Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[shogun338]

Tokyo - Workers in the damaged Fukushima nuclear plant were attempting to reduce radioactive contamination in waters off the coastal power station, the Jiji Press agency reported Saturday.
Some 300 kilograms of zeolith, a mineral that authorities hope will absorb radioactivity from water being pumped the Fukushima reactors, were deposited into the Pacific Ocean, just outside a pipe leading out of reactor 1.http://www.monstersandcritics.com/news/asiapacific/news/article_1633325.php/Work-underway-to-reduce-radioactivity-off-nuclear-plant

 

[shogun338]

The Case for Moving U.S. Nuclear Fuel to Dry Storage
Nuclear waste pools are packed more densely in the U.S. than those at Fukushima, with no removal plan in sight. The 2003 report said that in the event of coolant loss in a densely packed pool, air cooling would not suffice. Temperatures could rise to 600 °C within an hour, causing the zirconium fuel cladding to rupture, and then increase to 900 °C, whereupon the cladding would burn, resulting in huge quantities of released radioactive material, the report said.

The report proposed immediate reversion to lower-density pool configurations, with more cooled fuel put in dry casks and moved to central sites. In looser-packed pools, the report said, airflow alone could be enough to prevent fire in the event of coolant loss. It said this could be done for no more than $7 billion nationally, which would work out to a wholesale electricity price increase of 0.06 cents per kilowatt-hour generated from the fuel. http://www.technologyreview.com/energy/37388/?p1=A4&a=f

 

[AtomicWombat]

An object located near the "center" of a gas explosion presumably would be squeezed hard but not displaced by the explosion.

The naive impression I get looking at the building is that the main blast was on the level below the top floor.

I'm not sure it makes sense to look for the centre of a gas explosion. A hydrogen detonation in air propogates at nearly 2000 m/s with a peak blast pressure of nearly 16 bar (atmospheres).

http://www.gexcon.com/handbook/GEXHBchap6.htm"

For small objects in the fuel air mix, the detonation wave will race around the object, effectively compressing them by 16 bar. However, 16 bar applied to large external walls (with no balancing pressure) will produce a huge force. If there was a clear passage to lower levels in building 4 it is easy to understand how the blast pressure wave reached there too.

 

[AtomicWombat]

And as for a the couple of diagrams, I will claim responsibility for having given the impression that perhaps I had only looked at two diagrams. Instead, I have scoured almost every diagram, photograph, and reference posted here since day one, as well as all the other reasonable sources I could find in the process of coming up with several of my wild conjectures.

Does one of these look like what we have been seeing at Fukushima Unit 3 & 4 to anyone else? I think I commented on the apparent incongruity of the elevator shaft on one of the earlier diagrams. I believe the Fukushima photographs pretty clearly demonstrate the alternate position of the elevator shaft and access tunnels in version 2.

I think we've collectively got the general floor layout of all 4 buildings about right and TCups has made very important contributions to that.

The attached diagram (originally from TCups) appears to be the essential layout of the 4 buildings. Small details, such as how the cask pool corresponds to the rest of the SFP are not yet clear.

 

[AtomicWombat]

I'm trying to analyze more in detail this video to get some information about what flew in the sky ... mainly on its mass. Maybe someone can help me too.
http://energheia.bambooz.info/index.php?option=com_content&view=article&id=170%3Areactor-3-explosion-enhanced-view&catid=60%3Avideo&Itemid=85&lang=it

Some notes:
Take a look on the right side of the reactor 3 and follow the hard material falling down near the tower

1) at the time 0:16 there is an explosion of flammable material that expands almost sideways
2) immediately something shoot oneway directed upward the material as a recoil of the weapon (very strange, like a cannonball!)
3) about the time 0:21 comes to its maximum height
4) at the time 0:32 comes around on the ground near the tower under the law of gravitation http://en.wikipedia.org/wiki/Equations_for_a_falling_body

You state that the time to max elvation is 5 sec, and the time to fall is an additional 11 sec (meaning high drag force). This implies that the terminal (falling) velocity is low. Could you do a frame by frame analysis the determine the maximum elevation, the final velocity before it hits the ground, and the approximate dimensions of the object?
The drag force for an object in air is (for turbulent drag)
$$F= \frac{1 }{2 } \rho AC_dv^2$$

The terminal (falling) velocity is given by

$$\frac{1 }{2 } \rho AC_dv^2=mg$$

where ρ is the density of air, A is the cross-sectional area, C_d is the drag coefficient, v is the velocity, and mg is the gravitational force.

