Japan Earthquake: nuclear plants


by gmax137
Tags: earthquake, japan, nuclear
SpunkyMonkey
SpunkyMonkey is offline
#13033
Apr25-12, 03:30 PM
P: 63
Quote Quote by westfield View Post
Re - the mesh you mention - While it's all over the place in the SFP -
given that we do know we are looking at the end of the "Catwalk" that runs along the northern length of the FHM bridge it may be more likely it's mesh from the "catwalk" rather than the FHM proper, the trolley part.
The mesh is very close to the catwalk-railing screen we see on Unit-2 that you posted. But I don't see the same screen on the U3 crane except possibly on the trolley as I showed. Perhaps there are photos that show that mesh screening along the U3 catwalk?

Where is this mesh all over the SFP? I don't recall seeing it before.


Quote Quote by MadderDoc
The trolley deck I am talking about is that one the video you made of, the thing looked at from the concrete pump over the pool. It has several platforms, the main structure of most can be made out so-and-so, at least enough to make one doubt that they could be what we see in that position of the pool.
Sure it could be a lower deck of the trolley, but I believe the contents there are shaped closer to upper-deck contents.

Sorry, had this second quote attributed to westfield.
MadderDoc
MadderDoc is offline
#13034
Apr25-12, 05:09 PM
MadderDoc's Avatar
P: 698
Quote Quote by SpunkyMonkey View Post
<..>
Any ideas on what's the large flat object that's smashed down across the crane's bridge?


No, but it has two features which may aid an ID. Along its top, which is well sprinkled with rubble, can be seen three regular cylindrical shapes at regular intervals (wheel pins is my first impression, but those are not always right). Also at the top, but on the side of the object that is facing the camera, there is a regular pattern bright/dark/bright /dark etcetera . The dark fields could represent just cavity in the dark, but they could also be fair dinkum darker surface fields. Considering the regularity the object displays it is not likely a chunk of the wall.

closeup to top of object:

from the distance, and at a different angle:
MadderDoc
MadderDoc is offline
#13035
Apr25-12, 06:05 PM
MadderDoc's Avatar
P: 698
Quote Quote by Rive View Post
Still about the shield plug video: the spherical distortion and the shaking makes it a mess. After removing them, it's much more better (the result is under it's way up to the youtube).<..>
Ps: the video is available here: http://www.youtube.com/watch?v=xGu7tekk4XA
Thank you, you done a fine job there, it so much less straining to eye and brain.

<..> the concrete there has a strange bluish colour, maybe becouse of the temperature?
I think it could be blue pigment from the peeled off paint. Some blue pigments are surprisingly resistant to harsh conditions, including high temperatures. I think we see several signs of a previously applied blue layer of paint on surfaces of the room.

Ps.: it's worth to watch the video at highest resolution and full screen.
Yes indeed, and thank you again.
SpunkyMonkey
SpunkyMonkey is offline
#13036
Apr25-12, 06:57 PM
P: 63
Quote Quote by MadderDoc View Post
No, but it has two features which may aid an ID. Along its top, which is well sprinkled with rubble, can be seen three regular cylindrical shapes at regular intervals (wheel pins is my first impression, but those are not always right). Also at the top, but on the side of the object that is facing the camera, there is a regular pattern bright/dark/bright /dark etcetera . The dark fields could represent just cavity in the dark, but they could also be fair dinkum darker surface fields. Considering the regularity the object displays it is not likely a chunk of the wall.
Nice images, you can really bring out the details! Right, I don't think this is a wall. I have to say the easiest thing to guess it is is what was on top of the bridge span it is rather on top of now, the trolley. But were there enough trolleys to account for all them that I'm seeing, lol!

Though as you note the trolley had a couple levels, but if that big object is the lower level and the object I suspect is the upper level actually is the upper deck, then it seems maybe they were torn apart. As odd as that sounds, I don't know what to expect at this point. The bridge is in much worse shape than I'd have expected. And how about the crane's ladder entangled with a roof girder! That mess is like a surreal bad dream!


