Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[Dmytry]

Rising phase is not different. Objects decelerate at 10 m/s² from the moment they were blown up and the force that started them moving stopped to act, movement direction doesn't matter. As it was explained earlier there is a dependence between their speed and drag, which makes both phases slightly different, but there are too many unknowns to reliably calculate anything from this information.

Well, for the ascent, rest assured, there must be energy enough released to lift it up to the observed height (compared vs chimney). For the perspective - should not matter, video is taken from very far away through telephoto lens. However, that give such a low lower bound on the energy released as for it to be useless. Explosions are quite inefficient at throwing stuff upwards.

 

[ceebs]

There's one thing bugging me for weeks regarding this opening of holes... how exactly did they manage to do that?
I mean, they had to remove one of those big concrete panels (sat images show, that there's one panel missing on the east side), but I don't see how that would've been possible. As in Units 1, 3 and 4 there must have been large amounts of hydrogen around. So drilling or using explosives is a no-go. How did they manage it then?

I only remember talk of drilling holes into prevent explosives in reactor buildings 5 and 6, but I may be wrong

 

[Rive]

6. Entombment may be the only option for units 2 and 3.

Is it possible to entomb those reactors effectively with such contaminated groundwater around?

As it seems that 60000 m³ which is now in the turbine buildings is just the visible part of the problem. To stop the leaking a whole new waterproof layer must be built underneath... below the actual groundwater level.

 

[Borek]

Well, for the ascent, rest assured, there must be energy enough released to lift it up to the observed height (compared vs chimney).

Yes, but that height gives us only information about initial speed - we don't know mass, so we can't tell anything about amount of energy. And if I remember correctly the idea of OP was to calculate mass from this data - and this is simply impossible. It is not an accident that in the simplest approach - mgh=mv²/2 - mass cancels out

 

[Dmytry]

Yes, but that height gives us only information about initial speed - we don't know mass, so we can't tell anything about amount of energy. And if I remember correctly the idea of OP was to calculate mass from this data - and this is simply impossible. It is not an accident that in the simplest approach - mgh=mv²/2 - mass cancels out

Well yes. My idea is to instead look at rising cloud's width and velocity and figure out it's temperature, assuming it is rising by buoyancy. Not sure what would be the drag. I did fluid simulation (finite element method) years ago for explosions for CG, but not really the estimation of anything like this (plus i ended up drawing the cross-sections by hand anyway instead of using the simulation lol). Can someone here just do it for a balloon for now? Suppose a hot air balloon of negligible balloon weight, of the size of width of that smoke plume, rises with such speed (60m/s or so), what would be the temperature?

 

[Jorge Stolfi]

Unit 4 [...] It is possible that the pool was partially drained to the reactor cavity by damage to the gates. This neatly explains the thermal imaging showing heat in the pool and cavity. Since a large part of the pool water inventory was lost it would have reduced the time to start to uncover fuel in the pool.

Yes, this sounds plausible!

So whence cometh the damage to Unit #4 exterior? There appears to be photography showing Unit 4 intact after Unit #3 exploded. But look at Unit 3 in those pictures. There is concrete slab siding on the ground floor and two floors of open concrete support beams and girders. In the pictures showing Unit 4 damaged the seems to be another floor missing from Unit 3. The damage to Unit 4 is bent away from unit 3. Is it possible there was a second explosion at Unit 3 that caused the damage to Unit 4? The confusing reports of a possible explosion near unit 4 were during a period when there were few people on site and could actually have been from unit 3 which ahd significant containment damage but was probably still generating hydrogen.

The damage on the top edge of the north wall of unit 4 suggests something struck it horizonally coming from unit 3. There is a large piece of curved metal(?) sheet that fell sideways into the roof of unit 4, right next to its top edge. I cannot imagine how that object could have come from unit 4, since the roof of unit 4 seems to be made of narrow sheet strips covered with concrete or tarmac, over a steel framework whch is still largely intact.

To me it still looks like that object came horizontally from unit 3, damaged the top of the north wall of unit 4, tumbled over it, and crashed into the roof of unit 4.

