Japan Earthquake: nuclear plants


by gmax137
Tags: earthquake, japan, nuclear
MadderDoc
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#13285
May20-12, 04:44 PM
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Quote Quote by jim hardy View Post
first approximation, from high school physics

d = 1/2 at^2 and a = 9.8 m/s^2

d = 4.9 t^2
t= √(d/4.9)

√(7/4.9) = 1.2 sec (1.195 to too many places)

√(15/4.9) = 1.7 sec (1.749 " )

If they were set free at instant of explosion.
I'd guess west end probably was.
I am sure this is a stupid question: so it doesn't matter whether it hinges at one end or not?

Were any roof girders thrown to North and South?
The northernmost girder was twisted axially 180 deg and bent 90 degrees so appears to have been dragged down along the north face of the building. I imagine remaining fixture to the wall dragged it overboard and down, But at least it is still there and to have suffered nothing but mechanical damage, although in a gross manner. The southernmost girder appears as good as MIA. I believe we _may_ be seeing its end concrete anchor block pointing up in the photo crop, east of the pool and close to the level of the deck. (see encircled below) If so, it only further emphasises the question, how on earth did it degrade so utterly. I have no idea where the rest of it is.
MadderDoc
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#13286
May20-12, 05:07 PM
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Quote Quote by jim hardy View Post
I guess they could have got buckled upward by initial explosion if the roof fasteners can transmit tension. Sure need a civil type.
I assume you mean the fasteners for the corrugated iron. They are well visible
in this hi res photo.
r-j
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May20-12, 06:15 PM
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Did anyone ever figure out what was causing the smoke?

http://www.csmonitor.com/USA/2011/03...om-Fukushima-I

http://www.rt.com/news/fukushima-smo...tor-radiation/
jim hardy
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May20-12, 09:36 PM
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I am sure this is a stupid question: so it doesn't matter whether it hinges at one end or not?
not at all.
It changes things because instead of simply falling the beam rotates about the hinged end.
Which brings its moment of inertia into play. And where the trolley was parked.

It'll fall slower and hopefully some student who's taking dynamics will offer to help....

..


looking at those roof supports, whatever was attached to them must be pretty flimsy for it didn't fail any of them. I dont see them as buckling any beams. Thanks for pointing them out.

Those photos are amazing - i sure missed some photo releases. Got some catching up to do. Any pointers ? Maybe a new Cryptome file?
MadderDoc
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May21-12, 02:55 AM
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Quote Quote by r-j View Post
There is so little to go on, r-j. :-(
We have webcam images but no photos from the ground
(unlike as we have it for the black smoke event of March21st.)
We have the doserate at the main gate of the plant
(located to the west inland side of Unit 3, to the left side of the webcam images).
We have from officialdom at the time, the assurance that doserate did not change in connection with the black smoke event,
and some speculation of causes none of which involved the reactor. Wherein perhaps lies the answer.

hi res version of above
Borek
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May21-12, 03:03 AM
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To All, please remember to stay on topic.
zapperzero
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May21-12, 03:51 AM
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Quote Quote by jim hardy View Post
All the columns on west side were toppled outside and hanging by their rebar , early photos show that well.
These on east side were bent and almost toppled inside, fractured at deck level,
as if a slug of something inside with considerable momentum pushed building that way(west) and pulled east columns inward by tension through roof beams.
Explosive force should have pushed them all outside.
old jim
For what it's worth, the blast would probably have started at deck level, east side.

So, columns get fractured at that level, walls fly away but the columns don't have time to fall, because moments later the blast (augmented now as parts of it got reflected off the walls and ceiling) WHACKS into the west side of the building, pushing the whole construction (which is still connected with roof girders) over that way. I also seem to remember the bridge collapsed at that end... but that might be my awful memory playing tricks again.

Does this make any sense?
Rive
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May21-12, 04:32 AM
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Quote Quote by jim hardy View Post
These on east side were bent and almost toppled inside, fractured at deck level,
as if a slug of something inside with considerable momentum pushed building that way(west) and pulled east columns inward by tension through roof beams.
Explosive force should have pushed them all outside.
Below the deck level the building is not symmetrical: there is more 'volume' on the west side.