Quote Quote by Rive View Post
Still about the shield plug video: the spherical distortion and the shaking makes it a mess. After removing them, it's much more better (the result is under it's way up to the youtube). I think the rusty-wet part is where the internal steel door meets its frame. The falling paint (?) chips are removed from the steel door.

Ps: the video is available here: http://www.youtube.com/watch?v=xGu7tekk4XA
Nice, thanks for posting! It gives a better feeling for the actual structures as you enter the curved area.

Quote Quote by Rive View Post
At 1:55 it's 'climbing' upward on the door: you can see that the upper part of the image is moving strange: it's because the upper part is actually the vertical door, while a lower parts are the almost horizontal part of the circular opening.
Exactly! That's what I was trying to describe before, that the camera there is in a 'corner', at the bottom of the screen is a surface that's 90˚ to the surface on top of the screen, and the 'slime trail' is in the corner of these two surfaces. It's just an impression, and it seems stronger in your deshaked video.
westfield
westfield is offline
#13037
Apr26-12, 04:14 AM
P: 143
Quote Quote by MadderDoc View Post
Yes, 'tis, but that is not where the cask area is.
I didn't phrase that very well. I was saying that IF that image was of U3's SFP (and not some other NPP) then it would be in the SW corner of that SFP. I wasn't neccesarily saying it is unit 3 SFP - The image is from the NHK video you linked to earlier.

Quote Quote by MadderDoc View Post
I have attached a marked up version of that other photo, which I believe is pointed along the west wall of the SFP3 towards its NW corner. Marked up is the outline of what I believe is the gate to the cask area. My clue was the horizontal X structure at its bottom which I see as the cask support. X always marks the spot :-)

It got clinched only recently, when we were told in no uncertain terms by Tepco that the cask area is in the NW corner -- which was where I had this photo figured out to be from, from combining information from other photos of the pool taken during the MOX refueling & a previous photo tour.
I'm fairly sure the "X" is a reflection of the roof bracing as is the almost vertical line - with the ceiling lights reflected in it.
Maybe it's me but I still can't see anything like a cask loading area in that image.

I'll come straight out with it at my peril, I may end up looking a right wally :)
I know Tepco indicated the U3 SFP cask loading area in the NW corner of the SFP in the recent debris map.
This was a surprise to me because I was sure the only other diagram TEPCO has shown us has the cask area on the Eastern side. That diagram was published by Tepco months ago and I haven't found it again yet. Does anyone remember it or have it?

It was also a surprise to me because I've never seen any alleged image of Unit 3's SFP with the cask area in the NW or NE corner.
Are lots of alleged Unit 3 SFP images wrong, mislabelled? I don't know. I have 3 alleged U3 images showing the cask area in the SE corner.

This is what I'm trying to get to the bottom of.

Finally if U3 SFP cask area was in the NW corner where did it go, it's not a lightweight structure.

For reference Unit 4 SFP - looking to NW corner, cask loading area marked - underwater view of the cask loading area - overhead view of cask area
westfield
westfield is offline
#13038
Apr26-12, 05:27 AM
P: 143
Quote Quote by SpunkyMonkey View Post
The mesh is very close to the catwalk-railing screen we see on Unit-2 that you posted. But I don't see the same screen on the U3 crane except possibly on the trolley as I showed. Perhaps there are photos that show that mesh screening along the U3 catwalk?

Where is this mesh all over the SFP? I don't recall seeing it before.

Sure it could be a lower deck of the trolley, but I believe the contents there are shaped closer to upper-deck contents.

Sorry, had this second quote attributed to westfield.
Sorry, I said "all over the SFP" but meant all over the FHM, not literally though. - The mesh is on the lower half of all personel walkways and in some areas as machinery guard, there's alot of it - we don't see a lot of it because images of the northern side of the U3 FHM\Bridge are few and far between.
MadderDoc
MadderDoc is offline
#13039
Apr26-12, 05:47 AM
MadderDoc's Avatar
P: 698
Quote Quote by SteveElbows View Post
Some interesting stuff there.
This one deals with how to improve modelling to establish core damage etc.
http://www.tepco.co.jp/en/nu/fukushi...20314_02-e.pdf
This appears to be saying that the model, latest ver., has been tailored to simulate the RPV pressure, and because of that, RPV pressure is well simulated.