On the other hand, the other damage to unit 4 (such as the missing roof cover and the extensive damage to West and South walls) seems to require an explosion inside it. Possibly at the bottom of the SFP, blowing out through its walls into the lower floors?.

So perhaps there was a second explosion in unit 3 AND an explosion in the SFP of unit 4, both occurring at night and hence both going unrecorded?

"If a reactor explodes in the middle of a plant without any webcam to record it, would it make any noise?"

 

[clancy688]

Conclusions and consequences.

1. RPVs may be leaking, but remain intact and are still containing most damaged fuel. Evidence for this is a lack of evidence of core-concrete interaction.

2. Unit 1 containment is intact but leaking. Good thing or site doses would be much larger.

3. Unit 2 and Unit 3 have breached containments and adding water is washing more of the core into the environment. Inerting the containment may be impossible so feed and bleed is really the only choice they have.

4. Unit 4 fuel pool will have to be cleaned out and damaged fuell removed. Then this unit can be put into a storage condition.

5. Unit 1 may need repairs to containment to stop leakage but could be used to store its damaged core for a TMI-2- like cleanup.

6. Entombment may be the only option for units 2 and 3.

7. If core cooling is unsuccessful or RPV failures occur, this couuld still get a lot worse.

Kyodo News posted some outlines of the TEPCO plan to stabilize the plant:

STEP 1 (In roughly three months)

-- Filling containment vessels of Nos. 1, 3 reactors with water.

-- Sealing with sticky cement part in No. 2 reactor's containment vessel believed breached.

-- Injecting nitrogen into Nos. 2, 3 reactors to avoid possible hydrogen explosion.

-- Restoring circulatory cooling system for spent fuel pools.

-- Installing facility to decontaminate highly tainted water and purify seawater.

STEP 2 (In roughly six to nine months)

-- Bringing reactors into stable condition known as 'cold shutdown.'

-- Blanketing buildings housing Nos. 1, 3, 4 reactors with covering.

MIDTERM GOALS

-- Extracting fuel assemblies from pools holding spent fuel.

-- Covering reactor buildings with containers, such as those using concrete.

Don't know if that's old news, but it looks like only the containment of Unit 2 has been flooded so far. Maybe because they are fearing that a meltdown will breach/has already breached the RPV?

Moreover, the last statement sounds as if they are planning entombment for Units 1 to 3? And they only want to retract fuel from the SFPs, not from the RPVs...


http://english.kyodonews.jp/news/2011/04/86072.html

 

[Astronuc]

Image from TEPCO of concrete pump used to take pictures of unit 4 reactor service floor and SFP

http://www.tepco.co.jp/en/news/110311/images/110412_1f_4.JPG

Yellow containment cap in Unit 4.
http://www.tepco.co.jp/en/news/110311/images/110415_1f_3_8.jpg

I suspect what was cited as spent fuel rods outside of containment is actually rebar blown out of the walls (image of south face of unit 4).
http://www.tepco.co.jp/en/news/110311/images/110415_1f_3_5.jpg

I can't find the source (other than TEPCO) for the attached images, but they show the sampling vessel and top view of Unit 4 SFP. The water is turbid - maybe from boric acid or from suspended fission products and/or corrosion products.

Update: Source of images - http://www.tepco.co.jp/en/news/110311/

 

[Krikkosnack]

Yes, but that height gives us only information about initial speed - we don't know mass, so we can't tell anything about amount of energy. And if I remember correctly the idea of OP was to calculate mass from this data - and this is simply impossible. It is not an accident that in the simplest approach - mgh=mv²/2 - mass cancels out

5) determine how much energy is in the game using http://en.wikipedia.org/wiki/Conservation_of_energy
Estart = U = mgh
Estop = T = 1/2mv^2

Estart=Estop

 

[tsutsuji]

Can anyone unzip the topmost 3 videos here:
http://www.tepco.co.jp/en/news/110311/index-e.html"

Thank you for the http://www.tepco.co.jp/en/news/110311/index-e.html link. Can you say how you found it ?

Is it linked from the Tepco website's main English page ? I cannot find it there (on http://www.tepco.co.jp/en/index-e.html) .

Is there a Japanese version of that page (which one might expect to be updated faster than the English one) ?

