- #2,731
razzz
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Jorge Stolfi said:
Unit 1 doesn't look so good.
Japan Earthquake: Nuclear Plants at Fukushima Daiichi
- Thread starter gmax137
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- Earthquake Japan Nuclear Plants
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The Fukushima Daiichi nuclear plant is facing significant challenges following the earthquake, with reports indicating that reactor pressure has reached dangerous levels, potentially 2.1 times capacity. TEPCO has lost control of pressure at a second unit, raising concerns about safety and management accountability. The reactor is currently off but continues to produce decay heat, necessitating cooling to prevent a meltdown. There are conflicting reports about an explosion, with indications that it may have originated from a buildup of hydrogen around the containment vessel. The situation remains serious, and TEPCO plans to flood the containment vessel with seawater as a cooling measure.
Unit 1 doesn't look so good.
- #2,732
Jorge Stolfi
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Based on an earlier post and the generic GE BWR reactor manual, here is my uderstanding of how the water level measurements are taken:
There are two or more water-filled tubes that extend fom some accessible location into the core, through the bottom of the RPV. One tube ends well above the normal water level, the other(s) end(s) somewhere between the core shroud and the RPV wall, below the shroud's upper edge. The difference in pressure between the two tubes is interpreted as the water level.
The same post warned that what is being measured is actually the water level between the shroud and the RPV wall, which, given the current situation, may not be the water level in the core proper.
Is this correct?
Another question: since the crisis days, the water levels have been quite stable (#2's level barely budged when the pumping rate was doubled) and well below the top of the fuel (1.7, 1.5, and 2.3 meters in #1-#3). Why and why?
There are two or more water-filled tubes that extend fom some accessible location into the core, through the bottom of the RPV. One tube ends well above the normal water level, the other(s) end(s) somewhere between the core shroud and the RPV wall, below the shroud's upper edge. The difference in pressure between the two tubes is interpreted as the water level.
The same post warned that what is being measured is actually the water level between the shroud and the RPV wall, which, given the current situation, may not be the water level in the core proper.
Is this correct?
Another question: since the crisis days, the water levels have been quite stable (#2's level barely budged when the pumping rate was doubled) and well below the top of the fuel (1.7, 1.5, and 2.3 meters in #1-#3). Why and why?
- #2,733
|Fred
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Jorge Stolfi said:
more data for you ;) (only reactor 1)
https://www.physicsforums.com/showthread.php?p=3225222&highlight=missing#post3225222
also to be noted:
Reactor core pressure before SCRAM was about 7MPa and DW pressure 0,1 Mpa
- #2,734
|Fred
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Cire said:
I would also like to know where are those vent (the one venting from the primary containment (drywell )to the segondary ) are
- #2,735
razzz
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If the RPV was breached and the DW is leaking a large amount of water then DW/RPV water will only maintain at the leak point level.
Rough sketch of a typical Boiling water reactor (BWR) Mark I Concrete Containment with Steel Torus including downcomers, as used in the BWR/1, BWR/2, BWR/3 and some BWR/4 model reactors.
* DW = Drywell
* WW = Wetwell
* SFP = Spent Fuel Pool
* RPV = Reactor Pressure Vessel
* SCSW = Secondary Concrete Shield Wall
Rough sketch of a typical Boiling water reactor (BWR) Mark I Concrete Containment with Steel Torus including downcomers, as used in the BWR/1, BWR/2, BWR/3 and some BWR/4 model reactors.
* DW = Drywell
* WW = Wetwell
* SFP = Spent Fuel Pool
* RPV = Reactor Pressure Vessel
* SCSW = Secondary Concrete Shield Wall
- #2,736
|Fred
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TCups said:
Unfortunately you got it wrong... and miss read the picture.. your over head crane need to be slided slightly to th right (north)
I'm 80% confident that we are seeing a round heat emitter bellow the crane, the round shape is the one of the Concrete stab or to be exact the lack of...
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- #2,737
razzz
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Have you seen a pic of one these things under construction yet?
- #2,738
elektrownik
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Great idea:
- #2,739
razzz
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- #2,740
razzz
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It's all they can do. Must keep cooling down the hot spots. first and foremost.elektrownik said:
- #2,741
ohohohoh
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razzz said:
Ok, that's the Areva PowerPoint.
At Page 12 the are data for the Batteries for two Units.
Unit 1 runs out of Batteries on 11. at 16:36 ! Much less then the 8 hours battery capacity!