Here is an example. A golf ball has a terminal falling velocity of 36 meters per second. A golf ball shot straight upward at 100 meters per second will hit the ground in 10.9 seconds, with a final velocity of only 34 meters per second.

Bob S

Some time ago (http://74.86.200.109/showpost.php?p=3222881&postcount=2324") I had a look at this and concluded that:

"As to the height of the blast. I timed how long it took from the initial explosion for heavy debris that fell to the left to hit the ground. It is 14-15 seconds. It reached maximum height in about half this time - there is no evidence of a "rocket effect". Using Newton's Laws of Motion this gives an estimated height of 0.5*g*t^2, where t is half the total time of flight. This gives 5*(7)^2 = 245 metres or 5*(7.5)^2 ~ 280 metres. The building height (50-60 metres) can be added if you like. So I'd say the heavy debris reached a height of about 250 metres above the roof of the building, or about 300 metres total.

The "launch velocity" was about 70-75 m/s or about 250-270 km/h, so air resistance can be neglected for large dense objects.

See here for a clearer video:
http://www.youtube.com/watch?v=haUawwm7l4k"

 

[|Fred]

I have a full picture of unit 4 north wall if it has not been posted yet , rather low quality , but clear enough to see that the east part is almost immaculate

 

[Dmytry]

the velocity estimate from falling debris - i would rather check through height of chimney to know for sure the objects are not reaching terminal velocity, or are not carried up in the plume. Shape matters and there's a lot of panels that are big but thin. Plus it *looks* like they reach terminal velocity as they fall.
I want to make estimate that can't be 'debunked'.
I was unable to find chimney height. Most stupidly, when I google for fukushima chimney height, i get this thread as top result.

 

[Borek]

I'm not sure it makes sense to look for the centre of a gas explosion.

I think it is not a thing to be ignored. I recall a story of gas explosion that happened in a power station somewhere in Poland. Welder standing close to the center of the large workshop used lighter to ignite acetylene torch, that started the explosion. Ironically, he got some burns but survived, while people other workers died from mechanical trauma - they were smashed on the walls by the blast.

Edit: obviously it will be different for deflagration vs detonation, but at this stage I doubt we can tell which one occurred.

Interestingly, I found this: http://www.gexcon.com/handbook/GEXHBchap5.htm#sect5_7 - note, how the effect of deflagration depends on the placement of obstacles. That can (doesn't have to) explain why parts of the upper wall were not blown out - some arrangement of internal objects could slow down the explosion in this particular direction.

I must admit at this moment it is rather anecdotal evidence, I can't give any details. I have heard the story back in seventies, probably from my Mom, she was an Electrical Engineer with PhD.

 

[Borek]

Shape matters and there's a lot of panels that are big but thin.

Plus they rotate, so their cross sections change. I have a gut feeling that possible guesstimates of the mass will differ by orders of magnitude depending on assumptions, making them virtually useless.

 

[AtomicWombat]

the velocity estimate from falling debris - i would rather check through height of chimney to know for sure the objects are not reaching terminal velocity, or are not carried up in the plume. Shape matters and there's a lot of panels that are big but thin. Plus it *looks* like they reach terminal velocity as they fall.
I want to make estimate that can't be 'debunked'.
I was unable to find chimney height. Most stupidly, when I google for fukushima chimney height, i get this thread as top result.

I couldn't find it either. Try starting with the building heights. From the #1 blueprint ground level is OP. 10000 and the roof is OP. 54750 giving about 45 metres.

I measured the height of building 2 in pixels (252) on the SW corner and did the same for the nearest stack (682) - using pythagoras theorem. I could not get a clear line of sight on building 1. So the stack is 2.70 times the building height. This is about 120 metres, assuming a 45 metre height, or 135 metres if you assume building 2 is 5 metres taller than 1 (they seem almost the same).