 

[Borek]

5) determine how much energy is in the game using http://en.wikipedia.org/wiki/Conservation_of_energy
Estart = U = mgh
Estop = T = 1/2mv^2

Estart=Estop

Geez.

mgh = mv²/2

gh = v²/2

You can calculate initial speed from known height, but you can't calculate amount of energy not knowing mass. And you don't know mass.

 

[rowmag]

Kyodo News posted some outlines of the TEPCO plan to stabilize the plant:

STEP 1 (In roughly three months)

-- Filling containment vessels of Nos. 1, 3 reactors with water.

-- Sealing with sticky cement part in No. 2 reactor's containment vessel believed breached.

-- Injecting nitrogen into Nos. 2, 3 reactors to avoid possible hydrogen explosion.
[...]

Don't know if that's old news, but it looks like only the containment of Unit 2 has been flooded so far. Maybe because they are fearing that a meltdown will breach/has already breached the RPV?

Moreover, the last statement sounds as if they are planning entombment for Units 1 to 3?

The Japanese version is a bit clearer: the plan is to "water entomb" all three reactors by filling up their containment vessels with water, after nitrogen purging. They plan to start this with Reactors 1 and 3 soon or right away, but have to seal up the leak in the containment vessel for Reactor 2 before they can do it there:

http://www.yomiuri.co.jp/zoom/20110417-OYT9I00585.htm

And they only want to retract fuel from the SFPs, not from the RPVs...

http://english.kyodonews.jp/news/2011/04/86072.html

The announced plan so far only goes up to "medium-term." I imagine core unloading is part of the long-term plan.

 

[|Fred]

There is concrete slab siding on the ground floor and two floors of open concrete support beams and girders. In the pictures showing Unit 4 damaged the seems to be another floor missing from Unit 3.

Could you please point to the item you are identifying as concrete slab.
Could you please point out to the picture you are referring to

Is it possible there was a second explosion at Unit 3 that caused the damage to Unit 4?

I can't see any thing in the available visual evidences sporting that

@Astronuc

full video

 

[Astronuc]

All videos of Unit 3 have shown steam or smoke at times escaping from reactor location . This shows that outer containment of RPV has been breached at least . I think this had a lot to do with the huge explosion we all seen at Unit 3 . Unit 3 is also the one loaded with the MOX fuel . This may have something to do with what is seen at Unit 3. NO one wants MOX fuel . ---The U.S. Department of Energy wants to redesign its partially built mixed oxide fuel plant to make nuclear fuel for a wider variety of reactors.
The facility under construction at Savannah River Site is designed to make fuel rods for pressurized water reactors in use at many commercial power plants. http://chronicle.augusta.com/news/metro/2011-04-15/officials-review-plan-changes-mox-facility

Any TVA move on the proposal has been put off pending a review of the behavior of MOX fuel at Japan's Fukushima Daiichi nuclear power plant, which was severely damaged last month by a 9.0-magnitude earthquake and tsunami . The federal investigation would address the extent to which the MOX fuel -- which comprised 6 percent of the material in the Japanese facility's No. 3 reactor -- has heated and broken down since the March disasters.
“We are studying the ongoing events in Japan very closely,” TVA spokesman Ray Golden said.
The Mixed-Oxide Fuel Fabrication Facility, a site under construction at the Savannah River Site in South Carolina, would convert 34 metric tons of excess weapons plutonium to nuclear power plant fuel, according to an earlier report. The facility's expense has reached almost $5 billion since the government signed a contract for its creation, and no entity has officially stepped forward to buy the fuel. http://www.globalsecuritynewswire.org/gsn/nw_20110411_6298.php

According my records, Unit 3 started up toward the end of October, 2010. It had about 4.5 months of operation at the time of the earthquake.

MOX fuel in unit 3 would have very little impact on the subsequent decay heat. It had very little exposure. For the most part, MOX fuel behavior at low exposure is no different the UO₂fuel behavior. I know this from experience. I also contributed to a report on MOX for TEPCO about 20 years ago.

The 2nd and 3rd cycle, and possibly 4th cycle, fuel is most at risk from decay heat.