So if you cut the explosion in half: there were an explosion on the top level, this just 'blow up' the upper part like a balloon and let fly the wall panels and roof, but did not break the connections between the roof beams and the columns, even if some columns were broken.

The explosion below the deck were asymmetrical and broke the columns only on the west, so they have collapsed and - through the roof beams - pulled the columns on the other end (east) inward.
MadderDoc
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May21-12, 05:37 AM
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Quote Quote by Rive View Post
<..> did not break the connections between the roof beams and the columns, even if some columns were broken. <..>
.
Post explosion, the only remaining attachment between roof beams and columns is at the middle column to the east. This column is broken and leans inward allowing the angling downwards of its attached roof beam.

Columns to the north of it are in relatively fine condition and still standing. Columns to the south of it are broken and have lost their tops, including the mounting socket for the roof beams.

The two northernmost roof beams have been retracted from their sockets in the top of the intact columns, with no apparent bending of the 8 steel guide rods of the sockets, and with only little damage done to the concrete around them. The retraction of roof beams from these sockets would therefore need to have been done while the roof construction was in a near horizontal position, and by employing a ccw rotation (as seen from above) of the entire roof construction, with the center of rotation close to the east middle column.

There is little to suggest the south roof beams were in a state at that moment, such as to be able to resist the ccw motion or to do damage to their columns by it, i.e. beams were likely not fixed in touch to their columns -- e.g. the roof had been lifted above their level, or the tops of the south columns were gone, or the roof beams had been structurally degraded.

hi res of above
westfield
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May21-12, 07:05 AM
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Quote Quote by MadderDoc View Post
<snip>

The two northernmost roof beams have been retracted from their sockets in the top of the intact columns, with no apparent bending of the 8 steel guide rods of the sockets, and with only little damage done to the concrete around them. The retraction of roof beams from these sockets would therefore need to have been done while the roof construction was in a near horizontal position, and by employing a ccw rotation (as seen from above) of the entire roof construction, with the center of rotation close to the east middle column.

<snip>
Maybe I've misunderstood, I can't see any evidence or need of a ccw rotation of the general roof structure in the horizontal plane. An overhead image doesn't show rotation in relation to those three trusses, they have just moved west. Two seperated from the wall (and caused considerable damage to the concrete around their "mounting slot") and one stayed attached, breaking the wall structure further down instead.

It appears to me the whole roof structure (in general) has moved west as Rive suggested. It would be unsurprising if the failure of the west wall structure, even without it's apparent westerly direction of movement was enough to cause the roof trusses to pull away from their east wall attachments or alternatively break a section of the east wall structure as we see those three trusses now. The attachment "studs" would not be damaged as the truss mounting block is clear of those before it falls out of the "slot".
Rive
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May21-12, 07:35 AM
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Regarding the explosion on U3 top level the actual status of U4 roof might be useful as it shows signs of various, but more or less systematic damages but without the side columns broken under the deck level.

I still think that the main difference was the breaking of west side columns under deck level (what was the result of the difference between the strength of the explosions).
MadderDoc
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May21-12, 07:36 AM
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Quote Quote by westfield View Post
<..> I can't see any evidence [..] of a ccw rotation of the general roof structure in the horizontal plane.<..>
westfield
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May21-12, 08:15 AM
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Quote Quote by MadderDoc View Post
The image shows the roof structure is wholly bent half way across. However if you look at the eastern end of the three trusses we have been referring to there is no rotation.
westfield
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May21-12, 08:42 AM
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Quote Quote by Rive View Post
Regarding the explosion on U3 top level the actual status of U4 roof might be useful as it shows signs of various, but more or less systematic damages but without the side columns broken under the deck level.