So start with a stack height of 120 metres. Now estimate the height that the heavy debris reaches in the explosion. This is hard because you can't see ground level, but to my eye it's at most 3 times the height of the stack or around 360 metres.

My two estimates are in rough agreement. I earlier estimated 245 to 280 m plus the building height, giving 290 - 325 metres.

http://www.youtube.com/watch?v=haUawwm7l4k"

 

[Dmytry]

Plus they rotate, so their cross sections change. I have a gut feeling that possible guesstimates of the mass will differ by orders of magnitude depending on assumptions, making them virtually useless.

Yep. I'm very surprised though that there was no word from explosion experts about the video. No estimates of energy, in traditional TNT equivalent.
I'm still looking for chimney height as quoted from official source. It seems clear to me that the explosion in #3 could not possibly have been a hydrogen explosion but I would love to have data to conclusively show it in the way that can't be easily denied.
I'm going to also base height on photo for now and figure out the air movements for the observed plume velocity (not the debris). I did some numerical fluid simulations in the past, this is going to take a while. But overall - this stuff is rising very very fast, I'm sure it is steam vented out of reactor, not steam from hydrogen combustion.

 

[Dmytry]

I couldn't find it either. Try starting with the building heights. From the #1 blueprint ground level is OP. 10000 and the roof is OP. 54750 giving about 45 metres.

I measured the height of building 2 in pixels (252) on the SW corner and did the same for the nearest stack (682) - using pythagoras theorem. I could not get a clear line of sight on building 1. So the stack is 2.70 times the building height. This is about 120 metres, assuming a 45 metre height, or 135 metres if you assume building 2 is 5 metres taller than 1 (they seem almost the same).

So start with a stack height of 120 metres. Now estimate the height that the heavy debris reaches in the explosion. This is hard because you can't see ground level, but to my eye it's at most 3 times the height of the stack or around 360 metres.

My two estimates are in rough agreement. I earlier estimated 245 to 280 m plus the building height, giving 290 - 325 metres.

http://www.youtube.com/watch?v=haUawwm7l4k"

hmm i got about 115 meters with similar calculations so that'd be it... now onto the cloud's velocity estimation, and cloud's temperature estimation (for it to rise this fast), and the thermal energy... going to take a while. And all that work to show something bloody obvious, that you need lot of thermal energy to make mushroom cloud, to provide scientific substitute for common sense of 'omfg mushroom cloud, really bad'. It would of been so much easier for military which probably got premade tables for this sort of calculation to estimate yield.
edit: going to take a while. I'd rather hope someone here can find how military would estimate energy given mushroom cloud width and rise speed, using experimental data. That'd give more confidence.

 

[AtomicWombat]

I think it is not a thing to be ignored. I recall a story of gas explosion that happened in a power station somewhere in Poland. Welder standing close to the center of the large workshop used lighter to ignite acetylene torch, that started the explosion. Ironically, he got some burns but survived, while people other workers died from mechanical trauma - they were smashed on the walls by the blast.

Which ironically proves my point about not looking for the centre based on the most damage.

Plus they rotate, so their cross sections change. I have a gut feeling that possible guesstimates of the mass will differ by orders of magnitude depending on assumptions, making them virtually useless.

I agree Borek. It looks powerful and "heavy" objects are thrown ~300 metres into the air. But beyond this too many assumptions must be made. (I assumed earlier - for the sake of argument - it was the concrete shield plug, but there is no real evidence of this.)

An interesting starting point might be:
http://en.wikipedia.org/wiki/TNT_equivalent"

 

[Dmytry]

Which ironically proves my point about not looking for the centre based on the most damage.
I agree Borek. It looks powerful and "heavy" objects are thrown ~300 metres into the air. But beyond this too many assumptions must be made. (I assumed earlier - for the sake of argument - it was the concrete shield plug, but there is no real evidence of this.)

