- #3,116
Jorge Stolfi
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RealWing said:... zero reference is at the top of the fuel strings and thus anything negative means exposed fuel elements?
That is my understanding too.
RealWing said:... zero reference is at the top of the fuel strings and thus anything negative means exposed fuel elements?
|Fred said:some one mentioned looking to see if other group of reflexion came up with different ideas..
I found this one http://forum.atominfo.ru/index.php?showtopic=575 It's in Russian.. could not make much of it ..
"Tsernobyl muuten oli reaktori joka pystyi tuottamaan aseplitoniumia."tsutsuji said:I also found that one : http://www.tiede.fi/keskustelut/geologia-maa-meri-ja-ilma-f7/japanin-tsunami-ja-ydinvoimalaonnettomuus-sen-jatkona-t50031-2415.html which is in Finnish.
razzz said:I'll give you some what ifs...I live near a shipyard (worked there once for a month) and the noise(s) on that Unit 3's launch soundtrack (even though I can't confirm it to be the matching soundtrack), before the flash and after the fallout, has the same sounds that emanate from a shipyard. I guarantee that a shipyard has metal structures make dwarf this nuclear contraption...with that in mind, first sounds on video are after our pressure capsule has/is venting to oversize metal doughnut echoing inside metal voids, water flashing to steam taking place, more venting then a explosion (probably hydrogen) releases any captured water bound nuke particles in the doughnut to air which gets caught in the updraft. Flash in video doesn't necessarily have to be an explosion, could be a burn. More water to steam flashing until water source is exhausted (take that both ways, up and sideways through constrictions). Finally last metallic sounds (lack of a better description) on video is either the crane beam landing or vessel and torus interacting or both. When I mention red cloud, I think you know what I mean. Our capsule survives but resembles a sieve, flight time unknown.
http://www.youtube.com/watch?v=nw2Aw3komgc"
Thanks for the tolerance.
ceebs said:I was talking somewhere else about control rods, in other designs I was reading if the power is cut as the control rods are attached at the top by electromagnets, the rods will fall back into the reactor and shut the reaction down, whereas on BWR's the rods are inserted from underneath by gas pressure. I assume that the control rods must be mounted fairly rigidly to enable them to line up with the fuel assemblages. If these things are true, let us say you have a partial core meltdown, now I was reading somewhere else that the melting point of the fuel rods is about 1800 C whereas the melting point of the control rods is around 2500 C, So in another type of reactor, the detached control rods would fall into the molten fuel mix as the structure of the rods melted and collapsed. but in A BWR if all is as I've put together, as the fuel melts you'd get less and less of the control rods moderating the reaction as the fuel slumps around the vertical rods.
Am I missing something obvious? or will the molten fuel start to react more readily as the moderation gradually disappears due to height and distance?
The BWR control rods are inserted hydraulically or pneumatically - with presserurized water. There is a latching mechanism that locks them in place. Below the core there is a guide tube that orients the blade vertically, and the tip of the blade is guided through a stainless steel fixture on which four assemblies sit. The control rod tip also has some rollers which roll along the surface of the channels, and that helps guide the control rod up into the core.ceebs said:I was talking somewhere else about control rods, in other designs I was reading if the power is cut as the control rods are attached at the top by electromagnets, the rods will fall back into the reactor and shut the reaction down, whereas on BWR's the rods are inserted from underneath by gas pressure. I assume that the control rods must be mounted fairly rigidly to enable them to line up with the fuel assemblages. If these things are true, let us say you have a partial core meltdown, now I was reading somewhere else that the melting point of the fuel rods is about 1800 C whereas the melting point of the control rods is around 2500 C, So in another type of reactor, the detached control rods would fall into the molten fuel mix as the structure of the rods melted and collapsed. but in A BWR if all is as I've put together, as the fuel melts you'd get less and less of the control rods moderating the reaction as the fuel slumps around the vertical rods.
Am I missing something obvious? or will the molten fuel start to react more readily as the moderation gradually disappears due to height and distance?
Astronuc said:The BWR control rods are inserted hydraulically or pneumatically - with presserurized water. There is a latching mechanism that locks them in place. Below the core there is a guide tube that orients the blade vertically, and the tip of the blade is guided through a stainless steel fixture on which four assemblies sit. The control rod tip also has some rollers which roll along the surface of the channels, and that helps guide the control rod up into the core.