The presence of MOX is largely irrelevant to the Fukushima accident. One utility had expressed interest in MOX, but withdrew due to commercial/finanical issues, not technical issues.

The MOX facility could have the capability to manufacture BWR fuel as well as PWR fuel.

 

[tsutsuji]

Packbot(s) entered into reactor buildings 1 & 3, after opening some of the doors connecting with the turbine buildings. Measurement results are expected to be released on April 18th or later : http://www.jiji.com/jc/c?g=soc_30&k=2011041700293

 

[ceebs]

https://www.youtube.com/watch?v=GNBKPRVckIU

Tepco robot film

 

[TedNugget]

Yep. And it being slow, it had to be *really* powerful.
Later on I'm going to see if i can find the approximate temperature of rising cloud from it's velocity and size. Assuming it's just rising by buoyancy. I'm very sure that #3 was not a premixed hydrogen+air explosion, but a hot steam+hydrogen venting (explosive venting if you wish), which ignited immediately, and the venting was powerful and fast enough to tear apart entire building, but nowhere near as fast as to create shockwave (confirmed both by lack of visible shockwave which was present in #1 and lack of dust raising by shockwave which was also present in #1).
The image analysis by MadderDoc indicates there was a jet of flame, damaging the steel with intense heat, rather than explosion.

Look over how small the shock wave is from Reactor Building 1. Not like a typical shock wave that projects in a hemisphere. For some reason this little shock wave was channeled by a building with older construction methods that allowed it an escape.
Look over the rebar hanging into SFP#3 and elsewhere. I'm still going with a much larger energy release in #3 versus Bldg #1 and that would be from explosions. A 'jet of flame' couldn't accomplish clean separation of the rebar from concrete.

 

[tsutsuji]

https://www.youtube.com/watch?v=GNBKPRVckIU

Tepco robot film

The first part of that video is a zooming on the still photographs released at http://www.tepco.co.jp/en/news/110311/index-e.html . It is not a release of a video taken by packbot(s).

 

[MadderDoc]

<..> Suppose a hot air balloon of negligible balloon weight, of the size of width of that smoke plume, rises with such speed (60m/s or so), what would be the temperature?

The buoyancy of water vapour is considerably more than for hot air (cf. water 18g/mol vs. atmospheric air 29 g/mol).

 

[MadderDoc]

Look over how small the shock wave is from Reactor Building 1. Not like a typical shock wave that projects in a hemisphere. For some reason this little shock wave was channeled by a building with older construction methods that allowed it an escape.
Look over the rebar hanging into SFP#3 and elsewhere. I'm still going with a much larger energy release in #3 versus Bldg #1 and that would be from explosions. A 'jet of flame' couldn't accomplish clean separation of the rebar from concrete.

Hydrogen explosion => severer structural damage to upper part of building => crash of overhead crane => critical damage to service deck => steam and whatnot explosion from the CV => objects going high in the air along with it => the most dense of those coming right back down, hitting destructively the NNW end of the building.

 

[jmelson]

I'm still not sure any of that happened.

I agree, that there would have been clear evidence of such an explosion.

I just tried to explain a theory put forth earlier in the thread though an acetlyene cylinder can be persuaded to release all of it's fuel by an explosion of a much thicker higher pressurized oxygen cylinder exploding beside it...since they are usually chained together.

The O2 tanks have fuse plugs that are supposed to melt and vent the tank in a non-explosive manner when subjected to fires, etc. They don't always work, of course, and a jet of O2 spewing from the fuse plug would also be a major hazard.


Jon

 

[TCups]

Look over how small the shock wave is from Reactor Building 1. Not like a typical shock wave that projects in a hemisphere. For some reason this little shock wave was channeled by a building with older construction methods that allowed it an escape.
Look over the rebar hanging into SFP#3 and elsewhere. I'm still going with a much larger energy release in #3 versus Bldg #1 and that would be from explosions. A 'jet of flame' couldn't accomplish clean separation of the rebar from concrete.