An interesting starting point might be:
http://en.wikipedia.org/wiki/TNT_equivalent"

Well that is all true, but it'd be strange for most damage to be located on bottom floor for a 'hydrogen produced and accumulated on top' scenario. Not a single other reactor building had wall panels blown off in the bottom floor. I don't believe that entire building worth of combustible hydrogen concentration had exploded. It's one thing for cloud of gas to produce most damage on it's boundary, it's entirely another thing for hydrogen-air mix below the roof to blow off first floor's panels but not top floor's panels, and for reactor building 4 to have less top floor damage but more bottom floor damage than any other reactor building. You can't just shrug this evidence off with 'explosions are complicated'.

 

[liamdavis]

The naive impression I get looking at the building is that the main blast was on the level below the top floor. Could something else have blown up besides hydrogen? Are there any gas or fuel tanks on the 4th floor? Going back to the original (day of blast) speculation of lubricating oil fire, is lubricating oil explosive? (Maybe if it gets aerosolized for some reason?)

Seems hard to believe anything explosive would be present in a reactor building on purpose. Though, since the reactor was undergoing core shroud replacement, which apparently involves welding (according to the link given by MiceAndMen), might oxy-acetylene welding equipment have been temporarily located there?

Speaking about Unit 4, I have posted this position as well. Someone (I apologize, I do not remember who) answered my question about the weight of acetylene. Approximately the same as air, so it would not rise. The more I consider it I would be very surprised if there were not oxy-acetylene equipment present. Forty year old equipment, installed at the seashore, with pools of hot water continually present inside and down for maintenance would be cause to bring on site as many bottles as the contractor/maintenance team thought they would need.

An additional thought is that acetylene is unstable above 8-14psi and so is dissolved into a tank filled with acetone. Tanks are secured (chained) upright but after five minutes of shaking in a 7M (at the plant) earthquake nothing of their condition can be assumed. Acetone vapors could also be present. Once again I am at the mercy of someone more knowledgeable about the specific gravity of acetone vapors.

Add (and stir) the variables of hot water in the top of the building, 0 degree C temps outside, no power/HVAC, and unknown leakage of air into the post-quake building. Apply that to acetylene and acetone vapors and take a wild guess.

 

[Dmytry]

Seems scientifically plausible to hazard a guess they have been breaking a couple dozen regulations at any time, and more during maintenance. Nuclear safety standards are very strict, to the point that i'd think 999 times out of 1000 violating them won't make anything bad happen but would save the money.
I think that could explain various strange aspects of the information availability & disaster management.
However - why would acetylene leave the bottles? And explode after those SFP issues? Why wouldn't they try to do something about it - carry the bottles out - if anything, to cover up the violation? edit: also, acetylene and other hydrocarbons leave soot.

 

[TCups]

I'm trying to analyze more in detail this video to get some information about what flew in the sky ... mainly on its mass. Maybe someone can help me too.
http://energheia.bambooz.info/index.php?option=com_content&view=article&id=170%3Areactor-3-explosion-enhanced-view&catid=60%3Avideo&Itemid=85&lang=it
[/url]

@K:
I have looked at the videos until my eyes are crossed. Don't know how much of the earlier threads you have read in depth. When looking at the viedo, keep some things in mind.

1) as has been pointed out, video compression used for internet display generaly uses compression algorithms that reduce resolution and can sharpen or blur the edges of objects, especially moving objects -- there are compression artifacts in even the best video available of the explosion. Perhaps (but I don't know for sure) the grayscale video is somewhat less prone to artifactual distortion.

2) sunlight and shadow cause an interesting interplay in the video, particularly with regard to the smoke plume and what appears to be in the plume. For example, watch what happens to the brightness and detail of the tower just north of the plume and imagine the same effect occurring with the falling debris in and to the north of the vertical plume. To me, it seems a lot of "things" seem to appear and disappear in that plume. Some of them I believe to be shadows. And all of them are affected by #1 above.

3) Velocities of the visible falling "objects" (which could be anything from sheets of insulation material, to sheet metal, to metal beams to concrete plugs), whatever they are, vary pretty significantly, and their acceleration and velocities no doubt varied on the way up, too.

So if it's hard to identify what is what on the ground and in the buildings on the still photos and videos available, then how much harder is it to be sure what is going up and coming down in that column of smoke?

Ultimately, what appears to be seen on the ground (and in the pools) is much more significant and reliable than what appears to be seen in the column of smoke, IMO.