I still think that the main difference was the breaking of west side columns under deck level (what was the result of the difference between the strength of the explosions).
Thinking the same way. The U3 roof structure collapse and damage to east wall framing may not be caused directly by the explosion at all but indirectly by the structural failure in the NW corner of the RB in turn pulling the roof and east wall down. As you say, Unit 4 is great evidence of how once the wall panels and roof cladding are blown away the remaining structure still remains incredibly strong. To add to that, the "slice" of roof cladding in the north end of U4's roof may hint at how the cross braces in the same area of U3 were severed.
MadderDoc
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May21-12, 11:03 AM
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Quote Quote by westfield View Post
The image shows the roof structure is wholly bent half way across. However if you look at the eastern end of the three trusses we have been referring to there is no rotation.
I wonder how you come to that conclusion. On the eastern stretches, the projection of the three trusses to the floor appear to me to be either parallel to the crane beams or rotated somewhat ccw relative to them. However the crane beams are rotated ccw relative to the building, so something parallel to them would seem to have been too.
MadderDoc
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May21-12, 04:06 PM
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Quote Quote by jim hardy View Post
<..>
I am trying to decide whether to attach significance to the columns .
All the columns on west side were toppled outside and hanging by their rebar , early photos show that well.
Indeed, they have been arranged such that the most natural thought is they fell rather much in unison.
These on east side were bent and almost toppled inside, fractured at deck level,
as if a slug of something inside with considerable momentum pushed building that way(west) and pulled east columns inward by tension through roof beams.
Explosive force should have pushed them all outside.
Yes, but in the macro scale that may also have happened. If you look in drone photos from the south side, the whole eastern wall of unit 3 does appear to curve outward. Then of course there are details like the top pillars, as you mention 4 of which have become fractured, and are leaning.

One of those, the middle one is forced down by the roof truss to which it is still attached, so no wonder it is leaning inwards. The next leaning pillar towards the south, we find devoid of its top, apparently resting against the sunken remains of the roof truss it was originally attached to, under the influence of gravity of concrete fragments dangling from its top, and perhaps also because most concrete matrix was lost from the inwards side of the fracture.

I am not saying this arrangement couldn't have involved a series of events with at one stage an inward tension from the roof beam, however I fail to see why it should be a necessary assumption to make. We are in that exact area where we saw the initial huge flare or fireball shooting out the building, to the east and upwards far above the roof. So wouldn't it be simpler to assume this really caused a whole lot of destruction in this upper corner of the building, to the end of the roof beams as well as to the top section of the pillars where they were attached, i.e. to where they were fixed to each other. And after that, well, gravity is always ready to make the final arrangement out of the pieces.

(Similarly just for completion, with the next pillar towards the south, which is almost vertical and has its roof beam MIA, why should we try to explain that its roof beam first pulled inwards the pillar, after which the roof beam disappeared, when we know about that huge fireball? And then finally there is the south-most pillar which has a big chunk of concrete hanging from its top, making it lean north around its fracture at the level of the crane beams, that one never had a roof beam attached to it.)
MadderDoc
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May21-12, 04:58 PM
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Quote Quote by jim hardy View Post
looking at those roof supports, whatever was attached to them must be pretty flimsy for it didn't fail any of them. I dont see them as buckling any beams. Thanks for pointing them out.
I was surprised that there were so little in the way of attachment. The ~7 m corrugated iron roof coverings appear to have been just clipped on at the ends. and then tied in with some rebar and concrete poured on top of it. But then of course it was never built to resist a volcanic eruption from below :-)

Those photos are amazing - i sure missed some photo releases. Got some catching up to do. Any pointers ? Maybe a new Cryptome file?
I think I got them from cryptome .. yes here:.
http://cryptome.org/2012-info/daiich...chi-022012.zip
but as you can see they are from February 2012, when the press with cameramen were invited in. I hope, and I'd expect a repeat photo safari at time soon, for a balanced winding down of PR -- not to often but also not too far apart -- 3 months would seem a good technical choice at this stage. Perhaps not much more to be hoped coming from Tepco, now more than one year on, but the existing photo and video collection built over the last year is still a great resource, and the content could still be improved by replacing with versions of higher fidelity to the original material.
MadderDoc
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May22-12, 06:29 AM
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Quote Quote by jim hardy View Post
I guess they could have got buckled upward by initial explosion if the roof fasteners can transmit tension. Sure need a civil type.
But i see what you mean about the heat. Were ones on other side that aren't so discolored, bent similarly?
I find it curious that the hypothesis of possible heat damage to structures in the upper SE corner of Unit 3 is commonly met with disbelief. To me it would seem to be rather the default position that such heat damaged structures should exist in the wrecked building. Indeed were nothing immediately obvious it would make sense to me to look more carefully for evidence of it. Weird then, to experience an urge rather to explain away, or be blind to it.



hires version of above


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