The stainless steel melts at aroudn 1400 C, while Zircaloy melts at 1850 C. The concern is that the stainless steel would melt before the fuel, or would crack and leach boron. If the control rods melted to the bottom or the core, or the boron was lost, then the concern would be criticality. This is one reason that when the operators lose the ability to cool the core, they would have to inject borated water into the core to ensure that there is sufficient boron to prevent criticality.
Well before the cladding and channels melt, they would undergo oxidation/corrosion by the steam. If the cladding fails, then the fuel rods can balloon or split open and the fuel pellets can start disintegrating. Then bits of fuel can drop out into the coolant. In contact with the coolant (water or steam), some fuel can oxidize into particles, and some can dissolve.
The UO2 ceramic melts at 2800 C, well above the cladding and steel melting temperatures.
As long as there is water in the core, the fuel does not melt.
Even if the water doesn't cover the core, the fuel does not melt. Only if there is stagnant steam with essentially no heat transfer (i.e., more or les adiabatic) would the fuel melt.Joe Neubarth said:As long as there is water "covering" the core the fuel does not melt.
I took a quick look at the document, and it really doesn't apply to Fukushima. For one, KKL has a Mk-III containment, and one will not that the spent fuel pool is in a separate area.JustGuessing said:I've also been trying to understand this "Minimum Debris Retention Injection Rate (MDRIR)" terminology from the NRC report.
I found this slide show from Wolfgang Hoesel and Peter Keller for the Leibstadt Nuclear Power Plant, that covers Severe Accident Management Guidelines:
http://www.docstoc.com/docs/38671644/Folie-eins
Does any of these accident scenarios apply to Fukushima?
Thanks
TCups said:... the roof of Bldg 3 seems to implode before the blast ...
TCups said:The vertical plume of dense smoke is the final visible event.
TCups said:REGARDING THE INITIAL EXPLOSION OF BLDG 3
1) |Fred's earlier observation that the roof of Bldg 3 seems to implode before the blast is correct...
I have converted video to different formats and went frame by frame . What I think your seeing is the walls expand at the same time the fireball starts to eject . The roof seems to travel down at this point then explodes upwards with everything else and fireball is sucked back into upward explosion . A lot of the dust in this explosion is pulverized concrete. Thats why you don't see more of it laying around. Some of the large pieces fell between Unit 2 and Unit 3 onto the building attached to Unit 3. There is a mirage also in the video because it was taken at such long range that makes the structure move some .TCups said:REGARDING THE INITIAL EXPLOSION OF BLDG 3
1) |Fred's earlier observation that the roof of Bldg 3 seems to implode before the blast is correct
2) The initial fireball (Boom) isn't a fireball -- it is a pure, white puff of steam or smoke that only ignites after entering the outside air. After that, it doesn't expand or blow outward, it just seems to burn up and consumes itself. The building explodes next. The vertical plume of dense smoke is the final visible event. I haven't matched each of these to the boom, boom, boom sounds, though.
Each frame = 1/30th of a second (--15.png is at 15/30ths, or 1/2 second after --1.png)
http://i306.photobucket.com/albums/nn270/tcups/Fukushima%20Foto%20Files/Picture1.png
http://i306.photobucket.com/albums/nn270/tcups/Fukushima%20Foto%20Files/Picture2.png
http://i306.photobucket.com/albums/nn270/tcups/Fukushima%20Foto%20Files/Picture3.png
http://i306.photobucket.com/albums/nn270/tcups/Fukushima%20Foto%20Files/Picture5.png
http://i306.photobucket.com/albums/nn270/tcups/Fukushima%20Foto%20Files/Picture15.png
There is much more information in this audio and video to be extracted! Wish I had better video skills.
shogun338 said:The government is preparing to raise the legal radiation limits to adjust to the fact that people near the plant are sustaining cumulative exposure. The original policy was set to cover reactor workers briefly sustaining high doses in an accident. WHAT ! This is how there government thinks . http://www.reuters.com/article/2011/04/07/us-japan-idUSTRE72A0SS20110407
AntonL said:pdf pages 46 to 55 of "[URL assessment procedures for determining protective actions during a reactor accident
IAEA-TECDOC-955[/URL] gives the method to asses core damage from CAMS radiation data that is published regularly
TCups said:REGARDING THE INITIAL EXPLOSION OF BLDG 3
1) |Fred's earlier observation that the roof of Bldg 3 seems to implode before the blast is correct
2) The initial fireball (Boom) isn't a fireball -- it is a pure, white puff of steam or smoke that only ignites after entering the outside air. After that, it doesn't expand or blow outward, it just seems to burn up and consumes itself. The building explodes next. The vertical plume of dense smoke is the final visible event. I haven't matched each of these to the boom, boom, boom sounds, though.