 

[liamdavis]

Seems scientifically plausible to hazard a guess they have been breaking a couple dozen regulations at any time, and more during maintenance. Nuclear safety standards are very strict, to the point that i'd think 999 times out of 1000 violating them won't make anything bad happen but would save the money.
I think that could explain various strange aspects of the information availability & disaster management.
However - why would acetylene leave the bottles? And explode after those SFP issues? Why wouldn't they try to do something about it - carry the bottles out - if anything, to cover up the violation? edit: also, acetylene and other hydrocarbons leave soot.

why would acetylene leave the bottles?

Bottles left on when the earthquake hit, toppled or damaged by falling material.

Why wouldn't they try to do something about it - carry the bottles out

Within eight hours of total power loss things were going very bad. People had been injured and some (two at Daiichi) were unaccounted for. I do not know if protocol required the maintenance personal or contractor to leave Unit 4 until structural safety was ascertained. And there was the shock of dealing with earthquake, tsunami and power outage.

 

[Dmytry]

Bottles left on when the earthquake hit, toppled or damaged by falling material.

Then explode, let's see, 4 days after, all while there were fires that were extinguished by firefighters. (edit: or that's what i remember from the news of the time)
Does not compute.

Within eight hours of total power loss things were going very bad. People had been injured and some (two at Daiichi) were unaccounted for. I do not know if protocol required the maintenance personal or contractor to leave Unit 4 until structural safety was ascertained. And there was the shock of dealing with earthquake, tsunami and power outage.

a curious mix of diligent following of the protocol and violation of the rules. I'd expect that if they're violating the rules, the first thing they would do, they'd attend to covering up ongoing violations.

 

[liamdavis]

Originally Posted by liamdavis
Bottles left on when the earthquake hit, toppled or damaged by falling material.

Then explode, let's see, 4 days after, all while there were fires that were extinguished by firefighters.
Does not compute.

The quake was not a single event.

http://www.japanquakemap.com/

As of today 1015 aftershocks since 3-11-11. And there was debris falling from other explosions. Damage to tanks could have occurred at many times and could have originated from many sources. I am not meaning to be argumentative. It is just that the number of variables thrown into this event between the initial quake and the subsequent explosions make reconstruction of events worthy of a 3000+ post thread... oh, wait!
liam

 

[rowmag]

Then explode, let's see, 4 days after, all while there were fires that were extinguished by firefighters. (edit: or that's what i remember from the news of the time)
Does not compute.

The fires came after the explosion (or more precisely, were first observed after the explosion), and went out by themselves (possibly after one day).

a curious mix of diligent following of the protocol and violation of the rules. I'd expect that if they're violating the rules, the first thing they would do, they'd attend to covering up ongoing violations.

No, the first thing they would do, in a dazed state, is try to remember what the earthquake drill is -- which probably involves gathering at some outdoor location for a count of hands. At least that was how it was where I was when the quake hit. Events from there (incoming tsunami) would have quickly taken priority in driving their actions. I would bet that if there were any rules violations going on before the quake, nobody remembered about that until much later.

 

[rowmag]

acetylene and other hydrocarbons leave soot.

The vomitus coming out of the hole in the north wall does look pretty blackened...

 

[triumph61]

New Fotos

http://cryptome.org/eyeball/daiichi-npp9/daiichi-photos9.htm

 

[shogun338]

Zeolites have uses in advanced reprocessing methods, where their micro-porous ability to capture some ions while allowing others to pass freely allow many fission products to be efficiently removed from nuclear waste and permanently trapped. --Shooting location: the south side of the screen of Unit 3 of the
Fukushima Daiichi Nuclear Power Station -
-From 2:30 pm to 3:45 pm on April 15th, TEPCO installed 3 sandbags containing
zeolite (as an absorbent material) between the screen pump rooms of the
Unit 3 and Unit 4.

 

[shogun338]

In this image taken by T-Hawk drone aircraft, Tokyo Electric Power (TEPCO) Co.'s crippled Fukushima Daiichi Nuclear Power Plant No.1 reactor building's rooftop is seen in Fukushima, northern Japan April 15, 2011 . We have found one thing out for sure . That the T-Hawk drone is not worth the money that has been spent on it . I can't believe how bad the pictures and videos taken with it are .