REGARDING THE INTERNAL BALLISTICS OF EXPLOSIONS IN CONFINED SPACES

I cannot speak with authority about hydrogen gas + oxygen explosions, but I can speak with authority about reloading ammunition with various gunpowders and primers so, for what its worth, consider this:

Reloading is very tricky and the limits of a safe reload are determined by the absolute pressure that develops in the cartridge and subsequently in the barrel of the firearm behind the projectile. Exceed the safe pressure and your firearm becomes a bomb.

The internal pressure developed depends on the weight of the projectile, the length & diameter of the barrel, and the speed that the primer and powder burn, as well as how firmly the bullet is crimped in the neck of the cartridge. It may seem counterintuitive, but high power rifles develop the most extreme pressures, muzzle velocities and bullet energies with slow burning powders. The tighter the bullet is crimped, and the more powerful the primer, the faster the pressure rises within the cartridge, and the more energy it develops. But the heavier the bullet used in a given rifle load, the lighter and slower burning a powder charge must be to safely propel the bullet without exceeding the safe pressure limits, because acceleration of the heavier bullet down the barrel takes longer, and more pressure builds behind the bullet.

As an analogy, again, for what it may be worth, the containment of the upper portion of Bldg 1 seems to have been structurally weaker than that of Bldg 3 or 4. When the ignition of the hydrogen gas occurred, the pressure in the top part of Bldg 1 rose very rapidly, and it blew out relatively quickly, without the internal build up of larger pressures, and perhaps without the efficient and complete ignition and combustion of all of the contained gas mixture.

The explosions in Bldg 3 and 4 were much more tightly contained, or "tightly crimped", so to speak. A much greater internal pressure (and heat) build up might have been possible, with a longer burn time (and here, we are talking only fractions of a second) and more complete combustion of the internal gasses before the external building exploded. If so, then much more energy might ultimately have been released when the external containment did explode, even starting with about the same amount of combustible gas within the building.

Perhaps this was even greater in the case of Bldg 3 than Bldg 4 because Bldg 3 was in service and during operation, as someone pointed out earlier, many of the internal doors of Bldg 3 were closed.

If the kinetic energy from the stored heat in the water of SFP3 released as steam is a correct scenario, then that, added to the hydrogen explosion, gives even more energy to the explosion of Unit 3 (and perhaps Unit 4?).

 

[etudiant]

The striking difference between the two explosions, at least to a layman, is that whereas building 1 exploded with a clean shock wave, almost a textbook case. the building three explosion was a much messier affair. Lots of flame and smoke, blasts going up and sideways, almost Hollywood production values.
It would be helpful to understand the basis for these differences, because there may be quite different mechanisms at work. It is for instance interesting that building 2 may in fact have had an even more damaging explosion, yet there is much less external apparent damage.

 

[elektrownik]

Can anyone look on new nisa report and write here what think about new data ? They add values from many sensors: http://www.meti.go.jp/press/2011/04/20110417002/20110417002-2.pdf

 

[etudiant]

It has been suggested elsewhere that the fuel rods could have been protected effectively against failure by a thin gold coating, to protect the zirconium cladding from oxidation.
Is this valid even if the fuel rods overheat substantially because of lack of cooling?
Obviously the gold coating could fail once the temperature reaches the melting point of gold, but a very thin coating might well remain intact even if above melting.
Any studies or references would be very much appreciated.

 

[|Fred]

The striking difference between the two explosions.

Beside the cause of the explosion , one could notice that the roof and wall structure of unit 1 and 3 are different.
Unit 1 does not seems to have been made to contain an explosion

 

[Dmytry]

It has been suggested elsewhere that the fuel rods could have been protected effectively against failure by a thin gold coating, to protect the zirconium cladding from oxidation.
Is this valid even if the fuel rods overheat substantially because of lack of cooling?
Obviously the gold coating could fail once the temperature reaches the melting point of gold, but a very thin coating might well remain intact even if above melting.
Any studies or references would be very much appreciated.

Gold, Au-197, captures a neutron and turns into Au-198 , then beta-decays (half life about 2 and half days) into Hg-198 , stable mercury. AFAIK, gold has big enough neutron capture cross section for gold to be practically unusable in reactors.
Putting this aside, I don't think thin coating would help a lot if it reaches melting point of gold or zirconium, or even earlier when gold starts to diffuse into zirconium.

