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Japan Earthquake: nuclear plants

by gmax137
Tags: earthquake, japan, nuclear
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etudiant
#12349
Feb13-12, 02:40 PM
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Quote Quote by Gaffney View Post
One thing I don't understand is how the amount of water has been multiplied 6x over February but there has been no change in the reactor water level. Is the gauge broken, is the water evaporating quicker or is the water escaping the reactor?
Seen that the water level in the reactor was too low to be seen by the borescope, one can assume the RPV has some leaks, maybe large ones and that any reported reactor water level may be invalid. Obviously the increased injections will gradually raise the water level in the plant basement, but with 80,000 cubic meters there already, it will take some time to make a substantial increase.
The JAIF used to publish daily, then weekly situation reports that included the water levels in the various parts of the facility, but that stopped about a month ago when a more generic summary was substituted. TEPCO was the source of their data, so it may still be available there if one knows where to look.
Yamanote
#12350
Feb13-12, 02:55 PM
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Quote Quote by etudiant View Post
TEPCO was the source of their data, so it may still be available there if one knows where to look.
If this is what you mean:

-> http://www.tepco.co.jp/en/nu/fukushima-np/index-e.html

-> Scroll down to "Situation of water level, transfer and treatment of the accumulated water"

This information is also provided with the daily press conference report and every now and then there is a more detailed report:

http://www.tepco.co.jp/en/press/corp...s/120201e3.pdf
mheslep
#12351
Feb13-12, 02:59 PM
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Quote Quote by elektrownik View Post
Unit 2 sensor is damaged because it is 250+ C now, and it is impossible
is it possible that the water boiled/drained away?
etudiant
#12352
Feb13-12, 03:02 PM
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Quote Quote by Yamanote View Post
If this is what you mean:

-> http://www.tepco.co.jp/en/nu/fukushima-np/index-e.html

-> Scroll down to "Situation of water level, transfer and treatment of the accumulated water"

This information is also provided with the daily press conference report and every now and then there is a more detailed report:

http://www.tepco.co.jp/en/press/corp...s/120201e3.pdf
Thank you, that is exactly what I was thinking of.
A very helpful reference that also gives some insight into the functioning of the water decontamination effort.
zapperzero
#12353
Feb13-12, 03:38 PM
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Quote Quote by jim hardy View Post
Anyhow dont bet a lot of money or invest much worry on a lone thermocouple that's suffered the abuse those have. But keep an eye on it.
It's great info from you as usual, jim. But it makes it sound to me as if the other thermocouples failing too is pretty much a given.
elektrownik
#12354
Feb14-12, 03:18 AM
P: 296
Strange temps in unit 2 (data from today):
Attached Thumbnails
Capture.PNG   Capture2.PNG  
zapperzero
#12355
Feb14-12, 04:24 AM
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Quote Quote by elektrownik View Post
Strange temps in unit 2 (data from today):
More sensors on the fritz? Maybe because of the extra water?
gbettanini
#12356
Feb14-12, 04:28 AM
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Quote Quote by elektrownik View Post
Strange temps in unit 2 (data from today):
Is a melt-through possible?
elektrownik
#12357
Feb14-12, 04:44 AM
P: 296
Interesting that all strange temperature data are from bottom of RPV or close to this part of RPV so it is possible that something bad is in progress.
jim hardy
#12358
Feb14-12, 05:12 AM
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Multiple sensors trending together is worrisome.

But do i see readings of 118, 251 and 4 ?
Those need to be cross checked against other indications such as visible steam, temperature and particulate analysis of air exiting building.

and ask the technnicians whether those tc's are wet.
swl
#12359
Feb14-12, 07:08 AM
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Quote Quote by Borek View Post
I have not followed the situation for a long time, so I am not sure about details. What pressures are we talking about? Temperature shouldn't go above boiling point, 276℃ means boiling unless pressure is over 60 atm.
I'm guessing it will be difficult to pressurize that RPV much above one atmosphere. And if the TC is away from water, there need not be any pressure.
Borek
#12360
Feb14-12, 07:29 AM
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Quote Quote by swl View Post
I'm guessing it will be difficult to pressurize that RPV much above one atmosphere.
That's what I was aiming at - as the pressure is unlikely to be that high, if the sensor is under water it must be wrong.

And if the TC is away from water, there need not be any pressure.
Yes, but what is the water level and is the TC under water or above? Or do we simply not know?
tsutsuji
#12361
Feb14-12, 08:14 AM
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http://www3.nhk.or.jp/news/genpatsu-...0_ondokei.html The NISA instructed Tepco to write a report by 15 February, on such things as the cause of the high thermometer values and the way to measure temperatures by other methods.

http://www.mbs.jp/news/jnn_4953273_zen.shtml Tepco tested 15 of the 41 thermometers installed inside unit 2's PCV, and found that two more thermometers were broken. Nothing abnormal was found with the two thermometers located at the same height as the one that had abnormal values.

http://www.47news.jp/CN/201202/CN2012021401002271.html 8 thermometers are broken out of a total of 41 at unit 2's RPV. Adding to the thermometer that momentarily reached 400C, two other thermometers were found with an abnormal electric resistance. Tepco had judged that 5 other thermometers were broken. Tepco is judging the RPV's temperature trend with the remaining 33 thermometers.
elektrownik
#12362
Feb14-12, 09:07 AM
P: 296
Xenon detected in unit 2: http://enenews.com/tepco-press-hando...hour-half-life
http://www.tepco.co.jp/en/nu/fukushi...20214_07-e.pdf
tsutsuji
#12363
Feb14-12, 11:24 AM
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These results are hardly different from those of 6 February, are they?

Quote Quote by tsutsuji View Post
http://www.tepco.co.jp/en/nu/fukushi...20208_07-e.pdf Fukushima Daiichi unit 2 charcoal filter nuclides, February 6
Yamanote
#12364
Feb14-12, 12:43 PM
P: 68
Quote Quote by tsutsuji View Post
These results are hardly different from those of 6 February, are they?
Right. That's why I ignore all the stuff on enenews.
etudiant
#12365
Feb14-12, 01:04 PM
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Quote Quote by Yamanote View Post
Right. That's why I ignore all the stuff on enenews.
Well, ENENews has been in the forefront of the disaster focused reporting, so they deserve to be taken with more than a pinch of salt.
That said, we've not had afaik a nuclear reactor of this size experience as catastrophic a failure, so Fukushima is writing new chapters in the book.
The layman's understanding is that there is no plausible mechanism to achieve recriticality in the damaged fuel, but that residual decay heat is a serious issue. Is this incorrect and are there plausible ways the damaged fuel can be brought back to criticality in any substantial way as a consequence of this accident?
Rive
#12366
Feb14-12, 01:30 PM
P: 355
Quote Quote by etudiant View Post
The layman's understanding is that there is no plausible mechanism to achieve recriticality in the damaged fuel, but that residual decay heat is a serious issue. Is this incorrect and are there plausible ways the damaged fuel can be brought back to criticality in any substantial way as a consequence of this accident?
ftp://ftp.cordis.europa.eu/pub/fp5-e...cs/09-sara.pdf

So they think it's likely happens in some circumstances.

But Tsutsuji is right about the Xenon levels, so in this particular case it's not likely happened.


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