 

[Borek]

'hydrogen produced and accumulated on top' scenario.

I wonder where this scenario came from. From what I remember separation of gases is negligible. What may happen is that gases don't necessarily mix fast, so they can flow - similarly to what liquids do - up or down, but once mixed they remain mixed.

 

[Dmytry]

Originally Posted by liamdavis
Bottles left on when the earthquake hit, toppled or damaged by falling material.The quake was not a single event.

http://www.japanquakemap.com/

As of today 1015 aftershocks since 3-11-11. And there was debris falling from other explosions. Damage to tanks could have occurred at many times and could have originated from many sources. I am not meaning to be argumentative. It is just that the number of variables thrown into this event between the initial quake and the subsequent explosions make reconstruction of events worthy of a 3000+ post thread... oh, wait!
liam

Well the point is, it's just unlikely... you need tanks (plural) to be undamaged by original quake, then you need tanks to be damaged by much weaker aftershock, and the damage itself must not create a spark, nor should be it like regulator knocked off (with the tank taking off like a missile), etc. It's not that it is impossible, it's that it is too specific for the data we got.
Some unidentified **** left over from maintenance, exploding, that is plausible. Who knows. They may have been doing some weird things to the reactor pressure vessel to cover up some defect. http://www.bloomberg.com/news/2011-03-23/fukushima-engineer-says-he-covered-up-flaw-at-shut-reactor.html" . They may have had some unofficial fuel transfer in progress (see the cask vehicle on photos). It seems very plausible that various minor violations would be commonplace, given very interesting accidents like criticality at Tokaimura, accidents that would just be too unlikely without background of violations that don't result in any accident. Suppose they had some fuel in a cask, and it, left to itself, overheated.

 

[Borek]

We have found one thing out for sure . That the T-Hawk drone is not worth the money that has been spent on it . I can't believe how bad the pictures and videos taken with it are .

Assuming video that was published is really the best they have. Could be they don't want to reveal the high quality footage - for number of reasons.

 

[TedNugget]

@K:
2) sunlight and shadow cause an interesting interplay in the video, particularly with regard to the smoke plume and what appears to be in the plume. For example, watch what happens to the brightness and detail of the tower just north of the plume and imagine the same effect occurring with the falling debris in and to the north of the vertical plume. To me, it seems a lot of "things" seem to appear and disappear in that plume. Some of them I believe to be shadows. And all of them are affected by #1 above.

TCups:
Looking over the enhanced video there appears to be two distinct 'colors' to the plume that are not entirely explained by shadow. On the left a darker substance, on the right and eventually capping the column is a lighter gray. However, the darker crosses over at least partially eliminating shadow as an explanation for its color.
This two tone column could be the product of; different materials from the same blast or two different explosions.
My apologies if this has been discussed before.

Although I doubt that the time frames would fit there could be an explosion above the shield plug that was self-venting plausibly, (see post 3852), that forced the cookies back down re-establishing a pressure build-up in the containment area and then it blew the cookies off.

Maybe I've developed Fukushima Video Fatigue Syndrome, (FVFS), but the column appears to advance vertically in spurts.

Also of interest is when comparing 3 to the reactor building 1 explosion there doesn't appear to be a pronounced blast wave in 3 but there is a fireball.
This could be simply facets of what each video did or didn't capture.

 

[Dmytry]

Also of interest is when comparing 3 to the reactor building 1 explosion there doesn't appear to be a pronounced blast wave in 3 but there is a fireball.

I noticed that right away. Not only lack of the blast, but also dirt flying sideways quick in #1
And all around #3 looking much slower.
To me it looks like a best example of difference between hydrogen+air explosion vs venting of huge volume of hydrogen and steam. I did CG fluid work, its actually sort of my area of expertise. Reactor stuff, they report pressure not to be zero, i dunno, maybe the lid can be lifted off and then come back down, or maybe gauges failed.