 

[Dmytry]

The striking difference between the two explosions, at least to a layman, is that whereas building 1 exploded with a clean shock wave, almost a textbook case. the building three explosion was a much messier affair. Lots of flame and smoke, blasts going up and sideways, almost Hollywood production values.

Exactly! I've been doing production for some studio at Hollywood, in fact (not explosions though, just regular clouds). To be exact, I've been developing software for rendering of clouds, that can do explosions. I even did some mushroom clouds with it.
http://dmytry.com/mojoworld/bigshrooms_aa3_pp_tiled.jpg

It would be helpful to understand the basis for these differences, because there may be quite different mechanisms at work. It is for instance interesting that building 2 may in fact have had an even more damaging explosion, yet there is much less external apparent damage.

Movie explosions are made by blowing up a small charge inside a balloon of gasoline. Physically, they are equivalent to tank rupture. In this case, rapid venting of a HUGE volume of hydrogen + very hot steam fits the video perfectly. Most definitely it does not look like a detonation or deflagration of hydrogen-air mix at all. If you fill entire building with hydrogen at above detonation limit (above 60% hydrogen or so), then you might obtain this result, but then it is absolutely inconceivable you would not have substantial volume of hydrogen at detonation concentrations, with shockwave.
Movies try to use as slow explosions as possible for safety reasons.

If I were to make a CGI shot for movie that looks like building 3 explosion, using fluid simulation, I'd just create huge volume of hot air there (during timespan of 0.5 second or so). It would not cool very much by adiabatic expansion because it wouldn't be created at very high pressure. I'd also colour it burning for the fireball.
Product of typical explosion are hot at very high pressure, and cool down rapidly by adiabatic expansion, and thus don't look hollywood-ish at all. You need something that is hot at not so high pressure.

edit: I just realized, why nukes make such awesome mushroom clouds, whereas explosives typically don't. Chemical explosions produce huge amount of hot gas at extremely high pressure, which, once it expands, is not hot. Precisely what we seen in #1 video. I believe #3 is only perceived as explosion at all thanks to Hollywood 'explosions'.

 

[shogun338]

According my records, Unit 3 started up toward the end of October, 2010. It had about 4.5 months of operation at the time of the earthquake.

MOX fuel in unit 3 would have very little impact on the subsequent decay heat. It had very little exposure. For the most part, MOX fuel behavior at low exposure is no different the UO₂fuel behavior. I know this from experience. I also contributed to a report on MOX for TEPCO about 20 years ago.

The 2nd and 3rd cycle, and possibly 4th cycle, fuel is most at risk from decay heat.

The presence of MOX is largely irrelevant to the Fukushima accident. One utility had expressed interest in MOX, but withdrew due to commercial/finanical issues, not technical issues.

The MOX facility could have the capability to manufacture BWR fuel as well as PWR fuel.

The new Mox Savannah River Site is way over budget and had no one who wanted the MOX it will produce . The two plants that where thinking about it are stepping back and evaluating it more . That's why there changing some things now at the Savannah River Site . Everyone seen the explosion in Unit 3 and the MOX is in the back of there minds . It looked different from Unit 1 explosion and still looks different with all the steam and smoke it keeps releasing . A review of the behavior of MOX in the Unit is ongoing . I guess they want to see if it elevated the crisis more in anyway . Either way I think this has got more people looking at the new MOX plant and the billions being put into it .

 

[TedNugget]

The explosions in Bldg 3 and 4 were much more tightly contained, or "tightly crimped", so to speak. A much greater internal pressure (and heat) build up might have been possible, with a longer burn time (and here, we are talking only fractions of a second) and more complete combustion of the internal gasses before the external building exploded. If so, then much more energy might ultimately have been released when the external containment did explode, even starting with about the same amount of combustible gas within the building.

I agree.

But that little shock wave, give it a few percentile of a full one, going out through poorly or unreinforced concrete doesn't mean that explosion was more powerful.