And at Unit 3 they reached march 13. at 2:44! Much much more than the 8 hours.
And there is no source mentioned for their data!
Sorry, I'm not necessarily believing that!
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- #2,742
razzz
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ohohohoh said:
Wait until you read how long they were without water.
- #2,743
shogun338
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Tepco to release 11500 tons of radioactive water into Pacific Ocean . To make room for all the water coming out of damaged reactors . Just announced on CNN LIVE .
- #2,744
|Fred
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3500 tons less than half an hour ago ? at this rate they won't be releasing anything at the end of the day.. (excuse the sarcasm targeting the way the press takes liberty with numbers..)
- #2,745
elektrownik
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[PLAIN]http://img856.imageshack.us/img856/7640/capturevi.jpg
Why it is so hot at the right side ? There is no core or SFP...
Look at 00:30 this is reactor 1.
http://www.liveleak.com/view?i=694_1301894964UPDATE: new temp data: http://www.mod.go.jp/j/approach/defense/saigai/tohokuoki/kanren/230404.pdf
Why it is so hot at the right side ? There is no core or SFP...
Look at 00:30 this is reactor 1.
http://www.liveleak.com/view?i=694_1301894964UPDATE: new temp data: http://www.mod.go.jp/j/approach/defense/saigai/tohokuoki/kanren/230404.pdf
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- #2,746
- #2,747
ohohohoh
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razzz said:
Do you mean the data on page 19?
- #2,748
|Fred
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According to the paper hot is between 10 and 16° .. not so hot..elektrownik said:
I'm thinking that the reinforced top structure of unit 3 , 4 and 2 might have been a bad idea..
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- #2,749
TCups
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CORRECTED THERMAL IMAGE BLDG 3 -- OVERHEAD CRANE'S POSITION CHANGED
Per Fred's observations:
If the plug is gone, then it is indeed unfortunate. I stand corrected on the position of the crane, Fred. And I can see heat leaks around the edges, yes, but do you really think the entire concrete plug is gone? Where? For that to be the case, wouldn't the greatest visible damage to Bldg 3 have to be in the center of the building? Or did the plug hit the underside of the crane and fragment? Or did the plug blast free and then an intact section of roof girders and the crane fall back into place over the open mouth of the reactor's primary containment?
http://i306.photobucket.com/albums/nn270/tcups/Picture47.png
Per Fred's observations:
|Fred said:
If the plug is gone, then it is indeed unfortunate. I stand corrected on the position of the crane, Fred. And I can see heat leaks around the edges, yes, but do you really think the entire concrete plug is gone? Where? For that to be the case, wouldn't the greatest visible damage to Bldg 3 have to be in the center of the building? Or did the plug hit the underside of the crane and fragment? Or did the plug blast free and then an intact section of roof girders and the crane fall back into place over the open mouth of the reactor's primary containment?
http://i306.photobucket.com/albums/nn270/tcups/Picture47.png
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- #2,750
AtomicWombat
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razzz said:
Not quite. This is true only if there is no water added to the RPV or DW.
If water is added at a constant flow rate to the RPV, the water in the RPV will find a level such that leakage balances additions (i.e. until it is in steady state), where "leakage" can be interpreted to mean all losses including by steam. Obviously if the leak is large then more water is required to maintain the required water level.
- #2,751
artax
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I thought that concrete plug was a missile protection, so it would be incredibly strong and would have remained in one (or 8) pieces after a blow out.
- #2,752
TCups
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artax said:
The strong evidence says reactor 3's primary containment was breeched at the time of the blast (as was Unit 2's). Fred and I agree on that I am pretty certain. I can understand a blast from the primary containment loosening the plug -- maybe even leaving it completely askew, or fragmenting its sections, if it is in multiple sections. But I still believe it was the FHM that went ballistic, and that most of the blast diverted through the transfer chute. I am not sure it makes a lot of difference either way at this point. The biggest problem is and will continue to be the hottest thing in the thermal images of B3 and B4 -- the spent fuel pools, which were never "contained" from the beginning, and this has been my greatest worry from the onset of the first explosion. What a mess . . .
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- #2,753
elektrownik
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WFT is with reactor 4 thermal image ? It appear that there is fuel in core ?!
- #2,754
nicuss
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|Fred said:
Why the lack of? Given the low IR temps recorded wouldn't it make sense for the round plug to be in place but slightly warm from the very hot (melting?) fuel rods inside?