SteveElbows
SteveElbows is offline
#13040
Apr26-12, 05:56 AM
P: 630
Quote Quote by MadderDoc View Post
This appears to be saying that the model, latest ver., has been tailored to simulate the RPV pressure, and because of that, RPV pressure is well simulated.
My understanding of this, based on the limited info available, is that the 2nd graph is a much better fit than the first one because they have now taken account of the fact that operators were manually controlling the HPCI in a manner different to the original assumption. I think I read more about this mode of operation somewhere, will have a look when I find time.
SteveElbows
SteveElbows is offline
#13041
Apr26-12, 07:11 AM
P: 630
Quote Quote by SteveElbows View Post
My understanding of this, based on the limited info available, is that the 2nd graph is a much better fit than the first one because they have now taken account of the fact that operators were manually controlling the HPCI in a manner different to the original assumption. I think I read more about this mode of operation somewhere, will have a look when I find time.
OK pages 14 to 19 of this document should shed light on their thinking and modified analysis.

http://210.250.7.21/en/press/corp-co.../111222e16.pdf

So a combination of the way the HPCI was operated (e.g. flow rate), other spraying operations, and ruling out the idea of steam leak from HPCI caused them to change their analysis.
westfield
westfield is offline
#13042
Apr26-12, 07:50 AM
P: 143
Quote Quote by MadderDoc View Post
No, but it has two features which may aid an ID. Along its top, which is well sprinkled with rubble, can be seen three regular cylindrical shapes at regular intervals (wheel pins is my first impression, but those are not always right). Also at the top, but on the side of the object that is facing the camera, there is a regular pattern bright/dark/bright /dark etcetera . The dark fields could represent just cavity in the dark, but they could also be fair dinkum darker surface fields. Considering the regularity the object displays it is not likely a chunk of the wall.

closeup to top of object:

from the distance, and at a different angle:
If you imagine this on the other side of the FHM and with the "stops" torn off it's not a bad match to this.
We can't see if there's a middle wheel in this image which would have helped.

MadderDoc
MadderDoc is offline
#13043
Apr26-12, 07:51 AM
MadderDoc's Avatar
P: 698
Quote Quote by SteveElbows View Post
My understanding of this, based on the limited info available, is that the 2nd graph is a much better fit than the first one because they have now taken account of the fact that operators were manually controlling the HPCI in a manner different to the original assumption. I think I read more about this mode of operation somewhere, will have a look when I find time.
My understanding it that whereas the model includes code to model behaviour during automatic HPCI operation, it has no code for manual operation. So, during the period of manual operation of the HPCI, for which the modellers have no model, the code is just set to roughly reproduce the actual RPV pressure measurements. Of course one can then say that the 'RPV pressure is well simulated' during that period, but it does seem a bit too pretentious for my taste, and is liable to leave the false impression that the model has been improved by the exercise.
SpunkyMonkey
SpunkyMonkey is offline
#13044
Apr26-12, 09:34 AM
P: 63
There appears to be some large heavy-metal debris in the NE quadrant of SFP3 (the video is motion stabilized and so the frame moves):


This is an area close to the object I suspect is the trolley's upper deck. One only gets the briefest glimpse, and for the life of me I can't make out what those objects are. But I'm sure I can see machined shapes, especially on a piece of debris at approximately 4 o'clock if you imagine a clock face over the video screen. The brief view is clear enough that someone who worked there or who just saw it in a photo could probably recognize it.

Here's a video clip where I attempt to outline some of these heavy-metal objects so you can see which objects I refer to.
MadderDoc
MadderDoc is offline
#13045
Apr26-12, 09:51 AM
MadderDoc's Avatar
P: 698
Quote Quote by SteveElbows View Post
OK pages 14 to 19 of this document should shed light on their thinking and modified analysis.