Each frame = 1/30th of a second (--15.png is at 15/30ths, or 1/2 second after --1.png)
http://i306.photobucket.com/albums/nn270/tcups/Fukushima%20Foto%20Files/Picture1.png
http://i306.photobucket.com/albums/nn270/tcups/Fukushima%20Foto%20Files/Picture2.png
http://i306.photobucket.com/albums/nn270/tcups/Fukushima%20Foto%20Files/Picture3.png
http://i306.photobucket.com/albums/nn270/tcups/Fukushima%20Foto%20Files/Picture5.png
http://i306.photobucket.com/albums/nn270/tcups/Fukushima%20Foto%20Files/Picture15.png
There is much more information in this audio and video to be extracted! Wish I had better video skills.
Razzz you can look at the layout of the plant and see from where this was filmed the camera had to be a least 2 miles away . Some say it was 5 miles from plant . At 2 miles it would have taken around 10 seconds for that sound to reach the camera and on the one video it reached the camera at 2 seconds . That is why I say they sound was added to that video . On the video that is zoomed in more you can see the walls expand then a split second later the fireball explodes out upper right side facing turbine building .razzz said:Without knowing the distance the camera is from the blast it would be hard to re-adjust the sound track to the video explosion by eliminating the delay-distance factor. As I read comments to the video, some complained that the sound was not played during the first showing of the video and later aired with a soundtrack, making commenters suspicious that a soundtrack was added in. I think the distance causing delay in sound travel was confusing to viewers.
Here I'll link Unit 1's explosion again, not for the sound but lack of a noticeable flash, also notice towards the middle of the explosion where a dark rise, contrasting against the white surrounding clouds, begins to balloon upwards but quickly recedes and a link to Unit 3 without sounds.
http://www.youtube.com/watch?v=9oNEIj7EmNo&feature=related"
http://www.youtube.com/watch?v=9oNEIj7EmNo&feature=related"
Astronuc said:FK-I Units 1-5 are MK I containment, but FK-I Unit 6 is Mk II.
Unit 1 is a BWR/3, Units 2-5 are BWR/4 and Unit 6 is a BWR/5.
Jorge Stolfi said:You must be aware that MPEG and JPEG compression add very complicated artifacts to the frames. Roughly, each 8x8 pixel block is "simplified" independently of the other blocks. So one gets blurring and/or spurious streaks within each block, and spurious sharp edges between the blocks. For MPEG there are also complicated tricks to simplify apparent motion, that generate more artifacts when you try to grab a single frame. The video was recorded at high compression (= low quality) so these artifacts are quite strong. To make things worse, an edge-enhancement filter was used before compression --- which adds its own artifacts, such as spurious "grains" and "echoes" along sharp light/dark boundaries. Unfortunately, most of this damage is irreparable, since no filter can restore the information that was lost in the encoding.
For example, although the reddish flash spans a dozen pixels across, the video does not record any detail about its position, shape, and texture. The flash basically got simplified to one or two very bright 8x8 squares, with no internal detail; and that is all we are ever going to get.
What seems to be "the roof caving in" could also be a ring of black dust being blown horizontally al around the building, along the edge of the tar/cement roof, as the latter begins to be lifted off the underlying metal framework. This ring of dust becomes wider in the succeeding frames, covering more and more of the wall, from the top down.
I believe the rising column and mushroom is just a late convection artifact (i.e. not thrown out by the explosion, but lifted by buoyancy.) Like the mushroom of a nuclear bomb, or of a large gas tank explosion.
That was copy and pasted from the news report then link added . I just went back and read it and its not there now. It was on page # 2 of this report and they have changed it . I will look and see if its reported anywhere else .|Fred said:are you sure you linked to the right article ? Where did you read that
Yes . I hope so . I have been searching news sites for more info on that statement and have found nothing official yet .|Fred said:I've google it as well and the quote was edited out from a number of media, might be an interpretation mistake that was cut out
TCups said:the overall general motion and time frame of the motion are preserved in the context of a frame to frame analysis at 1/30 rate.
TCups said:Also, compression artifact isn't what turns the initial white puff into red. Only heat does that. ... there is very little doubt that a whole pile of garbage is falling out of it, streaking ground-ward in later frames. ... rising heat alone will [not] casually toss large, heavy chunks of debris almost straight and then quickly drop them on and around the building. It takes significant mechanical force and the impulse of a blast to accomplish that.