 

[TCups]

I noticed that right away. Not only lack of the blast, but also dirt flying sideways quick in #1
And all around #3 looking much slower.
To me it looks like a best example of difference between hydrogen+air explosion vs venting of huge volume of hydrogen and steam. I did CG fluid work, its actually sort of my area of expertise. Reactor stuff, they report pressure not to be zero, i dunno, maybe the lid can be lifted off and then come back down, or maybe gauges failed.

Take care in analyzing the ground wave blast -- especially any that appears to be moving slowly. Remember, one fundamental difference between the ground level images at Bldg 1 and 3 -- shadow from the plume.

Also, it gives pause to consider any difference that might be due to the giant vertical plume and updraft over Bldg 3 vs Bldg 1 at the time the lower Bldg 3 exploded, if the premise of a three-phase explosive event is correct -- 1) blast from primary containment, out the chute or under the plug, 2) steam blast from the SFP3 with vertical plume, and, last, hydrogen explosion of the lower building (after the vertical plume is rising).

Addendum: and perhaps most importantly, all of the explosion at Unit 1 originated from the upper level only, and that superstructure was steel beam and sheet metal, not reinforced concrete. Also, a bunch of the "new batch" of images are concentrating on the northeast corner of Bldg 4. I wonder why . . .

http://cryptome.org/eyeball/daiichi-npp9/daiichi-photos9.htm

And pict32 is a very interesting photo of FHM 4. The FHM has been "de-masted". Perhaps pretty strong evidence something violent happened within the confines of the SFP?

Pict25, Bldg 3 looks pretty similar to the elevator shaft, cask transfer pool, SFP layout suggested earlier. Steam still venting from the general area of the fuel transfer chute?

 

[GJBRKS]

In this image taken by T-Hawk drone aircraft, Tokyo Electric Power (TEPCO) Co.'s crippled Fukushima Daiichi Nuclear Power Plant No.1 reactor building's rooftop is seen in Fukushima, northern Japan April 15, 2011 . We have found one thing out for sure . That the T-Hawk drone is not worth the money that has been spent on it . I can't believe how bad the pictures and videos taken with it are .

Indeed , they have much better helicopter footage , like :



or



I do hope it is not a disinformation tactic ,

by suggesting that they don't have good quality info to be forthcoming enough

 

[Dmytry]

i don't find it at all hard to believe that t-hawk is a lot worse than hexacopter:

Hexacopter uses state of the art cheap camera from this year. T-hawk uses state of the art certified ultra expensive milspec camera, which is an overpriced version of a cheap camera from several years ago when they started the project. Military drones been consistently years behind hobbyist drones on anything but the cost - hobbyists can't afford big aircraft jet engines.
edit:
I do not think it's even radiation hardened. There's not supposed to be any particularly high dose rates, it's not chernobyl - and in chernobyl, regular cameras worked fine. This thing doesn't fly inside a reactor or anything.
Besides, they never reported trying anything non-radiation-hardened and it failing, so it is really nonscientific to just assume that non-radiation-hardened would be unsuitable.

 

[I_P]

Indeed , they have much better helicopter footage , like :



or



I do hope it is not a disinformation tactic ,

by suggesting that they don't have good quality info to be forthcoming enough

I wonder if the image quality has to do with radiation-hardened camera. Maybe there is some difficulty in getting good images because of this. Seems a bit hard to believe, but (like with the robots - lack of) perhaps there just hasn't been the incentive to develop appropriate equipment for this task and off-the-shelf stuff is not particularly suitable given the requirements.

 

[TedNugget]

To me it looks like a best example of difference between hydrogen+air explosion vs venting of huge volume of hydrogen and steam. I did CG fluid work, its actually sort of my area of expertise. Reactor stuff, they report pressure not to be zero, i dunno, maybe the lid can be lifted off and then come back down, or maybe gauges failed.

In reverse order:
We can see the 'shield plugs - cookies' off the containment in #3. One of the explosions can be just from the containment and not from the reactor. If, IF there still is reactor pressure that would strongly tend to indicate no explosion in the reactor. Just venting from under great pressure.

My sense as a fire fighter is that there is far more energy released in the Reactor 3 building than from #1. #3 took out all walls and roof.
Now this could be just a component of the size of the buildings or different construction methods later on.
Or it could be different explosive materials or the amount of in a larger space ...