http://210.250.7.21/en/press/corp-co.../111222e16.pdf

So a combination of the way the HPCI was operated (e.g. flow rate), other spraying operations, and ruling out the idea of steam leak from HPCI caused them to change their analysis.
Yes, thank you. What I get, of what they did to their analysis is that "the quantity of water injected by the HPCI system was adjusted through the test line to prevent unnecessary halt of the HPCI system due to the reactor water level (L-8)". Which seems fair enough, seeing that was their narrative of what the operator was trying to achieve. The rub, of course, lies in the lack of definition in 'enough to prevent unnecessary halt'. How much is that? Anyway, in the same document we see the result of that flow adjustment in this figure:


Funny how the adjustment of flow needed under the stated criterium: "what it takes to prevent unnecessary halt of the HPCI system due to the reactor water level (L-8)" seems to be identical to the adjustment that would have been needed under the criterium "what it takes to bring the modelled RPV pressure down to the level suggested by the measured data".
SteveElbows
SteveElbows is offline
#13046
Apr26-12, 10:29 AM
P: 630
Quote Quote by MadderDoc View Post
My understanding it that whereas the model includes code to model behaviour during automatic HPCI operation, it has no code for manual operation. So, during the period of manual operation of the HPCI, for which the modellers have no model, the code is just set to roughly reproduce the actual RPV pressure measurements. Of course one can then say that the 'RPV pressure is well simulated' during that period, but it does seem a bit too pretentious for my taste, and is liable to leave the false impression that the model has been improved by the exercise.
I feel you have made unsafe assumptions here. I do not claim that their model is perfect, and obviously they are looking to change code & variables so that the output of the model more closely matches the actual data. But I don't think they just threw away proper code and fudged stuff to give suitable results, I find it more likely that they did actually make changes to the model or fed a more sophisticated set of data into the model.

Although they are obviously interested in getting the model analysis to match the measured data, I believe their priority is to be able to use the model to test assumptions about the state of various facilities at the plant. They would also like to make the model better for future use. Neither of these things is well served by simply fudging stuff to get a match, as opposed to improving the code used by the model or the data thats fed into it.

We see an example of this later in the document, when they move on to issues of containment pressure of reactor 3. They still can't get their model to match the measured data, so they have to think about what other factors may be involved, with the hope of modelling these factors later on and getting better results. They did not simply fudge things at this point to give a nice clean match between model and measured data.

In another document mentioned recently in this thread, we see that they are looking at improving the core melt model, since they know that the model is vastly oversimplified compared to the realities inside the reactor pressure vessel. But since they lack much in the way of real data about the state of the cores, this is not going to be so easy. I already ranted in the past at how their model seems to give wrong results in terms of RPV damage occurring/time of this occurring, and I speculated that this may be because they have made wrong assumptions about how much decay heat and how much water cooling was available at key points for reactors 2 and probably 3. But until they actually have far more detailed evidence that state of melted fuel & RPV is much worse than model results, I doubt they really know how far away their model is from reality.
clancy688
clancy688 is offline
#13047
Apr26-12, 10:57 AM
P: 546
Quote Quote by SteveElbows View Post
I already ranted in the past at how their model seems to give wrong results in terms of RPV damage occurring/time of this occurring, and I speculated that this may be because they have made wrong assumptions about how much decay heat and how much water cooling was available at key points for reactors 2 and probably 3. But until they actually have far more detailed evidence that state of melted fuel & RPV is much worse than model results, I doubt they really know how far away their model is from reality.
I think they've come to the same conclusions themselves. To quote from the recently posted document: "However, calculation results show no damage on RPV."
But on the last page they seem to be convinced that there's at least some of the fuel left the RPV.
So I'd interpret the "However" phrase as "There may be something wrong with the model since it doesn't show any RPV damages, but we're convinced there are."
Of course I can be mistaken, but that's at least what it sounds like to me. Moreover, you all know the radiation readings from the Unit 2 PCV. Is it possible that there are such high readings if there's absolutely no fuel escape? That should be obvious to TEPCO as well.
MadderDoc
MadderDoc is offline
#13048
Apr26-12, 12:09 PM
MadderDoc's Avatar
P: 698
Quote Quote by SteveElbows View Post
I feel you have made unsafe assumptions here. I do not claim that their model is perfect, and obviously they are looking to change code & variables so that the output of the model more closely matches the actual data. But I don't think they just threw away proper code and fudged stuff to give suitable results, I find it more likely that they did actually make changes to the model or fed a more sophisticated set of data into the model.