- #2,755
Giordano
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Jorge Stolfi said:
Very useful plots but data don't seem updated since Apr 02. And I think latest release from NISA is 70 (at least in English).
----
Pressure in RPV 1 is increasing. Here is the latest update from JAIF (61) : http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1301899872P.pdf
Is that a big concern? Is there a greater risk of H2 explosion if the pressusre increases? Or do they have to release pressure?
We have been informed about that they we were planning to inject N2 in unit 1 to reduce risk for explosion. Does anyone know if this has been successful?
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- #2,756
artax
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TCups said:
Yes... complete mess! And very worrying.
I am hopefull that this use of dye will give them some form of plan.
Question, is nearly all the radioactivity coming from damaged fuel rods (with some from neutron activation but very little as there's no areas with high enough neutron flux), and if all the fuel assemblies can be kept cool, the radioactivity will drop off with time as the active isotopes are washed out and concentration decreases?
They need tons of ion exchange resins to the site ASAP and start polishing this water.
They need a lot more help to get this under control.
Why does it seem it's being left to TESCO? (sorry TEPCO)
- #2,757
NUCENG
Science Advisor
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PietKuip said:
From the Fission Product Yield Curve for U235 (and Pu) 3% of fissions produce fission products with mass number 129 including Cd, In, Sn, Sb, Te, and Iodine. The List is a Beta decay chain. Starting with any isotopr the chain eventually reached I129 which is radiactve but has a very long halflife. Further information based on a reactor source term anaysis for BWRs (proprietary), but based on NRC code ORIGEN-2, there is about 9.6E3 Ci/MW of Te129 in both natural and meta-states. After 30 days the addition of Te from the other parent isotopes results in only a reduction of the Te by a factor of 8. So it should be no surprise that there is still measureable Te after 3 weeks. It clearly does not support a conclusion that there is recriticality. I am still looking for evidence.
Cl-38 was a possibility due to no clear parent decay chain. The only sources for CL-38 are neutron activation and proton interaction with Ar similar to what happens in the atmosphere from cosmic rays. But we haven't seen any more reports of CL-38 and TEPCO has apparently indicated it was measurement error. We have heard news reports with unatriuted descriptions of blue flashes and neutron beams. The Gunderson, Markhijani, Dalmnoki-Feress study is being reviewed with some pretty strong comments. See "http://lewis.armscontrolwonk.com/archive/3822/localized-criticalities-at-fukushima" Even Lyman at the Union of Concerned Scientists has doubts that CL-38 was real.
Are their local bursts of criticality or chain reactions? I don't know. It is possible and therefor we need to be alert to signs that it is happening. Neutron radiation would be a serious risk to workers. If it were happening we would see short lived fission products and there are neutron detectors. The people on site need to using their tools. For us, it is an intellectual exercise.
As to the battle of personal qualifications of sources, personal attacks are usually a reactions to being put on the defensive to justify your opinion. Better is to go back and see if the opinion should be defended or amended. Somebody may be pro or anti-nuc and still be right.
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- #2,758
ohohohoh
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- #2,759
TCups
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elektrownik said:
An interesting question. But these are thermal images, not images of radioactivity. If reactor 4 were shut down, then the starting point would be an equal level of water in both the reactor vessel and spent fuel pool, connected by an open transfer chute. As the water in the SFP boils off, it drops, but it would also have to boil off the volume of water in the chute, and in the upper portion of the primary containment to the level of the transfer chute before the water level in the SFP alone began to drop.
If, thereafter, efforts to restore water into the SFP were successful, then it could mean that the water level is rising and therefor, warm water is flowing from the SFP back into the upper containment. That, I suppose, would be a good sign, indicative of effective filling of the SFP.
It seems less likely somehow (I can't really say why) that actual fuel rods displaced from the explosion could have ended up inside of the reactors primary containment, but I can't dismiss the possibility. If they did, then that is probably fortunate versus the alternative -- that they are out of the pool and not in water.
Or, it could be that there is just a large volume of residual warm water in the reactor core left over from normal operations. I am not sure how long it had been shut down.
Which brings another interesting question to mind. Would it be, or have been possible to pump water into the primary containment, as was done in units 1-3, and have it replenish the water in the SFP through an open transfer chute? Did I hear that the two fatalities were in the basement of Bldg 4 -- I can't remember for sure? If they were working in the basement of Bldg 4, then were they perhaps trying to do just that when the explosion occurred?
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- #2,760
Giordano
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ohohohoh said:
Excellent, thanks!