown -- start pumping seawater."
It just took them too long to acknowledege the inevitable. And we in the USA may have that same lack of alacrity in a big emergency, if the utilities persist in training for Normal Ops, and leaving out ugly emergencies. The Navy trains for the hard stuff first, thus they develop superb operators.
"It ain't Rocket Science, it's just a big teakettle with some pecularities"
Robots don't work in real nuclear disaster situations.
Anything with an integrated circuit chip gets 'fried' due to the gamma-ray and neutron flux. They ran into this at 3-Mile Island. You have to operate robots on an umbilical, with only macro-sized components on the robot. Microelectronics cannot take the radiation.
While that's true I don't think either of those problems had anything to do with radiation.
Keith Cress
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Keith Cress
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