Although they are obviously interested in getting the model analysis to match the measured data, I believe their priority is to be able to use the model to test assumptions about the state of various facilities at the plant. They would also like to make the model better for future use.
Perhaps. In the present case, though, they did nothing to the model, only fed new data to it. Perhaps I am too cynical in thinking that it is not coincidental that that made the model match the measured data to perfection. Perhaps they truly just fed the data they assumed to be most likely, in an effort to validate the model and hoorah, it came out exactly reproducing the measured data, the modeller's wet dream.

Neither of these things is well served by simply fudging stuff to get a match, as opposed to improving the code used by the model or the data thats fed into it.

We see an example of this later in the document, when they move on to issues of containment pressure of reactor 3. They still can't get their model to match the measured data, so they have to think about what other factors may be involved, with the hope of modelling these factors later on and getting better results.
Yeah, right. :-) And in that process all discrepancies are equal but some discrepancies are more equal than others. In their latest model of the PCV pressure of unit 3, I see they have meticulously made assumptions of S/C vent operations matching every remaining unexplained significant change in pressure trends -- except the precipitous pressure drop at the time of the explosion, and the curious incident of the S/C vent some hours earlier.



They also seem to have gotten into trouble by assuming a lower decay heat than in previous attempt. Now the model undershoots, appears insensitive to interventions, and cannot reproduce the measured pressure increase rates in the PCV.

Although this latest version produces a much poorer fit than the previous attempt they seem quite happywith it, except they have one outstanding issue, an unexplained pressure increase in the initial phase under RCIC operation, which they seem to speculate might be fixable by assuming S/C stratification.
MadderDoc
MadderDoc is offline
#13049
Apr26-12, 01:43 PM
MadderDoc's Avatar
P: 698
Quote Quote by SpunkyMonkey View Post
There appears to be some large heavy-metal debris in the NE quadrant of SFP3 (the video is motion stabilized and so the frame moves):


This is an area close to the object I suspect is the trolley's upper deck. One only gets the briefest glimpse, and for the life of me I can't make out what those objects are. But I'm sure I can see machined shapes, especially on a piece of debris at approximately 4 o'clock if you imagine a clock face over the video screen. The brief view is clear enough that someone who worked there or who just saw it in a photo could probably recognize it.

Here's a video clip where I attempt to outline some of these heavy-metal objects so you can see which objects I refer to.
I think those are parts of the roof covering, they seem to have been caught above the level of the pool, and be of low thickness. You can see them from another angle later in the video. Straight underneath them there are more parts of the FHM than you can point a stick at, here, there and everywhere there are glimpses of cross beamed greenish structures through all that stuff hunkering above. In a way it was predictable all along that there would big objects to find in the east end of the pool. Otherwise, what kept us from seeing the water surface, what dampened the heat signature. Certainly Tepco would have a pretty good picture of what is in the east end of the pool, but we have to date not been let in on it. Maybe they think we are not interested in that end of the pool? But we are, we are.
MadderDoc
MadderDoc is offline
#13050
Apr26-12, 02:03 PM
MadderDoc's Avatar
P: 698
Quote Quote by westfield View Post
If you imagine this on the other side of the FHM and with the "stops" torn off it's not a bad match to this.
We can't see if there's a middle wheel in this image which would have helped.

Right, it is not a bad match at all. It would be reasonable to think the other side is similar but that side is well hidden in all photos. Anyone got drawings of a classical Toshiba FHM? ;.)

We should also be cautious to accept those tree wheel pins, and we can certainly not exclude that e.g. the one of the middle is just a piece of rubble caught in our minds fabrication. Maybe they all are? It is difficult to not see pins after first having seen them, though.


Register to reply

Related Discussions
8.9 earthquake in Japan: tsunami warnings Current Events 671
New Nuclear Plants Nuclear Engineering 9
Gen IV Nuclear Plants Nuclear Engineering 10
New Nuclear Plants Nuclear Engineering 14
Astronomer Predicts Major Earthquake for Japan General Discussion 65