 

[NUCENG]

It has been suggested elsewhere that the fuel rods could have been protected effectively against failure by a thin gold coating, to protect the zirconium cladding from oxidation.
Is this valid even if the fuel rods overheat substantially because of lack of cooling?
Obviously the gold coating could fail once the temperature reaches the melting point of gold, but a very thin coating might well remain intact even if above melting.
Any studies or references would be very much appreciated.

Zirconium is near the bottom of the list at 0.184 barns ( a measure of the cross section for thermal neutron capture. Basically zirconium is transparent to neutrons. Thus it makes an excellent cladding material for efficient use of fuel. Gold is about 3 orders of magnitude higher at 98.7 barns. As Dmytry said it would take away from the neutrons available to the fuel. That would require increasing the fuel load or enrichment to get the same power production.

Boron is used for control rods and in chemical shutdowns because its cross section is 767 barns.

 

[shogun338]

The robots entered the plant's number 3 reactor building and were due to take radiation and temperature readings. They are equipped with video cameras that can provide a live feed to operators

 

[TCups]

I see more of a collapsed wall, by a lateral blast than a death from above damage, the last roof structure with wise has been bent toward north .
Tcup I'm not sure I understood you, In my opinion they are 3 cranes, 2 small for pool operations on big for slab, and shield handling.

nb: it's a MPEG2 Video
ps: I'm skeptical at the "rings" theory, as it does not have to be a ring from the outside does it ?

@Fred:

I have been studying the "ring" thing. Again, at the danger of comparison to the Oyster Creek diagram as a reference, see:

http://www.appsmini.com/alertnews/OysterCreekReactorNo40.jpg

Notice that the legend indicated (4) is a 'Removable Shield Plug". Notice, also, that structurally, the stainless steel lining of the primary containment vessel terminates at the steel drywell cap. The removable shield plugs would be so to allow the north side of the upper containment to be opened to the equipment pool. This would mean that the removable shield plugs would not only have to be segmented, rather than forming a continuous, unbroken ring, but also that they would lack a continuous internal layer of stainless steel reinforcing them.

I think it credible that the earlier images suggest damage to the upper containment in the specific area of the removable shield plugs at and adjacent to the gates for the SFP3 and equipment pool of unit 3 (with persistent venting of steam), and further, that any significant damage or displacement of the "lateral" (east and west side) portions of the shield plug rings might very well allow a radial component of a blast originating in the drywell to vent directly into the floor below the service floor, accounting for the apparent degree of damage to that area visible.

The curvilinear piece of debris (be it sheet metal or perhaps a portion of the shield plug ring) neither confirms nor refutes that possibility, but if it were a large, curved piece of concrete blown outward and impacting on the inner wall of the west face of Bldg 3, that would certainly be consistent. But I must agree that that piece of photographic evidence, while it prompted the line of though above, is equivocal at best.

http://i306.photobucket.com/albums/nn270/tcups/Picture8-2.png

As for the existence of 3 separate crane structures in the service floor of Bldg 3, I can find no reference to support that. One thing that does make me question the interpretation that the some of the latest videos show a portion of the FHM that may have fallen onto the northwest corner of Bldg 3 is that the "green machine" whatever it is, looks to be in pretty good shape for having made that trip. On the other hand, it is sitting right there on top of everything else with no debris on top of it. That would be a neat trick if it hadn't fallen there from above.

http://i306.photobucket.com/albums/nn270/tcups/Picture7.png

http://i306.photobucket.com/albums/nn270/tcups/Picture6-1.png

 

[ottomane]

@dmytry: I looked at some other clouds made with your sw. Fantanstic, great job!

Clouds and explosions have many variables, but wouldn't it be possible to simulate an explosion? With some sort of simulation it should be possible to find out some more detail about the explosion of R3.


Btw: New sensor data from R3. Radiation now at 253 Sv/h. Noone can tell me the core is still closed if this value is real.

 

[I_P]

The robots entered the plant's number 3 reactor building and were due to take radiation and temperature readings. They are equipped with video cameras that can provide a live feed to operators

Wow, finally - now that is cool! How about a live feed? Somehow I don't think TEPCO will be as forthcoming as BP in the Gulf oil spill (well, actually BP was ordered to provide the ROV feeds if I recall..)